Nonlinear stability of auxetic-core porous FG-GPLRC curved panels under combined loading

This paper presents an analytical approach for nonlinear buckling and postbuckling responses of functionally graded porous graphene platelet-reinforced composite (FG-PGPLRC) sandwich panels resting on the nonlinear three-parameter elastic foundation. The panels are subjected to external pressure, axial compression, and proportional combined axial compressionexternal pressure loading with uniformly distributed temperature change. Some types of shell panels are considered, including cylindrical panels, sinusoid panels, and parabolic panels, and the distributions of graphene platelets (GPLs) and porosities are examined. Reddy’s higher-order shear deformation shell theory (HSDST) with nonlinearly large deflection is used to establish the total energy of panels, and the Ritz energy method is applied with an approximate stress function and trigonometric form of solutions. The expressions of critical buckling loads and postbuckling responses of panels are explicitly addressed. A homogenization technique for the auxetic core is used, taking into account the thermal stress to model the thermo-mechanical responses of the auxetic core. The numerical examples prove the outstanding beneficial effects of GPLs, porosities, auxetic core, and PGPLRC face sheets on the nonlinear buckling behavior of sandwich panels.