Evaluating pedestrian head Sub-System test procedure against full-scale vehicle-pedestrian impact

The current Euro NCAP pedestrian head test procedure encourages the industry to optimise their vehicle design towards a simplistic, sub-system test procedure instead of the full-scale pedestrian impact. Thus, the effectiveness of this procedure in reducing real-world pedestrian injury risk and severity depends on how accurately the sub-system test procedure can correlate the full-scale impact. The objective of this study is to evaluate the Euro NCAP head test procedure against full-scale vehicle-pedestrian impact using finite element models of a human pedestrian, sub-system impactor, and vehicle. The impactor response and pedestrian head response in the full-scale vehicle-pedestrian impacts were compared at the same vehicle impact location across a diverse range of impact scenarios, and with a hypothesis that changes in vehicle hood stiffness will result in different response trends between the impactor response and head response. The results suggest that the difference between the impactor responses and head responses may depend on the impact configurations, particularly in the presence of hood deformation prior to head impact. When there was no vehicle pre-deformation on the head impact area, the trends between impactor response and head response were similar under changes to the vehicle stiffness. However, when there is vehicle pre-deformation caused by upper body impacting the hood, the impactor response could show different trends than head response. This was more evident in cases pedestrian laterally facing vehicle. These results suggest that designing the hood structure to the sub-system test procedure alone might be not sufficient for optimising pedestrian head safety.