A Phenomenological Constitutive Model for the Tension–compression Asymmetry in Magnesium Alloys

The phenomenon of asymmetry exists in yield stress, hardening evolution, and damage accumulation under tension and compression loading paths for Magnesium (Mg) alloys. In order to simulate accurately the plastic deformation and damage occurrence during Mg sheet metal forming processes, advanced constitutive model accounting for asymmetry is highly required. This paper aims to develop a thermodynamically consistent constitutive model to treat the asymmetry in magnesium alloys. The proposed model is based on the fully coupled constitutive equations accounting for combined isotropic and kinematic hardenings, in which the hardening parameters are evolving with the plastic strain to capture the hardening asymmetry. A carefully parametric study of the new parameters is conducted to show the predictive capabilities of the proposed model. Through comparison between the simulation results and experimental observations, the proposed model could reproduce the stress-strain curves of Mg alloys under tensile and compressive loading conditions with high accuracy.