Bending Collapse Behaviour of Polyurethane Foam-Filled Rectangular Magnesium Alloy AZ31B Tubes

Abstract

Quasi-static/dynamic three-point bending tests were conducted to assess the crash performance of magnesium alloy AZ31B extruded and sheet tubes at the German Aerospace Centre (DLR) – Institute of Vehicle Concepts in Stuttgart. Different foam-filled AZ31B beams with a variation of foam density and thickness were fabricated through several manufacturing processes: cold bending, tungsten inert gas welding, cathodic dip painting and polyurethane foam injection. The experimental results were compared with those from mild steel DC04 tubes. It shows that empty magnesium alloy AZ31B outperforms steel DC04 in terms of specific energy absorption for the empty tubes with equivalent volume when subjected to bending loads. It was found that the foam-filled tubes achieved much higher load carrying capacity and specific energy absorption than the empty tubes. Moreover, there is a tendency showing that a foam-filled beam with a higher foam density reaches higher load carrying capacity, but fractures earlier. The foam-filled AZ31B tube with 0.20 g/cm3foam obtained the highest specific energy absorption, but this outperformance was weakened due to the earlier fracture. In addition, the numerical simulation utilising material model MAT_124 in LS-DYNA explicit FEA package was performed. The simulation results indicate that using calibrated stress-strain curves and failure parameters, material model MAT_124 yields a general good agreement with the experimental results.