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B. Viernstein, E. Kozeschnik:
"Integrated Physical-Constitutive Computational Framework for Plastic Deformation Modeling";
Talk: EUROMAT 2021, Graz; 2021-09-13 - 2021-09-17.

An integrated framework for deformation modeling has been developed, which combines a physical state parameter-based formulation for microstructure evolution during plastic deformation processes with constitutive creep models of polycrystalline materials. The implementations of power law, Coble, Nabarro-Herring and Harper-Dorn creep and grain boundary sliding are described and their contributions to the entire stress response at a virtual applied strain rate are discussed. The effective diffusion coefficient is considered, which includes trapping of vacancies at solute atoms, excess vacancies, and dislocation pipe diffusion as inherent diffusion mechanisms. In contrast to constitutive correlations between stress and strain, physical effects, such as precipitation hardening, solid solution hardening and cross core diffusion effects can conveniently be included into these models by the mechanical threshold concept, to ensure a realistic reflection of the material behavior during even complex thermo-mechanical processing. The combination of thermally activated stress contributions and the athermal stress contribution from dislocation hardening allows simulating the stress-strain relations over a wide range of temperatures and strain rates. The present framework simultaneously allows calculating the plastic deformation under prescribed strain rate or constant stress, as well as stress relaxation after preceding stress or strain loading. In this presentation, the theoretical background of the underlying physical models of microstructure evolution are reviewed and exemplary stress calculations at a strain rate range of many orders of magnitude are presented.

Dislocation glide; Dislocation climb; Diffusional creep

https://publik.tuwien.ac.at/files/publik_302015.pdf