Study of Seat and Head-Support Performance During Full-Scale Rear-End Collisions 670921

Scientific methodology and engineering techniques were applied to the initial 4 of a series of 12 automobile rear-end collision experiments to provide data relating to seat and head support design. Two speeds of impact, three seatback heights, and two seatback strength values were studied. This is a study to evaluate the relative protective merits and the practicality of various seat designs with respect to the many

variables common to rear-end collisions. This basic research data will provide a standard reference system for determining collision performance of seat and head support designs with respect to occupant size, posture, and proximity to injury-producing structures.

IN THIS SERIES OF FOUR COLLISION EXPERIMENTS, a stationary 1967 4-door sedan was rear-ended by an identical striking car for each experiment. In the first experiment, the striking car was traveling at 30 mph; in the second experiment, at 20 mph; and in the remaining two experiments, at 30 mph. Triaxial acceleration data for the heads and chests of the four 95th percentile anthropometric dummies, considered in conjunction with micromotion analysis of body kinematics and related instrumentation, provided information on the relative effectiveness of the head support and seatback designs. For the rear-ended motorist, the forces of collision involuntarily place him in an acutely adverse posture, representing the primary injury problem; the magnitude of force application is secondary. Using high-speed photography, micromotion analysis of the rear-ended motorist provided a basis for correlating relative performances of whiplash restraining systems, with respect to the forced movements and recorded accelerations of occupants. Other factors relating to the rear-end collision problem that were evaluated and quantified include performance of seats, head supports, seat anchorages, seatback deflection and permanent deformation, lap belts, and padding for passenger protection.

Photographic instrumentation included eight high-speed cameras mounted on the collision vehicles to provide close-up, continuous monitoring of occupant movements during these quarter-second collision events. These vehicle cameras were supported by 19 additional photographic units installed on towers and at ground positions about the collision impact area. Data from photographic and electronic instrumentation are presented in this report using techniques designed to facilitate information retrieval and to convey a maximum amount of information with a cursory review of the paper.