A Comparison Between NHTSA Crash Test Data and CRASH3 Frontal Stiffness Coefficients

The appropriateness of the set of eight frontal stiffness coefficients used by the CRASH3 program to estimate vehicle deformation energy (and to subsequently derive estimates of vehicle delta-V) is examined. This examination consists of constructing so-called CRASH energy plots based on 402 frontal fixed barrier impact tests contained in the NHTSA's Vehicle Test Center Data Base (VTCDB) digital tape file. It is concluded that the use of category coefficients within the CRASH3 program can result in large delta-V errors, reaffirming the inappropriateness of this program for use in individual accident reconstructions. The use of the CRASH3 category stiffness coefficients is seen to generally overestimate vehicle energy absorption for vehicles with small amounts of frontal crush and to underestimate vehicle energy absorption for vehicles sustaining large crush. Comparisons among the stiffnesses of different size vehicles indicates little or no dependence of stiffness on vehicle size and it appears that the current set of eight frontal stiffness coefficients could, for statistical purposes, be reduced to two - a set applicable to passenger cars and a second set for light trucks and vans.