Suitability of the Available Mechanical Neck Models in Low Velocity Rear End Impacts

Paper in proceeding, 1996

Neck injuries in car accidents are usually classified as AIS 1 but they often cause long term pain and disability. The number of these injuries is on the increase and the costs for the society and the insurance companies are significant. Rear-end impacts give the largest contribution to the number of neck injuries. Head-restraints offer little protection against neck injuries in rear-end collisions and there is no established method for performance testing. The injury symptoms are well documented but the actual injury, causing the symptoms, has not yet been established. Consequently the relationship between head-neck motion and injury risk is unknown. A research program to address these problems is ongoing at Chalmers University and one of the main activities is the development of new dummy components for improved rear-end impact testing. Several investigators have noted limitations of the commonest crash test dummy, the Hybrid III. It has a too stiff neck and torso response in rearward sagittal bending.
As a first step, a new RID-neck (Rear Impact Dummy-neck) was designed and validated. This dummy neck has been used to investigate the head-neck motion in various standard car seats during rear-end impacts. TNO have now started producing a more durable and well defined version (TRID-neck). As more test data from volunteer tests have become available, further evaluation of the RID-neck has been undertaken and a need for a decreased resistance to retraction-protraction motion of the head-neck system has been revealed. It has also become evident that realistic stiffness and shape of the whole spine needed to attain.
At the moment a new RID-neck with less resistance to retraction-protraction and a more realistic spinal shape is under development. In parallel, a mathematical model (MADYMO) of the new RID-neck is being developed. A first generation articulated thoracic and lumbar spine for rear-impact testing has been developed and with further refinement it is expected that a complete dummy spine from pelvis to head will result in a dummy with significantly improved biofidelity in the rear-end impact situation.