Influence of the seat and head rest stiffness on the risk of cervical injuries in rear impact

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Foret-Bruno, J. Y.¹; Dauvilliers, F.¹; Tarriere, C.¹; Mack, P.¹

Influence of the seat and head rest stiffness on the risk of cervical injuries in rear impact

Proceedings of the 13th International Technical Conference on Experimental Safety Vehicles (ESV)

Affiliations

¹Renault
Abstract
A seat with an integral seat belt is a means by which the occupant can be restrained more effectively in the case of frontal impact. This of course involves stiffening the seat back whose current relative fragility limits the risk of cervical injury to occupants involved in rear impact at impact speeds over 20 - 25 km/h. This study addresses the question of what solutions exist which guarantee adequate protection against cervical injury in the case of rear impact with a stiffened seat, while still ensuring the higher restraint effectiveness desired in the case of frontal impact. The study consists of the following:
- accidentology study of the frequency and severity of injuries to occupants in rear impact accidents, taking into account the presence or absence of a head rest and the seat’s resistance upon impact.
- definition of the accident conditions in which the greatest risk of cervical injury occurs so as to relate this risk to neck load measurements carried out on a Hybrid III dummy.
- tests carried out using a Hybrid III dummy, manipulating the following variables—the horizontal head/ head rest distance, head rest stiffness, seat back elasticity, and impact speed, in order to study the influence of these variables on dummy neck measurements.
- resentation of the response limitations of the Hybrid III dummy.
- recommendations for obtaining adequate protection in current and future vehicle models.

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