Material and shape crash-box influence on the evaluation of the impact energy absorption capacity during a vehicle collision

During a light collision between two vehicles or a vehicle and an obstacle, the internal structure of the car is irrecoverably damaged. In order to limit as much as possible the body in white defacement the new vehicles are equipped with so called crash boxes situated in front and rear of the car. The purpose of our study is to analyze the influence of the crash box material in order to reduce the side member permanent deformations, since once damaged, this component, even repaired, will never assure a good safety in case of major collision. Although the speed necessary for of a car homologation is 16 km/h, a second purpose of this paper is to identify the influence of the velocity upon the crash box behaviour. Consequently, a numerical study has been undertaken to investigate axial crushing responses, energy absorption performance of empty & foam filled steel and aluminium concentric tubes with different density of foam.