Validation of the Use of Quasistatic Force Deformation Measurements for Determining Collision Force in Low-Speed Override/Underride Collisions

The purpose of this study was to investigate the use of quasistatic force deformation (QSFD) data to represent the collision forces in low-speed collinear collisions when there is damage to vehicle body structures as well as the bumpers. In this study five full-scale underride/override crash tests were performed and simulated with QSFD data. In each crash test a bumper or a trailer underride guard on a bullet vehicle overrode the rear or front bumper of a target vehicle and damaged structures above the bumper of the target vehicle. A QSFD measurement was performed substantially similar to the vehicle interactions in the crash using a complete exemplar target vehicle that was rigidly attached to the earth. The output of a QSFD measurement is force deflection data for the vehicle pair. Each crash test was simulated using the QSFD data, the weights of the test vehicles, the closing speed of the test vehicles, and the restitution measured in the crash test. The output of a simulation was the velocity vs. time history of the target vehicle. The change in velocity (ΔV) of the target vehicle in the simulations was determined by analysis of the force deflection data. The ΔV ranged from 3.9 to 8.6 mph. The average differences between the ΔV measured in a crash test and the calculated in the simulation of that crash test was 0.16 mph. The crash pulses of the target vehicle in the simulations were similar to the crash pulses in the full-scale tests. In three of the full-scale crash tests a load cell array measured the force of the collision. The simulations using QSFD data were able to accurately predict the collision force during the crash. This work demonstrates the utility of the QSFD methodology to represent the collision forces in low-speed crashes when there is damage beyond the bumper systems of vehicles.