Journal articleAIAA Journal · June 1, 2026
A nonlinear aeroelastic model for a flexible panel is expanded to consider the effect of the viscous boundary layer using a Reynolds-averaged Navier–Stokes (RANS) solver. This study presents the use of the dynamically linearized time-domain approach reduce ...
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Journal articleScience advances · May 2026
Dynamic acoustofluidics enables precise, contact-free manipulation of particles, colloids, and cells and shows great potential for applications in physics, materials science, and life sciences. However, existing strategies struggle to realize contrast-base ...
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Journal articleAIAA Journal · February 1, 2026
The unsteady pressure distribution over a pitching NACA 0012 airfoil with and without a control surface is measured in a low-speed wind tunnel. Two sets of motions (step change and oscillatory) are enforced on the wing angle of attack and the control surfa ...
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Journal articleActa Mechanica Sinica Lixue Xuebao · January 1, 2026
This study explores the nonlinear resonance of a rotating solar sail membrane exposed to time-varying solar thermal and solar radiation pressure. The sail membrane is modeled using a cantilever membrane, applying the von Kármán theory for membrane large de ...
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Journal articleJournal of Aircraft · December 1, 2025
A point collocation nonintrusive polynomial chaos approach is presented for nonlinear aeroelastic uncertainty quantification analysis. A unique aspect of the approach is the use of a nonlinear frequency-domain harmonic balance aeroelastic solution methodol ...
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Journal articleAIAA Journal · September 1, 2025
Nonlinear unsteady aerodynamic reduced-order models (ROMs) based on machine learning or artificial intelligence algorithms can be complex and computationally demanding to train, meaning that for practical aeroelastic applications, the conservative nature o ...
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Journal articleAnalysis and Applications · July 1, 2025
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 ...
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Journal articleActa 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 ...
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Journal articleAIAA Journal · April 1, 2025
It is essential for advanced turbine design and wind-farm control strategy formulation to acquire an improved understanding of the aerodynamic behavior in the rotor plane and the wake downstream of a wind turbine under blade pitching motion, reacting to hi ...
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Journal articleJournal of Fluids and Structures · April 1, 2025
A loosely coupled approach for the prediction of fluid–structure interactions is investigated for a high Reynolds number flow with a shock-wave impinging on a thin flexible panel. The fluid domain is solved using a wall-modeled large eddy simulation (LES), ...
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Journal articleAIAA Journal · February 1, 2025
Fluid–structure interaction of an elastic plate with piezoelectric elements, turbulent freestream flow at Mach 2.5, and a pressurized cavity is investigated computationally and correlated with a recent experiment. The pressure field on the plate is measure ...
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Journal articleJournal of Fluids and Structures · January 1, 2025
This paper investigates the aeroelastic stability and nonlinear aeroelastic behavior of a two-dimensional heated panel in irregular shock reflection and extends prior work to include the effects of viscoelasticity. The aeroelastic model is formulated using ...
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Journal articleAIAA Science and Technology Forum and Exposition AIAA Scitech Forum 2025 · January 1, 2025
Correction Notice Subsection III.B.2. Table 1: the boundary layer thickness percentage from the ReD configuration at x/a = 0 is as indicated in red below. (Table presented). ...
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Journal articleNonlinear 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, ...
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Journal articleScience advances · November 2024
Ring resonator (RR) devices are closed-loop waveguides where waves circulate only at the resonant frequencies. They have been used in sensor technology and optical tweezers, but controlling micron-scale particles with optical RR tweezers is challenging due ...
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Journal articleJournal of Fluid Mechanics · October 25, 2024
Structural damage in turbomachinery is a primary origin of aeronautic accidents, which is receiving increased attention. This study is thus focused on the aeroelastic analysis of damaged blades, including the onset of flutter and underlying mechanisms. Fir ...
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Journal articleJournal 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 ...
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Journal articleEnergy · 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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. ...
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Journal articleAIAA Journal · January 1, 2024
A nonlinear aeroelastic model for a flexible panel is extended to consider the Euler equation as the aerodynamic model. A highly efficient method is presented to compute the generalized aerodynamic forces from a CFD simulation, and the results are compared ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleTheoretical 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleEnergy 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 ...
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Journal articleAIAA 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 ...
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Journal articleJVC 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 ...
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Journal articleAIAA 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) ...
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Journal articlePhysics 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleArchive 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA Journal · June 1, 2021
Correction Notice This correction pertains to the numerical values of the non-dimensional in-plane edge stiffness presented in the results section in the original article when it was first published online [https://doi.org/10.2514/1.J059551]. The error is ...
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Journal articleScientia 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 ...
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Journal articleJournal 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. ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA Journal · January 1, 2021
This correction pertains to the numerical values of the non-dimensional in-plane edge stiffness presented in the results section in the original article when it was first published online [https://doi.org/10.2514/1.J059660]. The error originates in an erro ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleNonlinear 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 ...
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Journal articleAstrophysical 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. ...
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Journal articleEngineering 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleEnergies · 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleMechanical 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 ...
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Journal articleAerospace 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 ...
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Journal articleScience 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 ...
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Journal articleCommunications 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleHangkong 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleSmart 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleThe 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 ...
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Journal articleJournal 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 l ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleEuropean 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJVC 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 ...
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Journal articleAdvances 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 ...
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Journal articleInternational 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAsian 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 ...
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Journal articleAGARD 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleApplied 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 ...
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Journal articleAerospace · 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleMathematical 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleSolid 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. ...
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Journal articleSolid 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleMechanics 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 ...
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Journal article55th 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleAnnual 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleAIAA 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 ...
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Journal article54th 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 ...
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Journal article54th 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 ...
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Journal article54th 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleThe 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 ...
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Journal articleAIAA 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 ...
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Journal articleInternational 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 ...
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Journal articleIet 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 ...
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Journal articleJournal 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 ...
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Journal article53rd 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 ...
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Journal articleCollection 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 ...
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Journal article53rd 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 ...
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Journal articleCollection 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 ...
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Journal article53rd 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. ...
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Journal article53rd 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 ...
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Journal articleCollection 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 ...
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Journal articleAIAA 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleAutomatica · 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 compat ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleApplied 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 ...
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Journal articleJournal 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, ...
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Journal articleProceedings 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 ...
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Journal articleCollection 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 ...
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Journal articleProceedings 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleProceedings 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 developmen ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleCollection 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAeronautical 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleASME 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 ...
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Journal articleAIAA 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 ...
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Journal article2007 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 ...
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Journal articleJournal 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 ...
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Journal articleTrans. 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 ...
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Journal articleTrans. 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJ. 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleNonlinear 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJ. 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal article3rd 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 ...
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Journal articleActa 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 ...
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Journal articleJournal 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleProceedings 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 ...
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Journal articleProceedings 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleJournal 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 ...
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Journal articleFluid 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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. ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleCollection 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 ...
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Journal article44th 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 ...
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Journal article44th 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 ...
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Journal article44th 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJ. 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleNonlinear 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 ...
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Journal articleAmerican 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. ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleCollection 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 textCite
Journal articleCollection 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 ...
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Journal article40th 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 ...
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Journal articleInternational 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 ...
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Journal articleProceedings 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 ...
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Journal articleTrans. 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleASME 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 ...
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Journal articleJournal 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 ...
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Journal article19th 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAnnual 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleAmerican 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 ...
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Journal article41st 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 ...
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Journal article41st 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 ...
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Journal articlePhysica 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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. ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJ. 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleInternational 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 ...
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Journal articleAIAA 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleInternational 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 ...
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Journal articleNonlinear 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 ...
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Journal articlePhysica 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleProceedings 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 ...
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Journal articleJournal 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 ...
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Journal articleApplied 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 ...
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Journal articlePhysical 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 ...
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Journal articleCollection 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 function ...
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Journal articleProceedings 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleApplied 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleCollection 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleAmerican 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 ...
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Journal articleAmerican 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAmerican 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 ...
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Journal articleNonlinear 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 ...
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Journal articleJournal 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 ...
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Journal articleApplied 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 ...
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Journal articleAIAA 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 ...
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Journal articleMathematical 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 ...
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Journal articleJournal 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 ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAnnual 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 ...
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Journal articleInternational 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. ...
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Journal articleAIAA 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 ...
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Journal articleAmerican 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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. ...
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Journal articleCollection 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 ...
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Journal articleCollection 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleAmerican 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 ...
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Journal articleJournal 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 ...
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Journal articleComputational 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleApplied 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 ...
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Journal articlePhysica 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 ...
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Journal articleComputers 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 ...
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Journal articleJournal 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 ...
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Journal articleIEEE 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 ...
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Journal articleAmerican 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 ...
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Journal articleJournal 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 ...
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Journal articleAmerican 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 ...
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Journal articleAmerican 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleInternational 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 ...
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Journal articleProceedings 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. ...
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Journal articleJournal 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 ...
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Journal articleJournal 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, ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleCollection 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAmerican 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 ...
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Journal articleAmerican 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 ...
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Journal articleAmerican 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 ...
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Journal articleAmerican 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 ...
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Journal articleAmerican 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 ...
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Journal articleAMD 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 ...
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Journal articleAmerican 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 ...
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Journal articleAmerican 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 ...
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Journal articleJournal 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 ...
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Journal articleApplied 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAmerican 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 ...
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Journal articleIn 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) ...
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Journal articleTrans 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleInternational 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJ. 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 ...
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Journal articleSemiconductor 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 ...
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Journal articleCollection 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 ...
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Journal articleNASA 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 ...
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Journal articleNASA 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 ...
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Journal articleAGARD 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAmmonia 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. ...
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Journal articleTrans. 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 ...
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Journal articleAeronautical 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 ...
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Journal articleJournal 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 ...
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Journal articleJ. 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 ...
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Journal articleJ 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 ...
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Journal articleundefined · 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 ...
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Journal articleundefined · 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleAeronaut 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 ...
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Journal articleJournal 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 ...
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Journal articleAmerican 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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- ...
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Journal articleundefined · 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 ...
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Journal articleAIAA 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 ...
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Journal articleInternational 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleTrans. 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 ...
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Journal articleAIAA 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, ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleTrans. 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleJ. 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleJournal 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 ...
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Journal articleAcoustical 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 ...
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Journal articleJournal 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 ...
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Journal articleAIAA 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 ...
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Journal articleInternational 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 ...
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Journal articleJournal 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 ...
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Journal articleASME -- 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 ...
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Journal articleAIAA 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 ...
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Journal articleQuarterly 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAIAA 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 ...
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Journal articleAGARD 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 ...
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