Engineering Thermoplastic Energy Absorber Solutions for Pedestrian Impact

This paper will describe an approach to satisfying proposed European Enhanced Vehicle Safety Committee (EEVC) legislation for lower leg pedestrian impact. The solution for lower leg protection is achieved through a combination of material properties and design. Using Computer Aided Engineering (CAE) modeling, the performance of an energy absorber (EA) concept was analyzed for knee bending angle, knee shear displacement, and tibia acceleration. The modeling approach presented here includes a sensitivity analysis to first identify key material and geometric parameters, followed by an optimization process to create a functional design.

Results demonstrate how an EA system designed with a polycarbonate/polybutyelene terephthalate (PC/PBT) resin blend, as illustrated in Figure 1, can meet proposed pedestrian safety requirements. Engineering thermoplastics offer higher energy absorption efficiency and a more consistent impact performance over a range of temperatures, than conventional foam systems. This permits the engineering of pedestrian safety solutions that fit within current styling and packaging space specifications.