Constitutive behavior of magnesium alloy sheet at high strain rates

Abstract
In an effort to improve the fuel efficiency of automobiles, car designers are investigating new materials to reduce the overall automobile weight. Magnesium alloys are good candidates to achieve that weight reduction due, in part to their low density. As part of a project on the interaction between forming and crashworthiness, constitutive parameters of AZ31B sheets were determined in order to support finite element analysis of the material response throughout the forming process and in crash structures. Stress-strain data was collected at 0.003s⁻¹, 100s⁻¹ and 1000s⁻¹ in both the rolling and transverse directions. The intermediate strain-rate response was collected with an instrumented falling weight impact test for a rate of 100s⁻¹, while 1000s⁻¹ tests were performed with a tensile split Hopkinson bar. The Johnson-Cook model was successfully fit to the experimental data which showed significant strain rate dependence in both directions.