PARAMETER-IDENTIFICATION FOR FINITE DEFORMATION ELASTOPLASTICITY IN PRINCIPAL DIRECTIONS

This work is concerned with identification of material parameters base d on experimental data, which represent nonuniform distributions of st resses and deformations within the volume of the specimen. Both elasti c and inelastic material non-linearities in the frame of a finite defo rmation theory are taken into account. Gradient-based descent methods (e.g. Gauss-Newton method, Quasi-Newton method) are used for minimizat ion of a least-squares function. To this end a sensitivity analysis is performed, and the resulting expressions are presented in a spatial a nd a material setting. In particular, the cases of an isotropic hypere lastic model and a multiplicative plasticity model with an exponential type integration scheme, both formulated in principal directions, are considered. Two numerical examples, based on simulated data and exper imental data obtained by a grating method, demonstrate the versatility of our approach.