Postbuckling behavior of sandwich plates with functionally graded auxetic 3D lattice core

Abstract

In this paper, an investigation on the postbuckling behavior of sandwich plates with functionally graded (FG) auxetic 3D lattice core is presented. Firstly, an auxetic 3D lattice metamaterial is designed and analyzed, of which all six effective Poisson’s ratios (EPRs) are negative, and the in-plane negative Poisson’s ratio (NPR) property can enhance the structural buckling capacity. For the first time, two symmetric FG configurations of the auxetic 3D lattice core through the plate thickness direction are proposed, and compared with the uniform distribution case. Two kinds of compressive postbuckling due to in-plane uni-axial or bi-axial compression, and thermal postbuckling under uniform temperature rise are taken into account. In the current study, full-scale FE modelling and nonlinear analysis are carried out, in which the constituent materials possess temperature-dependent properties. The results of comparison study show that the compressive buckling and thermal postbuckling loads of sandwich plates with NPR core are remarkably higher than those of their counterparts having the 3D lattice core with positive EPR. Parametric studies are further performed to demonstrate the effects of functionally graded configurations, temperature changes, load-proportional parameters and plate aspect ratios on the postbuckling load-deflection curves, along with the EPR-deflection curves in the large deflection region.