Modeling of the Anisotropic Evolution of Yield Surface Based on Non-associated Flow Rule

This work is concerned with a new approach for modeling of a yield function that is able to describe the anisotropic hardening considering general loading directions. A new model explicitly integrates eight flow stress curves including the strain hardening response under balanced-biaxial stress state into the yield criterion in a closed-form solution, which makes it possible to deal with the anisotropy-induced distortional yielding behavior as implied in experimental tests. The new approach accordingly induces relatively small systemic errors in stresses in different loading directions compared to conventional hardening models considering the low and high levels of plastic deformation, which will lead to a significant improvement in the accuracy of numerical analyses for sheet metal forming processes.