Scholars@Duke
Earl H. Dowell

Earl H. Dowell

William Holland Hall Distinguished Professor
Thomas Lord Department of Mechanical Engineering and Materials Science
earl.dowell@duke.edu
185 Hudson Hall, Box 90300, Durham, NC 27708-0300
185 Hudson Hall, Box 90300, Durham, NC 27708

Selected Publications

Quantitative measure and visualization for local shock strength in two-dimensional flow

Journal Article Acta Mechanica Sinica/Lixue Xuebao · May 1, 2025 The concept of local shock strength and a quantitative measure index str of local shock strength are proposed, derived from the oblique shock relation and the monotonic relationship between total pressure loss ratio and normal Mach number. Utilizing the hi ... Full text Cite

Nonlinear aeroelastic behavior of a panel impinged by oscillating shock

Journal Article Nonlinear Dynamics · November 1, 2024 The aeroelastic responses and nonlinear behaviors of a two-dimensional panel impinged by an oscillating Mach stem shock are investigated through theoretical analysis. Through the nonlinear descriptors, such as Poincaré maps and Largest Lyapunov exponents, ... Full text Cite

Asymmetric instability of flow-induced vibration for elastically mounted cube at moderate Reynolds numbers

Journal Article Journal of Fluid Mechanics · October 1, 2024 The asymmetric instability in two streamwise orthogonal planes for three-dimensional flow-induced vibration (FIV) of an elastically mounted cube at a moderate Reynolds number of 300 is numerically investigated in this paper. The full-order computational fl ... Full text Cite

Comparative analysis of flag based energy harvester undergoing extraneous induced excitation

Journal Article Energy · May 15, 2024 This study presents a detailed comparative analysis of the piezoelectric flexible plate under the influence of oscillating wakes of different bluff bodies. The piezoelectric plate is tested to determine the optimal configuration for energy harvesting from ... Full text Cite

Two-dimensional pressure field imaging of an elastic panel executing post-flutter oscillations

Journal Article Journal of Fluids and Structures · March 1, 2024 Two dimensional pressure field was acquired at 10 kHz to study the post flutter oscillations of a thin elastic panel placed beneath a Mach 2.5 turbulent boundary layer. The panel was made of aluminum and is secured to the mounting fixture using a collectio ... Full text Cite

Correction: Panel Aeroelastic Stability in Irregular Shock Reflection (AIAA Journal Vol. 60, No. 11, 10.2514/1.J061902)

Journal Article AIAA Journal · February 1, 2024 The aeroelastic model of the two-dimensional panel in irregular shock reflection presented in the paper set the impingement location at the midpoint of the panel, which results in the inability to verify the model with existing results from the literature. ... Full text Cite

Dynamically Linearized Euler Time-domain Approach with Shock Impingement for LCO Prediction for an Elastic Panel

Conference AIAA SciTech Forum and Exposition, 2024 · January 1, 2024 The application of a nonlinear aeroelastic model for a flexible panel is expanded to consider the Euler equation as the aerodynamic model. This study presents the method to compute the generalized aerodynamic force from a CFD simulation and compares the re ... Full text Cite

Prediction of SBLI Induced Flexible Panel Motion using Wall-Modeled LES Coupled to an Aeroelastic Solver

Conference AIAA SciTech Forum and Exposition, 2024 · January 1, 2024 Wall-modeled large eddy simulation (WMLES) and a theoretical-computational aeroelastic solver are used to predict the motion of a thin flexible panel under an impinging shock wave. Panel displacements imposed by the resulting shock-wave/boundary-layer inte ... Full text Cite

Convolution Kernels for a NACA 0012 Airfoil Based on Unsteady Pressure Wind Tunnel Measurements

Conference AIAA SciTech Forum and Exposition, 2024 · January 1, 2024 The unsteady pressure distribution over a NACA 0012 air foil is measured in a low-speed wind tunnel for a rigid airfoil and control surface configuration. The experimental protocol is to give a step change in the airfoil angle of attack and the control sur ... Full text Cite

Comparison of Transonic Buffet Over Several Airfoil Geometries using URANS

Conference AIAA SciTech Forum and Exposition, 2024 · January 1, 2024 In this study, we apply computational fluid dynamics (CFD) to compare transonic buffet over several airfoil geometries and flow conditions. Transonic buffet is a fluid instability in which a recompression shock oscillates over the upper surface of an airfo ... Full text Cite

WMLES of SBLI with Flexible Panel Motion Predicted A Priori Using an Aeroelastic Solver

Conference AIAA Aviation Forum and ASCEND, 2024 · January 1, 2024 An approach to incorporate the motion of a flexible panel under an impinging shockwave/ boundary-layer interaction (SBLI) at Mach 2.5 into a wall-modeled large eddy simulation (WMLES) is developed and implemented. The panel oscillations predicted by an aer ... Full text Cite

A new development of the harmonic balance method: The hybrid harmonic balance method

Journal Article Analysis and Applications · January 1, 2024 The harmonic balance (HB) method is efficient in predicting the limit cycle oscillations for many dynamic systems including very high dimensional systems in fluid dynamics. Recently, some variations and extensions of the HB method have been developed and e ... Full text Cite

Study of Nonlinear Stiffness and Damping Effects on Shimmy and Flutter

Journal Article Journal of Aircraft · November 1, 2023 This work deals with the fundamentally similar dynamic behavior of two apparently different aircraft systems, namely, landing gears and all-movable control surfaces. Both systems typically contain stiffness and damping nonlinearities, leading to shimmy/flu ... Full text Cite

Flutter and Limit-Cycle Oscillations of a Panel Using Unsteady Potential Flow Aerodynamics

Journal Article AIAA Journal · November 1, 2023 The potential aerodynamic theory is implemented to model the flow over a flexible panel. The present study compares the more complete unsteady version of the potential flow theory with its simplification known as the linear piston theory for different Mach ... Full text Cite

Feature identification in complex fluid flows by convolutional neural networks

Journal Article Theoretical and Applied Mechanics Letters · November 1, 2023 Recent advancements have established machine learning's utility in predicting nonlinear fluid dynamics, with predictive accuracy being a central motivation for employing neural networks. However, the pattern recognition central to the networks function is ... Full text Cite

Correlation of supersonic wind tunnel measurements with a nonlinear aeroelastic theoretical/computational model of a thin plate

Journal Article Journal of Fluids and Structures · October 1, 2023 Supersonic wind tunnel test data is compared with a nonlinear aeroelastic computational model, considering a freestream flow with Mach nearly 2, coupled cavity, and no-shock impingement. The measurements include Limit Cycle Oscillations (LCO) for the given ... Full text Cite

Study Membrane Solarelasticity Using a Wave Model and a Corpuscular Model of Light

Journal Article AIAA Journal · September 1, 2023 The difference between solarelastic interaction and aeroelastic interaction is illustrated from the perspective of external forces. Membrane solarelastic responses of the solar cell and solar sail are studied through a wave model and a corpuscular model of ... Full text Cite

Critical effect of fore-aft tapering on galloping triggering for a trapezoidal body

Journal Article Journal of Fluid Mechanics · July 17, 2023 The critical effect of the windward interior angles of elastically mounted trapezoidal bodies on a galloping instability is numerically investigated in this paper using two methodologies of high-fidelity computational fluid dynamics simulations and data-dr ... Full text Cite

Reduced-order modeling: a personal journey

Journal Article Nonlinear Dynamics · June 1, 2023 Reduced-order models (ROM) have captured the interest and effort of many investigators over the years. As is well known the cost of computation can easily outpace the available computational resources, especially for multidisciplinary mathematical/computat ... Full text Cite

Buckling of a Vertically Mounted Cantilevered Plate Under Static Torsional Corner Loads—Experiment and Theory

Journal Article Journal of Applied Mechanics, Transactions ASME · June 1, 2023 The results of an experimental study on the buckling of a vertically cantilevered plate under corner twisting forces are reported. In this configuration, an interesting and somewhat counter-intuitive behavior is observed in which a laterally loaded slender ... Full text Cite

A new look at the Equivalent Linearization Technique to predict LCO in aeroelastic systems with discrete nonlinearities

Journal Article Journal of Fluids and Structures · May 1, 2023 Control surfaces nonlinearities can lead to limit cycle oscillations (LCO). Several methods have been proposed to predict LCO, such as Harmonic Balance-based methods (HB). Describing function (DF) is the HB with a single harmonic motion assumed, and the ap ... Full text Cite

Aerodynamic Characteristics of Morphing Supersonic Cascade Under Low-Upstream-Mach-Number Condition

Journal Article AIAA Journal · April 1, 2023 For fans of a variable-cycle engine, a good aerodynamic performance over a wide range of rotating speeds is essential. However, when supersonic cascades designed for a high upstream Mach number operate under a low upstream Mach number, a starting problem m ... Full text Cite

Triggering of galloping in structures at low Reynolds numbers

Journal Article Journal of Fluids and Structures · April 1, 2023 The fundamental mechanisms that are important for the triggering of galloping in a flow-induced vibration (FIV) system consisting of the flow past an elastically-mounted body (D-section, isosceles-triangular, rectangular) is investigated in this paper usin ... Full text Cite

Parametric aerodynamic and aeroelastic study of a deformable flag-based energy harvester for powering low energy devices

Journal Article Energy Conversion and Management · March 15, 2023 Extensive wind tunnel experiments were performed to find the optimal and most influential parameters for energy harvesting from piezoelectric membranes (thin elastic cantilevered plates), herein called flags. Four different piezoelectric flags were tested ... Full text Cite

Comparative Study of Beam and Plate Theories for Moderate Aspect Ratio Wings

Journal Article AIAA Journal · February 1, 2023 The main objective of the present study is to identify the best structural model for both aeroelastic and structural analysis of unswept rectangular wings with aspect ratios between 2 to 5. The paper presents a detailed study of the similarities and differ ... Full text Cite

Estimating the oscillation frequency of a payload mass on quadcopter in non-autonomous flight

Journal Article JVC/Journal of Vibration and Control · January 1, 2023 Unmanned aerial vehicles (UAVs) have been employed in several engineering applications, such as aerial photography, environmental surveillance, delivery tasks, and others. Most of these applications have attracted increasing attention due to their ability ... Full text Cite

COMPUTATIONAL STUDY OF TRANSONIC BUFFET’S SENSITIVITY TO REYNOLDS NUMBER AND WIND TUNNEL WALL EFFECTS

Conference AIAA SciTech Forum and Exposition, 2023 · January 1, 2023 This study applies computational fluid dynamics (CFD) to transonic buffet, a flow field instability characterized by an oscillating shock on the upper surface of an airfoil in transonic flow. Despite years of research in this area, understanding of the und ... Full text Cite

Using Broyden’s Method to Improve the Computational Performance of a Harmonic Balance Aeroelastic Solution Technique

Conference AIAA SciTech Forum and Exposition, 2023 · January 1, 2023 Presented is a technique that significantly improves the computational performance of an existing harmonic balance-based flutter onset and limit-cycle oscillation aeroelastic solution methodology. The existing harmonic balance aeroelastic solution methodol ... Full text Cite

Flutter and Limit Cycle Oscillations of a Panel Using Unsteady Potential Flow Aerodynamics

Conference AIAA SciTech Forum and Exposition, 2023 · January 1, 2023 The Potential Aerodynamic Theory is implemented to model the flow over a flexible panel. The present study compares the more complete unsteady version of the potential flow theory with its simplification known as the Linear Piston Theory for different Mach ... Full text Cite

Convolution/Volterra Reduced-Order Modeling for Nonlinear Aeroelastic Limit Cycle Oscillation Analysis and Control

Journal Article AIAA Journal · December 1, 2022 A methodology for leveraging a combination of linear (through convolution integrals) and nonlinear (through Volterra series) reduced-order modeling (ROM) development was demonstrated on both a two-and three-degree-of-freedom (2-DOF and 3-DOF, respectively) ... Full text Cite

Data-driven stability analysis via the superposition of reduced-order models for the flutter of circular cylinder submerged in three-dimensional spanwise shear inflow at subcritical Reynolds number

Journal Article Physics of Fluids · December 1, 2022 In this paper, we present a novel data-driven theory for the stability analysis of a flow-induced vibration (FIV) system consisting of an elastically mounted circular cylinder submerged in three-dimensional (3D) spanwise shear inflow at a subcritical Reyno ... Full text Cite

Panel Aeroelastic Stability in Irregular Shock Reflection

Journal Article AIAA Journal · November 1, 2022 Full text Cite

Response of a plate with piezoelectric elements to turbulent pressure fluctuation in supersonic flow

Journal Article Journal of Fluids and Structures · October 1, 2022 The aeroelastic response of a plate with supersonic freestream flow on one side and a shallow cavity on the other to turbulent pressure fluctuations is investigated computationally and experimentally. An empirical model is developed for the pressure fluctu ... Full text Cite

Static and Dynamic Nonlinear In-Plane Effect in the Response of a Cantilevered Plate With Tip Mass Load: Theory and Experiment

Journal Article Journal of Applied Mechanics, Transactions ASME · October 1, 2022 In this article, two nonlinear effects are investigated. One is the effect of the static stiffness nonlinearity in changing the linear dynamic natural frequency, and the other is the combination of nonlinear stiffness and nonlinear inertia effects in chang ... Full text Cite

Analytical Model of Strong Mach Reflection

Journal Article AIAA Journal · September 1, 2022 A Mach reflection structure in steady supersonic flow is studied in which a transonic region exists behind the reflected shock wave. Here, the measure of a strong Mach reflection is the total pressure loss of the shock reflection system. A corresponding cl ... Full text Cite

Dynamic equations of motion for inextensible beams and plates

Journal Article Archive of Applied Mechanics · June 1, 2022 The large deflections of cantilevered beams and rectangular plates are modeled and discussed. Traditional nonlinear elastic models (e.g., von Karman’s) employ elastic restoring forces based on the effect of stretching on bending, and these are less applica ... Full text Cite

Preface to the first edition

Book · January 1, 2022 Cite

Aeroelastic Models Design/Experiment and Correlation with New Theory

Chapter · January 1, 2022 Several examples of experimental model designs, wind tunnel tests and correlation with new theory are presented in this chapter. The goal is not only to evaluate a new theory, new computational method or new aeroelastic phonomenon, but also to provide new ... Full text Cite

Preface to the third edition

Book · January 1, 2022 Cite

Introduction

Chapter · January 1, 2022 This brief chapter touches on the basic questions to be addressed in the book and provides some historical context for the development of the field of aeroelasticity. ... Full text Cite

Preface to the fourth edition

Book · January 1, 2022 Cite

Some Recent Advances in Nonlinear Aeroelasticity

Chapter · January 1, 2022 This brings the discussion of nonlinear aeroelasticity up to date. See the earlier discussion in Chap. 11. Much of the recent advances are based on new understanding of such subjects as limit cycle oscillations due to structural non-linearities, including ... Full text Cite

Modeling of Fluid-Structure Interaction

Chapter · January 1, 2022 Modeling of aerodynamic forces has now moved beyond the classical potential flow theory at least in the research community and to some degree in engineering practice. These more sophisticated fluid models are based upon the Euler or Navier- Stokes equation ... Full text Cite

Static Aeroelasticity

Chapter · January 1, 2022 The basics of static aeroelasticty, in contrast to dynamic aeroelasticity, are reviewed and some classic subjects such as divergence and control surface reversal are treated. The discussion starts with simple mathematical and physical models and progresses ... Full text Cite

Nonlinear Aeroelasticity

Chapter · January 1, 2022 This is an introduction and overview of the work that has been done in nonlinear aeroelasticity prior to the last decade. Many of the issues discussed here are still under active investigation. Of particular interest are the limit cycle oscillations that m ... Full text Cite

Preface to the fifth edition

Book · January 1, 2022 Cite

Dynamic Aeroelasticity

Chapter · January 1, 2022 Dynamic aeroelasticty is considered and the dynamic stability (Flutter) of linear aeroelastic systems is considered as well as the response to external disturbances including atmospheric turbulence (Gusts). The discussion proceeds from simpler physical mod ... Full text Cite

Nonsteady Aerodynamics of Lifting and Non-lifting Surfaces

Chapter · January 1, 2022 The classical theory for unsteady potential flow models in the supersonic, Subsonic and transonic mach number ranges is presented including representative computational methods and results. The discussion with the simplest case of super- sonic flow in two ... Full text Cite

Preface to the sixth edition

Book · January 1, 2022 Cite

Fluid/Structural/Thermal/Dynamics Interaction (FSTDI) in Hypersonic Flow

Chapter · January 1, 2022 Hypersonic flight is a major technical challenge and substantial efforts are currently underway to provide the understanding and technology required to design and operate effectively and safely a hypersonic aircraft for commercial or military purposes. Ley ... Full text Cite

Experimental Aeroelasticity

Chapter · January 1, 2022 This is a brief account of the basic elements underlying experiments in Aeroelasticity. ... Full text Cite

Preface to the second edition

Book · January 1, 2022 Cite

Convolution/Volterra Reduced-Order Modeling for Flutter and LCO Predictions in Highly Nonlinear Systems

Conference AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022 · January 1, 2022 A methodology for leveraging a combination of linear (through convolution integrals) and nonlinear (through Volterra series) reduced-order modeling (ROM) development was demonstrated on both a 2 and 3 degree of freedom (DOF) aeroelastic system. The linear/ ... Full text Cite

Control-Surface Structural Nonlinearities in Aeroelasticity: A State of the Art Review

Journal Article AIAA Journal · January 1, 2022 This paper presents a review and assessment of more than six decades of research in aeroelastic stability, including control-surface nonlinearities. The work covers free play, friction, cubic stiffness, and an actuator in a failure mode. The basic modeling ... Full text Cite

Convolution and Volterra Series Approach to Reduced-Order Modeling of Unsteady Aerodynamic Loads

Journal Article AIAA Journal · January 1, 2022 A combined approach of linear convolution and higher-order Volterra series (VS) to reduced-order modeling of unsteady transonic aerodynamic loads is presented. Our framework offers a simple method to determine the memory depth of the system, clearly separa ... Full text Cite

Non-Intrusive Polynomial Chaos Approach for Nonlinear Aeroelastic Uncertainty Quantification

Conference AIAA AVIATION 2022 Forum · January 1, 2022 Presented is a point collocation non-intrusive polynomial chaos approach for nonlinear aeroelastic uncertainty quantification analysis. A unique aspect of our approach is that we are using a nonlinear frequency-domain harmonic balance aeroelastic solution ... Full text Cite

COMPUTATIONAL STUDY OF CANTILEVERED PLATE IN HIGH SPEED AXIAL FLOW

Conference Proceedings of the International Forum of Aeroelasticity and Structural Dynamics 2022, IFASD 2022 · January 1, 2022 A cantilevered plate at an angle of attack in axial high speed flow represents a prototypical control surface. Using a computationally efficient modal structural model coupled with a novel enhanced piston theory aerodynamic method, a nonlinear aeroelastic ... Cite

A note on the state space representation of aeroelastic systems for time domain analysis

Journal Article Journal of Fluids and Structures · July 1, 2021 The time domain state space model for describing an aeroelastic system has usually been obtained by using rational function approximations to write unsteady aerodynamics in the time domain. This strategy has been employed by many researchers because the st ... Full text Cite

Fully coupled nonlinear aerothermoelastic computational model of a plate in hypersonic flow

Journal Article AIAA Journal · July 1, 2021 A recent structural model of a plate is extended to include a nonuniform temperature differential that varies in time using a modal expansion. The nonlinear structural plate model with first-order piston theory aerodynamics and cavity dynamics is coupled w ... Full text Cite

Novel technique for dynamic analysis of shear frames based on energy balance equations

Journal Article Scientia Iranica · May 1, 2021 In this paper, an effcient computational solution technique based on the energy balance equations is presented to perform the dynamic analysis of shear frames, as an example of a multi-degree-of-freedom system. After deriving the dynamic energy balance equ ... Full text Cite

Primary resonance suppression of a base excited oscillator using a spatially constrained system: Theory and experiment

Journal Article Journal of Sound and Vibration · March 31, 2021 This paper studies the dynamic behaviors of a magnetically coupled oscillator with two-degrees-of-freedom. For the certain parameter combinations, the target component (TC), which is excited by a base movement, enters the saturated steady-state responses. ... Full text Cite

Nonlinear dynamics and flutter of plate and cavity in response to supersonic wind tunnel start

Journal Article Nonlinear Dynamics · March 1, 2021 The transient response of a plate and a cavity is investigated in a supersonic wind tunnel start experiment where the freestream flow inside the test section reaches turbulent flow at Mach 2. Experimentally measured plate displacement time history shows fl ... Full text Cite

A modal approach for designing controllers for active flutter suppression

Journal Article Journal of the Brazilian Society of Mechanical Sciences and Engineering · January 1, 2021 Flutter is an important topic to be considered during an aircraft development mainly due to its potentially catastrophic behavior. Typically a new aerial vehicle can require the addition of mass and limitations on its flight envelope to be flutter free. As ... Full text Cite

Fluid-thermal-structural interactions in ramp-induced shock-wave/boundary-layer interactions at mach 6

Conference AIAA Scitech 2021 Forum · January 1, 2021 Experiments were conducted to study the fluid-thermal-structural interactions of a compliant panel exposed to ramp-induced shock-wave/boundary-layer interactions (SWBLIs) at Mach 6 for laminar and transitional incoming boundary-layers. For some cases, boun ... Cite

Automatic differentiation based nonlinear reduced-order model with geometric gradient computation capability

Conference AIAA Scitech 2021 Forum · January 1, 2021 Presented is an automatic differentiation based nonlinear reduced-order modeling technique which includes geometric variation computation capability. The method is based on a Taylor series expansion of a nonlinear frequency-domain harmonic balance based co ... Cite

Nonlinear theoretical aeroelastic model of a plate: Free to fixed in-plane boundaries

Journal Article AIAA Journal · January 1, 2021 It is well known that the nonlinear response of a beam or plate is sensitive to the assumptions made about the in-plane boundary constraints. This is true for any static or dynamic loading, and especially for aerodynamic loads that may lead to a dynamic in ... Full text Cite

Enhancement to least square-based approach for time-domain unsteady aerodynamic approximation

Journal Article Journal of Aircraft · January 1, 2021 The modeling of different problems in aeroelasticity requires a time-domain equation of motion, especially to design modern controllers and study nonlinear characteristics. Typically, unsteady aerodynamic forces are written in the (reduced) frequency domai ... Full text Cite

Flutter and limit cycle oscillations of cantilevered plate in supersonic flow

Journal Article Journal of Aircraft · January 1, 2021 Research interest is growing for theoretical models of highly deflected structures in aeroelastic settings. Presented here is a model of a cantilevered plate subjected to axial supersonic flow to determine the flutter boundary and postflutter characteristi ... Full text Cite

A Benchmark Method for Predicting Oblique Shock Structure

Conference 32nd Congress of the International Council of the Aeronautical Sciences, ICAS 2021 · January 1, 2021 The spatial scheme method and adaptive mesh technique are chosen directly to determine the accuracy of the shock capture. Judging the correctness of one scheme by one dimensional Burgers equation is probably not enough for some real situation. A benchmark ... Cite

Nonlinear Aeroelastic Reduced-Order Modeling Approach with Geometric Gradient Computation Capability

Conference AIAA Aviation and Aeronautics Forum and Exposition, AIAA AVIATION Forum 2021 · January 1, 2021 We have recently developed an automatic differentiation based nonlinear reduced-order modeling technique. The method is based on a Taylor series expansion of a nonlinear frequencydomain harmonic balance based computational fluid dynamic solver residual. In ... Full text Cite

Aeroelastic analysis of cantilever plates using Peters’ aerodynamic model, and the influence of choosing beam or plate theories as the structural model

Journal Article Journal of Fluids and Structures · July 1, 2020 In this paper, the aeroelastic analyses of a rectangular cantilever plate of varying aspect ratio is presented. The classical plate theory has been selected as the structural model. The main point that distinguishes this study from previously reported rese ... Full text Cite

Influence of friction and asymmetric freeplay on the limit cycle oscillation in aeroelastic system: An extended Hénon's technique to temporal integration

Journal Article Journal of Fluids and Structures · July 1, 2020 Nonlinear effects such as friction and freeplay on the control surfaces can affect aeroelastic dynamics during flight. In particular, these nonlinearities can induce limit cycle oscillations (LCO), changing the system stability, and because of this it is e ... Full text Cite

Improving the predictable accuracy of fluid Galerkin reduced-order models using two POD bases

Journal Article Nonlinear Dynamics · July 1, 2020 A fundamental limitation of fluid flow reduced-order models (ROMs) which utilize the proper orthogonal decomposition is that there is little capability to determine one’s confidence in the fidelity of the ROM a priori. One reason why fluid ROMs are plagued ... Full text Cite

Relativistic oblique shock: A geometric object

Journal Article Astrophysical Journal · April 20, 2020 A geometric perspective for the relativistic oblique shock structure is proposed. The proposed oblique shock geometry in angle-phase space may be helpful to better understand the physical structure of an interstellar shock. ... Full text Cite

On the stiffness and damping characteristics of magnetorheological dampers and their implications for flutter analysis

Journal Article Engineering Research Express · March 1, 2020 Aeroelastic stability analysis plays an important role during the development of new aircraft. It can affect flight envelope, the aircraft geometry, and the design of components, like control surface actuators, for example. However, the aerial vehicle need ... Full text Cite

A theoretical computational model of a plate in hypersonic flow

Journal Article Journal of Fluids and Structures · February 1, 2020 A theoretical model of an elastic panel in hypersonic flow is derived to be used for design and analysis. The nonlinear von Kármán plate equations are coupled with 1st order Piston Theory and linearized at the nonlinear steady-state deformation due to stat ... Full text Cite

Nonlinear Response of an Inextensible, Free-Free Beam Subjected to a Nonconservative Follower Force

Journal Article Journal of Computational and Nonlinear Dynamics · February 1, 2020 A free-free beam with a compressive follower force applied to one end exhibits interesting flutter and limit cycle oscillation (LCO) responses. Here, the derivation from Lagrange's equations is given for the nonlinear inextensible beam with such a force ap ... Full text Cite

An experimental study on the actuator line method with anisotropic regularization kernel

Journal Article Energies · January 1, 2020 Nowadays, actuator line method (ALM) has become the most potential method in wind turbine simulations, especially in wind farm simulations and fluid-structure interaction simulations. The regularization kernel, which was originally introduced to ALM to avo ... Full text Cite

Nonlinear limit cycle oscillation and flutter analysis of clamped curved plates

Journal Article Journal of Aircraft · January 1, 2020 This Paper studies the instability (flutter) and poststability limit cycle oscillations of elastic shallow shells in a supersonic gas flow. In a previous paper by the authors, a nonlinear dynamic aeroelastic analysis of streamwise square curved plates was ... Full text Cite

Gust response computations with control surface freeplay using random input describing functions

Journal Article AIAA Journal · January 1, 2020 An analytical and computational investigation of the effect of control surface freeplay on aeroelastic behavior, including random gust response and limit cycle oscillations (LCO), is presented. An efficient method to compute the total gust+LCO response is ... Full text Cite

Hypersonic fluid–structure interactions in compression corner shock-wave/boundary-layer interaction

Journal Article AIAA Journal · January 1, 2020 The fluid–structure interaction of a flexible panel exposed to a ramp-induced shock-wave/boundary-layer interaction (SWBLI) at Mach 6 is investigated experimentally for transitional and turbulent incoming boundary layers. Panel deformations are measured us ... Full text Cite

Methodology for numerically stabilizing a harmonic balance based aeroelastic solution approach

Conference AIAA Scitech 2020 Forum · January 1, 2020 Presented is a methodology for numerically stabilizing harmonic balance based aeroelastic solution approaches. The governing harmonic balance based aeroelastic equations are a stationary/steady system of equations. In order to solve these equations, many r ... Full text Cite

On the importance of numerical error in constructing pod-based reduced-order models of nonlinear fluid flows

Conference AIAA Scitech 2020 Forum · January 1, 2020 The proper orthogonal decomposition (POD) provides a useful method for studying nonlinear fluid dynamics; however, the construction and use of the POD basis modes for Reduced Order Modeling (ROM) introduces several sources of error which can jeopardize the ... Full text Cite

Discrete adjoint constrained design optimization approach for unsteady transonic aeroelasticity and buffet

Conference AIAA AVIATION 2020 FORUM · January 1, 2020 We present the details of two primary research topics in the area of aeroelastic optimization that we are currently working on. The first topic is a new discrete adjoint aeroelastic design optimization solution methodology, which has a computational cost t ... Full text Cite

Natural frequencies of a heated plate: Theory and experiment

Journal Article AIAA Journal · January 1, 2020 Researchers conducted a study to investigate natural frequencies of a heated plate. Natural frequencies were measured and correlated with a finite element model, which included the effect of material property variation with temperature. The researchers inv ... Full text Cite

Revisiting the fundamentals of control surface reversal including nonlinear effects

Journal Article Journal of Aircraft · January 1, 2020 Control surface reversal is a classical aeroelastic phenomenon commonly investigated during aircraft development. It occurs under static equilibrium between the elastic restoring torque and the aerodynamic moment on the system. Besides the equilibrium, it ... Full text Cite

An assessment and extension of geometrically nonlinear beam theories

Journal Article Mechanical Systems and Signal Processing · December 1, 2019 Equations of motion for beams assuming only longitudinal, normal stress are derived for large-amplitude beam deflection. The formulation includes various physical extensibility conditions without expansion or truncation of their nonlinear nature. The Lagra ... Full text Cite

Computational investigation of wind tunnel wall effects on buffeting flow and lock-in for an airfoil at high angle of attack

Journal Article Aerospace Science and Technology · December 1, 2019 Wind tunnel walls may significantly affect the aerodynamic characteristics of an airfoil if the distance between walls is not large enough and the experimental data may be influenced by the confinement effect. The purpose of this paper is to investigate th ... Full text Cite

Stress distribution and fatigue life of nonlinear vibration of an axially moving beam

Journal Article Science China Technological Sciences · July 1, 2019 In this paper, the effects of the nonlinear vibration on stress distribution and fatigue life of the axially moving beam are studied. The parametric excitation of the flexible material is created by the pulsating moving speed. Three-to-one internal resonan ... Full text Cite

A study of the regularized lid-driven cavity's progression to chaos

Journal Article Communications in Nonlinear Science and Numerical Simulation · June 15, 2019 Computational simulations of a two-dimensional incompressible regularized lid-driven cavity flow were performed and analyzed to identify the dynamic behavior of the flow through multiple bifurcations which ultimately result in Eulerian chaotic flow. Semi-i ... Full text Cite

Experimental and theoretical correlations for energy harvesting from a large flapping flag response

Journal Article Journal of Fluids and Structures · April 1, 2019 Two experimental models are constructed, i.e. partially covered and fully covered, cantilevered plates with piezoelectric piezo patches and film sensors. Two different experimental methods are used to obtain large flapping vibrations, a mechanically forced ... Full text Cite

Nonlinear Response of an Inextensible, Cantilevered Beam Subjected to a Nonconservative Follower Force

Journal Article Journal of Computational and Nonlinear Dynamics · March 1, 2019 The dynamic stability of a cantilevered beam actuated by a nonconservative follower force has previously been studied for its interesting dynamical properties and its applications to engineering designs such as thrusters. However, most of the literature co ... Full text Cite

Numerical prediction of impact of clearance on rotordynamic coefficients for labyrinth brush seal

Journal Article International Journal of Turbo and Jet Engines · March 1, 2019 The clearance has an obvious influence on the rotordynamic characteristics of brush seals. In order to better know the influence of brush seal on the stability of the rotor bearing system, the rotordynamic coefficients of labyrinth brush seal under differe ... Full text Cite

A comparative study of nonlinear aeroelastic models for high aspect ratio wings

Journal Article Journal of Fluids and Structures · February 1, 2019 Linear and nonlinear aeroelastic analyses and results for a cantilevered beam subjected to an unsteady subsonic airflow are presented as a model of a high aspect ratio wing. A third-order nonlinear beam model is used as the structural model. This model inc ... Full text Cite

Nonlinear structural, inertial and damping effects in an oscillating cantilever beam

Conference Conference Proceedings of the Society for Experimental Mechanics Series · January 1, 2019 The nonlinear oscillations of a cantilever beam are studied with a theoretical computational model and the results are compared to experimental results obtained in a previous study. In order to explore the various possible nonlinear effects, the cantilever ... Full text Cite

Progress toward efficient compression algorithms for application in flight simulation environments

Conference Journal of Aerospace Information Systems · January 1, 2019 Modern computational fluid dynamic simulations of flows about naval vessels produce an enormous amount of flow-field data. The computations are performed in order to model details of the erratic unsteady flows that can occur about naval superstructures. Th ... Full text Cite

Nonlinear interaction of a flutter induced limit cycle oscillation of a cantilevered wing with a forced gust excitation

Conference AIAA Scitech 2019 Forum · January 1, 2019 Within the framework of a linear mode (physical or theoretical/computational) the dynamic instability (flutter) of the system and the forced response of the system (due to gust excitation, for example) can be considered separately and there is no interacti ... Full text Cite

Modal analysis of transonic shock buffet on 2D airfoil

Conference AIAA Journal · January 1, 2019 This paper presents a study of the shock buffet phenomenon on the RA16SC1 supercritical airfoil using the proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) modal approaches. The computational fluid dynamics simulation is validated, ... Full text Cite

Correlation of experimental and computational results for flutter of streamwise curved plate

Journal Article AIAA Journal · January 1, 2019 This work studies the instability (flutter) and poststability oscillations of an elastic shallow shell in a supersonic gas flow. The only available experimental results for flutter of a shallow shell with clamped edges are provided by Anderson. A compariso ... Full text Cite

Measuring the Aero-Refueling Hose Model’s Sectional-Bending-Stiffness in the RMCFLM Experimental System

Conference Lecture Notes in Electrical Engineering · January 1, 2019 By modeling an aero-refueling hose as a flexible pipe, an experimental research is performed on measuring the sectional bending stiffness of a flexible pipe withstanding a internal-pressurized fluid. A Revised Midpoint-Concentrate-Force-Loading Methodology ... Full text Cite

Discrete adjoint approach for nonlinear unsteady aeroelastic design optimization

Journal Article AIAA Journal · January 1, 2019 Presented is a discrete adjoint approach for computing nonlinear unsteady aeroelastic geometric design sensitivities, which can subsequently be used for nonlinear unsteady aeroelastic geometric design optimization. The methodology is applicable to compress ... Full text Cite

Flutter prediction based on dynamic eigen decomposition of coupled CFD-CSD flight simulation

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 © Universal Technology Corporation, 2018. During the design and analysis of aircraft flutter boundaries are typically computed using the p-k iterations, k iterations, p iterations, or eigenvalue analysis, that require computationally expensive and numerica ... Cite

RANS and DNS study of buffet in subsonic and transonic flow

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 © Universal Technology Corporation, 2018. This document explores a fluid instability known as buffet, which occurs in the subsonic, transonic and supersonic/hypersonic regimes. Buffet has been observed in experiments and various computational studies, and ... Cite

Computational study for the design of a hypersonic panel flutter experiment

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 © Universal Technology Corporation, 2018. This work describes the use of a nonlinear computational structural model coupled with Piston Theory aerodynamics for the design of a panel flutter experiment in hypersonic flow. The goal of the experiment is to re ... Cite

Improving piezoelectric energy harvesting from an aeroelastic system

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 © Universal Technology Corporation, 2018. Our experimental study sought to answer the question: how to maximize the piezoelectric power extraction of an aeroelastic system? A simple rectangular cantilever plate, which experiences non-linear aeroelastic lim ... Cite

Flutter and limit cycle oscillations of a cantilevered plate in supersonic/hypersonic flow

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 © Universal Technology Corporation, 2018. Development is ongoing of a new inextensible nonlinear beam and plate model to be used in aeroelastic analysis. Recently, the authors have described the theory and computations of the new structural model and have ... Cite

Flutter prediction based on dynamic eigen decomposition of coupled CFD-CSD flight simulation

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 During the design and analysis of aircraft flutter boundaries are typically computed using the p-k iterations, k iterations, p iterations, or eigenvalue analysis, that require computationally expensive and numerically sensitive procedures especially for co ... Cite

Flutter and limit cycle oscillations of a cantilevered plate in supersonic/hypersonic flow

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 Development is ongoing of a new inextensible nonlinear beam and plate model to be used in aeroelastic analysis. Recently, the authors have described the theory and computations of the new structural model and have published data illustrating the responses ... Cite

RANS and DNS study of buffet in subsonic and transonic flow

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 This document explores a fluid instability known as buffet, which occurs in the subsonic, transonic and supersonic/hypersonic regimes. Buffet has been observed in experiments and various computational studies, and yet its underlying physics are not well-es ... Cite

Improving piezoelectric energy harvesting from an aeroelastic system

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 Our experimental study sought to answer the question: how to maximize the piezoelectric power extraction of an aeroelastic system? A simple rectangular cantilever plate, which experiences non-linear aeroelastic limit cycle oscillations (LCO), was used as a ... Cite

Computational study for the design of a hypersonic panel flutter experiment

Conference International Forum on Aeroelasticity and Structural Dynamics 2019, IFASD 2019 · January 1, 2019 This work describes the use of a nonlinear computational structural model coupled with Piston Theory aerodynamics for the design of a panel flutter experiment in hypersonic flow. The goal of the experiment is to reach flutter onset within the available flo ... Cite

A new approach to determine the most efficient supersonic mach number

Conference AIAA Aviation 2019 Forum · January 1, 2019 The lower-bound and upper-bound transonic Mach numbers based upon metrics of efficiency are discussed using the concepts of temperature change and entropy change. For air, the Mach numbers from 0.845 to 1.205 are suggested as the transonic boundaries. Next ... Full text Cite

Theoretical solutions and physical significances for minimum ratio of total pressure loss by oblique shock

Journal Article Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica · December 25, 2018 Theoretical solutions for the minimum ratio of total pressure loss are derived based on the oblique shock relation and a definition of the strength by using normal Mach number for an oblique shock. First, the governing equation for the minimum ratio of tot ... Full text Cite

Analysis on global and chaotic dynamics of nonlinear wave equations for truss core sandwich plate

Journal Article Nonlinear Dynamics · October 1, 2018 This paper presents the study on the chaotic wave and chaotic dynamics of the nonlinear wave equations for a simply supported truss core sandwich plate combined with the transverse and in-plane excitations. Based on the governing equation of motion for the ... Full text Cite

Bending-torsional instability of a viscoelastic cantilevered pipe conveying pulsating fluid with an inclined terminal nozzle

Journal Article Journal of Mechanical Science and Technology · July 1, 2018 In the present study, dynamic stability of a viscoelastic cantilevered pipe conveying fluid which fluctuates harmonically about a mean flow velocity is considered; while the fluid flow is exhausted through an inclined end nozzle. The Euler-Bernoulli beam t ... Full text Cite

A study of the natural modes of vibration and aeroelastic stability of a plate with a piezoelectric material

Journal Article Smart Materials and Structures · June 15, 2018 The natural modes as well as the aeroelastic stability of a plate with attached piezoelectric material in response to a change in electric potential are studied. A finite element model is developed based on the classical lamented plate theory. The piezoele ... Full text Cite

Transmissibility of Bending Vibration of an Elastic Beam

Journal Article Journal of Vibration and Acoustics · June 1, 2018 This paper proposes an isolation transmissibility for the bending vibration of elastic beams. At both ends, the elastic beam is considered with vertical spring support and free to rotate. The geometric nonlinearity is considered. In order to implement the ... Full text Cite

Detecting multi-pulse chaotic dynamics of high-dimensional non-autonomous nonlinear system for circular mesh antenna

Journal Article International Journal of Non-Linear Mechanics · June 1, 2018 This paper investigates the global bifurcations and multi-pulse jumping chaotic dynamics of circular mesh antenna. An equivalent continuum circular cylindrical shell is employed to represent the circular mesh antenna. Based on the four-dimension non-autono ... Full text Cite

Nonlinear Characteristics Analysis of a Rotor-Bearing-Brush Seal System

Journal Article International Journal of Structural Stability and Dynamics · May 1, 2018 The vibration response and nonlinear dynamic behavior of a rotor-bearing-brush seal system were investigated with a new seal force model of the brush seal. The nonlinear oil-film force model was adopted based on a short bearing assumption. The dimensionles ... Full text Cite

Nonlinear Responses of Inextensible Cantilever and Free-Free Beams Undergoing Large Deflections

Journal Article Journal of Applied Mechanics, Transactions ASME · May 1, 2018 A theoretical and computational model has been developed for the nonlinear motion of an inextensible beam undergoing large deflections for cantilevered and free-free boundary conditions. The inextensibility condition was enforced through a Lagrange multipl ... Full text Cite

The sound field of a rotating dipole in a plug flow.

Journal Article The Journal of the Acoustical Society of America · April 2018 An analytical far field solution for a rotating point dipole source in a plug flow is derived. The shear layer of the jet is modelled as an infinitely thin cylindrical vortex sheet and the far field integral is calculated by the stationary phase method. Fo ... Full text Cite

On modal cross-coupling in the asymptotic modal limit

Journal Article Journal of Sound and Vibration · March 3, 2018 The conditions under which significant modal cross-coupling occurs in dynamical systems responding to high-frequency, broadband forcing that excites many modes is studied. The modal overlap factor plays a key role in the analysis of these systems as the mo ... Full text Cite

Iterative techniques for analyzing nonlinear vibrating dynamical systems in the frequency domain

Journal Article Nonlinear Dynamics · March 1, 2018 The nonlinear response of prototypical structures experiencing harmonic excitation is studied using novel techniques called iterative harmonic analysis (IHA) and iterative modal analysis (IMA). First, a simple damped oscillator with a cubic hardening stiff ... Full text Cite

Aeroelastic response and energy harvesting from a cantilevered piezoelectric laminated plate

Journal Article Journal of Fluids and Structures · January 1, 2018 A new nonlinear computational model and code for a piezoelectric–aeroelastic coupled system has been developed. A cantilevered piezoelectric laminated plate in yawed flow (β≤900) and inverted yawed flow (β>900) with a rotated vortex lattice aerodynamic mod ... Full text Cite

Catastrophe-theory-based modeling of airfoil-stall boundary at low reynolds numbers

Journal Article AIAA Journal · January 1, 2018 Airfoil stall at low Reynolds numbers is a complex nonlinear dynamic phenomenon, which is characterized by catastrophe and hysteresis. It is difficult but important to mathematically describe the stall points under different Reynolds numbers. In this paper ... Full text Cite

A fixed point iteration approach for harmonic balance based aeroelastic computations

Conference AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2018 · January 1, 2018 Presented is a fixed point iteration approach for harmonic balance computational flow solver based nonlinear aeroelastic computations. The methodology allows for the aeroelastic governing equations to be solved simultaneously, in an iterative manner, along ... Full text Cite

Flutter prediction based on dynamic eigen decomposition of flight data with limited actuators and sensors

Conference AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2018 · January 1, 2018 Typically, during the design, analysis, flight test phases aircraft flutter boundaries are computed using the p-k iterations, k iterations, p iterations, or eigenvalue analysis, all of which require computationally expensive and numerically sensitive proce ... Full text Cite

Buffeting and lock in of an airfoil at high angle of attack

Journal Article Journal of Aircraft · January 1, 2018 In subsonic flow, buffeting refers to a fluid instability caused by flow separation in the flow around a bluff body or an airfoil at high angle of attack. Typically, there is a dominant frequency of these flow oscillations called the (nondimensional) Strou ... Full text Cite

Computational study of aeroelastic limit cycles due to localized structural nonlinearities

Conference Journal of Aircraft · January 1, 2018 Aeroelastic systems including all-moving control surfaces and aircraft wings with stores may experience limit cycling caused by nonlinear structural and/or aerodynamic mechanisms. These systems are examined here via two different and complementary models, ... Full text Cite

Progress toward efficient compression algorithms for application in flight simulation environments

Conference 2018 Modeling and Simulation Technologies Conference · January 1, 2018 In the following paper, we demonstrate the use of both proper orthogonal decomposition and Fourier series decomposition approaches for airwake dataset compression. The proper orthogonal decomposition method is used for compressing airwake data in the time- ... Full text Cite

Nonlinear response of an inextensible, cantilevered beam subjected to a nonconservative follower force

Conference Proceedings of the ASME Design Engineering Technical Conference · January 1, 2018 The dynamic stability of a cantilevered beam actuated by a nonconservative follower force has previously been studied for its interesting dynamical properties and its applications to engineering designs such as thrusters. However, most of the literature co ... Full text Cite

Design of a panel flutter experiment in a short duration hypersonic facility

Conference Proceedings of the 21st Australasian Fluid Mechanics Conference, AFMC 2018 · January 1, 2018 © 2018 Australasian Fluid Mechanics Society. All rights reserved. This work discusses the design of a panel flutter experiment in a Mach 5.8 free-piston compression-heated Ludwieg tube. Small test duration, low freestream pressure and limited space availab ... Cite

Design of a panel flutter experiment in a short duration hypersonic facility

Conference Proceedings of the 21st Australasian Fluid Mechanics Conference, AFMC 2018 · January 1, 2018 © 2018 Australasian Fluid Mechanics Society. All rights reserved. This work discusses the design of a panel flutter experiment in a Mach 5.8 free-piston compression-heated Ludwieg tube. Small test duration, low freestream pressure and limited space availab ... Cite

Design of a panel flutter experiment in a short duration hypersonic facility

Conference Proceedings of the 21st Australasian Fluid Mechanics Conference, AFMC 2018 · January 1, 2018 This work discusses the design of a panel flutter experiment in a Mach 5.8 free-piston compression-heated Ludwieg tube. Small test duration, low freestream pressure and limited space available within the coreflow have driven the choice of boundary conditio ... Cite

Natural frequencies of a super-critical transporting Timoshenko beam

Journal Article European Journal of Mechanics, A/Solids · November 1, 2017 Super-critical transporting continua are often discussed in the context of an Euler beam model. Here Timoshenko beam theory is applied to study free vibration of high-speed transporting continua. Therefore, effects of rotary inertia and shear deformation o ... Full text Cite

High Frequency Analysis of a Point-Coupled Parallel Plate System

Journal Article Journal of Vibration and Acoustics · October 1, 2017 The root-mean-square (RMS) response of various points in a system comprised of two parallel plates coupled at a point undergoing high frequency, broadband transverse point excitation of one component is considered. Through this prototypical example, asympt ... Full text Cite

Sound transmission and radiation from a plate-cavity system in supersonic flow

Journal Article Journal of Aircraft · September 1, 2017 Noise transmission into and radiation from a rectangular cavity through a flexible structure in a noisy/thermal environment at supersonic flow is studied. Most works in acoustic fluid/solid interaction have focused on linear models in the preflutter domain ... Full text Cite

An adaptive controller for nonlinear flutter suppression and free-play compensation

Journal Article JVC/Journal of Vibration and Control · August 1, 2017 A technique aimed at neutralizing the presence of free-play effects in a control surface actuation chain is presented. It is based on an adaptive inversion of a function approximating such a nonlinearity. A simple, yet robust, on-line adaptive algorithm is ... Full text Cite

Non-linear aero-elastic response of a multi-layer TPS

Journal Article Advances in Aircraft and Spacecraft Science · July 1, 2017 The aim of the present work is to present a computational study of the non-linear aero- elastic behavior of a multi-layered Thermal Protection System (TPS). The severity of atmospheric re-entry conditions is due to the combination of high temperatures, hig ... Full text Cite

Influence of Geometry on Rotordynamic Coefficients of Brush Seal

Journal Article International Journal of Turbo and Jet Engines · May 1, 2017 It has been observed that the geometry of a brush seal has a significant effect on the sealing performance. However, the relationship between rotordynamic coefficients and geometry factors of the brush seal itself are rarely considered. In this article, th ... Full text Cite

Hamilton’s principle and Hamilton’s equations with holonomic and non-holonomic constraints

Journal Article Nonlinear Dynamics · April 1, 2017 Hamilton’s Principle is written in terms of generalized displacements and momenta. This allows holonomic and non-holonomic constraints to be treated on an equal basis using Lagrange multipliers to derive equations of motion for a dynamical system. Three ex ... Full text Cite

Normal form analysis of a forced aeroelastic plate

Journal Article Journal of Sound and Vibration · March 3, 2017 A nonlinear elastic plate in a supersonic unsteady flow forced by a dynamic excitation and a biaxial compressive load is studied. The physical behavior of the plate is modelized by the Von Kármán equations and the aerodynamic loads are modeled by using the ... Full text Cite

Two-domain and three-domain limit cycles in a typical aeroelastic system with freeplay in pitch

Journal Article Journal of Fluids and Structures · February 1, 2017 Freeplay is a significant source of nonlinearity in aeroelastic systems and is strictly regulated by airworthiness authorities. It splits the phase plane of such systems into three piecewise linear subdomains. Depending on the location of the freeplay, lim ... Full text Cite

Aeroelastic response and limit cycle oscillations for wing-flap-tab section with freeplay in tab

Journal Article Journal of Fluids and Structures · January 1, 2017 A linear and nonlinear theoretical and experimental aeroelastic investigation of a wing-flap-tab typical section model undergoing two-dimensional incompressible airflow is described. The linear flutter velocity (LFV) and frequency are predicted using linea ... Full text Cite

A novel experimental mechanics method for measuring the light pressure acting on a solar sail membrane

Conference Proceedings of SPIE - The International Society for Optical Engineering · January 1, 2017 Solar sail is a high potential 'sailing craft' for interstellar exploration. The area of the first flight solar sail demonstrator named "IKAROS" is 200 square meters. Future interplanetary missions will require solar sails at least on the order of 10000 sq ... Full text Cite

Calculation of aeroelastic limit cycles due to localized nonlinearity and static preload

Journal Article AIAA Journal · January 1, 2017 The presence of a static preload can significantly alter the limit cycle oscillation response of nonlinear aeroelastic systems. This paper reports a numerical study of two distinct types of preload, mechanical (i.e., independent of flow velocity) and aerod ... Full text Cite

Dynamic analysis of SDOF systems using modified energy method

Journal Article Asian Journal of Civil Engineering · January 1, 2017 In this research, a new numerical method is presented to evaluate the linear and especially the nonlinear dynamic response of single degree of freedom systems. This technique is based on the simultaneous usage of energy and force equilibrium equations whic ... Cite

Linear and nonlinear aeroelastic analysis of a high aspect ratio wing

Conference Proceedings of the ASME Design Engineering Technical Conference · January 1, 2017 In this study, analysis and results of linear and nonlinear aeroelastic of a cantilever beam subjected to the airflow as a model of a high aspect ratio wing are presented. A third-order nonlinear beam model is used as structural model to take into account ... Full text Cite

Nonlinear responses of inextensible cantilever and free-free beams undergoing large deflections

Conference ASME 2017 Dynamic Systems and Control Conference, DSCC 2017 · January 1, 2017 A theoretical and computational model has been developed for the nonlinear motion of an inextensible beam undergoing large deflections for cantilevered and free-free boundary conditions. The inextensibility condition was enforced through a Lagrange multipl ... Full text Cite

High frequency analysis of a dynamically coupled parallel plate system

Conference ASME 2017 Dynamic Systems and Control Conference, DSCC 2017 · January 1, 2017 The behavior of a system comprised of two parallel plates coupled by a discrete, linear spring and damper is studied. Classical Modal Analysis (CMA) is used to illustrate this behavior, while specifically observing the effects of varying the stiffness and ... Full text Cite

ASSESSMENT OF THEORETICAL MODELS FOR VISCOUS AND TRANSONIC FLOW.

Journal Article AGARD Conference Proceedings · January 1, 2017 Some current and proposed methods of treating viscous and transonic effects in theoretical aerodynamic models suitable for aeroelastic applications are reviewed critically. Where possible, theoretical results of such models are compared with experiment. To ... Cite

Parametrically rich nonlinear reduced-order modeling: An application in viscous incompressible flow

Conference 17th International Forum on Aeroelasticity and Structural Dynamics, IFASD 2017 · January 1, 2017 In this work, we seek parametrically rich modes that can be used to analyze nonlinear systems for a continuous variation of operating conditions. Towards this end, based on the Modally Equivalent Perturbed System (MEPS) and the Degenerate Transformation (D ... Cite

Linear Versus Nonlinear Response of a Cantilevered Beam under Harmonic Base Excitation: Theory and Experiment

Journal Article Journal of Applied Mechanics, Transactions ASME · October 1, 2016 A computational and experimental study of a uniform cantilever beam with a tip mass under base excitation was performed. The beam was excited at various levels of base displacement to provoke tip displacements greater than 15% of the beam length. Damping a ... Full text Cite

Modal damping in a finite element model (L)

Journal Article Journal of the Acoustical Society of America · October 1, 2016 Damping in vibration models is often treated on an empirical basis based upon experimental measurement of damping in the eigenmodes of the model. Thus if one starts with a finite element model, for example, the undamped eigenmodes are found and then the da ... Full text Cite

High frequency analysis of a plate carrying a concentrated nonlinear spring–mass system

Journal Article Journal of Sound and Vibration · September 29, 2016 Examining the behavior of dynamical systems with many degrees of freedom undergoing random excitation at high frequency often requires substantial computation. These requirements are even more stringent for nonlinear systems. One approach for describing li ... Full text Cite

Minimal subspace rotation on the Stiefel manifold for stabilization and enhancement of projection-based reduced order models for the compressible Navier-Stokes equations

Journal Article Journal of Computational Physics · September 15, 2016 For a projection-based reduced order model (ROM) of a fluid flow to be stable and accurate, the dynamics of the truncated subspace must be taken into account. This paper proposes an approach for stabilizing and enhancing projection-based fluid ROMs in whic ... Full text Cite

Dynamic characteristics of double-helical planetary gear sets under time-varying mesh stiffness

Journal Article Journal of Harbin Institute of Technology (New Series) · August 1, 2016 Internal and external meshes are two of primary excitation sources which induce vibration while double-helical planetary gear sets are in transmission. Based on the analysis of tooth movement principle, three cases of mesh stiffness are derived via investi ... Full text Cite

Nonlinear Elastic Plate in a Flow of Gas: Recent Results and Conjectures

Journal Article Applied Mathematics and Optimization · June 1, 2016 We give a survey of recent results on flow-structure interactions modeled by a modified wave equation coupled at an interface with equations of nonlinear elasticity. Both subsonic and supersonic flow velocities are considered. The focus of the discussion h ... Full text Cite

Experimental aeroelastic models design and wind tunnel testing for correlation with new theory

Journal Article Aerospace · June 1, 2016 Several examples of experimental model designs, wind tunnel tests and correlation with new theory are presented in this paper. The goal is not only to evaluate a new theory, new computational method or new aeroelastic phonomenon, but also to provide new in ... Full text Cite

Panel flutter prediction in two dimensional flow with enhanced piston theory

Journal Article Journal of Fluids and Structures · May 1, 2016 Piston theory may be used in the high Mach number supersonic flow region and/or in very high frequency subsonic or supersonic flow. In this flow model, the pressure at a point on the fluid-solid interface only depends on the downwash at the same point. How ... Full text Cite

An aeroelastic model for vortex-induced vibrating cylinders subject to frequency lock-in

Journal Article Journal of Fluids and Structures · February 1, 2016 This work presents a novel way to calculate the response amplitude of an elastically supported cylinder experiencing vortex-induced vibrations. The method couples a computational fluid dynamic (CFD) model of the shedding vortex flow to a structural model r ... Full text Cite

Far field predicted by piston theory

Journal Article AIAA Journal · January 1, 2016 A study is conducted to predict far field using piston theory. Piston theory is usually thought of as a high supersonic flow theory in that it can be derived as the limit of potential flow theory as the Mach number M becomes large. It is demonstrated that ... Full text Cite

Evolution of airplanes, and what price speed?

Journal Article AIAA Journal · January 1, 2016 The constructal theory of flight accounts not only for speed, body size, and medium density r but also for physical parameters that are an integral part of the derivation of these equations in their original sources. One parameter is the Reynolds number, w ... Full text Cite

Bifurcation Observation of Combining Spiral Gear Transmission Based on Parameter Domain Structure Analysis

Journal Article Mathematical Problems in Engineering · January 1, 2016 This study considers the bifurcation evolutions for a combining spiral gear transmission through parameter domain structure analysis. The system nonlinear vibration equations are created with piecewise backlash and general errors. Gill's numerical integrat ... Full text Cite

Store-induced limit-cycle oscillations due to nonlinear wing-store attachment

Journal Article Journal of Aircraft · January 1, 2016 Several high-performance fighter aircraft exhibit store-induced limit-cycle oscillations, leading to pilot discomfort, potential structural fatigue, and flight envelope restrictions. The roles of various aerodynamic and structural factors causing the limit ... Full text Cite

Proper orthogonal decomposition method for analysis of nonlinear panel flutter with thermal effects in supersonic flow

Journal Article Journal of Sound and Vibration · February 17, 2015 The proper orthogonal decomposition (POD) method for analysis of nonlinear panel flutter subjected to supersonic flow is presented. Optimal POD modes are extracted from a chaotic Galerkin mode responses. The aeroelastic equations of motion are constructed ... Full text Cite

Aeroelastic stability of thermal protection system for inflatable aerodynamic decelerator

Journal Article Journal of Spacecraft and Rockets · January 1, 2015 A theoretical aeroelastic stability analysis has been performed on the flexible thermal protection system for an inflatable aerodynamic decelerator. Structural models consist of one or more truncated conical shells of the Donnell type, which may be elastic ... Full text Cite

Stability of rectangular plates in subsonic flow with various boundary conditions

Journal Article Journal of Aircraft · January 1, 2015 The aeroelastic stability of rectangular plates in subsonic flow is well documented in literature. For example, the stability of a cantilever plate with a clamped edge parallel to the flow is well understood due to the similarity of this system to an aircr ... Full text Cite

Nonlinear aeroelastic analysis with inextensible plate theory including correlation with experiment

Journal Article AIAA Journal · January 1, 2015 A computational aeroelastic model is presented for a cantilevered plate rotated from a position with the clamped edge normal to the flow (0 deg) to where the clamped edge is aligned with the flow (90 deg) using a new inextensible plate theory. A large-ampl ... Full text Cite

Reduced-order models for computational-fluid-dynamics-based nonlinear aeroelastic problems

Journal Article AIAA Journal · January 1, 2015 In this work, a nonlinear state-space-based identification method is proposed to describe compactly unsteady aerodynamic responses. Such a reduced-order model is trained on a series of signals that implicitly represent the relationship between the structur ... Full text Cite

Landing gear design/maintenance analysis for nonlinear shimmy

Journal Article Journal of Aircraft · January 1, 2015 A concise harmonic-balance-(HB) based method is demonstrated that yields the limit-cycle oscillation (LCO) response as a function of forward speed for models of any order. The linear shimmy boundary of the system is generated as a function of stiffness in ... Full text Cite

In-flight aeroelastic stability of the thermal protection system on the NASA HIAD, part II: Nonlinear theory and extended aerodynamics

Conference 56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · January 1, 2015 © 2015, American Institute of Aeronautics and Astronautics Inc. All rights reserved. Conical shell theory and a supersonic potential flow aerodynamic theory are used to study the nonlinear pressure buckling and aeroelastic limit cycle behavior of the therm ... Cite

Store-induced limit cycle oscillations due to nonlinear wing-store attachment

Conference 56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · January 1, 2015 © 2015, American Institute of Aeronautics and Astronautics Inc. All rights reserved. Fighter aircraft encounter aeroelastic Limit Cycle Oscillations (LCO) when carrying certain combinations of under-wing stores, leading to structural fatigue, pilot discomf ... Cite

Aeroelastic control

Journal Article Solid Mechanics and its Applications · January 1, 2015 Active control of aeroelastic systems is a subject of continuing interest and this chapter provides an introduction to this fascinating topic. ... Full text Cite

Stall flutter

Journal Article Solid Mechanics and its Applications · January 1, 2015 As the name implies, stall flutter is a phenomenon which occurs with partial or complete separation of the flow from the airfoil occurring periodically during the oscillation. In contrast to classical flutter (i.e., flow attached at all times) the mechanis ... Full text Cite

Recent advances in heliogyro solar sail structural dynamics, stability, and control research

Conference 2nd AIAA Spacecraft Structures Conference · January 1, 2015 © 2015, American Institute of Aeronautics and Astronautics Inc. All rights reserved. Results from recent NASA sponsored research on the structural dynamics, stability, and control characteristics of heliogyro solar sails are summarized. Specific areas unde ... Cite

Guidance and ignition control of lateral-jet-controlled interceptor missiles

Journal Article Journal of Guidance, Control, and Dynamics · January 1, 2015 The guidance and ignition control strategies of lateral-jet-controlled interceptor missiles are proposed based on capture region. The system states keeping inside the capture region will lead to a successful interception. The designs of the non-ignition re ... Full text Cite

Discrete adjoint design optimization approach for increasing transonic buffet onset angle-of-attack

Conference 16th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference · January 1, 2015 © 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All rigths reserved. Presented is a discrete adjoint method for transonic buffet design optimization. The method is based on a frequency do-main approach for modeling unsteady aerodynami ... Cite

CFD analysis of aerodynamic coefficients in labyrinth brush seal

Conference ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) · January 1, 2015 The aerodynamic force between a bristle pack and a rotor should be considered in order to predict the stability of a rotor brush seal system. The high pressure flow region in a brush seal makes the interaction of bristle pack, leakage flow and rotor compli ... Full text Cite

Recent advances in heliogyro solar sail structural dynamics, stability, and control research

Conference 2nd AIAA Spacecraft Structures Conference · January 1, 2015 Results from recent NASA sponsored research on the structural dynamics, stability, and control characteristics of heliogyro solar sails are summarized. Specific areas under investigation include coupled nonlinear finite element analysis of heliogyro membra ... Full text Cite

Store-induced limit cycle oscillations due to nonlinear wing-store attachment

Conference 56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · January 1, 2015 Fighter aircraft encounter aeroelastic Limit Cycle Oscillations (LCO) when carrying certain combinations of under-wing stores, leading to structural fatigue, pilot discomfort and flight envelope restrictions. The roles of various aerodynamic and structural ... Full text Cite

Discrete adjoint design optimization approach for increasing transonic buffet onset angle-of-attack

Conference 16th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference · January 1, 2015 Presented is a discrete adjoint method for transonic buffet design optimization. The method is based on a frequency do-main approach for modeling unsteady aerodynamics. Automatic differentiation is used to derive the computer code representing the adjoint ... Full text Cite

In-flight aeroelastic stability of the thermal protection system on the NASA HIAD, part II: Nonlinear theory and extended aerodynamics

Conference 56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · January 1, 2015 Conical shell theory and a supersonic potential flow aerodynamic theory are used to study the nonlinear pressure buckling and aeroelastic limit cycle behavior of the thermal protection system for NASA’s Hypersonic Inflatable Aerodynamic Decelerator. The st ... Full text Cite

Membrane paradox for solar sails

Journal Article AIAA Journal · December 1, 2014 A study was conducted to investigate membrane paradox for solar sails. The study particularly provided a framework for analyzing the stability of a restrained solar sail membrane where the aspect ratio was large or the ratio of the tension on the bending s ... Full text Cite

Effects of a free-to-roll fuselage on wing flutter: Theory and experiment

Journal Article AIAA Journal · December 1, 2014 A theoretical study of a wing-fuselage combination with a rigid-body roll degree of freedom for the fuselage and elastic modes for the wing is presented along with a companion wind-tunnel test. The full-span wing dynamics are modeled using a linear-plate w ... Full text Cite

Effects of nonlinear damping suspension on nonperiodic motions of a flexible rotor in journal bearings

Journal Article Nonlinear Dynamics · October 7, 2014 Nonlinear damping suspension is a promising method to be used in a rotor-bearing system for vibration isolation between the bearing and environment. However, the nonlinearity of the suspension may influence the stability of the rotor-bearing system. In thi ... Full text Cite

Simulation of aeroelastic limit-cycle oscillations of aircraft wings with stores

Conference AIAA Journal · October 1, 2014 Aircraft wings carrying stores are susceptible to nonlinear aeroelastic limit-cycle oscillations, which can lead to reduced flight and mission performance. Limit-cycle-oscillation dynamics and control simulation studies, although of great importance, are o ... Full text Cite

Observation and evolution of chaos for a cantilever plate in supersonic flow

Journal Article Journal of Fluids and Structures · October 1, 2014 For a wing-like plate in supersonic flow cantilevered at its root, chaotic motions are studied in this paper. Prior literature has mainly focused on a simply supported plate or the limit cycle oscillations (LCOs) of a cantilever plate. The governing equati ... Full text Cite

Inextensible beam and plate theory: Computational analysis and comparison with experiment

Journal Article Journal of Applied Mechanics, Transactions ASME · June 1, 2014 A new inextensible theory of beam and plate deformation has been developed. For validation of this inextensible beam and plate theory, computational codes for the static and dynamic nonlinear beam and plate modal equations have been developed. The computat ... Full text Cite

Post-buckling longterm dynamics of a forced nonlinear beam: A perturbation approach

Journal Article Journal of Sound and Vibration · April 28, 2014 The aim of this paper is to determine by a singular perturbation approach the dynamic response of a harmonically forced system experiencing a pitchfork bifurcation. The model of an extensible beam forced by a harmonic excitation and subject to an axial sta ... Full text Cite

Damping analysis in beams subject to presliding friction

Journal Article Mechanics Based Design of Structures and Machines · April 3, 2014 A pinned-pinned beam with one end fixed and the other end free to slide horizontally is studied. Dry friction damping is modeled at the support boundaries of the beam. In order to analyze the variation of the equivalent viscous damping caused by the presli ... Full text Cite

In-flight aeroelastic stability of the thermal protection system on the NASA HIAD, Part I: Linear theory

Journal Article 55th AIAA/ASMe/ASCE/AHS/SC Structures, Structural Dynamics, and Materials Conference · February 28, 2014 Conical shell theory and piston theory aerodynamics are used to study the aeroelastic stability of the thermal protection system (TPS) on the NASA Hypersonic In atable Aerodynamic Decelerator (HIAD). Structural models of the TPS consist of single or multip ... Full text Cite

Proper orthogonal decomposition reduced-order model for nonlinear aeroelastic oscillations

Journal Article AIAA Journal · February 1, 2014 In this study, the proper orthogonal decomposition method in conjunction with a Galerkin projection scheme is employed to solve the title problem of a fluttering plate in both two and three dimensions undergoing supersonic flow using von Kármán's large def ... Full text Cite

Flow field around the flapping flag

Journal Article Journal of Fluids and Structures · 2014 Cite

Flow field around the flapping flag

Journal Article Journal of Fluids and Structures · January 1, 2014 The flapping flag is a canonical fluid-structure interaction problem that describes a cantilever plate with flow along its elastic axis. When the flapping flag loses stability it enters a large amplitude Limit Cycle Oscillation (LCO). While theoretical mod ... Full text Cite

Experimental aerodynamic response for an oscillating airfoil in buffeting flow

Journal Article AIAA Journal · January 1, 2014 In prior work, several authors including the present ones have noted the analogy between the fluid oscillations induced by a bluff body in cross flow (e.g., the classic von Kármán vortex street behind a cylinder) and the flow oscillations often called buff ... Full text Cite

Aeroelastic stability of a cantilevered plate in yawed subsonic flow

Journal Article Journal of Fluids and Structures · January 1, 2014 The aeroelastic stability of cantilevered plates with their clamped edge oriented both parallel and normal to subsonic flow is a classical fluid-structure interaction problem. When the clamped edge is parallel to the flow the system loses stability in a co ... Full text Cite

Stability of rotorcraft for interplanetary space flight

Journal Article Annual Forum Proceedings - AHS International · January 1, 2014 NASA is currently exploring propellantless spacecraft propulsion technologies required to enable missions ranging from orbital debris capture and removal to station keeping in unstable locations in space to deep space exploration. In this paper we explore ... Cite

Discrete adjoint approach for aeroelastic design optimization

Conference AIAA AVIATION 2014 -15th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference · January 1, 2014 Using aeroelastic flutter geometric design sensitivities provided by a recently developed discrete adjoint aeroelastic solver, the shape of a NLR 7301 airfoil section is optimized to increase flutter onset velocity for a benchmark transonic aeroelastic con ... Cite

Projection-free proper orthogonal decomposition method for a cantilever plate in supersonic flow

Journal Article Journal of Sound and Vibration · January 1, 2014 This paper explores the use of the proper orthogonal decomposition (POD) method for supersonic nonlinear flutter of a cantilever plate or wing. The aeroelastic equations are constructed using von Karman plate theory and first-order piston theory. The two-d ... Full text Cite

Structural-Acoustic Modal Analysis and Synthesis

Chapter · January 1, 2014 This chapter develops the modal series solution method to predict the interior sound pressure response in an enclosure with flexible and absorptive walls. It also explains the component mode synthesis (CMS) methodology to couple individual structural subst ... Full text Cite

Damage detection of an aeroelastic panel using limit cycle oscillation analysis

Journal Article International Journal of Non-Linear Mechanics · January 1, 2014 Most of real systems are non-linear and they require damage detection. For such non-linear systems, non-linear damage detection methods are necessary for more accurate results. In this paper, a novel non-linear method is introduced using limit cycle oscill ... Full text Cite

Experimental aeroelastic response for a freeplay control surface in buffeting flow

Journal Article AIAA Journal · December 1, 2013 A partial control surface is constructed near the midspan of a NACA 0012 airfoil model with and without freeplay gaps. Static and dynamic control surface pitch motion measurements were performed in wind-tunnel tests at higher angles of attack including buf ... Full text Cite

New look at unsteady supersonic potential flow aerodynamics and piston theory

Journal Article AIAA Journal · September 1, 2013 Piston theory is an inherently quasi-steady theory, in that higher powers of frequency do not appear, as well as a local theory in that the pressure at a point on the airfoil only depends on the downwash at the same point. In the extension to piston theory ... Full text Cite

Rectangular solar sail flutter

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · August 15, 2013 Solar sail spacecraft have been proposed for extended timescale missions because of the spacecraft's ability to generate continuous propellant-less thrust. Due in part to the recent success of the JAXA IKAROS (Interplanetary Kite-craft Accelerated by the R ... Cite

Aeroelastic analysis of a folding wing: Comparison of simple and higher fidelity models for a wide range of fold angles

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · August 15, 2013 The goal of folding wing research is to enable wing shape changes during flight in order to optimize aircraft performance over a multitude of mission segments. However, the additional mechanisms needed to implement the morphing capability tends to increase ... Cite

An approach to aeroelastic modeling and simulation of limit cycle oscillations of aircraft wings with stores

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · August 15, 2013 Aircraft wings carrying stores are susceptible to nonlinear, aeroelastic Limit Cycle Oscillations (LCO), which can lead to reduced flight and mission performance. LCO dynamics and control simulation studies, although of great importance, are often based on ... Cite

Discrete adjoint method for nonlinear aeroelastic sensitivities for compressible and viscous flows

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · August 15, 2013 Presented is a discrete adjoint approach for computing nonlinear aeroelastic design sensitivities for transonic and viscous flows based on Reynolds Averaged Navier-Stokes computational fluid dynamic models. The method is based on a harmonic balance nonline ... Cite

Flutter analysis of the thermal protection layer on the NASA HIAD

Journal Article AIAA Aerodynamic Decelerator Systems (ADS) Conference 2013 · August 2, 2013 A combination of classical plate theory and a supersonic aerodynamic model is used to study the aeroelastic flutter behavior of a proposed thermal protection system (TPS) for the NASA HIAD. The analysis pertains to the rectangular configurations currently ... Full text Cite

Aeroelastic analysis of a folding wing: Comparison of simple and higher fidelity models for a wide range of fold angles

Journal Article 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · August 2, 2013 The goal of folding wing research is to enable wing shape changes during flight, in order to optimize aircraft performance over a multitude of mission segments. However, the additional mechanisms needed to implement the morphing capability tends to increas ... Full text Cite

Rectangular solar sail flutter

Journal Article 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · August 2, 2013 Solar sail spacecraft have been proposed for extended timescale missions because of the spacecraft's ability to generate continuous propellant-less thrust. Due in part to the recent success of the JAXA IKAROS (Interplanetary Kite-craft Accelerated by the R ... Full text Cite

Discrete adjoint method for nonlinear aeroelastic sensitivities for compressible and viscous flows

Conference 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · August 2, 2013 Presented is a discrete adjoint approach for computing nonlinear aeroelastic design sensitivities for transonic and viscous flows based on Reynolds Averaged Navier-Stokes computational fluid dynamic models. The method is based on a harmonic balance nonline ... Full text Cite

An approach to aeroelastic modeling and simulation of Limit Cycle Oscillations of aircraft wings with stores

Journal Article 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · August 2, 2013 Aircraft wings carrying stores are susceptible to nonlinear, aeroelastic Limit Cycle Oscillations (LCO), which can lead to reduced flight and mission performance. LCO dynamics and control simulation studies, although of great importance, are often based on ... Full text Cite

Compact implementation strategy for a harmonic balance method within implicit flow solvers

Journal Article AIAA Journal · June 1, 2013 A two-step approximate factorization technique for implementing a computationally stable nonlinear unsteady frequency-domain harmonic balance solution method within existing implicit computational fluid dynamic flow solver codes is presented. The approach ... Full text Cite

Resonant frequency determination of a multistore high-altitude/long- endurance wing

Journal Article AIAA Journal · June 1, 2013 It is desirable to predict the resonant frequencies and mode shapes of extremely high-aspect ratio wings for highaltitude/long-endurance applications. Such results give insight into structural response and serve as a precursor to flutter and gust response ... Full text Cite

Comment on "On Dowell's simplification for acoustic cavity-structure interaction and consistent alternatives [J. Acoust. Soc. Am. 127, 22-32 (2010)]".

Journal Article The Journal of the Acoustical Society of America · March 2013 This Letter describes a correction to the equations used in Ginsberg [J. Acoust. Soc. Am. 127, 22-32 (2010)] to include the rigid-body (Helmholtz) cavity mode in the modal series solution when using Dowell's method. While the correction is easy to implemen ... Full text Cite

Computational/experimental aeroelastic study for a horizontal-tail model with free play

Journal Article AIAA Journal · February 1, 2013 A computational code has been developed for aeroelastic analysis for an all-movable horizontal tail, and a companion wind-tunnel test program has been conducted. The structural bending and torsional stiffness are based upon an experimental tail model that ... Full text Cite

Harmonic balance methods applied to computational fluid dynamics problems

Journal Article International Journal of Computational Fluid Dynamics · February 1, 2013 In this paper, we briefly review the classical harmonic balance method, and describe the adaptation of the method required for its application to computational fluid dynamics models of unsteady time periodic flows. We describe several variations of the met ... Full text Cite

Adaptive fault-tolerant robust control for a linear system with adaptive fault identification

Journal Article IET Control Theory and Applications · January 17, 2013 An integrated design of the adaptive robust control and the fault identification for a linear system with actuator faults is proposed. When actuators suffer from unpredicted faults, the proposed control strategy can track the actuator fault parameters adap ... Full text Cite

Nonlinear aeroelastic response of a flat panel. A normal form approach

Conference IFASD 2013 - International Forum on Aeroelasticity and Structural Dynamics · January 1, 2013 The model of a nonlinear plate in a supersonic unsteady flow forced by a dynamic excitation and subject to a biaxial compressive load is considered. Indeed, the aeroelastic model can represent a variety of mechanical systems and it gives the opportunity to ... Cite

Low-dimensional modelling of high-Reynolds-number shear flows incorporating constraints from the Navier-Stokes equation

Journal Article Journal of Fluid Mechanics · January 1, 2013 We generalize the POD-based Galerkin method for post-transient flow data by incorporating Navier-Stokes equation constraints. In this method, the derived Galerkin expansion minimizes the residual like POD, but with the power balance equation for the resolv ... Full text Cite

An automatic differentiation based nonlinear reduced order modeling technique for unsteady separated flows

Conference 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition · December 1, 2012 This paper discusses the development and implementation of an automatic differentiation based nonlinear reduced order model for unsteady separated flows. The objective of the research presented herein has been to test the capability and limits of the metho ... Full text Cite

Aeroelastic behavior of noise-reducing membranes for aircraft lifting surfaces part I: Theory

Journal Article 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 · December 1, 2012 Commercial transport aircrafts generate a significant amount of noise during approach and landing. A substantial portion of this noise is due to the interaction of vortices and structure at the discontinuity between the wing and the deployed trailing edge ... Cite

Aeroelastic responses of spring-suspended airfoil systems in transonic buffeting flows

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2012 Computer simulations are performed to determine the responses of a single DOF pitch airfoil system, as well as those of a two DOF pitch-and-heave system, in buffeting flows. The buffeting flow exhibits shock-wave oscillations of a unique frequency that occ ... Cite

Flutter and LCO of an all-movable horizontal tail with freeplay

Journal Article 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 · December 1, 2012 In this paper, the impact of freeplay on flutter and limit-cycle oscillation (LCO) of an allmovable horizontal tail is studied. A 3D finite element model and a 3D finite volume model with unstructured gird of the all-movable horizontal tail are established ... Cite

Flutter and lco of an all-movable horizontal tail with freeplay

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2012 In this paper, the impact of freeplay on flutter and limit-cycle oscillation (LCO) of an allmovable horizontal tail is studied. A 3D finite element model and a 3D finite volume model with unstructured gird of the all-movable horizontal tail are established ... Cite

Aeroelastic behavior of noise-reducing membranes for aircraft lifting surfaces part II: Experimen

Journal Article 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 · December 1, 2012 Commercial transport aircrafts generate a large amount of noise during approach and landing. A significant portion of this noise is due to the interaction of vortices and structure at the discontinuity between the wing and the deployed trailing edge flap. ... Cite

Aeroelastic responses of spring-suspended airfoil systems in transonic buffeting flows

Journal Article 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 · December 1, 2012 Computer simulations are performed to determine the responses of a single DOF pitch airfoil system, as well as those of a two DOF pitch-and-heave system, in buffeting flows. The buffeting flow exhibits shock-wave oscillations of a unique frequency that occ ... Cite

Aeroelastic behavior of noise-reducing membranes for aircraft lifting surfaces part I: Theory

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2012 Commercial transport aircrafts generate a significant amount of noise during approach and landing. A substantial portion of this noise is due to the interaction of vortices and structure at the discontinuity between the wing and the deployed trailing edge ... Cite

Scaling analysis for aeroelastic phenomena using the navier-stokes fluid model

Journal Article AIAA Journal · November 1, 2012 The scaling analysis of the Navier Stokes equation is examined and is extended to compressible aerodynamic flows where the characteristic Reynolds number is large and the Prandtl number is of order unity. A compressible flow of a Newtonian fluid is conside ... Full text Cite

Stabilization of projection-based reduced order models of the Navier-Stokes

Journal Article Nonlinear Dynamics · October 1, 2012 A new method of stabilizing low-order, proper orthogonal decomposition based reduced-order models of the Navier-Stokes equations is proposed. Unlike traditional approaches, this method does not rely on empirical turbulence modeling or modification of the N ... Full text Cite

Theory and experiment for flutter of a rectangular plate with a fixed leading edge in three-dimensional axial flow

Journal Article Journal of Fluids and Structures · October 1, 2012 This paper explores cantilevered beam flutter for both clamped and pinned leading edge boundary conditions. Specifically, a three-dimensional vortex lattice panel method is coupled with a classical Lagrangian one-dimensional beam structural model to predic ... Full text Cite

A general H ∞ fault tolerant control and management for a linear system with actuator faults

Journal Article Automatica · August 1, 2012 This brief paper investigates the optimal selection of online controllers for a linear system with actuator faults in the framework of H ∞ control. The occurrence of actuator faults is modeled as a Markov chain to predict future faults. A compatible relati ... Full text Cite

Aeroelastic responses of spring-suspended airfoil systems in transonic buffeting flows

Conference 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 · January 1, 2012 Computer simulations are performed to determine the responses of a single DOF pitch airfoil system, as well as those of a two DOF pitch-and-heave system, in buffeting flows. The buffeting flow exhibits shock-wave oscillations of a unique frequency that occ ... Full text Cite

Flutter and LCO of an all-movable horizontal tail with freeplay

Conference 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012 · January 1, 2012 In this paper, the impact of freeplay on flutter and limit-cycle oscillation (LCO) of an allmovable horizontal tail is studied. A 3D finite element model and a 3D finite volume model with unstructured gird of the all-movable horizontal tail are established ... Full text Cite

Aeroelastic model of multisegmented folding wings: Theory and experiment

Journal Article Journal of Aircraft · January 1, 2012 Morphing-wing research has garnered much attention in the aerospace community over the last decade, and the folding wing is a promising concept that can improve aircraft performance over multiple types of missions. Several high-fidelity analyses of folding ... Full text Cite

Integrated adaptive fault-tolerant H∞ output feedback control with adaptive fault identification

Journal Article Journal of Guidance, Control, and Dynamics · January 1, 2012 An adaptive fault-tolerant H∞ output feedback controller is designed for a linear system with actuator faults by incorporating an observer for actuator faults. This observer is improved from an unknown input observer to make it more appropriate for trackin ... Full text Cite

Nonlinear nonconservative behavior and modeling of piezoelectric energy harvesters including proof mass effects

Journal Article Journal of Intelligent Material Systems and Structures · January 1, 2012 Nonlinear piezoelectric effects in flexural energy harvesters have recently been demonstrated for drive amplitudes well within the scope of anticipated vibration environments for power generation. In addition to strong softening effects, steady-state oscil ... Full text Cite

An investigation on the sensitivity of limit cycle oscillations for detecting damage in an aeroelastic panel

Journal Article Applied Mechanics and Materials · January 1, 2012 There are many nonlinear systems used in engineering which require damage detection. For such systems, nonlinear damage detection methods may be useful. In this paper, a novel method is introduced that uses limit cycle oscillations that arise once the bifu ... Full text Cite

Reduced-order modeling of flutter and limit-cycle oscillations using the sparse volterra series

Journal Article Journal of Aircraft · January 1, 2012 For the past two decades, the Volterra series reduced-order modeling approach has been successfully used for the purpose of flutter prediction, aeroelastic control design, and aeroelastic design optimization. The approach has been less successful, however, ... Full text Cite

Flutter of rectangular plates in three dimensional incompressible flow with various boundary conditions: Theory and experiment

Journal Article Proceedings of the ASME Design Engineering Technical Conference · January 1, 2012 The aeroelastic stability of rectangular plates are well-documented in literature for certain sets of boundary conditions. Specifically, wing flutter, panel flutter, and divergence of a plate that is clamped on all sides are well-understood. However, the o ... Full text Cite

A structural dynamics model of a multi-segmented folding wing: Theory and experiment

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2011 This paper presents a general structural dynamics model based on beam theory that predicts the natural frequencies of a folding wing with an arbitrary number of wing segments. The structural model is derived from a modal analysis using work-energy principl ... Full text Cite

Aeroelastic limit cycles as a small scale energy source

Journal Article Proceedings of the ASME Design Engineering Technical Conference · December 1, 2011 Nonlinear limit cycle oscillations of an aeroelastic energy harvester are exploited for enhanced piezoelectric power generation from aerodynamic flows. Specifically, a flexible beam with piezoelectric laminates is excited by a uniform axial flow field in a ... Full text Cite

A study of the aeroelastic behavior of flat plates and membranes with mixed boundary conditions in axial subsonic flow

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2011 In support of the noise reduction targets for future generations of transport aircraft, as set forth by NASA, the fundamental aeroelastic behavior of trailing edge flap technology was explored. Using a plate structural model to approximate the structural c ... Full text Cite

Airfoil transonic flow buffet calculations using the OVERFLOW 2 flow solver

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2011 An investigation of modeling unsteady transonic buffeting flow for the NACA 0012 airfoil when using the NASA OVERFLOW 2 flow solver code is presented. For a fixed freestream Mach number and Reynolds number, buffeting flow is modeled for various angles-of-a ... Full text Cite

Power extraction from aeroelastic limit cycle oscillations

Journal Article Journal of Fluids and Structures · November 1, 2011 Nonlinear limit cycle oscillations of an aeroelastic energy harvester are exploited for enhanced piezoelectric power generation from aerodynamic flows. Specifically, a flexible beam with piezoelectric laminates is excited by a uniform axial flow field in a ... Full text Cite

Can solar sails flutter?

Journal Article AIAA Journal · June 1, 2011 Full text Cite

Bifurcation boundary analysis as a nonlinear damage detection feature: Does it work?

Journal Article Journal of Fluids and Structures · February 1, 2011 Many systems in engineering and science are inherently nonlinear and require damage detection. For such systems, nonlinear damage detection methods may be useful. A bifurcation boundary analysis method as a new nonlinear damage detection tool was previousl ... Full text Cite

Aeroelastic response induced by free play, Part 2: Theoretical/experimental correlation analysis

Journal Article AIAA Journal · January 1, 2011 An experimental model for an all-movable horizontal tail with a free-play gap in the actuating mechanism at the root of the tail wing was designed and constructed. The flutter response and nonlinear limit-cycle oscillations induced by a free-play gap have ... Full text Cite

Aeroelastic analysis and experiment for wing/store model with stiction nonlinearity

Journal Article Journal of Aircraft · January 1, 2011 An experimental delta wing/store model with stiction nonlinearity has been designed and tested in a low-speed wind tunnel. The wing structure is modeled theoretically using von Kármán plate theory that accounts for geometric strain-displacement nonlinearit ... Full text Cite

Aeroelastic response induced by free play, Part 1: Theory

Journal Article AIAA Journal · January 1, 2011 A computational code has been developed for aeroelastic analysis. The structural bending and torsional stiffness for an all-movable horizontal tail are based upon the experimental data published in Wright Air Development Center technical report 54-53 (Nile ... Full text Cite

Online selection of H∞ controllers for a faulty linear system

Journal Article Proceedings of the IEEE Conference on Decision and Control · January 1, 2011 This paper investigates optimal selections of controllers online for a linear system with actuator faults in the framework of H∞ control. Actuator faults are modeled into three states: normal, loss of effectiveness and outage, and the development of the ac ... Full text Cite

Frequency lock-in phenomenon for oscillating airfoils in buffeting flows

Journal Article Journal of Fluids and Structures · January 1, 2011 Navier-Stokes based computer simulations are conducted to determine the aerodynamic flow field response that is observed for a NACA0012 airfoil that undergoes prescribed harmonic oscillation in transonic buffeting flows, and also in pre-buffet flow conditi ... Full text Cite

Structural Dynamics model of multisegmented folding wings: Theory and experiment

Journal Article Journal of Aircraft · January 1, 2011 Morphing wing research has garnered much attention in the aerospace community over the last decade, and the folding wing is a promising concept that can improve aircraft performance over multiple types of missions. Several high-fidelity analyses of folding ... Full text Cite

An efficient POD/ROM based aeroelasticity model

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 16, 2010 In this paper, an efficient reduced order model (ROM) for aeroelastic and aeroservoelastic modeling has been developed based upon proper orthogonal decomposition (POD). This model is validated by computing the flutter boundary and reduced frequency ratio o ... Cite

F-16 fighter aeroelastic computations using a harmonic balance implementation of the OVERFLOW 2 flow solver

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 16, 2010 Presented are flutter-onset trends of the F-16 fighter computed using a harmonic balance version of the NASA OVERFLOW 2 flow solver code. The harmonic technique enables one to model unsteady aerodynamics and aeroelastic response in the frequency domain wit ... Cite

Some recent advances in nonlinear aeroelasticity: Fluid-structure interaction in the 21 st Century

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 16, 2010 Aeroelasticity is the field that examines, models and seeks to understand the interaction of the forces from an aerodynamic flow and the deformation of an elastic structure. The forces produce deformation, but the structural deformation in turn changes the ... Cite

Gust response for flexibly suspended high-aspect ratio wings

Journal Article AIAA Journal · October 1, 2010 A theoretical aeroelastic study for a flexibly suspended high-aspect ratio wing aeroelastic model excited by gust loads is presented along with a companion wind-tunnel test. A flexible support system at the wing root has been constructed to simulate a rigi ... Full text Cite

Transonic unsteady potential flow: Scaling analysis of linear and nonlinear dynamics

Journal Article AIAA Journal · May 1, 2010 Scaling analysis of linear and nonlinear dynamics theory is applied to study transonic unsteady potential flow of a limit cycle oscillations of the F-16 aircraft. The governing field equation for the aerodynamic velocity potential in transonic unsteady pot ... Full text Cite

Aeroelastic airfoil with free play at angle of attack with gust excitation

Journal Article AIAA Journal · February 1, 2010 A theoretical and experimental aeroelastic study of a typical airfoil section with control surface free play for nonzero angle of attack in low subsonic flow is presented. The study includes the flutter and limit cycle oscillation behavior and also the lin ... Full text Cite

Nonlinear aeroelastic study for folding wing structures

Journal Article AIAA Journal · January 1, 2010 A folding wing structure consisting of three components (a fuselage, an inboard wing, and an outboard wing) is modeled computationally using a geometrically nonlinear structural dynamics theory based upon von Kármán strains and a three-dimensional vortex l ... Full text Cite

Nonlinear gust response of a control surface with free-play

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2010 Computational and experimental studies are conducted to investigate nonlinear aeroelastic responses of a typical airfoil section with control surface free-play excited by gust loads with various initial pitch angles. The experimental study has been conduct ... Full text Cite

Using automatic differentiation to create a nonlinear reduced-order-model aerodynamic solver

Journal Article AIAA Journal · January 1, 2010 A novel nonlinear reduced-order-modeling technique for computational aerodynamics and aeroelasticity is presented. The method is based on a Taylor series expansion of a frequency-domain harmonic balance computational fluid dynamic solver residual. The firs ... Full text Cite

Efficient aeroelastic model updating in support of flight testing

Journal Article AIAA Atmospheric Flight Mechanics Conference · December 1, 2009 Efficient aeroelastic model updating is developed based upon flight data to better predict the aircraft aeroelastic response at next flight condition, e.g. higher Mach numbers or low altitudes. By incorporating flight test data and using the highest fideli ... Cite

Flutter/LCO suppression for high-aspect ratio wings

Journal Article Aeronautical Journal · January 1, 2009 An experimental high-aspect ratio wing aeroelastic model with a device to provide a controllable slender body tip mass distribution has been constructed and the model response due to flutter and limit cycle oscillations has been measured in a wind tunnel t ... Full text Cite

Comparison of theoretical structural models with experiment for a high-aspect-ratio aeroelastic wing

Journal Article Journal of Aircraft · January 1, 2009 The effects of the geometrical nonlinearities on the four lowest natural frequencies of a cantilevered high-altitude long-endurance (HALE)-type wings are studied. The total spar length, maximum width, thickness, step distribution, and step width are held c ... Full text Cite

Improved flutter boundary prediction for an isolated two-degree-of-freedom airfoil

Journal Article Journal of Aircraft · January 1, 2009 A novel method of computing the flutter boundary for an isolated airfoil based on a high-fidelity computational fluid dynamics model reveals unusual behavior in a critical transonic range. Inviscid and viscous predictions of the flutter boundary for the tw ... Full text Cite

Theoretical predictions of F-16 fighter limit cycle oscillations for flight flutter testing

Journal Article Journal of Aircraft · January 1, 2009 A computational investigation of the flutter onset and limit cycle oscillation behavior of various F-16 fighter weapons and stores configurations is presented. A nonlinear harmonic balance compressible Reynolds-averaged Navier-Stokes computational fluid dy ... Full text Cite

Unsteady flow computation using a harmonic balance approach implemented about the OVERFLOW 2 flow solver

Conference 19th AIAA Computational Fluid Dynamics Conference · January 1, 2009 A novel approach for implementing a nonlinear unsteady frequency domain harmonic balance solution technique about existing implicit computational fluid dynamic flow solvers is presented. This approach uses an explicit discretization of the harmonic balance ... Full text Cite

High dimensional harmonic balance analysis for dynamic piecewise aeroelastic systerms

Journal Article ASME International Mechanical Engineering Congress and Exposition, Proceedings · January 1, 2009 This paper describes the extension and application of a novel solution method for the periodic nonlinear oscillations of an aeroelastic system. This solution method is a very attractive alternative to time marching algorithms in that it is much faster and ... Cite

Continuum aeroelastic model for a folding-wing configuration

Journal Article AIAA Journal · January 1, 2009 An aeroelastic model and analytical solution methodology are developed to find the flutter solutions for the continuous representation of a two-segment uniform folding wing. The model is developed such that different parameters can be easily modified to ex ... Full text Cite

Reduced order models in unsteady aerodynamic models, aeroelasticity and molecular dynamics

Conference ICAS Secretariat - 26th Congress of International Council of the Aeronautical Sciences 2008, ICAS 2008 · December 1, 2008 The state of reduced order modeling of unsteady aerodynamic flows for the efficient calculation of fluid-structure interaction (aeroelasticity) is discussed as well as very recent work on olecular dynamics simulations. Starting with either a time domain or ... Cite

The high dimensional harmonic balance analysis for second-order delay-differential equations

Journal Article 2007 Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, DETC2007 · June 17, 2008 In this paper we demonstrate the utility of the High Dimensional Harmonic Balance (HDHB) method to compute periodic orbits of second-order delay-differential equations. In particular, the method has been successfully applied to capture the unstable limit c ... Full text Cite

Computationally fast harmonic balance methods for unsteady aerodynamic predictions of helicopter rotors

Conference Journal of Computational Physics · June 1, 2008 A harmonic balance technique for the analysis of unsteady flows about helicopter rotors in forward flight and hover is presented in this paper. The aerodynamics of forward flight are highly nonlinear, with transonic flow on the advancing blade, subsonic fl ... Full text Cite

Free vibration of a cantilevered beam with multiple steps: Comparison of several theoretical methods with experiment

Journal Article Journal of Sound and Vibration · May 20, 2008 The flexural-free vibration of a cantilevered beam with multiple cross-section steps is investigated theoretically and experimentally. Experimental results are compared against Euler-Bernoulli beam theory solutions from Rayleigh-Ritz and component modal an ... Full text Cite

Nonlinear Vibration

Journal Article · April 8, 2008 Full text Cite

Free vibrations of a linear structure with arbitrary support conditions

Journal Article Trans. ASME, E, J. Appl. Mech. (USA) · 2008 A method for the analysis of the free vibrations of a linear structure supported in an arbitrary way is presented based upon the use of the normal modes of the unsupported or unconstrained structure in a Rayleigh-Ritz analysis with the support or constrain ... Cite

Free vibrations of an arbitrary structure in terms of component modes

Journal Article Trans. ASME, E, J. Appl. Mech. (USA) · 2008 A method for the analysis of the free vibrations of an arbitrary structure in terms of component modes is presented based upon the use of the normal, free-free modes of the components in a Rayleigh-Ritz analysis with the constraint or continuity conditions ... Cite

Theoretical and experimental aeroelastic study for folding wing structures

Journal Article Journal of Aircraft · January 1, 2008 Folding wing aeroelastic experimental models have been designed and tested in the Duke wind tunnel. The folding wing structure is also modeled theoretically using linear plate theory and divided into three components: the fuselage, the inboard wing, and th ... Full text Cite

Delta wing with store limit-cycle-oscillation modeling using a high-fidelity structural model

Journal Article Journal of Aircraft · January 1, 2008 The flutter and limit-cycle oscillation behavior of a 45-deg delta-wing-store model with various store spanwise locations is studied using an aeroelastic model that includes a high-fidelity nonlinear finite element structural solver and a vortex-lattice ae ... Full text Cite

A new solution method for unsteady flows around oscillating bluff bodies

Journal Article Solid Mechanics and its Applications · January 1, 2008 Full text Cite

Supersonic indicial lift functions from transform methods

Journal Article AIAA Journal · August 1, 2007 An alternative method to evaluate the classical linear indicial lift of airfoil downwash distribution in supersonic flow, derive the indical lift functions, and reduce the transient lift to quadrature, is discussed. The transient at short times to steady-s ... Full text Cite

A high dimensional harmonic balance approach for an aeroelastic airfoil with cubic restoring forces

Journal Article Journal of Fluids and Structures · April 1, 2007 This is a study of a two-dimensional airfoil including a cubic spring stiffness placed in an incompressible flow. A new formulation of the harmonic balance method is employed for the aeroelastic airfoil to investigate the amplitude and frequency of the lim ... Full text Cite

Non-linear theory of unstable plane Poiseuille flow

Journal Article J. Fluid Mech. (UK) · 2007 A theoretical study of plane Poiseuille flow is made using the full non-linear Navier-Stokes equations. The mathematical technique employed is to use a Fourier decomposition in the streamwise spatial variable, a Galerkin expansion in the lateral variable a ... Cite

A novel harmonic balance analysis for the Van Der Pol oscillator

Journal Article International Journal Of Non-linear Mechanics · January 2007 This study focuses on a novel harmonic balance formulation, the high-dimensional harmonic balance method. To investigate a non-linearity in the damping term, the system chosen for study is the Van der Pol's oscillator. Both unforced and forced oscillators ... Cite

Aerodynamic loading for an airfoil with an oscillating gurney flap

Journal Article Journal of Aircraft · January 1, 2007 A study of aerodynamic loadings on a NACA 0012 airfoil with a static and an oscillating trailing-edge Gurney flap was made. The focus is on the experimental measurement of the static and dynamic-pressure distributions on the airfoil surface. The experiment ... Full text Cite

An investigation of the sensitivity of F-16 fighter flutter onset and limit cycle oscillations to uncertainties

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2006 A computational investigation of flutter onset and limit cycle oscillations of the F-16 fighter using a nonlinear frequency-domain harmonic-balance approach is presented. In this latest study, we examine the sensitivity of computed aeroelastic behavior to ... Cite

Experimental and theoretical study of gust response for a wing-store model with freeplay

Journal Article Journal of Sound and Vibration · August 22, 2006 An experimental delta wing/store model with freeplay in a periodic gust field has been designed and tested in the Duke wind tunnel. The wing structure is modeled theoretically using von Karman plate theory that accounts for geometric strain-displacement no ... Full text Cite

Reduced order nonlinear system identification methodology

Journal Article AIAA Journal · August 1, 2006 A new method is presented which enables the identification of a reduced order nonlinear ordinary differential equation (ODE) which can be used to model the behavior of nonlinear fluid dynamics. The method uses a harmonic balance technique and proper orthog ... Full text Cite

Complex dynamics of a pyranose ring structure molecule attached to an atomic force microscope

Journal Article Nonlinear Dynamics · August 1, 2006 Dynamic numerical simulations were performed for a pyranose ring structure molecule attached to an Atomic Force Microscope (AFM) using a standard semiempirical potential energy surface model. The fundamental static force-extension behavior was first determ ... Full text Cite

Flutter/limit cycle oscillation analysis and experiment for wing-store model

Journal Article AIAA Journal · July 1, 2006 A delta wing experimental model with an external store has been designed and tested in the Duke University wind tunnel. The wing structure is modeled theoretically by using von Kármán plate theory that allows for geometric strain-displacement nonlinearitie ... Full text Cite

Modal reduction of mathematical models of biological molecules

Journal Article Journal of Computational Physics · January 1, 2006 This paper reports a detailed study of modal reduction based on either linear normal mode (LNM) analysis or proper orthogonal decomposition (POD) for modeling a single α-d-glucopyranose monomer as well as a chain of monomers attached to a moving atomic for ... Full text Cite

Aerodynamic flow control of an airfoil with small trailing-edge strips

Journal Article Journal of Aircraft · January 1, 2006 The effects of small trailing-edge strips (Gurney flaps) on the steady and unsteady flow about a NACA0012 airfoil are computationally examined using a Navier-Stokes code, INS2D. Two Reynolds numbers, Re = 107,000 and 169,000, are used in the paper, the for ... Full text Cite

Flutter and limit-cycle oscillations for a wing-store model with freeplay

Journal Article Journal of Aircraft · January 1, 2006 An experimental delta-wing/store model with freeplay has been designed and tested in the Duke wind tunnel. The wing structure is modeled theoretically using von Kármán plate theory that accounts for geometric strain-displacement nonlinearities in the plate ... Full text Cite

A comparison of classical and high dimensional harmonic balance approaches for a Duffing oscillator

Journal Article J. Comput. Phys. (USA) · 2006 The present study focuses on a novel harmonic balance formulation, which is much easier to implement than the standard/classical harmonic balance method for complex nonlinear mathematical models and algorithms. Both harmonic balance approaches are applied ... Full text Link to item Cite

Static/dynamic correction approach for reduced-order modeling of unsteady aerodynamics

Journal Article Journal of Aircraft · 2006 Presented is a newly devised static/dynamic correction approach for eigenvector expansion based reduced-order modeling (ROM). When compared to the fundamental Ritz ROM formulation, along with the static and multiple static correction ROM approaches, the te ... Cite

Stochastic analysis of a nonlinear aeroelastic model using the response surface method

Journal Article Journal of Aircraft · January 1, 2006 An efficient method is presented for quantifying the effect of parametric uncertainty on the response of a nonlinear aeroelastic system. The proposal stochastic model uses a response surface method to map the random input parameters of the system to the sp ... Full text Cite

Modeling cylinder flow vortex shedding with enforced motion using a harmonic balance approach

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2006 In recent years, new aeromechanical problems have been encountered in turbomachinery. In particular, non-synchronous vibrations (NSV) in blades have been observed by engine companies and occur as a result of flow instabilities. As a first step towards bett ... Full text Cite

Using automatic differentiation to create a nonlinear reduced order model of a computational fluid dynamic solver

Conference Collection of Technical Papers - 11th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference · January 1, 2006 Presented is a technique for developing a nonlinear reduced order model of a computational fluid dynamic solver. The method is based on a Taylor series expansion of a frequency domain harmonic balance computational fluid dynamic solver residual. The comput ... Full text Cite

Further investigation of modeling limit cycle oscillation behavior of the F-16 fighter using a harmonic balance approach

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 19, 2005 A computational investigation of limit cycle oscillation behavior of the F-16 fighter configuration using a nonlinear frequency-domain harmonic-balance approach is presented. The research discussed in this latest paper is a follow-on to our work presented ... Cite

A reduced order system ID approach to the modelling of nonlinear structural behavior in aeroelasticity

Journal Article Journal of Fluids and Structures · December 1, 2005 A method is proposed for identifying a set of reduced order, nonlinear equations which describe the structural behavior of aeroelastic configurations. The strain energy of the system is written as a (polynomial) function of the structures' modal amplitudes ... Full text Cite

Special issue in honour of Professor Michael P. Païdoussis

Journal Article Journal of Fluids and Structures · December 1, 2005 Full text Cite

Experimental/theoretical correlation study of nonlinear aeroelasticity for a wing-store model with freeplay

Journal Article 3rd M.I.T. Conference on Computational Fluid and Solid Mechanics · December 1, 2005 A theoretical and experimental correlation study of flutter/limit cycle oscillation (LCO) and also response to a periodic gust excitation is made for a delta wing/store model with freeplay. The quantitative flutter/LCO correlation between the theory and ex ... Cite

Reduced order unsteady aerodynamic models and aeroelasticity

Conference 12th International Congress on Sound and Vibration 2005, ICSV 2005 · December 1, 2005 The state of reduced order modeling of unsteady aerodynamic flows for the efficient calculation of fluid-structure interaction (aeroelasticity) is discussed. Reduced order modeling is a set of conceptually novel and computationally efficient techniques for ... Cite

A modern course in aeroelasticity

Book · December 1, 2005 Cite

Hopf-flip bifurcation of high dimensional maps and application to vibro-impact systems

Journal Article Acta Mechanica Sinica/Lixue Xuebao · August 1, 2005 This paper addresses the problem of Hopf-flip bifurcation of high dimensional maps. Using the center manifold theorem, we obtain a three dimensional reduced map through the projection technique. The reduced map is further transformed into its normal form w ... Full text Cite

Modeling delta wing limit-cycle oscillations using a high-fidelity structural model

Journal Article Journal of Aircraft · January 1, 2005 Flutter and limit-cycle oscillations(LCO) of a delta-wing model are studied theoretically and correlated with results from an earlier experiment and an earlier simpler theoretical model. The present theoretical model uses a high-fidelity nonlinear structur ... Full text Cite

Enhanced nonlinear dynamics for accurate identification of stiffness loss in a thermo-shielding panel

Journal Article Nonlinear Dynamics · January 1, 2005 The dynamics of a panel forced by transverse loads and undergoing limit cycle oscillations and chaos is investigated. The nonlinear von Karman plate theory is used to obtain a model for healthy and damaged panels. Damage is modeled by a loss of stiffness i ... Full text Cite

Nonlinear: Introduction

Journal Article Nonlinear Dynamics · 2005 Full text Link to item Cite

Worst-case gust-response analysis for typical airfoil section with control surface

Journal Article Journal of Aircraft · January 1, 2005 This paper determines the worst-case gust response of a typical airfoil section with a control surface. Matched filter theory is employed in order to compute the gust that produces a maximum response. These results are compared with a tuned one-minus-cosin ... Full text Cite

Harmonic balance approach for an airfoil with a freeplay control surface

Journal Article AIAA Journal · January 1, 2005 The nonlinear aeroelastic response of a two-dimensional airfoil, including a control surface with freeplay placed in an incompressible flow, is studied. The model equations are formulated as a set of first-order ordinary differential equations. First, the ... Full text Cite

Discrete adjoint approach for modeling unsteady aerodynamic design sensitivities

Journal Article AIAA Journal · 2005 A discrete adjoint approach is presented for computing steady and unsteady aerodynamic design sensitivities for compressible viscous flows about airfoil configurations. The nominal flow solver method is based on a harmonic balance solution technique, which ... Cite

A reduced order system ID approach to the modeling of nonlinear structural behavior in aeroelasticity

Journal Article Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - DETC2005 · January 1, 2005 A method is proposed for identifying a set of reduced order, nonlinear equations which describe the structural behavior of aeroelastic configurations. The strain energy of the system is written as a (polynomial) function of the structures' modal amplitudes ... Full text Cite

Computational models for nonlinear aeroelasticity

Conference 43rd AIAA Aerospace Sciences Meeting and Exhibit - Meeting Papers · January 1, 2005 Two distinctly different reduced-order models are formulated for fully nonlinear aeroelastic systems. The first is based on Proper Orthogonal Decomposition (POD). The velocity field is decomposed into a finite number of orthonormal modes, effecting order r ... Full text Cite

Modal reduction of mathematical models of biological molecules

Journal Article Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - DETC2005 · January 1, 2005 This paper reports a detailed study of modal reduction based on either linear normal mode(LNM) analysis or proper orthogonal decomposition(POD) for modeling a single α-D glucopyranose monomer as well as a chain of monomers. Also a modal reduction method co ... Full text Cite

A stochastic analysis of the limit cycle behavior of a nonlinear aeroelastic model using the response surface method

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2005 An efficient method is presented for quantifying the effect of parametric uncertainty on the response of a nonlinear aeroelastic system. The proposed stochastic model uses a response surface method to map the random input parameters of the system to the sp ... Full text Cite

Higher order harmonic balance analysis for limit cycle oscillations in an airfoil with cubic restoring forces

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2005 This is a study of a two dimensional airfoil including a cubic spring stiffness placed in an incompressible flow. A new formulation of the harmonic balance method is employed for the aeroelastic airfoil to investigate the amplitude and frequency of the lim ... Full text Cite

Modeling the LCO of a delta wing with an external store using a high fidelity structural model

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2005 The flutter and limit cycle oscillation(LCO) behavior of a 45 degree delta wing-store model, with various store spanwise locations, is studied using an aeroelastic model which includes a high fidelity, nonlinear finite element structural solver and a vorte ... Full text Cite

Reduced order dynamic model for polysaccharides molecule attached to an atomic force microscope

Journal Article Journal of Computational Physics · December 10, 2004 A dynamic analysis and numerical simulation has been conducted of a polysaccharides molecular structure (a ten (10) single-α-D-glucose molecule chain) connected to a moving atomic force microscope (AFM). Sinusoidal base excitation of the AFM cantilevered b ... Full text Cite

Nonlinear dynamics of very high dimensional fluid-structural systems

Journal Article Fluid Mechanics and its Applications · December 1, 2004 The dynamics of mechanical systems of high dimension or many degrees of freedom will be discussed. The modeling of both fluid and structural systems will be considered with special emphasis given to fluid-structural or aeroelastic systems. Novel and effect ... Full text Cite

Modeling limit cycle oscillation behavior of the F-16 fighter using a harmonic balance approach

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 2004 A computational investigation of limit cycle oscillation behavior of the F-16 fighter configuration using a nonlinear frequency-domain harmonic-balance approach is presented. Computed limit cycle response results correlate well with experiment. Details of ... Cite

Asymptotic modal analysis of dynamical systems: The effect of modal cross-correlation

Journal Article Journal of Sound and Vibration · September 6, 2004 Asymptotic modal analysis (AMA) has been shown to be a useful approximation and valid limiting case for classical modal analysis (CMA) when the number of resonant modes in a frequency bandwidth becomes sufficiently large and the cross-correlation between r ... Full text Cite

Reduced order model analysis for two-dimensipnal molecular dynamic chain structure attached to an atomic force microscope

Journal Article Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME · September 1, 2004 Dynamic analysis and numerical simulation of a protein-ligand chain structure connected to a moving atomic force microscope (AFM) has been conducted. The elements of the chain are free to extend and rotate relative to each other in a two-dimensional plane. ... Full text Cite

The secondary bifurcation of an aeroelastic airfoil motion: Effect of high harmonics

Journal Article Nonlinear Dynamics · July 1, 2004 The nonlinear dynamical response of a two-degree-of-freedom aeroelastic airfoil motion with cubic restoring forces is investigated. A secondary bifurcation after the primary Hopf (flutter) bifurcation is detected for a cubic hard spring in the pitch degree ... Full text Cite

Transient response study on rolling effectiveness of multiple control surfaces

Journal Article Journal of Fluids and Structures · June 1, 2004 A study of the effectiveness of trailing- and leading-edge control surfaces has been made for a rolling wing-fuselage model. An experimental model and wind tunnel test are used to assess the theoretical results. The theoretical model includes the inherentl ... Full text Cite

Study of airfoil gust response alleviation using an electro-magnetic dry friction damper. Part 1: Theory

Journal Article Journal of Sound and Vibration · January 22, 2004 An electro-magnetic controllable dry friction damper has been designed and numerically simulated. The gust response of a three degree-of-freedom typical airfoil section with a control surface using this non-linear damper has been studied theoretically. The ... Full text Cite

Study of airfoil gust response alleviation using an electro-magnetic dry friction damper. Part 2: Experiment

Journal Article Journal of Sound and Vibration · January 22, 2004 In Part 1 of this work, a theoretical simulation study of the non-linear gust response of a three degree-of-freedom typical airfoil section with a control surface using an electro-magnetic dry friction damper is presented. For validation of this theoretica ... Full text Cite

Limit-cycle oscillations of a typical airfoil in transonic flow

Journal Article Journal of Aircraft · 2004 Using an inviscid flow computational-fluid-dynamic model and a harmonic balance flow solver, a parametric investigation of how structural-inertial parameters and freestream Mach number of a transonic flow affect the limit-cycle oscillation characteristics ... Cite

Effects of geometric structural nonlinearity of flutter and limit cycle oscillations of high-aspect-ratio wings

Journal Article Journal of Fluids and Structures · January 1, 2004 In this paper structural equations of motion based on nonlinear beam theory and the ONERA aerodynamic stall model are used to study the effects of geometric structural nonlinearity on flutter and limit cycle oscillations (LCO) of high-aspect-ratio wings. F ... Full text Cite

Dynamic analysis of a protein-ligand molecular chain attached to an atomic force microscope

Journal Article Journal of Vibration and Acoustics · January 1, 2004 Dynamic numerical simulation of a protein-ligand molecular chain connected to a moving atomic force microscope (AFM) has been studied. A sinusoidal base excitation of the cantilevered beam of the AFM is considered in some detail. A comparison between resul ... Full text Cite

Transonic limit cycle oscillation analysis using reduced order aerodynamic models

Journal Article Journal of Fluids and Structures · 2004 Limit cycle oscillations have been observed in flight operations of modern aircraft, wind tunnel experiments and mathematical models. Both fluid and structural nonlinearities are thought to contribute to these phenomena. With recent advances in reduced ord ... Full text Link to item Cite

Modeling viscous transonic limit-cycle oscillation behavior using a harmonic balance approach

Journal Article Journal of Aircraft · 2004 Presented is a harmonic-balance computational fluid dynamic approach for modeling limit-cycle oscillation behavior of aeroelastic airfoil configurations in a viscous transonic flow. For the NLR 7301 airfoil configuration studied, accounting for viscous eff ... Cite

Improved understanding of transonic flutter: A three-parameter flutter surface

Journal Article Journal of Aircraft · 2004 An understanding of transonic flutter is often critical for high-speed aircraft development. A presentation of the transonic flutter velocity as a function of the Mach number and mass ratio is shown here to provide many advantages. Such a presentation offe ... Cite

Modeling the LCO of a delta wing using a high fidelity structural model

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2004 Flutter and limit cycle oscillations(LCO) of a delta wing model are studied theoretically and correlated with results from an earlier experiment and an earlier simpler theoretical model. The present theoretical model uses a high fidelity nonlinear structur ... Full text Cite

A discrete adjoint approach for modeling unsteady aerodynamic design sensitivities

Conference 41st Aerospace Sciences Meeting and Exhibit · December 1, 2003 Presented is a discrete adjoint approach for computing steady and unsteady aerodynamic design sensitivities for compressible viscous flows about airfoil configurations. The nominal flow solver method is based on a harmonic balance solution technique, which ... Cite

A harmonic balance approach for modeling nonlinear aeroelastic behavior of wings in transonic viscous flow

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 Presented is a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach for modeling flutter onset and limit cycle oscillation (LCO) behavior of viscous transonic aeroelastic wing configurations. The AGARD 445.6 transonic wing conf ... Cite

Modeling limit cycle oscillations for an NLR 7301 airfoil aeroelastic configuration including correlation with experiment

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 Presented is an investigation into the modeling of limit cycle oscillation (LCO) behavior of an experimental transonic airfoil aeroelastic configuration using a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach. The aeroelas ... Cite

Gust alleviation using an electro-magnetic dry friction damper

Journal Article 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 An electro-magnetic controllable dry friction damper has been designed and numerically simulated. The gust response of a three degree-of-freedom typical airfoil section with a control surface using this nonlinear damper has been studied theoretically. The ... Cite

Nonlinear aeroelasticity

Journal Article 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 Nonlinear aeroelasticity is a subject of high interest and activity. In this paper the authors aim is to provide a faithful account of the topic with an emphasis on key ideas and results which demonstrate our community's current theoretical, computational ... Cite

Modeling aerodynamic nonlinearities for two aeroelastic configurations: Delta wing and flapping flag

Journal Article 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · December 1, 2003 The flutter and limit cycle oscillation(LCO) behavior of two aeroelastic configurations, a delta wing model and a flapping flag model, are studied theoretically and the results are compared to experiment. The theoretical model uses a nonlinear aerodynamic ... Cite

A harmonic balance approach for modeling nonlinear aeroelastic behavior of wings in transonic viscous flow

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · August 28, 2003 Presented is a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach for modeling flutter onset and limit cycle oscillation (LCO) behavior of viscous transonic aeroelastic wing configurations. The AGARD 445.6 transonic wing conf ... Cite

Multiscale, multiphenomena modeling and simulation at the nanoscale: On constructing reduced-order models for nonlinear dynamical systems with many degrees-of-freedom

Journal Article Journal of Applied Mechanics, Transactions ASME · May 1, 2003 The large number of degrees-of-freedom of finite difference, finite element, or molecular dynamics models for complex systems is often a significant barrier to both efficient computation and increased understanding of the relevant phenomena. Thus there is ... Full text Cite

Flutter and limit cycle oscillations of two-dimensional panels in three-dimensional axial flow

Journal Article Journal of Fluids and Structures · February 1, 2003 Experimental flutter and limit cycle oscillations (LCO) of two-dimensional elastic plates in three-dimensional axial flow were observed. The plate is clamped at its leading edge and free at its trailing edge, i.e., it is a "flag" albeit one dominated by it ... Full text Cite

A theoretical and experimental investigation of the effects of a steady angle of attack on the nonlinear flutter of a delta wing plate model

Journal Article Journal of Fluids and Structures · February 1, 2003 Limit cycle oscillations (LCO) of wings on certain modern high performance aircraft have been observed in flight and in wind tunnel experiments. Whether the physical mechanism that gives rise to this behavior is a fluid or structural nonlinearity or both i ... Full text Cite

Modeling aerodynamic nonlinearities for two aeroelastic configurations: Delta wing and flapping flag

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2003 Full text Cite

A discrete adjoint approach for modeling unsteady aerodynamic design sensitivities

Conference 41st Aerospace Sciences Meeting and Exhibit · January 1, 2003 Presented is a discrete adjoint approach for computing steady and unsteady aerodynamic design sensitivities for compressible viscous flows about airfoil configurations. The nominal flow solver method is based on a harmonic balance solution technique, which ... Full text Cite

Nonlinear aeroelasticity

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · January 1, 2003 Nonlinear aeroelasticity is a subject of high interest and activity. In this paper the authors aim is to provide a faithful account of the topic with an emphasis on key ideas and results which demonstrate our community's current theoretical, computational ... Full text Cite

A harmonic balance approach for modeling nonlinear aeroelastic behavior of wings in transonic viscous flow

Conference 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference · January 1, 2003 Presented is a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach for modeling flutter onset and limit cycle oscillation (LCO) behavior of viscous transonic aeroelastic wing configurations. The AGARD 445.6 transonic wing conf ... Full text Cite

Today's ephemera, tomorrow's historical documentation: access options for artists files

Journal Article J. Libr. Adm. (USA) · 2003 Comprised of everything from newspaper clippings to exhibition catalogues and photographs, the artists file is perhaps one of the most under-utilized resources in an art library. Options for providing access to artists files range from simple Web-based lis ... Full text Link to item Cite

Compact methodology for computing limit-cycle oscillations in aeroelasticity

Journal Article Journal of Aircraft · January 1, 2003 A technique for computing limit-cycle oscillations of aeroelastic systems is presented. This technique can be used also for constructing and identifying reduced-order models that characterize accurately limit-cycle oscillations. The models presented use a ... Full text Cite

Parametric study of flutter for an airfoil in inviscid transonic flow

Journal Article Journal of Aircraft · 2003 A parametric study of flutter was conducted for an airfoil in inviscid transonic flow. An inviscid computational flow dynamic harmonic balance aerodynamic-Euler-based code was used for the investigation. The computational efficiency of the time-linearized ... Cite

Three-dimensional transonic aeroelasticity using proper orthogonal decomposition-based reduced-order models

Journal Article Journal of Aircraft · 2003 The proper orthogonal decomposition (POD-) based reduced-order modeling technique for modeling unsteady frequency-domain aerodynamics is developed for a large-scale computational model of an inviscid flow transonic wing configuration. When the methodology ... Cite

Localized basis function method for computing limit cycle oscillations

Journal Article Nonlinear Dynamics · January 1, 2003 An alternate approach to the standard harmonic balance method (based on Fourier transforms) is proposed. The proposed method begins with an idea similar to the harmonic balance method, i.e. to transform the initial set of differential equations of the dyna ... Full text Cite

Reduced Order Model Analysis For Two Dimensional Molecular Dynamic Chain Structure Attached To An Atomic Force Microscope

Journal Article American Society of Mechanical Engineers, Design Engineering Division (Publication) DE · January 1, 2003 Dynamic analysis and numerical simulation of a protein-ligand chain structure connected to a moving atomic force microscope (AFM) has been conducted. The elements of the chain are free to extend and rotate relative to each other in a two-dimensional plane. ... Full text Cite

Experimental and theoretical study on rolling effectiveness of multiple control surfaces

Journal Article AIAA Journal · January 1, 2003 It is well known that the effectiveness of a trailing-edge control surface can be substantially diminished due to the elastic twist of an airfoil or rolling wing. This aeroelastic phenomenon is known as control surface reversal when the lift or rolling rat ... Full text Cite

Aeroelastic wing with leading- and trailing-edge control surfaces

Journal Article Journal of Aircraft · January 1, 2003 It is well known that the effectiveness of a trailing-edge control surface can be substantially diminished due to the elastic twist of an airfoil or wing. This aeroelastic phenomenon is known as control surface reversal when the lift or roll rate vanishes ... Full text Cite

Nonlinear aeroelasticity

Journal Article Journal of Aircraft · January 1, 2003 Substantial progress has been made in modeling and understanding nonlinear aeroelastic phenomena. Experimental and theoretical investigations have shown good correlation for a number of nonlinear physical mechanisms. A number of physical mechanisms can lea ... Full text Cite

Theoretical/experimental study of gust alleviation using an electro-magnetic dry friction damper

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2003 An electro-magnetic controllable dry friction damper has been designed and numerically simulated. The gust response of a three degree-of-freedom typical airfoil section with a control surface using this nonlinear damper has been studied theoretically. The ... Full text Cite

Modeling limit cycle oscillations for an NLR 7301 airfoil aeroelastic configuration including correlation with experiment

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2003 Presented is an investigation into the modeling of limit cycle oscillation (LCO) behavior of an experimental transonic airfoil aeroelastic configuration using a frequency-domain harmonic-balance (HB) computational fluid dynamic (CFD) approach. The aeroelas ... Full text Cite

Nonlinear aeroelasticity

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2003 Nonlinear aeroelasticity is a subject of high interest and activity. In this paper the authors aim is to provide a faithful account of the topic with an emphasis on key ideas and results which demonstrate our community's current theoretical, computational ... Full text Cite

Nonlinear aeroelasticity and unsteady aerodynamics

Journal Article 40th AIAA Aerospace Sciences Meeting and Exhibit · December 1, 2002 In this first Von Karman Lecture of the twenty first century, a subject is addressed whose foundations were significantly influenced by the work of Theodore Von Karman. A classic paper by Von Karman and Sears first considered the determination of aerodynam ... Cite

Limit cycle oscillations of two-dimensional panels in low subsonic flow

Journal Article International Journal of Non-Linear Mechanics · October 1, 2002 Limit cycle oscillations of a two-dimensional panel in low subsonic flow have been studied theoretically and experimentally. The panel is clamped at its leading edge and free at its trailing edge. A structural non-linearity arises in both the bending stiff ... Full text Cite

The stability of limit-cycle oscillations in a nonlinear aeroelastic system

Journal Article Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences · September 8, 2002 The effects of a freeplay structural nonlinearity on an aeroelastic system are studied experimentally. Particular attention is paid to the stability of a periodic nonlinear aeroelastic response, known as limit-cycle oscillations (LCOs). The major thrust of ... Full text Cite

Nonlinear aeroelasticity and unsteady aerodynamics

Conference 40th AIAA Aerospace Sciences Meeting and Exhibit · January 1, 2002 In this first Von Karman Lecture of the twenty first century, a subject is addressed whose foundations were significantly influenced by the work of Theodore Von Karman. A classic paper by Von Karman and Sears first considered the determination of aerodynam ... Full text Cite

Mach number influence on reduced-order models of inviscid potential flows in turbomachinery

Journal Article Trans. ASME, J. Fluids Eng. (USA) · 2002 An unsteady inviscid flow through a cascade of oscillating airfoils is investigated. An inviscid nonlinear subsonic and transonic model is used to compute the steady flow solution. Then a small amplitude motion of the airfoils about their steady flow confi ... Full text Link to item Cite

Nonlinear aeroelasticity and unsteady aerodynamics

Journal Article AIAA Journal · January 1, 2002 In this von Kármán lecture, a subject is addressed whose foundations were significantly influenced by the work of Theodore von Kármán. A classic paper by von Kármán and Sears first considered the determination of aerodynamic forces on an airfoil undergoing ... Full text Cite

Time-tested survival skills for a publish or perish environment

Journal Article Journal of Engineering Education · January 1, 2002 There are several time-tested survival skills to consider when plotting a course to tenure in a "publish or perish" environment. These are: choosing an institution that matches your expectations, abilities, and goals; knowing what to expect (and avoid) onc ... Full text Cite

Limit-cycle hysteresis response for a high-aspect-ratio wing model

Journal Article Journal of Aircraft · January 1, 2002 An experimental high-aspect-ratio wing aeroelastic model with a slender body at the tip has been constructed, and the response due to flutter and limit-cycle oscillations (LCOs) has been measured in a wind-tunnel test. A theoretical model has been develope ... Full text Cite

System identification of a vortex lattice aerodynamic model

Journal Article AIAA Journal · January 1, 2002 The state-space representation of an aerodynamic vortex lattice model is considered from a classical, system identification perspective. By the use of an aerodynamic vortex model as a numerical simulator of a wind-tunnel experiment, both full-state and lim ... Full text Cite

Experimental and theoretical study of gust response for high-aspect-ratio wing

Journal Article AIAA Journal · January 1, 2002 A nonlinear response analysis of a high-aspect-ratio wing aeroelastic model excited by gust loads is presented along with a companion wind-tunnel test program. For the wind-tunnel tests, a high-aspect-ratio wing aeroelastic experimental model with a slende ... Full text Cite

Nonlinear inviscid aerodynamic effects on transonic divergence, flutter, and limit-cycle oscillations

Journal Article AIAA Journal · 2002 By the use of a state-of-the-art computational fluid dynamic (CFD) method to model nonlinear steady and unsteady transonic flows in conjunction with a linear structural model, an investigation is made into how nonlinear aerodynamics can effect the divergen ... Cite

Transient response study on rolling effectiveness of multiple control surfaces

Journal Article ASME International Mechanical Engineering Congress and Exposition, Proceedings · January 1, 2002 In the present paper, a transient response study of the effectiveness of trailing and leading edge control surfaces has been made for a rolling wing-fuselage model. An experimental model and wind tunnel test are used to assess the theoretical results. The ... Full text Cite

Effects of steady angle of attack on nonlinear gust response of a delta wing model

Journal Article Journal of Fluids and Structures · January 1, 2002 The effects of a steady angle of attack on the nonlinear aeroelastic response of a delta wing model to a periodic gust have been studied. For the theoretical analysis, a three-dimensional time-domain vortex lattice aerodynamic model and a reduced order aer ... Full text Cite

A harmonic balance approach for modeling three-dimensional nonlinear unsteady aerodynamics and aeroelasticity

Conference ASME International Mechanical Engineering Congress and Exposition, Proceedings · January 1, 2002 Presented is a frequency domain harmonic balance (HB) technique for modeling nonlinear unsteady aerodynamics of three-dimensional transonic inviscid flows about wing configurations. The method can be used to model efficiently nonlinear unsteady aerodynamic ... Full text Cite

Modeling viscous transonic limit cycle oscillation behavior using a harmonic balance approach

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2002 Presented is a harmonic-balance (HB) computational fluid dynamic (CFD) approach for modeling limit cycle oscillation (LCO) behavior of aeroelastic airfoil configurations in a viscous transonic flow. For the NLM 7301 airfoil configuration studied, accountin ... Full text Cite

A parameter study of transonic airfoil flutter and limit cycle oscillation behavior

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2002 A parameter study of transonic airfoil flutter and limit cycle oscillation (LCO) behavior was presented. The effect of structural parameters and freestream Mach number of a transonic flow on the flutter and LCO was found out using inviscid computational fl ... Cite

Transonic limit cycle oscillation analysis using reduced order aerodynamic models

Conference 19th AIAA Applied Aerodynamics Conference · December 1, 2001 Limit cycle oscillations have been observed in flight operations of modern aircraft, wind tunnel experiments and mathematical models. Both fluid and structural nonlinearities are thought to contribute to these phenomena. With recent advances in reduced ord ... Cite

Characterizing aeroelastic systems using eigenanalysis, explicitly retaining the aerodynamic degrees of freedom

Journal Article 19th AIAA Applied Aerodynamics Conference · December 1, 2001 Discrete time aeroelastic models with explicitly retained aerodynamic modes have been generated employing a time marching vortex lattice aerodynamic model. This paper presents analytical results from eigenanalysis of these models. The potential of these mo ... Cite

Three-Dimensional transonic Aeroelasticity using proper orthogonal decomposition based reduced order models

Conference 19th AIAA Applied Aerodynamics Conference · December 1, 2001 The proper orthogonal decomposition (POD) based reduced order modeling (ROM) technique for modeling unsteady frequency domain aerodynamics is developed for a large scale computational model of an inviscid flow transonic wing configuration. Using the method ... Cite

Nonlinear inviscid aerodynamic effects on transonic divergence, flutter and limit cycle oscillations

Conference 19th AIAA Applied Aerodynamics Conference · December 1, 2001 Using a state of the art computational fluid dynamic (CFD) method to model nonlinear steady and unsteady transonic flows in conjunction with a linear structural model, an investigation is made into how nonlinear aerodynamics can effect the divergence, flut ... Cite

A static/dynamic correction approach for reduced-order modeling of unsteady aerodynamics

Conference 39th Aerospace Sciences Meeting and Exhibit · December 1, 2001 Presented is a newly devised static/dynamic correction approach for eigenvector expansion based reduced-order modeling (ROM). When compared to the fundamental Ritz ROM formulation, along with the static and multiple static correction ROM approaches, the te ... Cite

Mathematical model of a nanopaddle oscillator

Journal Article Journal of Applied Physics · December 1, 2001 A model of a nanopaddle oscillator is developed to determine the resonant frequency (or the modulus of elasticity by inference from a measurement of the resonant frequency). Also modeled is the nonlinear stiffness of the oscillator and its nonlinear respon ... Full text Cite

A parametric analysis of reduced order models of potential flows in turbomachinery using proper orthogonal decomposition

Conference Proceedings of the ASME Turbo Expo · January 1, 2001 An unsteady inviscid flow through a cascade of oscillating airfoils is investigated. An inviscid nonlinear subsonic and transonic model is used to compute the steady flow solution. Then a small amplitude motion of the airfoils about their steady flow confi ... Full text Cite

Three-Dimensional transonic Aeroelasticity using proper orthogonal decomposition based reduced order models

Conference 19th AIAA Applied Aerodynamics Conference · January 1, 2001 The proper orthogonal decomposition (POD) based reduced order modeling (ROM) technique for modeling unsteady frequency domain aerodynamics is developed for a large scale computational model of an inviscid flow transonic wing configuration. Using the method ... Full text Cite

Transonic limit cycle oscillation analysis using reduced order aerodynamic models

Conference 19th AIAA Applied Aerodynamics Conference · January 1, 2001 Limit cycle oscillations have been observed in flight operations of modern aircraft, wind tunnel experiments and mathematical models. Both fluid and structural nonlinearities are thought to contribute to these phenomena. With recent advances in reduced ord ... Full text Cite

Nonlinear inviscid aerodynamic effects on transonic divergence, flutter and limit cycle oscillations

Conference 19th AIAA Applied Aerodynamics Conference · January 1, 2001 Using a state of the art computational fluid dynamic (CFD) method to model nonlinear steady and unsteady transonic flows in conjunction with a linear structural model, an investigation is made into how nonlinear aerodynamics can effect the divergence, flut ... Full text Cite

Characterizing aeroelastic systems using eigenanalysis, explicitly retaining the aerodynamic degrees of freedom

Conference 19th AIAA Applied Aerodynamics Conference · January 1, 2001 Discrete time aeroelastic models with explicitly retained aerodynamic modes have been generated employing a time marching vortex lattice aerodynamic model. This paper presents analytical results from eigenanalysis of these models. The potential of these mo ... Full text Cite

A static/dynamic correction approach for reduced-order modeling of unsteady aerodynamics

Conference 39th Aerospace Sciences Meeting and Exhibit · January 1, 2001 Presented is a newly devised static/dynamic correction approach for eigenvector expansion based reduced-order modeling (ROM). When compared to the fundamental Ritz ROM formulation, along with the static and multiple static correction ROM approaches, the te ... Full text Cite

System identification and proper orthogonal decomposition method applied to unsteady aerodynamics

Journal Article AIAA Journal · January 1, 2001 The representation of unsteady aerodynamic flowfields in terms of global aerodynamic modes has proven to be a useful method for reducing the size of the aerodynamic model over those representations that use local variables at discrete grid points in the fl ... Full text Cite

Experimental and theoretical study on aeroelastic response of high-aspect-ratio wings

Journal Article AIAA Journal · January 1, 2001 An experimental high-aspect-ratio wing aeroelastic model with a slender body at the tip has been constructed, and the response due to flutter and limit-cycle oscillations (LCO) has been measured in a wind-tunnel test. A theoretical model has been developed ... Full text Cite

Modeling of fluid-structure interaction

Journal Article Annual Review of Fluid Mechanics · 2001 The interaction of a flexible structure with a flowing fluid in which it is submersed or by which it is surrounded gives rise to a rich variety of physical phenomena with applications in many fields of engineering, for example, the stability and response o ... Full text Link to item Cite

Effects of angle of attack on nonlinear flutter of a delta wing

Journal Article AIAA journal · January 1, 2001 Limit cycle oscillations (LCOs) have been observed in flight for certain modern high-performance aircraft. The nonlinear physical mechanism responsible for the LCOs is still in doubt, even to the point of it not yet being determined whether the nonlinearit ... Full text Cite

Three-dimensional transonic aeroelasticity using proper orthogonal decomposition based reduced order models

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2001 The proper orthogonal decomposition (POD) based reduced order modeling (ROM) technique for modeling unsteady frequency domain aerodynamics is developed for a large scale computational model of an inviscid flow transonic wing configuration. Using the method ... Cite

Transonic limit cycle oscillation analysis using reduced order aerodynamic models

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2001 Limit cycle oscillations have been observed in flight operations of modern aircraft, wind tunnel experiments and mathematical models. Both fluid and structural nonlinearities are thought to contribute to these phenomena. With recent advances in reduced ord ... Cite

Reduced-order models of unsteady viscous flows in turbomachinery using viscous-inviscid coupling

Journal Article Journal of Fluids and Structures · January 1, 2001 The proper orthogonal decomposition technique is applied in the frequency domain to obtain a reduced-order model of the flow in a turbomachinery cascade. The flow is described by an inviscid-viscous interaction model where the inviscid part is described by ... Full text Cite

Nonlinear inviscid aerodynamic effects on transonic divergence, flutter and limit cycle oscillations

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2001 Using a state of the art computational fluid dynamic (CFD) method to model nonlinear steady and unsteady transonic flows in conjunction with a linear structural model, an investigation is made into how nonlinear aerodynamics can effect the divergence, flut ... Cite

Effects of steady angle of attack on nonlinear flutter of a delta wing plate model

Journal Article American Society of Mechanical Engineers, Applied Mechanics Division, AMD · December 1, 2000 Limit cycle oscillations(LCO) have been observed in flight for certain modern high performance aircraft. The nonlinear physical mechanism responsible for the LCO is still in doubt, even to the point of it not yet being determined whether the nonlinearity i ... Cite

Characterizing stability of responses in a nonlinear aeroelastic system

Journal Article 41st Structures, Structural Dynamics, and Materials Conference and Exhibit · December 1, 2000 A method for investigating the degree of stability of nonlinear limit cycle oscillations (LCO) observed in an aeroelastic system is presented. The system considered is a typical section airfoil model with a free-play nonlinear-ity in the control surface st ... Cite

Nonlinear aeroelastic response of a typical airfoil section with control surface freeplay

Journal Article 41st Structures, Structural Dynamics, and Materials Conference and Exhibit · December 1, 2000 A nonlinear response analysis of a typical airfoil section with control surface freeplay excited by periodic gust loads in low subsonic flow is presented along with a companion wind tunnel test program. The analytical model uses Peters' finite state model ... Cite

Untitled

Journal Article AEROSPACE AMERICA · September 1, 2000 Link to item Cite

Optimal multi-dimensional OGY controller

Journal Article Physica D: Nonlinear Phenomena · May 1, 2000 A technique which generalizes the standard OGY control scheme and may be applied to higher dimensional systems to stabilize both saddle nodes and fully unstable fixed points is presented. The proposed method is designed for nonlinear flows rather than maps ... Full text Cite

Characterizing stability of responses in a nonlinear aeroelastic system

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2000 A method for investigating the degree of stability of nonlinear limit cycle oscillations (LCO) observed in an aeroelastic system is presented. The system considered is a typical section airfoil model with a free-play nonlinearity in the control surface sti ... Cite

Nonlinear aeroelastic response of a typical airfoil section with control surface freeplay

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 2000 A nonlinear response analysis of a typical airfoil section with control surface freeplay excited by periodic gust loads in low subsonic flow is presented along with a companion wind tunnel test program. The analytical model uses Peters' finite state model ... Cite

Nonlinear aeroelastic response of a typical airfoil section with control surface freeplay

Conference 41st Structures, Structural Dynamics, and Materials Conference and Exhibit · January 1, 2000 A nonlinear response analysis of a typical airfoil section with control surface freeplay excited by periodic gust loads in low subsonic flow is presented along with a companion wind tunnel test program. The analytical model uses Peters' finite state model ... Full text Cite

Characterizing stability of responses in a nonlinear aeroelastic system

Conference 41st Structures, Structural Dynamics, and Materials Conference and Exhibit · January 1, 2000 A method for investigating the degree of stability of nonlinear limit cycle oscillations (LCO) observed in an aeroelastic system is presented. The system considered is a typical section airfoil model with a free-play nonlinear-ity in the control surface st ... Full text Cite

Effects of steady angle of attack on nonlinear flutter of a delta wing plate model

Conference ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) · January 1, 2000 Limit cycle oscillations(LCO) have been observed in flight for certain modern high performance aircraft. The nonlinear physical mechanism responsible for the LCO is still in doubt, even to the point of it not yet being determined whether the nonlinearity i ... Full text Cite

The Influence of a Nonzero Angle of Attack and Gust Loads on the Nonlinear Response of a Typical Airfoil Section with a Control Surface Freeplay

Journal Article International Journal of Nonlinear Sciences and Numerical Simulation · January 1, 2000 The influence of a "frozen" harmonic gust excitation on an aeroelastic nonlinear system with a control surface freeplay at nonzero angles of attack is examined in the context of a three-degree-of-freedom airfoil. The formulation of the numerical model is b ... Full text Cite

Nonlinear aeroelastic response of delta wing to periodic gust

Journal Article Journal of Aircraft · January 1, 2000 A nonlinear response analysis of a simple delta wing excited by periodic gust loads in low subsonic flow is presented along with a companion wind-tunnel test program. The analytical model uses a three-dimensional time-domain vortex lattice aerodynamic meth ... Full text Cite

Eigenmode analysis and reduced-order modeling of unsteady transonic potential flow around airfoils

Journal Article Journal of Aircraft · 2000 An eigenmode analysis and reduced-order models of the unsteady transonic aerodynamic flow around isolated airfoils are presented. The unsteady flow is modeled using the time-linearized frequency-domain unsteady transonic full potential equation. The full p ... Cite

Proper orthogonal decomposition technique for transonic unsteady aerodynamic flows

Journal Article AIAA Journal · 2000 A new method for constructing reduced-order models (ROM) of unsteady small-disturbance flows is presented. The reduced-order models are constructed using basis vectors determined from the proper orthogonal decomposition (POD) of an ensemble of small-distur ... Cite

Reduced-order models of unsteady transonic viscous flows in turbomachinery

Journal Article Journal of Fluids and Structures · 2000 The proper orthogonal decomposition (POD) technique is applied in the frequency domain to obtain a reduced-order model of the unsteady flow in a transonic turbomachinery cascade of oscillating blades. The flow is described by a inviscid - viscous model, i. ... Full text Link to item Cite

Nonlinear response of airfoil section with control surface freeplay to gust loads

Journal Article AIAA journal · January 1, 2000 A nonlinear response analysis of a typical airfoil section with control surface freeplay excited by periodic gust loads in low subsonic flow is presented along with a companion wind-tunnel test program. The analytical model uses Peters's finite state model ... Full text Cite

Control of a three-degree-of-freedom airfoil with limit-cycle behavior

Journal Article Journal of Aircraft · January 1, 2000 The effect of control surface freeplay nonlinearities on the closed loop performance of a three-degree-of-freedom airfoil was investigated. The controllers designed for the linear system with flap restoring force serve to reduce the limit cycle oscillation ... Full text Cite

AUTHOR'S REPLY

Journal Article Journal of Sound and Vibration · August 1999 Full text Cite

Reduced-order modelling of unsteady small-disturbance flows using a frequency-domain proper orthogonal decomposition technique

Conference 37th Aerospace Sciences Meeting and Exhibit · January 1, 1999 A new method for constructing reduced-order models (ROM) of unsteady small-disturbance flows is presented. The reduced-order models are constructed using basis vectors determined from the proper orthogonal decomposition (POD) of an ensemble of small-distur ... Full text Cite

REDUCED ORDER MODELS OF VISCOUS FLOWS IN TURBOMACHINERY USING PROPER ORTHOGONAL DECOMPOSITION

Conference ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) · January 1, 1999 The proper orthogonal decomposition technique is applied in the frequency domain to obtain reduced order models (ROM) of the flow in a cascade of airfoils. The flow is described by a inviscid-viscous interaction model where the inviscid part is described b ... Full text Cite

Reduced order models of viscous flows in turbomachinery using proper orthogonal decomposition

Conference American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED · 1999 The proper orthogonal decomposition technique is applied in the frequency domain to obtain reduced order models (ROM) of the flow in a cascade of airfoils. The flow is described by a inviscid-viscous interaction model where the inviscid part is described b ... Cite

Comments on “The high-frequency response of a plate carrying a concentrated mass/spring system” [and reply]

Journal Article J. Sound Vib. (UK) · 1999 See ibid., vol. 213, p. 843-63 (1998), Dowel and Tang present an investigation observing the high-frequency response of a plate carrying a concentrated mass/spring system. An understanding of high-frequency dynamics in coupled structures can be expanded th ... Full text Link to item Cite

Limit cycle oscillations of delta wing models in low subsonic flow

Journal Article AIAA journal · January 1, 1999 A nonlinear, aeroelastic analysis of a low-aspect delta wing modeled as a plate of constant thickness demonstrates that limit cycle oscillations (LCOs) of the order of the plate thickness are possible. The structural nonlinearity arises from double bending ... Full text Cite

Behavior of airfoil with control surface freeplay for nonzero angles of attack

Journal Article AIAA journal · January 1, 1999 The behavior of a three-degree-of-freedom typical airfoil is studied by numerical time integration using a standard state-space approximation, focusing on the effects of the mean or steady angle of attack. A variety of behavior is observed and the main ten ... Full text Cite

On the evolution of deterministic non-periodic behavior of an airfoil

Journal Article International Journal of Non-Linear Mechanics · January 1, 1999 This paper describes some interesting transitional behavior in the limit cycle response of a typical section airfoil with a loosely connected flap subject to a fluid flow. The freeplay non-linearity associated with the flap connection has considerable prac ... Full text Cite

Limit Cycle Oscillations of a Cantilevered Wing in Low Subsonic Flow

Journal Article AIAA Journal · January 1, 1999 A nonlinear, aeroelaslic analysis of a low-aspect, rectangular wing modeled as a plate of constant thickness demonstrates that limit cycle oscillations of the order of the plate thickness are possible. The structural nonlinearity arises from double bending ... Full text Cite

Aerodynamic and aeroelastic insights using eigenanalysis

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1999 This paper presents novel analytical results for eigenvalues and eigenvectors produced using discrete time aerodynamic and aeroelastic models. An unsteady, incompressible vortex lattice aerodynamic model is formulated in discrete time; the importance of se ... Cite

Limit cycle oscillations of delta wing models in low subsonic flow

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1999 A nonlinear, aeroelastic analysis of a low aspect, delta wing modeled as a plate of constant thickness demonstrates that limit cycle oscillations (LCO) of the order of the plate thickness are possible. The structural nonlinearity arises from double bending ... Cite

Reduced order models in unsteady aerodynamics

Conference Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1999 A review is given on the status of reduced order modeling of unsteady aerodynamic systems. Starting with either a time domain or frequency domain computational fluid dynamics (CFD) analysis of unsteady aerodynamic flows, a large, sparse eigenvalue is solve ... Cite

COMMENTS ON THE NONLINEAR VIBRATIONS OF CYLINDRICAL SHELLS

Journal Article Journal of Fluids and Structures · November 1998 Full text Cite

Stability estimation of high dimensional vibrating systems under state delay feedback control

Journal Article Journal of Sound and Vibration · July 16, 1998 The paper presents a method of assessing the stability of high dimensional vibrating systems under state feedback control with a short time delay. It is first proved that if the time delay is sufficiently short, an n -degree-of-freedom system with feedback ... Full text Cite

The high-frequency response of a plate carrying a concentrated mass/spring system

Journal Article Journal of Sound and Vibration · June 25, 1998 The high-frequency response of a plate carrying a concentrated mass/spring system under random forces has been studied. An approximate expression for the local response of the concentrated mass relative to the plate and the inertial displacement of the spr ... Full text Cite

Doubling research means doubling education

Journal Article Scientist · March 2, 1998 Cite

Basins of attraction in experimental nonlinear oscillators

Journal Article International Journal of Bifurcation and Chaos in Applied Sciences and Engineering · January 1, 1998 This paper addresses two relatively simple but fundamental questions in nonlinear oscillations: Given an arbitrary initial condition where will the trajectory go, and how long will it take to get there? These related questions are addressed from an experim ... Full text Cite

Basins of attraction in experimental nonlinear oscillators

Journal Article International Journal of Bifurcation and Chaos in Applied Sciences and Engineering · 1998 This paper addresses two relatively simple but fundamental questions in nonlinear oscillations: Given an arbitrary initial condition where will the trajectory go, and how long will it take to get there? These related questions are addressed from an experim ... Cite

Resonances of a Harmonically Forced Duffing Oscillator with Time Delay State Feedback

Journal Article Nonlinear Dynamics · January 1, 1998 The paper presents analytical and numerical studies of the primary resonance and the 1/3 subharmonic resonance of a harmonically forced Duffing oscillator under state feedback control with a time delay. By using the method of multiple scales, the first ord ... Full text Cite

On the optimality of the Ott-Grebogi-Yorke control scheme

Journal Article Physica D: Nonlinear Phenomena · January 1, 1998 Some of the characteristics of the Ott-Grebogi-Yorke (OGY) control technique are presented as applied to nonlinear flows, as distinct from nonlinear maps. Specifically, we consider the case where the magnitude of the control parameter varies in time within ... Full text Cite

Reduced order aerodynamic models based upon inflow eigenmodes

Journal Article Journal of the American Helicopter Society · January 1, 1998 Reduced order aerodynamic models have proven successful for fixed wing and turbomachinery flows in reducing the size, complexity and computational cost of the aerodynamic model. Typically the eigenmodes or other basis functions of the original aerodynamic ... Full text Cite

Unsteady aerodynamic forces and aeroelastic response for external store of an aircraft

Journal Article Journal of Aircraft · January 1, 1998 An experimental identification investigation of unsteady and stall aerodynamic coefficients for an external store of an aircraft has been made. The coefficient identification is performed by a least-squares procedure based on the measured time series obtai ... Full text Cite

Limit cycle behavior of an airfoil with a control surface

Journal Article Journal of Fluids and Structures · January 1, 1998 A three-degree-of-freedom aeroelastic model with freeplay is modeled theoretically using a small number of aerodynamic eigenmodes (i.e. a reduced order model) based upon Peters' finite-state model for two-dimensional aerodynamic flow. The limit cycle behav ... Full text Cite

Experimental active control of a typical section using a trailing-edge flap

Journal Article Journal of Aircraft · January 1, 1998 This paper presents an experimental implementation of an active control system used to suppress flutter in a typical section airfoil. The H2 optimal control system design is based on experimental system identifications of the transfer functions between thr ... Full text Cite

Reduced-order aerodynamic model and its application to a nonlinear aeroelastic system

Journal Article Journal of Aircraft · January 1, 1998 Starting from a finite state model for a two-dimensional aerodynamic flow over an airfoil, the eigenmodes of the aerodynamic flow are determined. Using a small number of these aerodynamic eigenmodes, i.e., a reduced-order model, the aeroelastic model is fo ... Full text Cite

The transient response of structures using asymptotic modal analysis

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1998 The transient response of a structure is predicted using an asymptotic modal approximation of the classical modal solution. The method is aimed at estimating the impulse response problem for high frequency regimes where typical numerical methods (e.g., fin ... Full text Cite

Reduced order aerodynamic modeling of how to make CFD useful to an aeroelastician

Conference American Society of Mechanical Engineers, Aerospace Division (Publication) AD · December 1, 1997 In this article, we review the status of reduced order modeling of unsteady aerodynamic systems. Reduced order modeling is a conceptually novel and computationally efficient technique for computing unsteady flow about isolated airfoils, wings, and turbomac ... Cite

Reflections on Fifty Years

Journal Article Applied Mechanics Reviews · September 1, 1997 Full text Cite

Nonlinear aeroelasticity of an airfoil with control surface freeplay

Conference 35th Aerospace Sciences Meeting and Exhibit · January 1, 1997 This paper presents a correlation study between numerical and experimental results for the response of a typical section airfoil with freeplay in the control surface. Since this is an inherently nonlinear system the equations of motion are integrated numer ... Cite

Reduced Order Aerodynamic Modeling of How to Make CFD Useful to An Aeroelastician

Conference ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) · January 1, 1997 In this article, we review the status of reduced order modeling of unsteady aerodynamic systems. Reduced order modeling is a conceptually novel and computationally efficient technique for computing unsteady flow about isolated airfoils, wings, and turbomac ... Full text Cite

Nonlinear behavior of a typical airfoil section with control surface freeplay: A numerical and experimental study

Journal Article Journal of Fluids and Structures · January 1, 1997 A three degree-of-freedom aeroelastic typical section with control surface freeplay is modeled theoretically as a system of piecewise linear state-space models. The system response is determined by time marching of the governing equations using a standard ... Full text Cite

Pattern formation and linear stability analysis in centreless grinding

Journal Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture · 1997 Quite often a centreless ground surface has an undesired wavy shape instead of a circular shape owing to a geometric instability. In this paper the equations describing the kinematics of the grinding process obtained by Rowe et al. (1) are used to build a ... Cite

Nonlinear rotor aeroelastic analysis with stall and advanced wake dynamics

Journal Article Journal of Aircraft · January 1, 1997 This paper studies an effective lag damping prediction method for a flexible flap-lag-torsional hingeless rotor model and correlation with the experimental data for a four-bladed rotor. The ONERA dynamic stall models of lift, drag, and pitching moment for ... Full text Cite

Eigenmode analysis in unsteady aerodynamics: reduced order models

Journal Article Applied Mechanics Reviews · 1997 In this article, we review the status of reduced order modeling of unsteady aerodynamic systems. Reduced order modeling is a conceptually novel and computationally efficient technique for computing unsteady flow about isolated airfoils, wings, and turbomac ... Cite

System identification for the Ott-Grebogi-Yorke controller design

Journal Article Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics · January 1, 1997 A technique to compute the linearized Poincaré map and the sensitivity vector required for the implementation of an Ott-Grebogi-Yorke (OGY) controller from experimental data is presented. Unlike previous methods, the linearized map and the sensitivity vect ... Full text Cite

Investigation of the experimental active control of a typical section airfoil using a trailing edge flap

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1997 This paper presents an experimental implementation of an active control system used to suppress flutter in a typical section airfoil. The H2 optimal control system design is based upon experimental system identifications of the transfer functions between t ... Cite

Pattern formation and linear stability analysis in centreless grinding

Journal Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture · January 1, 1997 Quite often a centreless ground surface has an undesired wavy shape instead of a circular shape owing to a geometric instability. In this paper the equations describing the kinematics of the grinding process obtained by Rowe et al. (1) are used to build a ... Full text Cite

Reduced order Euler equations for unsteady aerodynamic flows: Numerical techniques

Conference 34th Aerospace Sciences Meeting and Exhibit · January 1, 1996 Fluid eigenmodes can be used to construct extremely efficient reduced order unsteady aerodynamic models of the Euler equations, which can also be used to perform highly efficient aeroelastic analyses. This is done by transforming the large set of primitive ... Cite

Comments on the ONERA stall aerodynamic model and its impact on aeroelastic stability

Journal Article Journal of Fluids and Structures · January 1, 1996 The present comments address the fundamental dynamic behavior of the ONERA aerodynamic model and consider the interacting dynamics of that flow model with a simple structural model, the typical section. A classical linear flutter analysis clarifies and dee ... Full text Cite

Nonlinear response of a non-rotating rotor blade to a periodic gust

Journal Article Journal of Fluids and Structures · January 1, 1996 A rotating slotted cylinder (RSC) gust generator installed in the Duke University low speed wind tunnel was used to generate a gust excitation field, and the nonlinear response of a non-rotating flexible rotor blade to periodic gust excitations was studied ... Full text Cite

Eigenmode analysis in unsteady aerodynamics: Reduced-order models

Journal Article AIAA Journal · January 1, 1996 A conceptually novel and computationally efficient technique for computing unsteady flow about isolated airfoils, wings, and turbomachinery cascades is presented. Starting with either a time-domain or frequency-domain computational fluid dynamics analysis ... Full text Cite

Flow about a slotted cylinder-airfoil combination in a wind tunnel

Journal Article Journal of Aircraft · January 1, 1996 The flowfleld around a gust generator device, an airfoil/rotating slotted cylinder (RSC) system, is numerically simulated using the general-purpose finite element program FIDAP. The flow is assumed to be quasisteady, turbulent, incompressible, and two dime ... Full text Cite

The role of higher modes in the chaotic motion of the buckled beam - I

Journal Article International Journal of Non-Linear Mechanics · January 1, 1996 The goal of the present work is to combine the study of the chaotic motion of buckled beams with one of the most powerful and widely discussed analytical techniques in non-linear dynamics of the last 10 years. We explore the use of the generalized Melnikov ... Full text Cite

Experiments and analysis for a gust generator in a wind tunnel

Journal Article Journal of Aircraft · January 1, 1996 An experimental investigation was made of the gust field generated by a rotating slotted cylinder installed in the Duke University low-speed, closed-circuit wind tunnel. The system has a very simple configuration with low cost and can produce a controllabl ... Full text Cite

Damping prediction for hingeless rotor aeroelastic stability with experimental correlation

Journal Article Journal of Aircraft · January 1, 1996 A numerical simulation technique is applied to determine the transient response of a hingeless rotor model and predict the lag damping for correlation with experimental results from a wind-tunnel test. Numerical investigations indicate that the present the ... Full text Cite

The role of higher modes in the chaotic motion of the buckled beam - II

Journal Article International Journal of Non-Linear Mechanics · January 1, 1996 Part II of this work completes the analysis of the necessary conditions for the chaos in the system of modal equations of motion of the buckled beam, i.e. a system of coupled Duffing equations. The direct calculation of the stable and unstable perturbed ma ... Full text Cite

State-space modeling for aeroelastic panels with linearized potential flow aerodynamic loading

Journal Article Journal of Aircraft · January 1, 1996 This article presents a new method for the state-space modeling of aeroelastic panels subject to linearized potential flow aerodynamic loading. This is accomplished by approximating the aerodynamic generalized forces on the panel with discrete, infinite im ... Full text Cite

Active control of panel flutter with piezoelectric transducers

Journal Article Journal of Aircraft · January 1, 1996 This article investigates the active control of panel flutter with piezoelectric transducers and including linearized potential flow aerodynamics. The aerodynamic modeling is accomplished by approximating the aerodynamic generalized forces with infinite im ... Full text Cite

Routes to escape from an energy well

Journal Article Journal of Sound and Vibration · October 19, 1995 Dynamical systems characterized by the possibility of escape from a local potential energy well occur in a great many physical problems, including a rigid-arm pendulum passing over its inverted equilibrium position, snap-through buckling in arch and shell ... Full text Cite

Science community must reexamine its own 'contract with America'

Journal Article Scientist · February 20, 1995 Cite

Damping prediction for stalled rotor flap-lag stability with experimental correlation

Journal Article Applied Mechanics Reviews · January 1, 1995 A direct numerical time marching integration is used to compute the transient response (free oscillation) of the flap-lag motion of a stalled rotor. A time-domain quasilinear model identification technique is applied to identify the damping and frequency f ... Full text Cite

On the accuracy of modal analysis in reverberant acoustical systems with damping

Journal Article Journal of the Acoustical Society of America · January 1, 1995 That the modal analysis method works well regardless of the amount of damping in the system, provided that modal coupling is included in the analysis, is shown. The soundfield produced by a vibrating piston in a tube with an absorptive end is calculated. A ... Full text Cite

Response of a nonrotating rotor blade to lateral turbulence part I: Theory

Journal Article Journal of Aircraft · January 1, 1995 Theoretical simulation of a rotor blade in forward flight by a nonrotating rotor blade in a longitudinal sinusoidal pulsating flow, and the flapping and torsional response of a flexible nonrotating rotor blade model to lateral turbulence have been investig ... Full text Cite

Damping prediction for a stalled rotor in flap-lag with experimental correlation

Journal Article Journal of the American Helicopter Society · January 1, 1995 A direct numerical time-marching integration is used to compute the transient response (free oscillation) of the flap-lag motion of a rotor. A time-domain quasilinear model identification technique is applied to identify the damping and frequency for the r ... Full text Cite

Aeroelastic analysis of an airfoil using eigenmode based reduced order unsteady aerodynamics

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1995 Euler based reduced order unsteady aerodynamic models are used to construct very efficient reduced order aeroelastic analyses for a two dimensional `typical section' isolated airfoil. The reduced order aeroelastic models are shown to compute accurately the ... Cite

Flutter of an infinitely long panel in a duct

Journal Article AIAA Journal · January 1, 1995 The aeroelastic stability is examined of an infinitely long panel of finite width enclosed in a duct such that both the upper and lower surfaces of the panel are exposed to an inviscid, and compressible flow. The panel behavior is accounted for by small de ... Full text Cite

Response of a nonrotating rotor blade to lateral turbulence Part II: Experiment

Journal Article Journal of Aircraft · January 1, 1995 In Part I of this work, a theoretical simulation study of rotor blade response to turbulence in forward flight is presented. For verification of this theoretical computational method, a new experimental method based on a special gust field generated by a r ... Full text Cite

Buckling and post-buckling behavior of a pipe subjected to internal pressure

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1995 It is well known that a thin elastic shell under external pressure may undergo buckling and collapse. Less well known is that a hollow beam under internal pressure may buckle as an Euler column. This is the subject of the present study. The buckled deflect ... Full text Cite

Experimental investigation of three-dimensional dynamic stall model oscillating in pitch

Journal Article Journal of Aircraft · January 1, 1995 The ONERA semiempirical theoretical model for unsteady aerodynamics in the stall regime has been extended to three-dimensional flow. Parameter identification for the model is obtained from experimental dynamic stall data for a low AR rectangular wing with ... Full text Cite

State space modeling for aeroelastic panels subject to linearized potential flow aerodynamic loading

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1995 This paper presents a new method for the state space modeling of aeroelastic panels subject to linearized potential flow aerodynamic loading. This is accomplished by approximating the aerodynamic generalized forces on the panel with discrete, infinite impu ... Cite

Active control of panel flutter with linearized potential flow aerodynamics

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1995 This paper investigates the active control of panel flutter including linearized potential flow aerodynamics. The aerodynamic modeling is accomplished by approximating the aerodynamic generalized forces, as developed by Dowell with infinite impulse respons ... Cite

Eigenmode analysis in unsteady aerodynamics: Reduced order models

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1995 A conceptually novel and computationally efficient technique for computing unsteady flow about isolated airfoils, wings, and turbomachinery cascades is presented. A large, sparse eigenvalue problem is solved using the Lanczos algorithm starting with either ... Cite

On necessary conditions for chaotic motion of a buckled plate with external excitation in an aerodynamic flow

Journal Article American Society of Mechanical Engineers, Applied Mechanics Division, AMD · December 1, 1994 We study the system of the modal Galerkin equations of motion of a buckled plate with external exitation in an aerodynamic flow using the famous Melnikov method. The possibility of the occurrence of chaos is considered through the behavior of the stable an ... Cite

Using eigenmodes to form an efficient Euler based unsteady aerodynamics analysis

Journal Article American Society of Mechanical Engineers, Aerospace Division (Publication) AD · December 1, 1994 Fluid eigenmodes are used to created an efficient unsteady aerodynamics analysis for a 2D isolated airfoil immersed in a compressible flow field. For the first time, the eigenmodes are used to transform the large set of coupled, primitive variable (density ... Cite

Limited amplitude panel flutter with a temperature differential

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 1994 Panel flutter is a self-excited aeroelastic phenomenon in which a panel's oscillations are derived from energy absorbed from the flow over the panel. This paper addresses the nonlinear response of a square, cantilevered isotropic panel subject to quasi-ste ... Cite

Flutter of an infinitely long panel in a duct

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · December 1, 1994 The aeroelastic stability is examined of an infinitely long panel of finite width enclosed in a duct such that both the upper and lower surfaces of the panel are exposed to an inviscid, and compressible flow. The panel behavior is accounted for by small de ... Cite

FROM SINGLE WELL CHAOS TO CROSS WELL CHAOS: A DETAILED EXPLANATION IN TERMS OF MANIFOLD INTERSECTIONS

Journal Article International Journal of Bifurcation and Chaos · August 1994 The study of stable and unstable manifolds, and their intersections with each other, is a powerful technique for interpreting complex bifurcations of nonlinear systems. The escape phenomenon in the twin-well Duffing oscillator is one such bifurcat ... Full text Cite

Experimental study of asymptotic modal analysis applied to a rectangular plate with concentrated masses

Journal Article Journal of Sound and Vibration · March 10, 1994 Asymptotic Modal Analysis (AMA) has been developed to predict the response of structures which vibrate with a large number of modes. A combined experimental and analytical approach was used to test this theory for a plate carrying concentrated masses. A th ... Full text Cite

Simplified predictive criteria for the onset of Chaos

Journal Article Nonlinear Dynamics · 1994 Two alternative criteria for predicting the onset of chaos are presented. Both are based on the notion that it is the interaction between a stable and nearby unstable limit cycle pair in the phase space that disrupts the stable motion, thereby producing ch ... Cite

Flutter and forced response of a cantilevered pipe: The influence of internal pressure and nozzle discharge

Journal Article Journal of Fluids and Structures · January 1, 1994 A physically based is provided for the description of the lateral internal forces in a vertical cantilevered pipe conveying an incompressible fluid. This is a basic ingredient for the study of the bending oscillations of the pipe. When there is a nozzle at ... Full text Cite

Acoustic radiation damping of flat rectangular plates subjected to subsonic flows. Part II: Composite

Journal Article Journal of Fluids and Structures · January 1, 1994 The acoustic radiation damping for various laminated composite and aluminum plates subjected to a uniform, subsonic, and steady flow has been predicted. The predictions are based on the linear equations of motion of a flat plate. The fluid loading is chara ... Full text Cite

Acoustic radiation damping of flat rectangular plates subjected to subsonic flows. Part I: Isotropic

Journal Article Journal of Fluids and Structures · January 1, 1994 The acoustic radiation damping for various plates and semi-infinite strips subjected to a uniform, subsonic and steady flow has been predicted. The predictions are based on the linear vibration of a flat plate. The fluid loading is characterized as the per ... Full text Cite

Flutter and forced response of a cantilevered pipe: the influence of internal pressure and nozzle discharge

Journal Article Journal of Membrane Science · January 1, 1994 A physically based model is provided for the description of the lateral internal forces in a vertical cantilevered pipe conveying an incompressible fluid. This is a basic ingredient for the study of the bending oscillations of the pipe. When there is a noz ... Cite

STABILITY MEASUREMENTS IN NONLINEAR MECHANICAL EXPERIMENTS GUIDED BY DYNAMICAL SYSTEMS THEORY

Conference NONLINEARITY AND CHAOS IN ENGINEERING DYNAMICS · January 1, 1994 Link to item Cite

Nonlinear behavior of low aspect ratio panels in subsonic flow: a preliminary study

Journal Article American Society of Mechanical Engineers, Aerospace Division (Publication) AD · December 1, 1993 We describe an experimental investigation into the nonlinear behavior of thin elastic panels in subsonic flow. Specially, an apparatus is detailed that supports a low aspect ratio panel by clamping it along the spanwise edges while leaving its leading and ... Cite

High-dimensional chaos can lead to weak turbulence

Journal Article Nonlinear Dynamics · December 1, 1993 One of the outstanding unresolved questions of nonlinear dynamics is the relationship between chaos and turbulence. This is a deep and difficult question, not the least reason being that the definitions of "chaos" and "turbulence" are not universally agree ... Full text Cite

Comparison of theory and experiment for non-linear flutter and stall response of a helicopter blade

Journal Article Journal of Sound and Vibration · August 8, 1993 The purpose of the present paper is to study the flutter instability and forced response of a non-rotating helicopter blade model with a parabolic or cubic and freeplay torsional stiffness non-linearity based upon the semi-empirical (linear and) non-linear ... Full text Cite

Theoretical and experimental study on nonlinear response of a rotor blade to a gust

Journal Article Applied Mechanics Reviews · January 1, 1993 A rotating slotted cylinder (RSC) gust generator installed in the Duke University low speed wind tunnel was used to generate a gust excitation field and the nonlinear response of a flexible rotor blade togust excitations was studied theoretically and exper ... Full text Cite

Experimental and theoretical study for nonlinear aeroelastic behavior of a flexible rotor blade

Journal Article AIAA Journal · January 1, 1993 The purpose of this paper is to study the flutter instability and forced response of a nonrotating flexible rotor blade model with a geometrical structural nonlinearity and a freeplay structural nonlinearity. The ONERA stall aerodynamic model is used. Exte ... Full text Cite

Nonlinear aeroelasticity in rotorcraft

Journal Article Mathematical and Computer Modelling · January 1, 1993 This paper is an overview of a research program for nonlinear aeroelasticity of rotorcraft in forward flight conducted at Duke University and supported by the Army Research Office. Theoretical and experimental investigations of rotor aeroelastic stability ... Full text Cite

Semi-Empirical model for prediction of unsteady forces on an airfoil with application to flutter

Journal Article Journal of Fluids and Structures · January 1, 1993 A semi-empirical model is described for predicting unsteady aerodynamic forces on arbitrary airfoils under mildly stalled and unstalled conditions. Aerodynamic forces are modelled using second-order ordinary differential equations for lift and moment with ... Full text Cite

Nonlinear aeroelastic response of panels

Journal Article Collection of Technical Papers - AIAA/ASME Structures, Structural Dynamics and Materials Conference · January 1, 1993 We consider the nonlinear aeroelastic response of panels supported by an elastic foundation in subsonic and supersonic flows. Previous studies of the nonlinear behavior of panels have revealed that they are capable of a variety of bifurcations, limit cycle ... Cite

Efficient procedure for cascade aeroelastic stability determination using nonlinear, time-marching aerodynamic solvers

Journal Article Collection of Technical Papers - AIAA/ASME Structures, Structural Dynamics and Materials Conference · January 1, 1993 A numerical eigenvalue problem formulation and a practical calculation procedure for exact eigenvalues and corresponding eigenvectors are developed and applied to a nonlinear, two-dimensional, time-marching full potential solver for cascade aeroelastic sta ... Cite

Nonlinear dynamics and chaos in mechanical systems

Journal Article International Conference on Fuzzy Theory and Technology Proceedings, Abstracts and Summaries · December 1, 1992 Chaotic oscillations have now been observed in non-linear mechanical systems by analytical, numerical and experimental methods. Nevertheless a more fundamental understanding of why and when such oscillations occur is of great importance. This will be discu ... Cite

Experimental mimicry of Duffing's equation

Journal Article Journal of Sound and Vibration · November 8, 1992 Extensive analytical and numerical investigations have focused on Duffing's equation. However, experimental work, in a mechanics context, has been limited to studying systems the stiffness characteristics of which can be approximated by a non-linear (cubic ... Full text Cite

Author's reply

Journal Article Journal of Sound and Vibration · January 22, 1992 Full text Cite

Experimental verification of the asymptotic modal analysis method as applied to a rectangular acoustic cavity excited by structural vibration

Journal Article Journal of Vibration and Acoustics, Transactions of the ASME · January 1, 1992 An experiment was performed on a rigid wall rectangular acoustic cavity driven by a flexible plate mounted in a quarter of one end wall and excited by white noise. The experiment was designed so that the assumptions of Asymptotic Modal A nalysis (AMA) were ... Full text Cite

Flutter and stall response of a helicopter blade with structural nonlinearity

Journal Article Journal of Aircraft · January 1, 1992 The purpose of the present paper is to study the flutter instability and forced response of a nonrotating helicopter blade model with a NACA-0012 airfoil and a pitch freeplay structural nonlinearity. In this paper, three typical combinations of linear and ... Full text Cite

Asymptotic modal analysis of a rectangular acoustic cavity excited by wall vibration

Journal Article AIAA Journal · January 1, 1992 Asymptotic modal analysis, a method that has recently been developed for structural dynamical systems, has been applied to a rectangular acoustic cavity. The cavity had a flexible vibrating portion on one wall, and the other five walls were rigid. Banded w ... Full text Cite

Effect of structural damping on flutter of plates with a follower force

Journal Article AIAA Journal · January 1, 1992 A plate-like large space structure may undergo dynamic instabilities when it is thrusted by a nonconservative compressive force. A flexible rectangular plate with four free edges, one of which is subjected to a tangential follower force, is considered. The ... Full text Cite

Study of intensification zones in a rectangular acoustic cavity

Journal Article AIAA Journal · January 1, 1992 The interior acoustic field of a rectangular acoustic cavity, which is excited by the structural vibration of one of its walls, or a portion of the wall, has been studied. Particularly, the spatial variations of sound pressure levels from the peak levels a ... Full text Cite

Chaotic stall response of helicopter rotor in forward flight

Journal Article Journal of Fluids and Structures · January 1, 1992 A typical evolution process for rotor blade stall response from periodic to aperiodic or chaotic motion and a necessary condition for the onset of chaotic response are discussed. This is the first such study of chaotic motion due to aerodynamic stall of a ... Full text Cite

Asymptotic modal analysis for sound fields of a reverberant chamber

Journal Article Journal of the Acoustical Society of America · January 1, 1992 Asymptotic modal analysis (AMA) has been applied to the sound fields of a reverberant chamber under narrow-band excitation by point sources. The result in the form usually given by geometrical acoustics also has been obtained by studying the asymptotic beh ... Full text Cite

Some comments on the 1988 Rayleigh medal lecture. (JSV 133(1), 1-27)

Journal Article Journal of Sound and Vibration · January 22, 1991 Full text Cite

A chaotic scenario

Journal Article Journal of Sound and Vibration · January 8, 1991 Full text Cite

Eigenvalue calculation procedure for an Euler/Navier-Stokes solver with application to flows over airfoils

Journal Article Journal of Computational Physics · January 1, 1991 A Lanczos procedure is applied to a Navier-Stokes solver for computing eigenvalues and eigenvectors. These eigenvalues and eigenvectors are associated with small perturbation analysis of a finite difference representation of the Navier-Stokes equations for ... Full text Cite

Role of artificial viscosity in Euler and Navier-Stokes solvers

Journal Article AIAA Journal · January 1, 1991 A method is proposed to determine directly the amount of artificial viscosity needed for stability using an eigenvalue analysis for a finite difference representation of the Navier-Stokes equations. The stability and growth of small perturbations about a s ... Full text Cite

Comparison of theory and experiment for nonlinear flutter and stall response of a helicopter blade

Journal Article Annual Forum Proceedings - American Helicopter Society · January 1, 1991 The purpose of the present paper is to study the flutter instability and forced response of a non-rotating helicopter blade model with parabolic and freeplay torisonal stiffness nonlinearity based upon the (linear and) nonlinear ONERA stall aerodynamic mod ... Cite

Effect of constant transverse force on chaotic oscillations of sinusoidally excited buckled beam

Journal Article International Journal of Non-Linear Mechanics · January 1, 1991 The chaotic oscillation of a buckled beam under sinusoidally varying and static constant transverse external forces is investigated. A harmonic balance method and a direct numerical integration are applied to a Duffings equation model of the buckled beam. ... Full text Cite

Limit cycle oscillation of a fluttering cantilever plate

Journal Article AIAA Journal · January 1, 1991 This is the first such study for a plate with some edges unsupported. Previous work has dealt with all edges supported. Von Karman theory for a plate and quasisteady, supersonic aerodynamic theory have been assumed. A Rayleigh-Ritz approach has been used t ... Full text Cite

Experimental verification of the Asymptotic Modal Analysis method as applied to a rectangular acoustic cavity excited by structural vibration

Journal Article American Society of Mechanical Engineers, Noise Control and Acoustics Division (Publication) NCA · December 1, 1990 An experiment was performed on a rigid wall rectangular acoustic cavity driven by a flexible plate mounted in a quarter of one end wall and excited by white noise. The experiment was designed so that the assumptions of Asymptotic Modal Analysis (AMA) were ... Cite

The high-frequency response of a plate carrying a concentrated mass

Journal Article Journal of Sound and Vibration · April 22, 1990 The high-frequency response of a plate carrying a concentrated mass under random forces has been studied. An approximate expression for the local response of the concentrated mass has been developed as the asymptotic limit of component modal analysis by us ... Full text Cite

Static subsonic aeroelastic stability of a shell wrapped around a rigid surface

Journal Article AIAA Journal · January 1, 1990 A thin elastic shell under tension is wrapped around a rigid curved surface; the latter renders the stiffness of the shell effectively nonlinear. Examples of such a configuration in practice include the NASA Skylab Space Project and certain submarine geome ... Full text Cite

On spatial chaos, asymptotic modal analysis, and turbulence

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1990 Full text Cite

Dynamic stability of a rectangular plate with four free edges subjected to a follower force

Journal Article AIAA Journal · January 1, 1990 The dynamic stability of a flexible rectangular plate, such as a plate-like large space structure, is analyzed. One of the four free edges of the plate is subjected to a tangential follower force. The plate shows both flutter and divergence instabilities. ... Full text Cite

Effect of a structural damping on dynamic stability of a free flexible plate subjected to a follower force

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1990 A plate-like large space structure may undergo dynamic instabilities when it is thrusted by a non-conservative compressive force. A flexible rectangular plate with four free edges, one of which is subjected to a tangential follower force, is considered. Th ... Cite

Nonlinear aeroelasticity

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1990 The study of nonlinear aeroelasticity has fluorished in the last decade in recognition of improved methods of modeling nonlinear phenomena and also the important role that nonlinearities sometimes play in various physical settings. A discussion is presente ... Cite

Dynamic stability of a completely free plate subjected to a controlled non-conservative follower force

Journal Article Journal of Sound and Vibration · July 8, 1989 The dynamic instability of a rectangular plate with four free edges is investigated. One edge of the completely free plate is subjected to a uniformly distributed non-conservative follower force, the direction of which is controlled in proportion to the ro ... Full text Cite

Effects of the Poisson ratio and negative thrust on the dynamic stability of a free plate subjected to a follower force

Journal Article Journal of Sound and Vibration · March 8, 1989 The macroscopic Poisson ratio of a large plate-like truss structure may vary due to the geometry of the truss. Studied are the effects of the Poisson ratio and negative thrust on the dynamic stability of a flexible rectangular plate which has four free edg ... Full text Cite

On the role of artificial viscosity in Navier-Stokes solvers

Conference 9th Computational Fluid Dynamics Conference, 1989 · January 1, 1989 A method is proposed to determine directly the amount of artificial viscosity needed for stability using an eigenvalue analysis for a finite difference representation of the Navier-Stokes equations. The stability and growth of small perturbations about a s ... Full text Cite

Generation and analysis of Lyapunov exponents for the buckled beam

Journal Article International Journal of Non-Linear Mechanics · January 1, 1989 In this paper, Lyapunov exponents are calculated for the one, two, three and four mode modal projections of the partial differential equation governing the buckled beam. The projection used was taken from a previous paper by Tang and Dowell [1]. Issues suc ... Full text Cite

Approach to modeling and estimation for uncertain systems

Journal Article Journal of Guidance, Control, and Dynamics · January 1, 1989 Optimal modeling and optimal estimation are discussed for uncertain dynamic systems. Uncertainty of the system is assumed to be presented by multiple models, or a set of possible parameters, and their own probabilities. Optimal solutions are derived by min ... Full text Cite

On the threshold force for chaotic motions for a forced buckled beam

Journal Article American Society of Mechanical Engineers (Paper) · December 1, 1988 The effects of higher modes on the chaotic oscillations of a buckled beam under forced external excitation are studied. Of principal interest are the threshold force required for chaotic motions and the influence of damping on the system response. A compar ... Cite

Bachelor's Booster

Journal Article Physics Today · December 1, 1988 Full text Cite

Frequency domain solutions to multi-degree-of-freedom, dry friction damped systems

Journal Article Journal of Sound and Vibration · June 22, 1988 Dry friction damping has been considered as a means of increasing the passive damping of a variety of systems including large space structures and turbomachinery blades. However, dry friction is highly non-linear, and hence, analytical investigations are d ... Full text Cite

Chaotic oscillations in mechanical systems

Journal Article Computational Mechanics · May 1, 1988 Chaotic oscillations have now been observed in non-linear mechanical systems by analytical, numerical and experimental methods. Nevertheless a more fundamental understanding of why and when such oscillations occur is of great importance. This goal will be ... Full text Cite

On necessary and sufficient conditions for chaos to occur in Duffing's equation: an Heuristic approach

Journal Article Journal of Sound and Vibration · March 8, 1988 Many different explanations have been offered for the occurrence of chaos in Duffing's equation. Holmes has derived a criterion for the onset of chaos using Melnikov theory that is based upon the initial entanglement of the unstable manifold with the stabl ... Full text Cite

On the threshold force for chaotic motions for a forced buckled beam

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1988 The effects of higher modes on the chaotic oscillations of a buckled beam under forced external excitation are studied. Of principal interest are the threshold force required for chaotic motions and the influence of damping on the system response. A compar ... Full text Cite

Unsteady transonic aerodynamics and aeroelasticity

Journal Article Applied Mechanics Reviews · January 1, 1988 In recent years substantial progress has been made in the development of an improved understanding of unsteady aerodynamics and aeroelasticity in the transonic flow regime. This flow regime is often the most critical for aeroelastic phenomena; yet it has p ... Full text Cite

On Chaos and fractal behavior in a generalized duffing's system

Journal Article Physica D: Nonlinear Phenomena · January 1, 1988 In this paper, three Duffing's equations, their attractors and their initial condition maps are examined for elements of universality. In the literature, all three equations have been examined briefly before, but their behavior has only been incompletely d ... Full text Cite

Chaotic oscillations in mechanical systems

Journal Article Computers and Structures · January 1, 1988 Chaotic oscillations have now been observed in nonlinear mechanical systems using analytical, numerical, and experimental methods. Nevertheless, a more fundamental understanding of why and when such oscillations occur is of great importance. This goal will ... Full text Cite

Asymptotic modal analysis and statistical energy analysis of an acoustic cavity

Journal Article Journal of Vibration and Acoustics, Transactions of the ASME · January 1, 1988 One of the outstanding theoretical questions in interior noise is the connection between modal analysis and statistical energy analysis. Recently substantial progress has been made in understanding this connection for structural vibrations including both f ... Full text Cite

An Estimator for Uncertain Output Matrix Systems

Journal Article IEEE Transactions on Automatic Control · January 1, 1988 A linear time-invariant optimal estimator for uncertain output matrix systems is considered. Uncertainty of the output matrix is represented by a set of multiple parameters, and the optimal estimator is introduced by minimizing the expected cost function o ... Full text Cite

On the threshold force for chaotic motions for a forced buckled beam

Journal Article American Society of Mechanical Engineers (Paper) · 1988 The effects of higher modes on the chaotic oscillations of a buckled beam under forced external excitation are studied. Of principal interest are the threshold force required for chaotic motions and the influence of damping on the system response. A compar ... Cite

Principal coordinate realization of state estimation and its application of order reduction

Journal Article Journal of Guidance, Control, and Dynamics · January 1, 1988 Full text Cite

Chaotic oscillations of a cantilevered pipe conveying fluid

Journal Article Journal of Fluids and Structures · January 1, 1988 A pipe-beam is clamped at its upper end, and free at its lower end. Two permanent magnets are placed to the right and left of the free end of the pipe-beam. The system may exhibit chaotic oscillations both for free and forced vibration when fluid passes th ... Full text Cite

CLASSICAL MODAL ANALYSIS, ASYMPTOTIC MODAL ANALYSIS, AND STATISTICAL ENERGY ANALYSIS.

Journal Article American Society of Mechanical Engineers, Noise Control and Acoustics Division (Publication) NCA · December 1, 1987 When calculating the response of linear vibratory systems under deterministic or random excitation, it is common to use classical modal analysis in the low frequency regime (lower modes, e. g. less than ten to one hundred) and statistical energy analysis i ... Cite

ASYMPTOTIC MODAL ANALYSIS AND STATISTICAL ENERGY ANALYSIS OF AN ACOUSTIC CAVITY.

Journal Article American Society of Mechanical Engineers, Noise Control and Acoustics Division (Publication) NCA · December 1, 1987 One of the theoretical questions in interior noise is the connection between modal analysis and statistical energy analysis. Recently progress has been made in understanding this connection for structural vibrations including both fundamental theoretical w ... Cite

An examination of initial condition maps for the sinusoidally excited buckled beam modeled by the Duffing's equation

Journal Article Journal of Sound and Vibration · September 8, 1987 The initial condition problem is studied for the dynamics of the buckled beam by using the forced Holmes-Duffing's equation, in an attempt to understand the route to chaos. Earlier results generated by Moon [1] for different parameter values are reconsider ... Full text Cite

Localization of vibrations by structural irregularity

Journal Article Journal of Sound and Vibration · May 8, 1987 An investigation of the localization phenomenon is presented for disrodered structural systems consisting of weakly coupled component systems. Emphasis is placed on the development of a perturbation method that allows one to obtain the localized modes of v ... Full text Cite

TRANSIENT MEAN SQUARE RESPONSE OF RANDOMLY DAMPED LINEAR SYSTEMS.

Journal Article Journal of Sound and Vibration · 1987 Transient responses of a randomly damped one-degree-of-freedom linear system subjected to white noise excitation is discussed. The time varying damping coefficient is considered either as Gaussian white noise or filtered white noise. Perturbation approxima ... Cite

Localized vibrations of disordered multispan beams: Theory and experiment

Journal Article AIAA Journal · January 1, 1987 The localization of the free modes of vibration of disordered multispan beams is investigated, both theoretically and experimentally. It is shown that small deviations of the span lengths from an ideal value may have drastic effects on the dynamics of the ... Full text Cite

Asymptotic modal analysis for dynamic stresses of a plate

Journal Article Journal of the Acoustical Society of America · January 1, 1987 Asymptotic modal analysis has been applied to stress analysis of a uniform thin rectangular plate under point forces that are bandlimited white noise. The asymptotic limits of the temporal averages of the bending stresses and the distortion energy have bee ... Full text Cite

Damping in beams with multiple dry friction supports

Journal Article Journal of Aircraft · January 1, 1987 An equivalent linear viscous damping formula for beams with rather general dry friction support conditions is proposed. The effect of normal force support reaction at the dry friction support on response is also discussed. Comparisons of experimental resul ... Full text Cite

EFFECTS OF NONLINEAR DAMPING IN LANDING GEAR ON HELICOPTER LIMIT CYCLE RESPONSE IN GROUND RESONANCE.

Journal Article Journal of the American Helicopter Society · January 1, 1987 An approximate theoretical method is presented which predicts the limit cycle behavior of a simplified helicopter model in ground resonance, considering the effects of one or two nonlinear dampers in the landing gear. The relationship between lagging motio ... Full text Cite

Numerical simulations of periodic and chaotic responses in a stable duffing system

Journal Article International Journal of Non-Linear Mechanics · January 1, 1987 A stable Duffing system is examined by numerical simulations in order to obtain a better understanding of the behavior of periodic and chaotic responses to sinusoidal excitations. It is found that beside the multiplicity of responses, there is a duality fo ... Full text Cite

Numerical simulations of jump phenomena in stable Duffing systems

Journal Article International Journal of Non-Linear Mechanics · January 1, 1987 In this paper the jump phenomena in quasilinear Duffing systems under sinusoidal and narrow band random excitations are examined by numerical simulations. The simulation results for sinusoidal excitations agree very well with analytical solutions obtained ... Full text Cite

Theory and application of dynamic decoupling in structural analysis: Another view

Journal Article Finite Elements in Analysis and Design · January 1, 1987 A conceptual and computational duality is established for addition and deletion of structural elements using a component mode analysis technique. This approach should be useful for re-analyzing structural systems with modifications. © 1987. ... Full text Cite

NONLINEAR AEROELASTICITY: AN OVERVIEW.

Journal Article Proceedings of the U.S. National Congress of Applied Mechanics · December 1, 1986 A conceptual framework is provided for the field of Nonlinear Aeroelasticity. Various important physical phenomena are identified and placed in context. Representative methodologies and experimental and theoretical results are discussed. ... Cite

Damping in beams and plates due to slipping at the support boundaries, part 2: Numerical and experimental study

Journal Article Journal of Sound and Vibration · August 8, 1986 A numerical and experimental study for a beam and rectangular plate with dry friction damping due to slipping at the support boundaries is described. The results of the numerical simulation show that the simpler, more approximate theory of the companion pa ... Full text Cite

Experimental investigation of asymptotic modal analysis for a rectangular plate

Journal Article Journal of Sound and Vibration · April 22, 1986 Experimental investigations of the response of a rectangular plate under a point random force have been performed to verify the asymptotic behavior predicted by Asymptotic Modal Analysis (AMA). Measurements have been made for various frequency bandwidths, ... Full text Cite

Damping in beams and plates due to slipping at the support boundaries

Journal Article Journal of Sound and Vibration · March 8, 1986 Dry friction damping due to axial sliding surfaces normal to the principal lateral direction of structural motion is studied. Primary emphasis is on sufficiently large motion that slipping occurs throughout a cycle. Beams with arbitrary support conditions ... Full text Cite

Random response of beams and plates with slipping at support boundaries

Journal Article AIAA Journal · January 1, 1986 A numerical and experimental study is made of the response to random excitation of a beam and rectangular plate with dry friction damping due to slipping at the support boundaries. The design of the beam experimental apparatus and the utilization of the as ... Full text Cite

RANDOM RESPONSE OF BEAMS AND PLATES WITH SLIPPING AT SUPPORT BOUNDARIES.

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1986 A numerical and experimental study is made of the response to random excitation of a beam and rectangular plate with dry friction damping due to slipping at the support boundaries. The design of the beam experimental apparatus and the utilization of the as ... Full text Cite

On the understanding of chaos in buffings equation including a comparison with experiment

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1986 The dynamics of a buckled beam are studied for both the initial value problem and forced external excitation. The principal focus is on chaotic oscillations due to forced excitation. In particular, a discussion of their relationship to the initial value pr ... Full text Cite

Influence of nonlinear blade damping on helicopter ground resonance instability

Journal Article Journal of Aircraft · January 1, 1986 The lagging motion of each helicopter blade is assumed to be of equal amplitude and equally apportioned phase, thus allowing a simplified analytical method to be used to calculate the ground resonance instability of a helicopter model with nonlinear damper ... Full text Cite

ASYMPTOTIC MODAL ANALYSIS AND STATISTICAL ENERGY ANALYSIS OF DYNAMICAL SYSTEMS.

Journal Article American Society of Mechanical Engineers (Paper) · December 1, 1985 A new derivation of the results commonly referred to as Statistical Energy Analysis (SEA) is given by studying the asymptotic behavior of classical modal analysis for a general, linear (structural) system. It is shown that, asymptotically, the response at ... Cite

MULTI-HARMONIC ANALYSIS OF DRY FRICTION DAMPED SYSTEMS USING AN INCREMENTAL HARMONIC BALANCE METHOD.

Journal Article American Society of Mechanical Engineers (Paper) · December 1, 1985 A multi-harmonic, frequency domain analysis of dry friction damped systems is presented which uses an incremental harmonic balance method. When compared with time domain solution methods, it is found that the incremental harmonic balance method can yield v ... Cite

EFFECTS OF COMPLIANT WALLS ON TRANSITION AND TURBULENCE.

Journal Article American Society of Mechanical Engineers, Noise Control and Acoustics Division (Publication) NCA · December 1, 1985 A review is undertaken to identify the major findings of the research community and to suggest future directions. An annotated, selective bibliography is also included. A fundamental theoretical approach to the problem is proposed. Two possible thrusts are ... Cite

ASYMPTOTIC MODAL ANALYSIS AND STATISTICAL ENERGY ANALYSIS OF DYNAMICAL SYSTEMS.

Journal Article American Society of Mechanical Engineers (Paper) · December 1, 1985 A new derivation of the results commonly referred to as Statistical Energy Analysis (SEA) is given by studying the asymptotic behavior of classical modal analysis for a general, linear (structural) system. It is shown that, asymptotically, the response at ... Cite

ON THE UNDERSTANDING OF CHAOS IN DUFFINGS EQUATION INCLUDING A COMPARISON WITH EXPERIMENT.

Journal Article American Society of Mechanical Engineers (Paper) · December 1, 1985 The dynamics of a buckled beam are studied for both the initial value problem and forced external excitation. The principal focus is on chaotic oscillations due to forced excitation. In particular, a discussion of their relationship to the initial value pr ... Cite

STRUCTURAL DYNAMICS.

Journal Article AMD (Symposia Series) (American Society of Mechanical Engineers, Applied Mechanics Division) · December 1, 1985 While much of the linear theory of structural dynamics has been codified in numerous computer software, important problems remain such as inverse methods (modal synthesis or system identification) and optimization problems. Nonlinear problems, however, are ... Cite

ON THE UNDERSTANDING OF CHAOS IN DUFFINGS EQUATION INCLUDING A COMPARISON WITH EXPERIMENT.

Journal Article American Society of Mechanical Engineers (Paper) · December 1, 1985 The dynamics of a buckled beam are studied for both the initial value problem and forced external excitation. The principal focus is on chaotic oscillations due to forced excitation. In particular, a discussion of their relationship to the initial value pr ... Cite

MULTI-HARMONIC ANALYSIS OF DRY FRICTION DAMPED SYSTEMS USING AN INCREMENTAL HARMONIC BALANCE METHOD.

Journal Article American Society of Mechanical Engineers (Paper) · December 1, 1985 A multi-harmonic, frequency domain analysis of dry friction damped systems is presented which uses an incremental harmonic balance method. When compared with time domain solution methods, it is found that the incremental harmonic balance method can yield v ... Cite

The behavior of a linear, damped modal system with a non-linear spring-mass-dry friction damper system attached, part II

Journal Article Journal of Sound and Vibration · July 8, 1985 In previous work, the title problem was studied. Unfortunately, a sign reversal in the damping term led to a misinterpretation of the effect of linear damping of the modal system. In the present paper this is corrected and the work previously reported is e ... Full text Cite

Structural dynamics

Journal Article Applied Mechanics Reviews · January 1, 1985 While much of the linear theory of structural dynamics has been codified in numerous computer software, important problems remain such as inverse methods (modal synthesis or system identification) and optimization problems. Nonlinear problems, however, are ... Full text Cite

Multi-harmonic analysis of dry friction damped systems using an incremental harmonic balance method

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1985 A multi-harmonic, frequency domain analysis of dry friction damped systems is presented which uses an incremental harmonic balance method. When compared with time domain solution methods, it is found that the incremental harmonic balance method can yield v ... Full text Cite

A study of dynamic instability of plates by an extended incremental harmonic balance method

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1985 The dynamic instability of plates is investigated with geometric nonlinearities being included in the model, which allows one to determine the amplitude of the parametric vibrations. A modal analysis allowing one spatial mode is performed on the nonlinear ... Full text Cite

STUDY OF DYNAMIC INSTABILITY OF PLATES BY AN EXTENDED INCREMENTAL HARMONIC BALANCE METHOD.

Journal Article American Society of Mechanical Engineers (Paper) · January 1, 1985 The dynamic instability of plates is investigated with geometric nonlinearities being included in the model, which allows one to determine the amplitude of the parametric vibrations. A modal analysis allowing one spatial mode is performed on the nonlinear ... Cite

The effects of compliant walls on transition and turbulence.

Journal Article IN: SHEAR FLOW - STRUCTURE INTERACTION PHENOMENA, PRESENTED AT ASME WINTER ANNUAL MEETING, (MIAMI BEACH, U.S.A.: NOV. 17-22, · January 1, 1985 Discusses the various effects that drag reduction mechanisms may have on transition and turbulence. (from author's abstract) ... Cite

Multi-harmonic analysis of dry friction damped systems using an incremental harmonic balance method.

Journal Article TRANS. ASME J. APPL. MECH. · January 1, 1985 A multi-harmonic, frequency domain analysis of dry friction damped systems is presented which uses an incremental harmonic balance method. When compared with time domain solution methods, it is found that the incremental harmonic balance method can yield v ... Cite

Reply by authors to K. L. Roger

Journal Article AIAA Journal · January 1, 1985 Full text Cite

Reply by authors to W.P. Rodden

Journal Article AIAA Journal · January 1, 1984 Full text Cite

Flutter analysis using nonlinear aerodynamic forces

Journal Article Journal of Aircraft · January 1, 1984 The nonlinear effects of transonic aerodynamic forces on the flutter boundary of a typical section airfoil are studied. The flutter speed dependence on amplitude is obtained by utilizing a novel variation of the describing function method which takes into ... Full text Cite

Doublet-point method for supersonic unsteady lifting surfaces

Journal Article AIAA Journal · January 1, 1984 A method to predict unsteady aerodynamic forces on lifting surfaces in supersonic flow is presented. The wing is divided into small segments in which the lift force is expressed by a single-point doublet of the acceleration potential. This is the same conc ... Full text Cite

OBSERVATION AND EVOLUTION OF CHAOS FOR AN AUTONOMOUS SYSTEM.

Journal Article American Society of Mechanical Engineers (Paper) · January 1, 1984 Cite

Observation and evolution of chaos for an autonomous system

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1984 Time histories, phase plane portraits, power spectra, and Poincare maps are used as descriptors to observe the evolution of chaos in an autonomous system. Although the motions of such a system can be quite complex, these descriptors prove helpful in detect ... Full text Cite

On asymptotic approximations to beam model shapes

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1984 Recently the author had occasion to investigate inter alia the asymptotic character of the mode shapes of uniform beams. These results do not seem to have been presented before in the literature and so are given here as they appear to be of general interes ... Full text Cite

NONLINEAR AEROELASTICITY.

Journal Article Advances in the Astronautical Sciences · December 1, 1983 Cite

Forced response of a cantilever beam with a dry friction damper attached, part II: Experiment

Journal Article Journal of Sound and Vibration · November 22, 1983 The experimental program is described along with comparison of the results to those obtained from the theory of the companion paper, Part I [1]. © 1983. ... Full text Cite

Forced response of a cantilever beam with a dry friction damper attached, part I: Theory

Journal Article Journal of Sound and Vibration · November 22, 1983 A theoretical-experimental study of the forced vibration response of a cantilevered beam with Coulomb damping non-linearity is described. Particular emphasis is placed upon the types of non-linear behavior and system response spectral characteristics obser ... Full text Cite

The behavior of a linear, damped modal system with a non-linear spring-mass-dry friction damper system attached

Journal Article Journal of Sound and Vibration · July 8, 1983 A component mode analysis is carried out based upon the use of constraint conditions and Lagrange multipliers. It is used to generalize the well known results for a single-degree-of-freedom dry friction damper to a multi-mode linear system with a spring-ma ... Full text Cite

Component mode analysis of nonlinear, nonconservative systems

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1983 In this paper a method for attacking coupled linear-nonlinear problems is developed. This method allows one to express the equations of motion with a number of equations proportional to the number of nonlinear constraints on the system rather than to the n ... Full text Cite

COMPONENT MODE ANALYSIS OF NONLINEAR, NONCONSERVATIVE SYSTEMS.

Journal Article American Society of Mechanical Engineers (Paper) · January 1, 1983 Cite

Postbuckling behavior of rectangular orthotropic plates with two free side edges

Journal Article International Journal of Mechanical Sciences · January 1, 1983 The postbuckling behavior of rectangular orthotropic plates with two free side edges is studied based on a perturbation method. Both exact and approximate solutions of the second-order perturbation equations are given. Numerical results for plates having v ... Full text Cite

Linear/nonlinear behavior in unsteady transonic aerodynamics

Journal Article AIAA Journal · January 1, 1983 The accurate calculation of the aerodynamic forces in unsteady transonic flow requires the solution of the nonlinear flow equations. The aeroelastician, on the other hand, seeks to treat his problems (flutter, for example) by means of linear equations when ... Full text Cite

Transient decay times and mean values of unsteady oscillations in transonic flow

Journal Article AIAA J. (USA) · 1983 Kerlick and Nixon (ibid., vol 19, p.1496, 1981) have made the important point that, when using a finite difference, time-marching computer code to investigate the lift on an oscillating airfoil in transonic flow, it is necessary to carry the solution suffi ... Cite

COMPONENT MODE ANALYSIS OF NONLINEAR, NONCONSERVATIVE SYSTEMS.

Journal Article American Society of Mechanical Engineers (Paper) · 1983 Cite

Flutter of a buckled plate as an example of chaotic motion of a deterministic autonomous system

Journal Article Journal of Sound and Vibration · December 8, 1982 For aeroelasticity of plates and shells, the equations of motion are well established. Results obtained by numerical time integration have been compared to those obtained by topological theories of dynamics and also from experiment. All of these suggest th ... Full text Cite

Component mode analysis of a simple non-linear, non-conservative system

Journal Article Journal of Sound and Vibration · January 22, 1982 A component mode analysis is carried out based upon the use of constraint conditions and Lagrange multipliers to treat exemplary physical systems with non-linear damping. Both viscous and dry friction dampers attached to a linear elastic (beam) system are ... Full text Cite

A new solution method for lifting surfaces in subsonic flow

Journal Article AIAA Journal · January 1, 1982 A simple method for calculating the unsteady aerodynamic loadings on harmonically oscillating thin wings in subsonic flow has been developed. The method is based on a concept of concentrated lift forces. The wing is divided into the element surfaces on whi ... Full text Cite

Crack extension in a double cantilevered beam model

Journal Article Journal of Applied Physics · December 1, 1981 A simple, phenomenological model is presented for crack extension in a double cantilevered beam model. It invokes a continuum description of the beam per se, but postulates a discrete spring mechanism (which bonds the two halves to the beam) to provide a m ... Full text Cite

Non-linear oscillator models in bluff body aero-elasticity

Journal Article Journal of Sound and Vibration · March 22, 1981 A critique of non-linear oscillator models is offered and a systematic and self-consistent procedure for constructing such a model is proposed based upon theoretical and experimental fluid mechanical information. Numerical studies are conducted for the pro ... Full text Cite

Absorption material mounted on a moving wall-Fluid/wall boundary condition

Journal Article J. Acoust. Soc. Am. (USA) · 1981 The case of a structural (elastic) wall on which is mounted an absorptive material does not appear to have a self-consistent derivation of a physically correct boundary condition. Such a derivation is the authors' goal ... Cite

MODAL ANALYSIS OF INTERIOR NOISE FIELDS.

Journal Article Semiconductor International · January 1, 1981 E. H. Dowell's linear theory of acoustoelasticity, which is capable of predicting the interior sound field for any structural model surrounding an arbitrarily shaped acoustic cavity subject to a prescribed internal sound source and/or external noise fields ... Cite

Control laws for adaptive wind tunnels

Journal Article AIAA Journal · January 1, 1981 Full text Cite

LINEAR/NONLINEAR BEHAVIOR IN UNSTEADY TRANSONIC AERODYNAMICS.

Journal Article Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference · January 1, 1981 The accurate calculation of aerodynamic forces in unsteady transonic flow requires the solution of the nonlinear flow equations. The aeroelastician, on the other hand, seeks to treat his problems by means of linear equations whenever possible. He may do th ... Cite

SIMPLE METHOD FOR CONVERTING FREQUENCY-DOMAIN AERODYNAMICS TO THE TIME DOMAIN.

Journal Article NASA Technical Memorandum · October 1, 1980 A simple, direct procedure is developed for converting frequency-domain aerodynamics into indicial aerodynamics. The data required for aerodynamic forces in the frequency domain may be obtained from any available (Linear) theory. The method retains flexibi ... Cite

SIMPLE METHOD FOR CONVERTING FREQUENCY-DOMAIN AERODYNAMICS TO THE TIME DOMAIN.

Journal Article NASA Technical Memorandum · January 1, 1980 A simple, direct procedure is developed for converting frequency-domain aerodynamics into indicial aerodynamics. The data required for aerodynamic forces in the frequency domain may be obtained from any available (Linear) theory. The method retains flexibi ... Cite

ASSESSMENT OF THEORETICAL MODELS FOR VISCOUS AND TRANSONIC FLOW.

Journal Article AGARD Conference Proceedings · January 1, 1980 Some current and proposed methods of treating viscous and transonic effects in theoretical aerodynamic models suitable for aeroelastic applications are reviewed critically. Where possible, theoretical results of such models are compared with experiment. To ... Cite

Master plan for prediction of vehicle interior noise

Journal Article AIAA Journal · January 1, 1980 Full text Cite

Interior noise studies for single- and double-walled cylindrical shells

Journal Article Journal of Aircraft · January 1, 1980 The modal theory of acoustoelasticity is applied to the determination of the sound levels caused by a prescribed external sound excitation which is transmitted through a cylindrical shell. A circumferential pseudotraveling pressure wave excitation is studi ... Full text Cite

Component mode analysis of nonlinear and nonconservative systems

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1980 Full text Cite

Comment on `direct solutions for Strum-Liouville systems with discontinuous coefficients' [and reply by D.H. Hodges]

Journal Article AIAA J. (USA) · 1980 Comments have been made on the work of D.H. Hodges (AIAA Journal, vol.17, p.924-926) on direct solutions for Strum Liouville systems with discontinuous coefficients, which may be applied to vibrations of nonuniform beams. Various approaches to treatment of ... Cite

ACOUSTOELASTICITY: REVIEW AND EXTENSION.

Journal Article Ammonia Plant Safety (and Related Facilities) · January 1, 1980 The paper discusses the interaction between the (acoustic) sound pressure field and the (elastic) flexible wall of an enclosure. Such problems frequently arise when the vibrating walls of a transportation vehicle induce a significant internal sound field. ... Cite

Bounds on modal damping by a component modes method using Lagrange multipliers

Journal Article Trans. ASME, J. Appl. Mech. (USA) · 1980 The author has deduced recently some general properties for the natural frequencies of dynamical systems which are composed of several components. It is shown that for two component systems a simple explicit formula for modal damping is available once the ... Cite

SIMPLIFIED THEORY OF OSCILLATING AEROFOILS IN TRANSONIC FLOW: REVIEW AND EXTENSION.

Journal Article Aeronautical Quarterly · January 1, 1980 Significant new results are presented to show to what extent a simplified theory for transonic flow may be used. Solutions are obtained by classical techniques and compared with experiment. Results are given for two-dimensional and three-dimensional, stead ... Full text Cite

COMPONENT MODE ANALYSIS OF NONLINEAR AND NONCONSERVATIVE SYSTEMS.

Journal Article Journal of Applied Mechanics, Transactions ASME · 1980 In a series of publications, the present author and others have exploited the power of Lagrange's equations and the use of Lagrange multipliers to study the dynamics of interconnected systems in terms of their several components. Studies to date have empha ... Cite

An elementary explanation of the flutter mechanism with active feedback controls

Journal Article J. Aircr. (USA) · 1979 An elementary explanation of wind flutter suppression problems with active feedback control is made using a standard root locus technique. The object is to obtain insight into the control of converging frequency flutter such as the classical bending-torsio ... Cite

On some general properties of combined dynamical systems

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1979 Full text Cite

ELEMENTARY EXPLANATION OF THE FLUTTER MECHANISM WITH ACTIVE FEEDBACK CONTROLS.

Journal Article J Aircr · 1979 An elementary explanation of wing flutter suppression problems with active feedback control is made using a standard root locus technique. The object of the study is to obtain insight into the control of converging frequency flutter such as the classical b ... Cite

THEORETICAL ANALYSIS OF NONLINEAR EFFECTS ON THE FLUTTER AND DIVERGENCE OF A TUBE CONVEYING FLUID.

Journal Article · January 1, 1979 There is a rich literature on the flow-induced vibrations of a tube conveying fluid. Most existing theoretical models are linear and used to examine the onset of an instability due to (infinitesimally) small disturbances. Here nonlinear models are construc ... Cite

Flutter of plates and shells in practice.

Journal Article · January 1, 1979 Several case histories of the flutter of plates and shells are recounted. These will provide the reader with a perspective on the variety of applications which are encountered in practice. They will also illustrate how the advances in our fundamental under ... Cite

Comments on non-linear flexural vibrations of a cylindrical shell

Journal Article Journal of Sound and Vibration · October 22, 1978 Full text Cite

ON SOME GENERAL PROPERTIES OF COMBINED DYNAMICAL SYSTEMS.

Conference American Society of Mechanical Engineers (Paper) · January 1, 1978 There are several well-known results due to Rayleigh left bracket 1 right bracket on the effects of mass and stiffness addition to a dynamical system. In this paper these results are reconsidered and generalized using the methods previously employed by the ... Cite

Active feedback control of a beam subjected to a nonconservative force

Journal Article International Journal of Solids and Structures · January 1, 1978 This study examines the possibility of controlling through feedback a thin cantilevered beam subjected to a nonconservative follower force. A converging frequency flutter instability which occurs in this model is similar to classical bending-torsion flutte ... Full text Cite

Reverberation time, absorption, and impedance

Journal Article Journal of the Acoustical Society of America · January 1, 1978 A rigorous theoretical model is derived and used to calculate reverberation time of a room in terms of impedance of absorption materials on the wall and geometrical factors associated with such materials and the room. In addition, the reverberation time al ... Full text Cite

COMPLIANT WALL, SUPERSONIC WIND TUNNEL.

Journal Article Aeronaut J · January 1, 1978 The concept of a self-correcting wind tunnel with impermeable flexible walls deformed into an a priori determined shape of fixed magnitude is broadened to allow at least the magnitude of the wall shape to vary with flow conditions, e. g. , flow dynamic pre ... Cite

The coupled response of a dynamic element riding on a continuously supported beam

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1978 The dynamic interaction between a Linear Induction Motor primary, modeled as a spring-mass-damper element, and its secondary-rail, modeled as a prestressed, continuously supported, infinitely long beam, is studied theoretically. The existence of two transi ... Full text Cite

ON SOME GENERAL PROPERTIES OF COMBINED DYNAMICAL SYSTEMS.

Journal Article American Society of Mechanical Engineers (Paper) · January 1, 1978 There are several well-known results due to Rayleigh left bracket 1 right bracket on the effects of mass and stiffness addition to a dynamical system. In this paper these results are reconsidered and generalized using the methods previously employed by the ... Cite

Acoustoelasticity: General theory, acoustic natural modes and forced response to sinusoidal excitation, including comparisons with experiment

Journal Article Journal of Sound and Vibration · June 22, 1977 A comprehensive theoretical model has been developed for interior sound fields which are created by flexible wall motion resulting from exterior sound fields. Full coupling between the wall and interior acoustic cavity is permitted. An efficient computatio ... Full text Cite

An experimental-theoretical correlation study of non-linear bending and torsion deformations of a cantilever beam

Journal Article Journal of Sound and Vibration · February 22, 1977 An experimental study of the large deformation of a cantilevered beam under a gravity tip load has been made. The beam root is rotated so that the tip load is oriented at various angles with respect to the beam principal axes. Static twist and bending defl ... Full text Cite

AERODYNAMIC EFFECTS OF INVISCID PARALLEL SHEAR FLOWS.

Journal Article AIAA Journal · 1977 A general theory of planar disturbances in inviscid parallel shear flows, analogous to thin-wing theory in potential flows, has been developed. Integral relations between surface pressure and deformation are obtained that are similar to, and can be solved ... Cite

Variable thickness shear layer aerodynamics revisited

Journal Article AIAA J. (USA) · 1977 For shear layers of slowly varying thickness it is shown that it is sufficient to replace the constant boundary-layer thickness used in the kernel function by Ventres (1975) in the analysis of lifting surfaces, by the varying thickness. (This kernel functi ... Cite

Flutter of an elastic plate under tension

Journal Article AIAA J. (USA) · 1977 A new interpretation of existing results is presented. Two-dimensional aerodynamic flow over a one-dimensional (infinitely wide) plate is considered. The effect is clarified of variations in plate bending stiffness on the flutter of a plate under a given t ... Cite

Response of space shuttle surface insulation panels to acoustic pressure

Journal Article Journal of Spacecraft and Rockets · January 1, 1977 The free vibration characteristics and dynamic response of reusable space shuttle surface insulation panels to acoustic random pressure fields are studied. The basic analytical approach in formulating the governing equations of motion uses a Rayleigh-Ritz ... Full text Cite

Variable thickness shear layer aerodynamics revis ited.

Journal Article AIAA Journal · 1977 The author points out that for shear layers of slowly varying thickness it is sufficient to replace the constant boundary layer thickness which appears in Ventres' Kernal function (AIAA J.,13 Sep. 1975 pp.1183-1189) by the varying thickness. The Kernal fun ... Cite

On the aeroelastic instability of two-dimensional panels in uniform incompressible flow

Journal Article Journal of Sound and Vibration · July 22, 1976 A theoretical and experimental study is presented of the aeroelastic instability of a panel with various boundary conditions on its leading and trailing edges, exposed to air flow over its upper surface or on both sides. The flow is incompressible and two- ... Full text Cite

AEROELASTICITY OF PLATES AND SHELLS.

Journal Article · January 1, 1975 CONTENTS: PREFACE; NOMENCLATURE; PHYSICAL NATURE OF THE PROBLEM AND EXPERIMENTS; LINEAR THEORETICAL AEROELASTIC MODELS; NONLINEAR THEORETICAL AEROELASTIC MODELS; AERODYNAMIC THEORY; STRUCTURAL RESPONSE TO TURBULENT BOUNDARY LAYER PRESSURE FLUCTUATIONS; COR ... Cite

Vibration and flutter analysis of reusable surface insulation panels

Journal Article Journal of Spacecraft and Rockets · January 1, 1975 Full text Cite

Radiation from panels as a source of airframe noise

Journal Article AIAA Journal · January 1, 1975 Full text Cite

SIMPLIFIED THEORY OF OSCILLATING AIRFOILS IN TRANSONIC FLOW.

Journal Article · January 1, 1975 A relatively simple, reasonably accurate, and symmetric procedure has been developed for transonic flow which is derived from the local linearization concept. It has the advantage of being simpler than the latter and is capable of being systematically impr ... Cite

Swirling flows between coaxial cylinders with injection by radial jets

Journal Article AIAA Journal · January 1, 1975 An experimental program has been carried out to investigate a class of flows which is of interest with regard to the aeroelastic flutter of flexible cylinders. The flowfield of interest is the swirling flow between two concentric cylinders, of which the in ... Full text Cite

AEROELASTICITY OF PLATES AND SHELLS.

Journal Article · January 1, 1975 CONTENTS: PREFACE; NOMENCLATURE; PHYSICAL NATURE OF THE PROBLEM AND EXPERIMENTS; LINEAR THEORETICAL AEROELASTIC MODELS; NONLINEAR THEORETICAL AEROELASTIC MODELS; AERODYNAMIC THEORY; STRUCTURAL RESPONSE TO TURBULENT BOUNDARY LAYER PRESSURE FLUCTUATIONS; COR ... Cite

Dynamic analysis of an elastic plate on a thin, elastic foundation

Journal Article Journal of Sound and Vibration · August 8, 1974 An improved theory for the motion of an elastic foundation is developed. Included is the interaction of two or more plates resting on a common foundation. A simplified model is deduced which appears useful for some applications. © 1974. ... Full text Cite

Comments on "Vibrations of point supported plates"

Journal Article Journal of Sound and Vibration · February 22, 1974 Full text Cite

The suppression of a dynamic instability of an elastic body using feedback control

Journal Article International Journal of Solids and Structures · January 1, 1974 A theoretical and experimental study is made to determine the feasibility of controlling a thin cantilevered beam subject to a (nonconservative) follower force. A theoretical model is developed using the equations for a thin beam under initial stress and G ... Full text Cite

Nonlinear panel response by a monte carlo approach

Journal Article AIAA Journal · January 1, 1974 The vibration of clamped and simply supported elastic panels due to subsonic and supersonic turbulent boundarylayer flows is investigated by a Monte Carlo technique. The resulting generalized random forces are simulated numerically from boundary-layer turb ... Full text Cite

Analysis of modal damping by component modes method using lagrange multipliers

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1974 Full text Cite

Aeroelastic stability of cylindrical shells subjected to a rotating flow

Journal Article AIAA Journal · January 1, 1974 It is experimentally demonstrated that a cylindrical shell subjected to a rotating flow may become dynamically unstable. The flutter motion takes the form of a circumferentially traveling wave. The data confirm qualitatively earlier theoretical predictions ... Full text Cite

Elastic sandwich beam or plate equations equivalent to classical theory

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1974 Full text Cite

Elastic sandwich beam or plate equations equivalent to classical theory

Journal Article Trans. ASME, E, J. Appl. Mech. (USA) · 1974 Classical beam (or plate) equation for homogeneous members is rather satisfactory in vibration analysis involving flexural vibrations and in normal and shear stress analysis. The authors arrive at such a single equation for the elastic sandwich plates and ... Cite

AEROELASTIC STABILITY OF CYLINDRICAL SHELLS SUBJECTED TO A ROTATING FLOW.

Journal Article AIAA Journal · January 1, 1974 IT IS EXPERIMENTALLY DEMONSTRATED THAT A CYLINDRICAL SHELL SUBJECTED TO A ROTATING FLOW MAY BECOME DYNAMICALLY UNSTABLE.THE FLUTTER MOTION TAKES THE FORM OF A CIRCUMFERENTIALLY TRAVELLING WAVE.THE DATA CONFIRM QUALITATIVELY EARLIER THEORETICAL PREDICTIONS, ... Cite

Aerodynamic boundary layer effects on flutter and damping of plates

Journal Article Journal of Aircraft · January 1, 1973 A previously developed shear flow model for describing the aerodynamic pressures on a moving flexible wall in a boundary layer type flow is utilized to perform stability (flutter) and response analyses for elastic plates. Results for flutter boundaries and ... Full text Cite

High-damping measurements and a preliminary evaluation of an equation for constrained-layer damping

Journal Article AIAA J. (USA) · 1973 The equation of motion for constrained layer damping of sandwich structures describing the lateral displacement of the plate or beam is evaluated experimentally by the classical half- power damping measurement. The inherent inaccuracy of this method as wel ... Cite

Derivation of aerodynamic kernel functions

Journal Article AIAA Journal · January 1, 1973 Full text Cite

Theoretical vibration and flutter studies of point supported panels

Journal Article Journal of Spacecraft and Rockets · January 1, 1973 Full text Cite

Cross-hatching as an aeroviscoelastic problem

Journal Article AIAA Journal · January 1, 1972 Full text Cite

Governing equations for vibrating constrained-layer damping sandwich plates and beams

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1972 For constrained-layer damping a simple differential equation for nonsymmetric sandwich plates or beams made of isotropic and homogeneous layers is deduced. The natural boundary conditions associated with this equation are also derived. Typical numerical re ... Full text Cite

Free vibrations of an arbitrary structure in terms of component modes

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1972 A method for the analysis of the free vibrations of an arbitrary structure in terms of component modes is presented based upon the use of the normal, free-free modes of the components in a Rayleigh-Ritz analysis with the constraint or continuity conditions ... Full text Cite

Governing equations for vibrating constrained-layer damping sandwich plates and beams

Journal Article Trans. ASME, E, J. Appl. Mech. (USA) · 1972 For constrained-layer damping a simple differential equation for nonsymmetric sandwich plates or beams made of isotropic and homogeneous layers is deduced. The natural boundary conditions associated with this equation are also derived. Typical numerical re ... Cite

Free vibrations of a linear structure with arbitrary support conditions

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1971 A method for the analysis of the free vibrations of a linear structure supported in an arbitrary way is presented based upon the use of the normal modes of the unsupported or unconstrained structure in a Rayleigh-Ritz analysis with the support or constrain ... Full text Cite

COMMENTS ON '%'TURBULENCE-INDUCED PLATE VIBRATIONS. AN EVALUATION OF FINITE-AND INFINITE- PLATE MODELS'%'

Journal Article Journal of the Acoustical Society of America · January 1, 1971 Communication to the Editor reports theoretical and experimental studies on the change in measured sound velocity due to coatings on samples placed in impedance tubes. Data include sound velocity for typical plastic surrounded by a water capillary and a po ... Cite

Generalized aerodynamic forces on a flexible plate undergoing transient motion in a shear flow with an application to panel flutter

Journal Article AIAA Journal · January 1, 1971 A theoretical solution to the title problem is obtained. Unlike previous solutions in the literature, the present method allows for finite plate dimensions and continuously varying mean velocity and temperature profiles. A computer program has been develop ... Full text Cite

Propagation of Harmonic Waves in a Composite Elastic Cylinder

Journal Article Journal of the Acoustical Society of America · January 1, 1971 In this paper, the propagation of harmonic waves with an arbitrary number of circumferential nodes in an infinitely long two-layered composite circular elastic rod is investigated. The composite rod is made of a circular solid rod encased by a circular she ... Full text Cite

The hydroelastic stability of a flat plate

Journal Article Journal of Applied Mechanics, Transactions ASME · January 1, 1971 Full text Cite

Comments on “Turbulence-Induced Plate Vibrations: An Evaluation of Finite- and Infinite-Plate Models” [W. A. Strawderman, J. Acoust. Soc. Amer. 46, 1294–1307 (1969)]

Journal Article Journal of the Acoustical Society of America · January 1, 1971 Comments are offered on a recent paper by Strawderman along with references to additional relevant literature. © 1971, Acoustical Society of America. All rights reserved. ... Full text Cite

Propagation of harmonic waves in a composite elastic cylinder

Journal Article J. Acoust. Soc. Am. (USA) · 1971 The propagation of harmonic waves with an arbitrary number of circumferential nodes in an infinitely long-layered composite circular elastic rod is investigated. The composite rod is made of a circular solid rod encased by a circular shell having different ... Cite

Comments on `turbulence-induced plate vibrations: An evaluation of finite- and infinite-plate models'

Journal Article J. Acoust. Soc. Am. (USA) · 1971 For abstract of original article see abstr. A19213 of 1970 ... Cite

Comparison of theory and experiment for nonlinear flutter of loaded plates

Journal Article AIAA Journal · January 1, 1970 The flutter behavior of clamped plates exposed to transverse pressure loadings, or buckled by uniform thermal expansion has been investigated theoretically, and the results compared with existing experimental data. Quasi-steady aerodynamic theory and von K ... Full text Cite

Fatigue life estimation of fluttering panels

Journal Article AIAA Journal · January 1, 1970 Full text Cite

Flutter of buckled plates at zero dynamic pressure

Journal Article AIAA Journal · January 1, 1970 Full text Cite

Flutter of low aspect ratio plates

Journal Article AIAA Journal · January 1, 1970 Full text Cite

Nonlinear flutter of curved plates, II

Journal Article AIAA Journal · January 1, 1970 In a series of papers by the author and his colleagues, nonlinear flutter analyses of plates have been made. Most recently in Part I curved plates were considered. In the present paper, Part II, numerical results are presented for three-dimensional curved ... Full text Cite

Noise or flutter or both?

Journal Article Journal of Sound and Vibration · January 1, 1970 The vibration of a flexible structure immersed in a fluid flow is considered. Particular attention is devoted to plate and shell configurations typical of local structure on flight vehicles. The relationship of forced vibration (due to turbulent boundary l ... Full text Cite

TRANSMISSION OF NOISE FROM A TURBULENT BOUNDARY LAYER THROUGH A FLEXIBLE PLATE INTO A CLOSE CAVITY

Journal Article Acoustical Soc America-J · 1969 Analysis of sound transmission through rectangular, elastic plate embedded in otherwise rigid surface, plate forming one wall of rectangular interior cavity; special effects studied are nonlinear plate stiffness and mutual interaction between plate and ext ... Cite

Transmission of Noise from a Turbulent Boundary Layer through a Flexible Plate into a Closed Cavity

Journal Article Journal of the Acoustical Society of America · January 1, 1969 The title problem is investigated, emphasizing two effects that are usually ignored in the literature. These are (i) nonlinear plate stiffness and (ii) mutual interaction between the plate and external and/or internal (cavity) air flow. The method of analy ... Full text Cite

Nonlinear flutter of curved plates

Journal Article AIAA Journal · 1969 Nonlinear Galerkin analysis of flutter of curved plates is made using shallow shell (von Karman) equations and quasi-steady aerodynamic theory; for two-dimensional curved plate, it is shown that flutter amplitude is of order of rise height of streamwise cu ... Cite

Modal equations for the nonlinear flexural vibrations of a cylindrical shell

Journal Article International Journal of Solids and Structures · January 1, 1968 A review is made of modal approximations in deriving the equations of motion for the nonlinear flexural vibrations of a cylindrical shell. An improved method is proposed and used which satisfies more exactly the boundary conditions of the problem. Comparis ... Full text Cite

On the flutter of multibay panels at low supersonic speeds

Journal Article AIAA Journal · January 1, 1967 Full text Cite

On the nonlinear flexural vibrations of rings

Journal Article AIAA Journal · January 1, 1967 Full text Cite

Aerodynamic forces on an oscillating cylindrical duct with an internal flow

Journal Article Journal of Sound and Vibration · January 1, 1967 A knowledge of the generalized aerodynamic forces on an oscillating cylindrical duct with an internal flow is a prerequisite for a study of its aeroelastic stability or response under dynamic loading. Here these forces are calculated within the framework o ... Full text Cite

Nonlinear analysis of flutter of plates and shells

Journal Article ASME -- Fluid-Solid Interaction · 1967 Methods for investigating flutter are reviewed emphasizing nonlinear aspects of problem; thin plate or shell is immersed in fluid stream with parallel fluid flow over one side of structure; primary concern is with final state of growing disturbance; flat p ... Cite

Nonlinear oscillations of a fluttering plate. II

Journal Article AIAA J. (USA) · 1967 In Part I [ibid, vol. 4, 1267-75 (1966)] the problem was studied using von Karman's large-deflection plate theory and quasi-steady aerodynamic theory. Here the latter is replaced by the full linearized (inviscid, potential flow) aerodynamic theory. Galerki ... Cite

Generalized aerodynamic forces on flexible plate undergoing transient motion

Journal Article Quarterly of Applied Mathematics · 1967 Aerodynamic forces on flexible plate embedded in rigid half-space, undergoing arbitrary temporal and spatial motion are determined; general case of arbitrary time (as well as spatial) dependence of plate motion is considered; pertinent to stability of flui ... Cite

Response of plates to fluid loading

Journal Article Journal of Sound and Vibration · January 1, 1967 Full text Cite

Flutter of infinitely long plates and shells. II - Cylindrical shell

Journal Article AIAA Journal · January 1, 1966 The aeroelastic stability of an infinitely long, isotropic cylinder with the outer surface exposed to an inviscid flow is re-examined. The cylinder behavior is described by the shell equations of Goldenvieser, whereas the aerodynamic forces are described b ... Full text Cite

Comments on “On Dynamic Snap Buckling of Shallow Arches”

Journal Article AIAA Journal · January 1, 1966 Full text Cite

Nonlinear oscillations of fluttering plate

Journal Article AIAA Journal · 1966 Problem of two- and three-dimensional plates undergoing limit cycle oscillations (subsequent to occurrence of linear, aeroelastic instability) is investigated; Von Karman's large deflection plate theory and quasi-steady aerodynamic theory are employed; eff ... Cite

Flutter of infinitely long plates and shells -- 1

Journal Article AIAA Journal · 1966 Aeroelastic stability of infinitely long panel of finite width with upper surface exposed to inviscid flow is examined; panel behavior is accounted for by small deflection plate theory, whereas aerodynamic forces acting on panel are described by classical ... Cite

Flutter of infinitely long plates and shells -- 2

Journal Article AIAA Journal · 1966 Aeroelastic stability of infinitely long, isotropic cylinder with outer surface exposed to inviscid flow is re-examined; cylinder behavior is described by shell equations of Goldenvieser, whereas aerodynamic forces are described by classical linearized pot ... Cite

Generalized aerodynamic forces on oscillating cylindrical shell -- Subsonic and supersonic flow

Journal Article AIAA Journal · 1966 Mathematical and numerical solution is presented for problem of determining aerodynamic forces on harmonically oscillating, cylindrical shell within framework of classical, linearized, potential flow theory; subsonic speeds are emphasized; method of soluti ... Cite

Theoretical and experimental panel flutter studies in mach number range 1.0 to 5.0

Journal Article AIAA Journal · 1965 Paper describes methods and results of coordinated experimental and theoretical investigation of flutter of flat, rectangular, isotropic panels; theoretical calculations are based upon classical, small, deflection-plate theory and three-dimensional, unstea ... Cite

Effect of aerodynamic damping on flutter of thin panels

Journal Article AIAA Journal · January 1, 1964 Full text Cite

Flutter of multibay panels at high supersonic speeds

Journal Article AIAA Journal · 1964 Flutter of 2-dimensional panels on multiple simple supports running in spanwise direction and equally spaced in streamwise direction is investigated; exact solution is effected by method employed by J.M. Hedgepeth, J.C. Houbolt, and A.A.Movehan for one-bay ... Cite

Subsonic flutter of panels on continuous elastic foundations

Journal Article AIAA Journal · 1963 Tests were conducted on 104×24-×0.018 in. rectangular aluminum panel in low-speed wind tunnel; definite flutter of traveling-wave-type was observed; principal instability was shown to be of traveling-wave, flutter-type; comparison of experiment ... Cite

Aerodynamic Modes in a Box

Journal Article AIAA Journal Cite

Mathematical Aeroelasticity: A Survey

Journal Article Journal of Dynamics and Differential Equations Cite

ASSESSMENT OF THEORETICAL MODELS FOR VISCOUS AND TRANSONIC FLOW.

Journal Article AGARD Conference Proceedings Some current and proposed methods of treating viscous and transonic effects in theoretical aerodynamic models suitable for aeroelastic applications are reviewed critically. Where possible, theoretical results of such models are compared with experiment. To ... Cite