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.