Effects of functionally graded graphene reinforcements on nonlinear post-local buckling and axial stiffness of laminated channel section struts

Abstract

The role of local buckling on the behavior of slender members under compression has received considerable attention in structural engineering. For thin-walled sections, in particular, there is a noticeable decrease in the axial compressive stiffness, resulting in a substantial reduction in their load-bearing capacity due to the occurrence of local buckling. The principal purpose of this article is to explore the potential improvements in the postbuckling characteristics of polymeric composite channel section struts subjected to a progressive end-shortening by employing multi-layer graphene sheets reinforcements. The solution methodology incorporates the von Karman geometrical nonlinearity and is based on the layerwise third-order shear deformation theory (LW-TSDT). To verify the accuracy of the results obtained based on LW-TSDT and to evaluate its computational efficiency, a three-dimensional (3D) finite element model is also developed using ABAQUS for the comparative analysis. A thorough examination of nonlinear instability is conducted on composite laminated channel section struts, featuring distinctive graphene distribution patterns through the thickness directions of the flanges and webs to identify the most effective material distribution with the objective of a significant increase in critical end-shortening and axial compressive stiffness. The influence of the geometrical parameters on the critical end-shortening, postbuckling equilibrium paths, and load-bearing capacity of functionally graded graphene reinforced composite (FG-GRC) laminated channel section struts are elicited. The conducted parametric analyses emphasize that altering the distribution patterns of graphene reinforcement across the flanges and web can enhance the critical end-shortening and load-bearing capacity by 80% and 25%, respectively.