Crystal plasticity-based impact dynamic constitutive model of magnesium alloy

The impact dynamic mechanical behavior of a magnesium alloy (extruded AZ31B) is first investigated by using the split-Hopkinson pressure bar (SHPB) apparatus. The dynamic tensile and compressive tests are performed at various strain rates ranging from 1250-2150 s−1 and from 1600-3500 s−1, respectively. The loading direction is set perpendicular to the extrusion direction of the AZ31B alloy. Experimental observation shows that the strain-rate sensitivity of the AZ31B alloy present under dynamic tension is higher than that under compression. Based on crystal plasticity and the approach of strain-rate sensitivity control used in the Preston-Tonks-Wallace model, a new impact dynamic constitutive model is established to describe the dynamic stress-strain responses of the AZ31B alloy. Finally, comparing simulations with corresponding experiments, the simulations are found to agree well with the experiments, thus verifying the developed model.