Evaluation of Seat Back Strength and Seat Belt Effectiveness in Rear End Impacts 872214

The issues of front seat energy absorption and seat belt effectiveness are investigated first through the review of prior experimental and analytical studies of rear impact dynamics. These prior studies indicate that the current energy absorption characteristic of seats is a safety benefit. Prior efforts to construct a rigidized seat indicate that such designs are likely to be impractical due to excessive weight and cost. Additionally, these studies indicate that seat belts provide an important safety function in rear impacts. Static tests of production seats were conducted, added to an existing data base, and analyzed to better understand the strength and energy absorbing characteristics of production seats. Crash test results from the New Car Assessment Program as well as earlier test programs were analyzed to describe the response of occupants and seats in rear impact and the protective function of seat belts in such collisions. Finally, accident statistics were reviewed to determine the present level of occupant protection provided by current seats. Field experience indicates that, even with a largely unbelted population, current seats are providing an impressive level of occupant protection in rear impact. A significant potential was observed for increasing rather than decreasing occupant injury potential in rear collisions by obviating the current energy absorbing characteristic of seats.