Calibration of a simple directional distortional hardening model for metal plasticity

Directional distortional hardening (DDH) is the change of shape of the yield surface such that a region of high curvature develops roughly in the loading direction while a region of lower curvature develops in the opposite direction. In this paper, a simple model of DDH involving six material parameters is calibrated by analytical means. Analytical integration results in equations for the stress-strain curve, the hysteresis loop and the cyclic stress-strain curve inherent to the model. Based on these curves, two calibration procedures for model's parameters are proposed, and consequent analysis shows some basic properties of the model. The first calibration procedure is suited to model monotonic loading whereas the second one is suited to model cyclic loading cases.