Frontal impact test data of vehicles which have various front structure configuration are analyzed, and relationship between crashworthiness and occupant injury level is discussed.

Specific displacement, R (ratio of actual to free vehicle displacement) is introduced as an index for estimating the crashworthiness of front structure. Value of R at a certain time (here t = 40 msec) can represent the feature of crashworthiness in earlier period of impact and has close correlation with occupant injury level. To keep less R value, that is, to keep less vehicle displacement in earlier period of impact is effective to reduce injury severity.

Presumed value of R is also obtained by computer simulation. It could give an indication for predicting occupant protection performance with certain exactness in the first stage of vehicle body design.