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Magnesium alloys are of growing research, development and commercial interest for their lightweight characteristics, notably in the automotive sector. Recent results based on experiments and simulations of beam components have shown that finite element (FE) predictions using commercial FE software may significantly overestimate the peak load and load beyond the peak load. This indicates that better deformation and failure criteria are needed for crashworthiness simulation and design of Mg alloys for the development of computer-assisted engineering (CAE) capacity for Mg alloys. In this study, yield and hardening laws for deformation simulation of Mg alloys are reviewed. An isotropic Lode angle dependent von Mises yield and flow model originally used for soil was modified by replacing shear strength with tensile or compressive flow strength for deformation simulation of Mg alloys.

Use of ultra high strength steel (UHSS) sheet in automotive components has potential to simultaneously reduce weight and increase crashworthiness. For crashworthiness design and simulation, constitutive equations are required; however, these are scarce for UHSS. Also, UHSS sheets may suffer unexpected fracture such as shear fracture, and toughness data for UHSS sheets is very limited. In this work, effects of strain rate and temperature on flow stress of two UHSS sheet steels (a dual-phase ferritic/martensitic DP980 and a martensitic boron (B) steel) are experimentally investigated and compared to a simple constitutive equation for structural steels based on thermal-activation theory of dislocation motion. The flow stress of the two UHSS steels obeys a constitutive equation similar to that of structural steels of other microstructures (ferrite, ferrite/pearlite, pearlite, ferrite/bainite, and bainite).