Under full frontal crash events, major factors affecting occupant injury are crash pulse severity, restraint system, and vehicle occupant packaging space. The crash pulse severity represents the total performance of collision energy absorbed by vehicle structure during the crash event. The pulse severity also has a close relationship with the energy absorbed by restraint system out of the occupant’s total kinetic energy induced by crash event. The capacity of energy absorption by restraint system is affected by the vehicle occupant packaging space. Thus, it is important to perform both restraint system and packaging space optimization simultaneously to manage the energy transfer under given severity of crash pulse.

In this study, severity function is defined to represent the regression curve of resultant energy absorbed by occupant, based on G-D curve and occupant packaging space. To build the regression curve, US NCAP top rated vehicles were analyzed and the relation between crash pulse severity and severity function is derived for various vehicle grades. Based on the result, target requirements of crash pulse severity and severity function are determined to satisfy occupant safety performance goals. This methodology is very useful to evaluate the crashworthiness performance of vehicle body design concept efficiently at early development stage.