COMPARISON OF DIFFERENT FINITE DEFORMATION INELASTIC DAMAGE MODELS WITHIN MULTIPLICATIVE ELASTOPLASTICITY FOR DUCTILE MATERIALS

The new contribution of this study is to formulate two wellknown isotr opic elastoplastic damage concepts for ductile materials in the framew ork of 'geometrically exact' finite multiplicative elastoplasticity. F or the model originally proposed by Lemaitre the damage evolution foll ows from a dissipation potential and the hypothesis of general associa tivity. In contrast, the Gurson model takes into account the balance o f mass separately to formulate damage evolution. In this contribution both formulations are based on logarithmic Hencky strains leading to a simple application of the so called 'exponential map' stress integrat or which is the algorithmic counterpart of the multiplicative elastopl astic formulation adopted. Special emphasis is directed towards the nu merical implementation of these models within the framework of finite element analysis of inelastic boundary value problems. To compare the results of numerical computations several standard examples within fin ite elastoplasticity are analysed with both damage models and the resu lts are contrasted to the outcome of an analysis with the classical v. Mises model. Thereby, the dramatic influence of damage on the behavio ur within necking and localization computations is highlighted. The di fferent behaviour of the two models considered within compression domi nated problems is appreciated.