USING ASSUMED ENHANCED STRAIN ELEMENTS FOR LARGE COMPRESSIVE DEFORMATION

The formulation of the assumed enhanced strain element proposed by Sim o and Armero [(1992). Geometrically non-linear enhanced strain mixed m ethods and the method of incompatible modes. Int. J. Num. Methods Engn g 33, 1413-1449] encountered difficulties for large compressive deform ation with hyperelastic or elastic/plastic materials. The improved for mulation presented by Simo et al. [(1993). Improved versions of assume d enhanced strain tri-linear elements for finite deformation problems. Comp. Methods Appl. Mech. Engng 110, 359-386] proposes to alleviate t his deficiency with a modified quadrature rule and shape function deri vative calculation. In this work, we show an alternative approach whic h attempts to avoid this limitation by treating the orthogonality cons traint on the enhanced field in rate form. Copyright (C) 1996 Elsevier Science Ltd.