Ein stochastisches Werkstoffmodell zur Beschreibung von Kriechen und zyklischem Verhalten metallischer Werkstoffe

The starting-point of this dissertation was the stochastic model of STECK which simulates the essential mechanisms of monotonic inelastic deformations on a stochastic basis. In order to describe cyclic material behaviour, the stochastic model has been extended by the simulation of internal back stresses. This extension is based on the widely accepted concept that at inelastic deformation the dislocation gliding processes are driven by the effective stress which results from the difference between the applied stress and the internal back stress. The evolution of back stresses has been added to the model by introducing additional transition probabilities which consider the influence of the effective stress on the deformation process. The extended stochastic model in mean-value formulation has been fitted to three different materials. Besides an extensive fitting to creep-tests of pure aluminium, simultaneous parameter-fittings to monotonic and cyclic tension-tests of the austenitic steels AISI 316 L and AISI 304 have been carried out. The results of the model-fittings and model-predictions confirm that the developed model is able describe in an averaged form material mechanisms which are important for the cyclic behaviour in the high temperature regime. (orig.)SIGLEAvailable from TIB Hannover: RR 5346(5) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDeutsche Forschungsgemeinschaft (DFG), Bonn (Germany)DEGerman