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 connection with 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 beamlongitudinal 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.

Assessment of yield and fracture criteria using shear and bending tests

“…The material was delivered as extruded profiles, see Kokkula et al [29] for details. As the yield criterion has previously been calibrated for this material [22], the details of the tests and identification procedure carried out in the previous study are not described here, but merely reviewed for a better overview of which tests that can be used for the identification of the material parameters.…”

Experimental and finite element robustness studies of a bumper system subjected to an offset impact loading

“…Equations (12) and (13). Basically, every residual is normalised with 1 − h ii , the variance for the ith residual.…”

“…Furthermore, articles that combine experimental and numerical sensitivity analyses of large systems are rare. Although Kokkula et al [13,12] investigate the offset impact behaviour of a bumper system both experimentally and numerically, their focus was not on the usage of a sensitivity analysis to assure the robustness of the design or to investigate the correlation between experimental and numerical dispersions. Instead, materials were varied and the sensitivities regarding the choice of material model and its parameters were studied, i.e.…”

Correlations between Axial and Oblique Loaded Column

“…Automotive structures are designed to sustain impact loading in diverse crash directions such as frontal, lateral and rear impact. Above all crash events, frontal collision was identified as the most common accidents on the road and gives rise to high portion of death [1][2]. Thus, it is vital to have an efficient energy absorbing structure on the front side of an automobile.…”