▎ 摘　　要

This article studies nonlocal postbuckling behavior of both uniaxially and biaxially loaded graphene sheets (GSs) in a polymer environment based on an orthotropic nano-plate model. The van der Waals interaction force between the graphene sheets and the polymer medium is considered as a nonlinear function of the graphene's deflection. Considering the small scale effect and using the thin plate theory, postbuckling equilibrium equations are derived with the von Karman-type geometrical nonlinearity. These equations are solved using the Galerkin method for GSs with different boundary conditions. Finally, postbuckling equilibrium path is plotted and the effects of nonlocal parameter, polymer medium, linear and nonlinear coefficients of the vdW interaction, boundary and loading conditions and geometric properties are studied in detail. (C) 2014 Elsevier Ltd. All rights reserved.