Car-rear-impact-induced cervical spine injuries present a serious burden on society and, in response, seats offering enhanced protection have been introduced. Seats are evaluated for neck protection performance but only at one specific backrest angle, whereas in the real world this varies greatly owing to the variation in occupant physique. Changing the backrest angle modifies the seat geometry and thereby the nature of its interaction with the occupant.Low-velocity rear-impact tests on a BioRID II anthropomorphic test dummy (ATD) have shown that changes in backrest angle have a significant proportionate effect on dummy kinematics. A close correlation was found between changes in backrest angle and the responses of neck injury predictors such as lower neck loading and lower neck shear but not for the neck injury criterion NIC max . Torso ramping was evident, however, with negligible effect in low-velocity impacts.The backrest angle ranged from 20°to 30°whereas the BioRID II spine was adapted to a range from 20°to 26.5°. Nevertheless, in general, instrumentation outputs correlated well, indicating that this ATD could be used for evaluating seats over a 20-30°range rather than solely at 25°as required by current approval test specifications.shown and the hypothesis that there is relationship between backrest angle and neck injury is tested.bolton.ac.uk D22404

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Quasi-static and dynamic roof crush simulations have been carried out successfully on a small European car that was loaded at different pitch/roll angles. The results obtained were validated against the MIRA experimental dynamic roof crush outputs and against the Bolton experiments performed under FMVSS 216. Overall, the outcomes show that bonded windscreens contribute to nearly 30 per cent of the roof strength, thus confirming similar results obtained by a number of other researchers. Furthermore, these results show that roof strength is a function of roll and pitch angles which also greatly influence the overall intrusion rate. The new findings illustrate that, having a fixed loading pitch angle, the roof strength decreases when the roll angles are between 15 and 45°. If the pitch angle is increased, the same phenomenon of reduced strength is observed. However, this does not signify that the roof becomes weaker with increasing pitch angle, because there are limits within which this can occur, and hence the worst-case loading that yields the smallest strength is found at pitch 10° and roll 45. Therefore, it is recommended in this paper that an update be made to the FMVSS 216, where a roll angle of 45° (not 25°) and a pitch angle of 10° (not 5°) be used as they constitute the worst-case loading condition. As a result, a more realistic test configuration with angles that replicate real-world accident data can be represented.

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The function of a head restraint system is to prevent injurious hyperextension of the occupant's neck in the event of a road vehicle rear end impact, and thus it must have adequate stiffness to limit the movement of the head relative to the torso. Also, it should absorb the kinetic energy progressively so that the head does not sustain any injury and does not roll on the cushion. Practically, a well-designed head restraint will have an optimum balance of these features and thereby offer adequate protection for both the head and the neck. This paper presents some pioneering thinking on head restraint design and develops criteria for qualifying the systems. It presents an airbag head restraint system that has optimum stiffness and good potential for reducing head and neck injuries suffered through rear end collisions. It also presents the results of experimental tests conducted on this novel airbag head restraint system and on several randomly selected existing head restraints. Furthermore, analysis of energy absorption capabilities, head injury criterion (HIC) values and a new criterion, called the equivalent impact power criterion (EIPC), is developed in order to quantify the relation between the rate at which energy is imparted to the head during the impact cycle and injury severity. Current test results show that, the lower the EIPC, the better is the head restraint system and the less is the risk of whiplash and head injuries. Moreover, the work has quantified a number of variables, including the optimum stiffness, as the factors governing the severity of injury to the occupant in a rear impact scenario.