Higher-order theories for thermal stresses in layered plates

First order shear deformation theory renders quite accurate in-plane stress es even for rather thick plates. By means of equilibrium conditions derivat ives of the in-plane stresses can be integrated to determine transverse she ar and normal stresses. The need to use in-plane derivatives requires at le ast cubic shape functions. Simplifying assumptions relieve these requiremen ts leading to the extended 2D method. While under mechanical load this meth od yields excellent results, poor transverse normal stresses have been obta ined for plates under a sinusoidal temperature distribution. This paper tra ces back these deficiencies to lentil-like deformations of each separate la yer. It is proved that third or fifth order displacement approximations thr ough the plate thickness avoid these deficiencies. (C) 2001 Elsevier Scienc e Ltd. All rights reserved.