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The impact of texture on r-value and its measurement in magnesium alloy sheets has been studied using digital image correlation and electron backscatter diffraction techniques. Two magnesium alloy sheets with distinct textures were used in the present study, namely, AZ31 with a strong basal texture and ZE21 with a randomized texture. It is well known that a conventionally processed AZ31 magnesium sheet has strong basal texture, necessitating contraction and double twinning to accommodate thinning strain. The strain distribution on the sheet surface evolves nonlinearly with strain, impacting the measured r-value. In particular, the normal approach to measuring r-value based on average strains over the gauge section leads to the erroneous conclusion that r-value increases with deformation. When the r-value is measured locally at any point inside or outside the neck, the r-value is shown to have a constant value of 3 for all strain values.

This paper presents the numerical validation of the impact response of a hot formed B-pillar component with tailored properties. A laboratory-scale B-pillar tool is considered with integral heating and cooling sections in an effort to locally control the cooling rate of an austenitized blank, thereby producing a part with tailored microstructures to potentially improve the impact response of these components. An instrumented falling-weight drop tower was used to impact the lab-scale B-pillars in a modified 3-point bend configuration to assess the difference between a component in the fully hardened (martensitic) state and a component with a tailored region (consisting of bainite and ferrite). Numerical models were developed using LS-DYNA to simulate the forming and thermal history of the part to estimate the final thickness and strain distributions as well as the predicted microstructures.

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.