ADAPTIVE MULTIPOINT QUADRATURE FOR ELASTIC-PLASTIC SHELL ELEMENTS

A multi-point integration scheme to enhance the coarse-mesh accuracy o f the four-node quadrilateral shell element for elastic-plastic simula tions by explicit methods is described. Compared to 1-point quadrature elements, considerably improved results can be obtained by using this multi-point scheme in beam bending problems where a model with one or two layers of elements along the depth is employed. In the interest o f efficiency, an adaptive scheme is devised in which the number of qua drature points depends on the state of the element. This speeds up the computation and maintains accuracy in the plastic range. The scheme i s designed so that no incompatibility is introduced upon switching fro m 1-point to multi-point quadrature. The speed-up achieved by adaptive quadrature depends on problem parameters. Numerical examples show tha t this adaptive quadrature method effectively captures the in-plane be nding behavior in elastic-plastic simulations and achieves good effici ency. (C) 1998 Elsevier Science B.V. All rights reserved.