Axisymmetric postbuckling analysis of size-dependent functionally graded annular microplates using the physical neutral plane

This paper investigates the axisymmetric postbuckling of functionally graded material (FGM) annular microplates based on the modified couple stress theory, Mindlin plate theory and von Kármán geometric nonlinearity. Material properties are assumed to be graded in the thickness direction according to Mori–Tanaka homogenization method. By using the physical neutral plane, the bending-extension coupling is eliminated in both nonlinear governing equations and boundary conditions of FGM microplates. The differential quadrature (DQ) method is employed to discretise the governing equations, which are then solved to obtain the postbuckling path of FGM microplates with different boundary conditions. Numerical results are presented to highlight the effects of length scale parameter, gradient index, inner-to-outer radius ratio and radius-to-thickness ratio on the postbuckling characteristics of FGM microplates. It is found that FGM microplates do exhibit the bifurcation-type buckling when the applied in-plane compressive load acts along the physical neutral plane.