The neck injury criterion (NIC) in dummy tests:​ a mathematical simulation study

Eichberger, A.<sup>1</sup>; Körner, W.<sup>1</sup>; Steffan, H.<sup>2</sup>

Recent progress in injury mechanics of the human cervical spine has introduced a new neck injury criterion (NIC) for soft tissue injuries following rear impacts. This Criterion was investigated in pig and human subject experiments and has shown promising results. However, no standard test procedure has been established so far that allows for comparable research on improved head restraint systems using anthropometric test devices. Especially, proposed thresholds of NIC are only valid for pigs and human beings but not for Dummies. The aim of the present study is to calculate NIC in Dummy tests and to investigate the influence of parameter that have proven to be of importance from accident investigations. Such parameters are velocity change, acceleration level, shape of the acceleration pulse, head restraint position, seat back properties, etc. Additionally, the relationship between NIC and neck is investigated.

The seat of a middle class car was modeled using multi-body simulation techniques (occupant simulation software MADYMO™) Properties of the seat cushion, recliner joint and the head restraint were measured in quasi static loading tests and implemented to the model. The test object, a database of the 50m percentile Hybrid-III Dummy - equipped with a more biofidelic neck (TRID neck) - was positioned according to standard seating procedures. Seat and head restraint were adjusted to standardized positions as used in frontal crash testing. To validate the whole model, a series of sled test tests were performed using the same conditions as in the numerical model. Tests were performed at three different velocities that were repeated several times to check the reproducibility of the test results. Results of simulation and sled experiments were compared and showed acceptable agreement. A parametric study was performed by variation of parameters listed above. NIC was calculated for these simulations using the formula agreed upon on a NIC standardization meeting (Gothenberg, 1998). NIC results were analyzed and compared to loads of upper and lower neck. The rebound motion was not investigated.

Year

Entry

1986

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1990

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1993

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1995

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1998

Eichberger A, Steffan H, Geigl B, Svensson M, Boström O, Leinzinger PE, Darok M. Evaluation of the applicability of the neck injury criterion (NIC) in rear end impacts on the basis of human subject tests. In: Proceedings of the 1998 International IRCOBI Conference on the Biomechanics of Impact. September 16-18, 1998; Göteberg, Sweden.321-333.