A method will be presented that allows for a special class of viscoplastic 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 not necessary to solve the model differential system numerically; approximations allow for almost all of these loading cases an analytical integration with sufficient precision. The procedure for the solving of the model differential equations as well as the fit procedure will be described. The computer 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°C will be presented for the viscoplastic models of Robinson, Chaboche and Walker. In addition to the fits, the models are subjected to a statistical investigation which makes evident their structures with respect to the convergence behaviour of the fit procedure and the sensitivity of the models to parameter variations.

Issue Section:
Technical Papers
Topics:
Constitutive equations, Approximation, Computers, Creep, Differential equations
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