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.