Nonlinear instability of axially loaded functionally graded multilayer graphene platelet-reinforced nanoshells based on nonlocal strain gradient elasticity theory

摘要

With the aid of a more comprehensive size-dependent continuum elasticity theory, the nonlinear instability of functionally graded multilayer graphene platelet-reinforced composites (GPLRC) nanoshells under axial compressive load is examined. To accomplish this end, the newly proposed theory of elasticity namely as nonlocal strain gradient elasticity theory is implemented into a refined hyperbolic shear deformation shell theory to establish a more accurate size-dependent shell model. The graphene platelets (GPLs) are supposed to be randomly oriented with uniform and three different functionally graded dispersions relevant to each layer as the weight fraction of GPL varies layerwise through the shell thickness direction. In accordance with the Halpin-Tsai micromechanical scheme, the effective material properties are achieved corresponding to uniform (U-GPLRC) and X-GPLRC, O-GPLRC, A-GPLRC functionally graded patterns of dispersion. The boundary layer theory of shell buckling and a two-stepped perturbation solving process are employed jointly to capture explicit analytical expressions for non local strain gradient stability curves of axially loaded functionally graded GPLRC nanoshells. Among different patterns of GPL distribution, it is observed that for both nonlocality and strain gradient size dependencies, the maximum and minimum size effects on the critical buckling loads are corresponding to X-GPLRC and O-GPLRC nanoshells, respectively. (C) 2017 Elsevier Ltd. All rights reserved.