In this paper, a previously developed MADYMO model of the first version of the Biofidelic Rear Impact Dummy (BioRID I) and four car seats ranked differently according to a disability ranking list are used to study the influence of crash pulse, seat force characteristics, and head restraint position on the NICmax (a neck injury criterion) in rear-end crashes. A set of 64 crash pulses with four pulse shapes, a peak acceleration from 2.5 to 1O g, and speed change (delta V) from 2 to 5 m/s were used. Also, 22 real-life rear-end crashes were used in the simulations. The results showed a correlation between the NICmax outcome and the disability ranking of the four seats. The critical parameters regarding the seat force characteristics were found to be the recliner torque stiffness and yield limit. The head restraint position had a major influence on the NICmax for one of the four seats. Regarding the crash pulse, the speed change during the first 85 ms of the impact, delta V85 ms, equivalent to mean acceleration during the same time period, was shown to be the best NICmax predictor. For the real-life crash pulses the levels of NICmax, and the delta V85 ms, correlated well with the duration of the occupants' symptoms.
Abstract