Vibration and flutter of mistuned bladed-disk assemblies
An analytical model for investigating vibration and flutter of mistuned bladed-disk assemblies is presented. This model accounts for elastic, inertial, and aerodynamic coupling between bending and torsional motions of each individual blade, elastic and inertial couplings between the blades and the disk, and aerodynamic coupling among the blades. The disk is modeled as a circular plate with constant thickness and each blade is represented by a twisted, slender, straight, nonuniform, elastic beam with a symmetric cross section. The elastic, inertia, and tension axes are noncoincident and structural warping of the section is considered explicitly. The blade aerodynamic loading in the subsonic and supersonic flow regimes is obtained from two-dimensional, unsteady cascade theories. AH of the possible standing wave modes of the disk and traveling wave modes of the blades are included. The equations of motion are derived by using the energy method in conjunction with the assumed mode shapes for the disk and blades. Continuities of displacement and slope at the blade-disk junction are maintained. The equations are solved to investigate the effects of blade-disk coupling and blade frequency mistuning on vibration and flutter. Results show that the flexibility of practical disks, such as those used for current generation turbofans, does not have a significant influence on either the tuned or mistuned flutter characteristics. However, the disk flexibility may have a strong influence on some of the system frequencies and on forced response. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.
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