Using Adjusted Force-Displacement Data to Predict the EBS of Car into Barrier Impacts

Our goal was to evaluate whether modifications to the force-displacement curves derived from a high-speed NHTSA frontal barrier test could be used to improve predictions of the equivalent barrier speed of a low-speed crash involving the same vehicle. Using an earlier iteration of the technique described here, Hunter et al. [2] showed that the F-D curves from higher-speed tests over-predicted the EBS of lower-speed tests by 21±17%. After modifying the earlier technique to account for powertrain stack-up and barrier force attenuation prior to reaching peak dynamic crush, the technique evaluated here reduced this error to 1% with a standard deviation that varied between ±9% and ±13% depending on which engine accelerometers were chosen for the adjustment. These findings suggest that the method and modifications proposed here can be used to reconstruct car crashes provided that there is a relationship between dynamic crush and residual crush. Of the 158 NHTSA tests used in this study, only seven of the crash tests reported residual crush measured to the bumper beam. These seven data points indicate the average residual crush measurement to a real-world crashed bumper beam is 12.4 ± 4.7cm less than the dynamic crush at time of barrier separation.