Thermo-Aeroelastic Flutter Instability and Nonlinear Aeroelastic Responses of Viscoelastic Sandwich Composite Panels

This study investigates the flutter instability and nonlinear aeroelastic responses of viscoelastic sandwich composite panels under thermal conditions. First, the Kelvin–Voigt model is employed to establish a stress–strain relationship that includes viscoelastic damping, and the effect of the temperature gradient is incorporated into the strain term. For the equation of motion, the influences of in-plane thermal expansion in the viscoelastic sandwich layer on the transverse bending deflection of the panel are taken into account. Second, based on the von Kármán nonlinear plate theory, third-order piston theory is employed to simulate the airflow aerodynamic pressure, and nonlinear dynamic equations for the panel are established by employing Hamilton’s principle. Finally, the Galerkin method is employed to spatially discretize the partial differential equations for the motion of the panel before obtaining the corresponding system of time-domain governing equations. Then the time-domain equations are linearized to derive the frequency-domain governing equations. The results show that increasing the volume fraction of viscoelastic sandwich layers can strengthen the viscoelastic damping effect, and the viscoelastic damping effectiveness scales with the sandwich layer volume fraction. Weak viscoelastic damping intensifies panel flutter, while strong viscoelastic damping can effectively suppress flutter. Under thermal conditions, the use of a viscoelastic sandwich layer with strong viscoelastic damping can compensate for the negative effects of thermal stress during flutter.