During the development of vehicles for pedestrian protection, plastic components are often regarded as minor contributors to the impact stiffness. Laboratory testing with and without these plastic components led to the hypothesis that they significantly increase this stiffness and subsequently the injury risk measured by the pedestrian headform impactor. This paper will focus on the contribution of the plastic cowl top to impact stiffness. Preliminary testing for specific impact locations found that more than 50% of the head injury criteria (HIC) and 35% of the average stiffness was attributed to the cowl top. Based on these findings, finite element analysis (FEA) was used to assess the potential effects cowl top stiffness reductions may have in terms of injury risk assessment. Further FEA was performed to assess various design changes, including thickness and shape, on the injury risk assessment. The analysis of cowl top changes led to a HIC reduction of 45% for the case focused on in this paper. The results of this study support the hypothesis that plastic components add significant stiffness to the impact, however with FEA supported design efforts, these components may be modified to minimize their influence. For the covering abstract see ITRD E825082.
Abstract