Simulation of the Cyclic Stress-Strain Behavior of the Magnesium Alloy AZ31B-F under Multiaxial Loading

Under strain control tests and cyclic loading, extruded magnesium alloys exhibit a special mechanism of plastic deformation ("twinning" and "de-twining"). As a result, magnesium alloys exhibit an asymmetric material behavior that cannot be fully characterized with the typical numerical tools used for steels or aluminum alloys. In this sense, a new phenomenological model, called hypo-strain, has been developed to correctly predict the cyclic stress-strain evolution of magnesium alloys. On this basis, this work aims to accurately describe the local cyclic elastic-plastic behavior of AZ31B-F magnesium alloy under multiaxial cyclic loading with Abaqus incremental plasticity. The phenomenological hypo-strain model was implemented in the UMAT subroutine of Abaqus/Standard to be used as a design tool for mechanical design. To evaluate this phenomenological approach, the results were correlated with the uniaxial and multiaxial proportional and non-proportional experimental tests. In addition, the estimates were also correlated with the Armstrong-Frederick nonlinear kinematic hardening model. The results show a good correlation between the experiments and the phenomenological hypo strain approach. The model and its implementation were validated in the strain range studied.