Electric-Thermal-Hygro Dynamic Behaviors of Functionally Gradient Viscoelastic Sandwich Plates under Various Boundary Conditions

Due to the special properties of composite structures in aerospace industries exposed to challenging conditions such as hygrothermal environments, the electric-thermal-hygro dynamic behaviors of functionally gradient viscoelastic (FGV) sandwich plates with various boundary conditions are investigated in this paper. The sandwich plate is composed of FGV core and piezoelectric facesheets. The viscoelastic properties of the core material are mainly described by a standard linear solid viscoelastic model with frequency–dependent viscoelastic parameters. Hamilton’s principle is adopted to formulate the dynamic governing equations considering the electric-thermal-hygro effects. The free vibration solutions, harmonic response and transient responses are achieved by using the Galerkin method. By comparisons with the previous literature and the finite element simulation, the theoretical models established are verified to be accurate. Then the influences of boundary conditions, external voltage, hygrothermal parameters as well as viscoelastic parameters on the dynamic behaviors of the structure are analyzed and discussed. This research provides a theoretical basis for the optimization design of the composite structure.