Material oriented crash-box design – Combining structural and material design to improve specific energy absorption

Abstract

Comprehensive design requires interdisciplinary knowledge. For crash-boxes as used in cars - lightweight design, safety requirements, and costs are relevant. Therefore, expertise from mechanical and material engineers is required to develop an optimized component, considering various conflicting constraints from structural design and material design.These critical constraints have been elaborated in order to exploit the extraordinary strain hardening of high manganese steels within a crash-box application, to achieve the optimum utilization of energy absorption potential. A new design for crash-boxes has been laid out and simulated using a finite element simulation model. The new design, has two separated deformation stages, which require different characteristics of the materials used. For each of the two stages, the chosen high-manganese steel was adapted to achieve the optimum specific energy absorption. An optimized processing of the materials, including deformation and annealing, treatments, improved the specific energy absorption. Design principles and the material processing parameters are elaborated. The experimental proof confirms the two-stage deformation behavior and the usability of the supporting structure, however, also shows that adjustments still need to be made to both the welding and the edges.