Hybrid-stress six-node prismatic elements

Abstract

This paper presents three novel hybrid-stress six-node prismatic elements. Starting from the element displacement interpolation, the equilibrating non-constant stress modes for the first element are identified and orthogonalized with respect to the constant stress modes for higher computational efficiency. For the second element, the non-constant stress modes are non-equilibrating and chosen for the sake of stabilizing the reduced-integrated element. The first two elements are intended for three-dimensional continuum analysis with both passing the patch test for three-dimensional continuum elements. The third element is primarily intended for plate/shell analysis. Shear locking is alleviated by a new assumed strain scheme which preserves the element accuracy with respect to the twisting load. Furthermore, the Poisson's locking along the in-plane and out-of-plane directions is overcome by using the hybrid-stress modes of the first element. The third element passes the patch test for plate/shell elements. Unless the element assumes the right prismatic geometry, it fails the patch test for three-dimensional continuum elements. It will be seen that all the proposed elements are markedly more accurate than the conventional fully integrated element. © 2004 John Wiley and Sons, Ltd.