Small Car Air Cushion Performance Considerations

Abstract

A critical performance issue in the development of any air cushion restraint system is the dicotomy that exists between the inflation rate required to meet the 30 mph frontal, rigid barrier restraint performance requirements and the effect that this parameter has on increasing the risk of deployment-induced injuries to out-of-position occupants. In general, small cars experience greater vehicle deceleration levels than large vehicles in FMVSS 208, 30 mph frontal, rigid barrier tests due to tighter packaging of their front-end components. In order to meet the FMVSS 208 performance requirements for such cars, the small car air cushion must be thicker and inflated faster than the large car air cushion. Such air cushion technology will increase the risk of life-threatening, deployment-induced injuries to out-of-position occupants of the small car. A harm reduction analysis is done that indicates that a greater benefit can be derived from installing a large car air cushion technology in a small car than from installing the same air cushion technology in a large car, even though the FMVSS 208 restraint performance requirements are not met when installed in the small car. This statement is true for any occupant restraint system (belts, passive interiors) identically applied to both the large and small car since small car occupants will always be exposed to more severe collision severities due to the car's lighter mass and reduced front-end crush space. Based on the analyses presented, it is suggested that performance requirements addressing deployment-induced injury concerns of out-of-position occupants be added to FMVSS 208 for evaluating air cushion restraints and that the FMVSS 208, 30 mph frontal, rigid barrier test conditions be changed to a frontal test of equal collision severity for all car sizes.