The Flutter Analysis For Viscoelastic Panel

Vibration and the stability of a rectangular sandwich panel with a viscoelastic core areinvestigated in this paper.In the second chapter, the rectangular sandwich panel is simply supported at twoopposite edges while the other two edges are free. First order piston theory is employed todescribe properties of aerodynamics force. Two governing equations resulted fromforce-equilibrium and moment-equilibrium relationship for Kelvin and Maxwell model areobtained. The Galerkin method is employed to investigate the stability and oscillation of thepanel when it is in supersonic flow. Nmerical resultss have been compared. Results show thatflutter occurs at an internal resonance point, where two order natural frequencies couples. Theamplitude of flutter is independent of the viscoelastic model of the core. Qualitative analysisis given at the end of the chapter.In the third chapter, the rectangular sandwich panel is simply supported at all edges. Firstorder piston theory was employed. The governing equations are derived in a way similar tothat in the second chapter. Numerical results obtained by Galerkin method give the sameconclusion as that in the second chapter. The conclusion in the second chapter changesnothing while the boundary condition changes.In the forth chapter, the subharmonic resonace of the rectangular sandwich panel with anaxially accelerating velocity is investigated. The time-dependent velocity is assumed to varyharmonically about a constant mean velocity. The equation of motion is solved by Method ofmultiple scales and Complex modal method. Results indicate that a subharmonic unstableregion emerges when the pulsing frequence is near the first natural frequence or the secondnatural frequence of the panel. When mean velocity or the bending stiffness enlarges, thenatural frequence of the panel increases and area of the subharmonic unstable regiondecreases.