Development of a head restraint for occupant protection in rear-end collisions

In France, rear impact accounts for 1.5 % of killed and 2.5 % of severely injured occupants in real world accidents involving passenger cars. Compared to other crash configurations, frontal and side impacts for instance, rear impact generates rather minor injuries (AIS 1 level), which in the majority of cases affect the cervical region. In terms of Delta V, the main area of concern for this type of injuries ranges below 15 to 20 km/h. There are a variety of parameters of importance in the rear end impact. The main parameters are the crash severity, the adjustment of the head restraint relative to occupant size and in particular relative to head neck area, the design of the seat and that of the head restraint. The two later parameters are key aspects as they influence directly occupant kinematics relative to the car. For instance, a head restraint that incorporates safety features might be insufficient in restraining head-neck region if the seat design is poor. The other way, i.e. a good seat design and poor head restraint, can not address the main biomechanical constraint : the limitation and central of head excursions relative to the neck. Based on this target, a head restraint has been developed in the frame of multidisciplinary team. The main features are: a curved structure that allows minimizing head restraint/head occiput distance, regardless of the adjustment, internal structure dimensions compatible with taller occupant and an adjustable comfort part to improve load distribution over head occipital region.