Automotive seat design requires knowledge of the structural response of the seat under various impact conditions as well as understanding the complex interactions between an occupant, seat content and restraint systems. For the case of rear impact collisions, the seat becomes the primary restraint while seatback and head restraint design become increasingly important in mitigating the risk of occupant injury. This study involved the testing of three different seatback designs under FMVSS 202a dynamic conditions to determine the effects of seatback comfort content on occupant response and injury risk measures. Controlled variables include seatback content and seatback stiffness. Three different recliner stiffness values were simulated that resulted in nominal seatback rotation angles of 5, 10 and 15 degrees. Additionally, three different lumbar support mechanisms were tested, including a static suspension, horizontal lumbar support and vertical lumbar support. Results from the 18 tests conducted are presented and analyzed.

It is expected that the various comfort content will affect torso penetration into the seatback, altering the torso angle and therefore influence the resulting head with respect to torso angle. It is determined that seatback rotation (stiffness) and backset are predictors of head angle and that lumbar support type and foam stiffness affect the backset. The time of maximum head with respect to torso angle (determined as the critical event time) is influenced by seatback stiffness, lumbar support type and lower torso rebound. Both seatback stiffness and lumbar type are found to be good predictors of torso penetration. The amount of torso penetration and the rebound effect on torso angle at the critical time in the event are key findings. None of the independent factors are found to have a significant influence on HIC