Experimental and numerical crushing analyses of thin-walled magnesium profiles
AbstractIn order to assess the crashworthiness of simple magnesium structures the axial deformation behaviour of different hollow rectangular profiles produced from wrought magnesium alloys Mg–3wt.%Al–1wt.%Zn–0.3wt.%Mn and Mg–1wt.%Zn–0.4wt.%rare earth mischmetal were investigated under quasi-static compressive loading conditions. Laser beam welding was applied to build the crush configurations from plane rolled sheets; indirect extrusion was used to manufacture seamless profiles. Numerical simulations were conducted to predict and assess the crush behaviour. The simulation results revealed that the material work hardening rates evidenced in uniaxial compression tests together with the cross section influenced the buckling modes as well as the energy dissipation. The performance of the magnesium profiles in terms of dissipated specific energy is better than that of aluminium profiles for small compressive displacements. However, for large displacements, shear-compressive failure limited the crush displacement and hence the energy dissipation. The weld itself did not influence the failure and the energy dissipation of the respective structure. For the alloy and process development of wrought magnesium, prospective improvements towards higher dissipated energy can be realised by increasing not only the strength but also the hardening rate of the material.