Postbuckling Behavior of Carbon-Nanotube-Reinforced Composite Toroidal Shell Segments Subjected to Thermomechanical Loadings

Motivated by evident absence of studies on doubly curved closed nanocomposite shells under complex thermomechanical loading conditions, this paper presents an analytical investigation on the buckling and postbuckling behavior of the carbon-nanotube-reinforced composite toroidal shell segment surrounded by an elastic foundation, exposed to preexisting thermal loadings and subjected to axial compression, external pressure, and combined mechanical loads. Carbon nanotubes are reinforced into the matrix phase through uniform or functionally graded distributions. The material properties of the constituents are assumed to be temperature dependent, and the effective properties of the nanocomposite are estimated by an extended rule of mixture. Two temperature conditions and various situations of mechanical loads are considered. Basic equations are established within the framework of the classical shell theory taking into account the geometrical nonlinearity and surrounding medium-shell interaction. Multiterm solutions of deflection and stress function are assumed to satisfy simply supported boundary conditions, and the Galerkin method is applied to obtain nonlinear load-deflection relations from which buckling loads and postbuckling paths are determined. Numerical examples are carried out, interesting discussions are given, and beneficial and deteriorative effects of various factors are analyzed.