Response of Out-of-Position Dummies in Rear Impact

Field accident data suggest that a significant number of occupants involved in rear impacts may be positioned at impact other than in the “Normal Seated Position” - the optimum restraint configuration that has been used almost exclusively in published seat testing. Pre-impact vehicle acceleration from braking, swerving, or a prior frontal impact could cause an occupant to be leaning forward at the instant of the collision, creating a situation where the vehicle “ride-up” potential would be limited. No rear impact tests involving yielding, production-type seats with forward-leaning dummies are found in the literature. Thirty rear-impact sled tests with a forward-leaning, “Out-of-Position” Hybrid III dummy are presented. Tests were performed with a calibrated seat set in either the rigidified or yielding configuration and with the dummy either unbelted or restrained by a production three-point belt system. Test speeds ranged from 5 to 20 mph. The available Hybrid III neck and lumbar instrumentation were used for comparative purposes. Lower injury measures were recorded with the seat in the yielding configuration at all test speeds and for both belted and unbelted dummies.