Crashworthiness Evaluation of Empty and Foam-Filled AZ31B Magnesium Beams under Three-Point Bending

Kurzfassung

As the lightest structural metal, magnesium alloys have been attractive to reduce vehicle weight and emissions by lightweight design in the automotive industry. As it is known, some die-cast and wrought magnesium alloys have advantages in weight specific energy absorption in some bending and buckling modes compared to steels and aluminium alloys. This study presents a hybrid structure in which a magnesium alloy shell surrounds a lightweight foam core. In order to evaluate the crashworthiness of this hybrid structure under bending loads, both empty and polyurethane foam-filled rectangular section beams, which were made of AZ31B magnesium extrusion and sheet, were constructed and tested by using the quasi-static/dynamic three-point bending facilities at German Aerospace Centre (DLR) – Institute of Vehicle Concepts. Both quasi-static and dynamic tensile/compressive tests on coupon specimens were also carried out to characterize the strain hardening, plastic anisotropy, tension-compression asymmetry and strain rate sensitivity of AZ31B magnesium alloy. The experimental results, which were compared with those from DC04 steel beams, demonstrate that the foam-filled beams have much higher specific energy absorption compared to the empty beams for both magnesium and steel profiles. The foam-filled AZ31B magnesium beams with proper foam density exhibit higher specific energy absorption compared to foam-filled DC04 steel beams.