Implementierung eines Thermoviskoplastizitätsmodells mit Schädigung für die simultane Kalt-/Warmumformung

For the analysis of simultaneous hot/cold forging processes, a thermoviscoplastic constitutive model is introduced, representing nonlinear isotropic and kinematic hardening, thermally activated recovery effects, strain rate sensitivity as well as damage evolution. Their thermal properties are considered in the large range from room temperature nearly up to the melting point. The material theory is based on an enhanced concept of rheological models which allows a largely intuitive interpretation of the material parameters and additionally on the concept of effective stresses. The constitutive model is implemented into LS-DYNA and the material parameters for a low alloyed steel are identified by using LS-OPT and validated by means of a simultaneous hot/cold forging process.