Buckling and postbuckling of concentrically stiffened piezo-composite plates on elastic foundations

This paper presents the modeling and analysis for the buckling and postbuckling behavior of sandwich plates subjected to thermal and mechanical loads. The lay-up configurations of plates are laminated composite with concentric stiffener and surface mounted piezoelectric actuators. The plates are in contact with three parameter elastic foundation with softening and/or hardening nonlinearity. Several types of grid shapes of stiffeners are studied such as ortho grid, angle grid, iso grid, and orthotropic grid. The equilibrium and compatibility equations of structures are formulated based on Kirchhoff assumptions with taking into account von-Karman nonlinear relationships. The equations are solved in two types of boundary conditions by definitions of the stress function and applying the Galerkin method. Numerical examples are well verified with available data in the literature. Several parametric investigations are conducted to examine the simultaneous effects of voltage through the thickness of piezoelectric actuators, different stiffeners, and nonlinear elastic foundations.