Stress evaluation with numerical integration schemes in finite element analysis of elasto-plastic bending

The paper is concerned with evaluation of stress components in elasto-plastic bending for each increment step in finite clement analysis using a four-node isoparameteric quadrilateral element. It demonstrates the effect of the integration scheme on the accuracy of a solution with stress evaluation. It is noted that conventional integration schemes cause inaccurate evaluation and oscillatory behaviour of stress components while a reduced integration scheme with hourglass control yields accurate evaluation. As a benchmark problem, elasto-plastic bending is investigated for calculation of the stress and strain. The results fully demonstrate that finite element simulation in the usual way is sometimes very dangerous since it could lead to a fatal pitfall and the selection of the integration scheme should be carefully done for specific problems. Copyright (C) 2000 John Wiley & Sons, Ltd.