Date of Award

Spring 1991

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Engineering Mechanics

Committee Director

Chuh Mei

Committee Member

Osama A. Kandil

Committee Member

Gene J.-W. Hou

Committee Member

Duc T. Nguyen

Committee Member

Thomas L. Jackson

Abstract

A finite-element approach is presented for determining the nonlinear flutter characteristics of two-dimensional isotropic and three-dimensional composite laminated thin panels using the third-order-piston, transverse loading, aerodynamic theory. The unsteady, hypersonic, aerodynamic theory and the von Karman large deflection plate theory are used to formulate the aeroelastic problem. Nonlinear flutter analyses are performed to assess the influence of the higher-order aerodynamic theory on the structure's limit-cycle amplitude and the dynamic pressure of the flow velocity. A solution procedure is presented to solve the nonlinear panel flutter and large-amplitude free vibration finite element equations. This procedure is a linearized updated mode with a nonlinear time function approximation (LUM/NTF) method. Nonlinear flutter analyses are performed for different boundary support-conditions and for various system parameters: plate thickness-to-length ratio, h/a; aspect ratio a/b; material orthotropic ratio, lamination angle, and number of layers; Mach number, M; flow mass-density-to-panel-mass-density ratio, μM; dynamic pressure, λ; and maximum-deflection-to-thickness ratio, c/h. For large amplitude free vibration, alternative classical analytical solutions are available for comparison. Linear finite element flutter for isotropic and composite panels and large-amplitude isotropic panel flutter results are compared with existing classical solutions. The large-amplitude panel flutter results using the full third-order piston aerodynamic theory are presented to assess the influence of the nonlinear aerodynamic theory.

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DOI

10.25777/8k69-3s53

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