Mechanical and thermal buckling of FG-GPLs sandwich plates with negative Poisson’s ratio honeycomb core on an elastic substrate

A modified four-unknown shear deformation theory is applied in this paper to investigate the mechanical and thermal buckling analyses of a sandwich plate composed of a negative Poisson’s ratio metallic honeycomb layer sandwiched by two metallic layers reinforced with functionally graded graphene platelets (GPLs). The honeycomb nanocomposite plate is subjected to thermal load as well as in-plane compressive load and resting on two-parameter foundations. The volume fraction of graphene is varied using a layer-wise law through the face layers thickness direction. The temperature field is obtained from the one-dimensional heat conduction equation. The nonlinear differential equations are established using the principle of virtual work. These equations are converted to a linear system employing the virtual displacements concept. The stability linear equations are analytically solved to get the critical buckling load and temperature. The accuracy of the obtained formulations is examined by introducing various comparison examples. From the executed parametric studies, it is important to observe that despite the fact that the plate stiffness is inversely proportional with honeycomb core thickness, the critical buckling temperature increases with increasing the core thickness. This is because the thermal conductivity of the honeycomb core is less than that of the GPLs-reinforced face layers.