Large elasto-plastic finite element analysis of solids and shells with the enhanced assumed strain concept

Abstract

A finite element simulation of arbitrarily large elasto-plastic deformations of three-dimensional and shell structures is described. Two numerical aspects originally developed by J. C. Simo have been combined, i.e. the multiplicative large strain plasticity and the enhanced assumed strain finite element concept. The constitutive model is worked out in its algorithmic version applying projection methods and consistent linearization. The enhanced strain field is added to the conventional hexahedral displacement elements avoiding volumetric locking in the plastic range. In addition, to solid structures, the three-dimensional material model without any modifications is also applied to thin-walled shell structures. Here an extended shell formulation, a so-called seven-parameter model, is used in which the thickness strain is augmented by a linear term. The applicability of the entire formulation is demonstrated by several numerical examples.