A continuum-based cyclic plasticity model for AZ31B magnesium alloy under proportional loading

This study investigates the cyclic plasticity of AZ31B extrusion under axial and shear loading conditions and presents a continuum-based cyclic plasticity model for the anisotropic behaviour of magnesium. An anisotropic form of the Armstrong-Frederick plasticity model is presented. It is shown that the model can independently produce hysteresis loops under pure axial and pure shear loading conditions. Two different parameters for loading and unloading were considered to address the asymmetric shape of the axial hysteresis loops. The model is evaluated by considering the cyclic stress-strain response of AZ31B extrusion in uniaxial and multiaxial loading cases. Stress amplitude, plastic energy and total energy densities are calculated using the proposed model and are compared with experimental results showing a good agreement.