Vladislav Levkovitch

Accurate Hardening Modeling As Basis For The Realistic Simulation Of Sheet Forming Processes With Complex Strain‐Path Changes

Sheet metal forming involves large strains and severe strain‐path changes. Large plastic strains lead in many metals to the development of persistent dislocation structures resulting in strong flow anisotropy. This induced anisotropic behavior manifests itself in the case of a strain path change through very different stress‐strain responses depending on the type of the strain‐path change. While many metals exhibit a drop of the yield stress (Bauschinger effect) after a load reversal, some metals show an increase of the yield stress after an orthogonal strain‐path change (so‐called cross hardening). To model the Bauschinger effect, kinematic hardening has been successfully used for years. However, the usage of the kinematic hardening leads automatically to a drop of the yield stress after an orthogonal strain‐path change contradicting tests exhibiting the cross hardening effect. Another effect, not accounted for in the classical elasto‐plasticity, is the difference between the tensile and compressive stre...