A {1,2}-order plate theory accounting for three-dimensional thermoelastic deformations in thick composite and sandwich laminates

A (1,2)-order theory for laminated composite and sandwich plates is extende d to include thermoelastic effects. The theory incorporates all three-dimen sional strains and stresses. Mixed-field assumptions are introduced which i nclude linear in-plane displacements, parabolic transverse displacement and shear strains, and a cubic distribution of the transverse normal stress. L east squares strain compatibility conditions and exact traction boundary co nditions are enforced to yield higher polynomial degree distributions for t he transverse shear strains and transverse normal stress through the plate thickness. The principle of virtual work is used to derive a 10th-order sys tem of equilibrium equations and associated Poisson boundary conditions. Th e predictive capability of the theory is demonstrated using a closed-form a nalytic solution for a simply-supported rectangular plate subjected to a li nearly varying temperature field across the thickness. Several thin and mod erately thick laminated composite and sandwich plates are analyzed. Numeric al comparisons are made with corresponding solutions of the first-order she ar deformation theory and three-dimensional elasticity theory. These result s, which closely approximate the three-dimensional elasticity solutions, de monstrate that through-the-thickness deformations even in relatively thin a nd, especially in thick, composite and sandwich laminates can be significan t under severe thermal gradients. The (1,2)-order kinematic assumptions ins ure an overall accurate theory that is in general superior and, in some cas es, equivalent to the first-order theory. (C) 2001 Published by Elsevier Sc ience Ltd. All rights reserved.