PARAMETER-ESTIMATION FOR A VISCOPLASTIC DAMAGE MODEL USING A GRADIENT-BASED OPTIMIZATION ALGORITHM

In this work a gradient-based optimization method is applied in order to determine material parameters for a viscoplastic model with dynamic yield surface coupled to damage as presented in 1997. To this end a s ensitivity analysis consistent with the integration scheme presented p reviously is performed in a systematic manner, both for strain and str ess controlled experiments. The algorithm is tested in two numerical e xamples: first, simulated data are used, in order to re-obtain paramet ers for the case of damage under monotonic loading. In the second exam ple material parameters are obtained based on experimental data for lc f-testing of an austenetic stainless steel, thus showing a very good a greement with respect to hardening, rate and damage effects.