Hybrid-stress isoparametric elements for moderately thick and thin multilayer plates

Abstract

A hybrid-stress formulation of isoparametric elements for the analysis of moderately thick and thin multilayer laminated composite plates is presented. The element displacement behavior is characterized by laminate reference-surface inplane and transverse displacements and laminate nonnormal crosssection rotations; as a result, the number of degrees of freedom is independent of the number of layers. All components of stress are included and are related to a set of laminate stress parameters, the number of which is independent of the number of layers. By isolating and analytically integrating all through-thickness contributions to the element matrices, the computation time for the element stiffness generation becomes nearly independent of the number of layers, and thus a computationally efficient element is produced. The formulation is used to develop an 8-node isoparametric multilayer plate element which is naturally invariant, of correct rank, and nonlocking in the thin-plate limit. Results for selected example problems show the range of applicability and convergence behavior of the element.