AUTOMATED EVALUATION OF MATERIAL PARAMETERS OF VISCOPLASTIC CONSTITUTIVE-EQUATIONS

A method will be presented that allows for a special class of viscopla stic constitutive models a fast and safe determination of the material parameters. All parameters are determined simultaneously from creep, tensile, and strain-controlled cyclic tests. It is nor necessary to so lve the model differential system numerically; approximations allow fo r almost all of these loading cases an analytical integration with suf ficient precision. The procedure for the solving of the model differen tial equations as well as the fit procedure will be described. The com puter time for the parameter evaluation lies in the range of only some minutes even for a large number of experimental data. Results of fits for the material AISI 316L at 700 degrees C will be presented for the viscoplastic models of Robinson, Chaboche nod Walker: In addition to the fits, the models are subjected to a statistical investigation whic h makes evident their structures with respect to the convergence behav iour of the fit procedure and the sensitivity of the models to paramet er variations.