Cervical Spine Loads Induced in Restrained Child Dummies II

Accident data seem to indicate that small children seated in forward facing restraint systems with a harness belt are at risk from serious neck injuries in moderate frontal impacts. TNO has undertaken a research programme to measure the neck loads induced in TNO-P3/4 child dummies seated in various types of restraint system. The test set-up and results of a series of dynamic sled tests and a series of mathematical simulations have been presented in SAE paper no. 912919.

This research programme was continued by conducting a reconstruction of a real accident with severe neck injuries. Sled tests were performed using similar car seats and a similar child restraint system as in the real accident. The dummy was modified to obtain an anthropometry close to that of the child involved in the accident. Several test parameters were varied and their influence on the measured neck loads analysed. In parallel with the experimental work, a series of mathematical simulations were performed, using the MADYMO CVS program. These analyses were aimed at assessing the best case and the worst case parameter combinations in terms of induced neck loads. A review on existing biomechanical data with respect to child injuries and tolerance limits was conducted. This review includes scaling techniques and accident reconstructions.

The results of the sled tests and mathematical simulations were summarized and are compared with the real accident. Based on the results of this phase of the research programme, preliminary child neck tolerance limits for shear force, tension force and bending moment are proposed.