Stage Two of the Occupant Restraint Technology Evaluation program involved obtaining representative samples of new technology restraint systems and conducting an objective evaluation of their influence on the performance of the current Australian production seat belt assembly. The devices tested included: 1. Webbing Clamps; devices designed to 'grab' the seat belt webbing under load to reduce slip and excessive reel out from the retractor mechanism. 2. Pretensioners; devices designed to remove the slack from seat belt assemblies at the on set of impact. 3. Low Elongation Webbing; webbing with less than standard elongation (stretch) characteristics designed to reduce occupant excursion. 4. Air Bags; devices utilising a fabric bag and a gas generator which inflates during impact to provide a protective barrier between the occupant and the vehicle interior, such as the steering assembly. In response to the accident research findings the structure of Stage Two was designed to home in on the specific problem of driver restraint. The restraint systems were tested under dynamic impact conditions and evaluated against the biomechanical responses obtained from an instrumented Hybrid III anthropomorphic test dummy. The main conclusions of this report are: The current Australian design lap and sash seat belt allows unnecessary forward excursion of the vehicle driver, with considerable scope for improved head restraint under severe impacts. When tested individually, the new technology occupant restraint devices performed successfully at the component level, (ie. performed the specific designed function such as reducing webbing slip), however, did not substantially alter the occupant to vehicle interaction. The new technology restraint systems, except for the air bag, provided insufficient restraint of the driver's head resulting in direct head contact with the steering wheel assembly. 1. The distribution of head injury response from steering wheel impacts was bimodal and was dependent on whether contact occurred between the steering wheel rim or hub. 2. Direct head impacts with the steering wheel hub were more severe than steering wheel rim impacts, with the former more likely to cause potentially fatal injuries.3. The air bag demonstrates the greatest potential for preventing direct head contact with the steering wheel and reducing the likelihood of potentially severe and fatal head and neck injuries.
Abstract