Offset impact behaviour of bumper beam—longitudinal systems: experimental investigations

Abstract Repeatability and robustness are the key factors that the automotive producers are demanding in connectionwith the crash performance of bumper beam systems. Bumper beam systems are important structures of an automotive that protect the passengers from front and rear collisions. Assessing the impact performance of only a bumper beam system through full-scale crash tests of a car is not easy. Thus, this paper presents experimental investigations on the bumper beam–longitudinal systems subjected to 40% offset impact. Bumper beam systems that are generally fitted to the automotives include ‘crashboxes’ besides the longitudinals. In the current study, the bumper beam system does not include any ‘crashboxes’. This is also the preferred system for some automotive producers. A longitudinal will offer higher resistance to deformation and thus gives higher energy absorption than if crashboxes are used. Using SIMLab's kicking machine, experiments were performed on rotary stretch–bent aluminium bumper beams, which were connected to two longitudinals at both ends and an experimental database was established. The repeatability and robustness of the bumper beam–longitudinal systems were studied by varying the material and temper condition of the longitudinals. Experimental investigations revealed that the longitudinal members with considerable strain-hardening would change the collapse mode into a global mode and reduce the energy absorption capability, due to the random development of lobes along the length.