Nonlinear static and dynamic thermo-mechanical buckling responses of incline stiffened functionally graded graphene platelet-reinforced composite panels with porous core

A semi-analytical model is developed in this study to investigate the nonlinear static and dynamic thermo-mechanical buckling behavior of functionally graded graphene platelet-reinforced composite (FG-GPLRC) panels with a porous core and inclined FG-GPLRC stiffeners. The panels are assumed to rest on a Pasternak elastic foundation and are subjected to axial compression and thermal loading. The formulation is based on the higher-order shear deformation theory (HSDT), incorporating geometrical nonlinearities described by the von Kármán strain-displacement relation. Three types of complex curvatures, including cylindrical, parabolic, and sinusoid, are considered in the panel geometries. An enhanced smeared stiffener technique is proposed to model the effect of inclined stiffeners, and the nonlinear stress function is approximated using a Galerkin approach. The governing motion equations are derived via the Lagrangian formalism, and numerical simulations are performed using the Runge-Kutta method to capture the time-dependent responses. The critical dynamic buckling loads are determined according to the Budiansky-Roth criterion. The results highlight the combined influences of stiffener, porosity distribution, curvature geometry, and foundation stiffness on the overall buckling performance of FG-GPLRC panels.