Constitutive parameters identification of AZ31B-H24 magnesium alloy and energy-Absorption analysis in structural panel use

Abstract

As a novel lightweight material, AZ31B magnesium alloy is considered as the most potential material to instead baseline steel in some automotive parts. However, their structural use is quite limited and so far proper numerical modeling has not been developed to represent magnesium alloy. In present study, the Split Hopkinson Pressure Bar (SHPB) test is utilized to investigate material dynamic mechanism for AZ31B-H24 over a wide range of strain rates from 1389 s-1 to 7296 s-1. Parametric identification for Johnson-Cook (J-C) constitutive model available in the commercial finite element package LS-DYNA is carried out. Proper parameters are obtained by curve fit using genetic algorithm with experimental results. Constitutive model after parametric identification is applied to automotive outer panels for crashworthiness analysis. Energy absorption with magnesium alloy substituted baseline steel under lightweight 51.18% is obtained and the key problem of thin-walled magnesium alloy applied in automotive structure is advanced.