Development and Validation of a Headform Impactor Finite Element Model with Application to Vehicle Hood Design for Pedestrian Protection

Head injuries are the most common cause of pedestrian deaths in car-to-pedestrian collisions. To reduce the severity of such injuries, international safety committees have proposed subsystem tests in which headform impactors are impacted upon the car hood. In the first part of the paper, the development and validation of an adult headform impactor finite element (FE) model is presented. The skin material model was assumed as viscoelastic and its parameters were identified by FE optimization to match the quasi-static and dynamic test data reported in literature. Overall, it was shown that the geometrical and inertial characteristics of the headfom FE model developed in this study satisfy the regulations of international safety agencies. The second part of the paper presents results of a hood optimization using simulations of the headform-hood impact test. A generic hood design was assumed consisting of two plates connected by buckling structures. The reductions of head injury risk under impact and the under-hood clearance space were included in an optimization problem which considered the geometry of connecting spools and the panel thicknesses as design variables. The automatic design process was shown to converge to an optimum design after several iterations. The methodology and recommendations for future work presented in this paper may assist in the hood design of new car models to reduce pedestrian head injuries and meet new safety requirements.