Re-Analysis of the RICSAC Car Crash Accelerometer Data

Data from the RICSAC1 car crashes have been presented and analyzed in the original reports and in technical papers by others. Some issues dealt primarily with respect to the transformation of data from the accelerometer locations to the centers of gravity. Accelerometers were attached to the moving vehicles and so most results have been presented in moving coordinates. It appears that an additional step to transform the velocity changes and final velocities into inertial coordinates remains to be done. The initial and final inertial velocities and vehicle physical properties are used to compare the experimental data to the law of conservation of momentum. Some of the collisions lead to a loss in total system momentum, as expected. Some show a gain in system momentum which is not physically possible. An analysis of variance of this momentum data shows that the loss or gain of momentum is not systematically related to the type of collision. Consequently, it can be concluded that the variations in the change of system momentum are random and due to factors that were not under control in the experimental collisions. The data indicate that the observed changes in system momentum of the 4 RICSAC impact configurations are not significantly different. Finally, the experimentally measured linear and angular velocity changes, ΔV and ΔΩ, of the vehicles and total energy loss of each collision are compared to theoretical values calculated using planar impact mechanics. These comparisons show that the theoretical energy losses tend to be lower than the experimental values whereas some of the theoretical ΔV and ΔΩ values are lower and some are higher, with no discernable systematic trend.