Offset impact behaviour of bumper beam-longitudinal systems: numerical simulations

The paper presents the results from numerical simulations of bumper beam-longitudinal systems subjected to 40% offset impact loading. Numerical simulations were carried out with the non-linear finite element code LS-DYNA, searching for an efficient, numerically robust and accurate representation of the observed system behaviour. A comparative study of an industrial-like modelling procedure and another procedure incorporating a user-defined material model has been performed. In the latter procedure, the material model consists of state-of-the-art anisotropic plasticity, an isotropic strain and a strain-rate hardening rule as well as some ductile fracture criteria. Both shell and solid elements were utilized in discretizing the bumper beam-longitudinal set-up. Numerical crash results revealed good agreement with the experiments with respect to overall deformation mode and energy dissipation. The simulations were capable of giving relatively accurate prediction of the collapse mode found in the experimental tests, except for the bumper beam-longitudinal system with AA7003-T1 longitudinals. Sensitivity studies were performed considering both physical and numerical parameters. The physical parameters were strain-rate effects and the heat-affected zone, whereas the numerical parameter considered was adaptive meshing.