Recent design characteristic changes in a small segment of production passenger car front seats have focused attention on the influence of seat back strength on occupant kinematics and potentially injurious loads placed on occupants during rear end collisions. The National Accident Sampling Study (NASS) database from the years of 1980 to 1993 was interrogated to determine the relationship between vehicle change in velocity, and the nature and severity of injuries sustained by passengers occupying those seats in rear end collisions. The results of the NASS data analysis show that the yielding seats in most current automobiles perform well as a passive restraint system. When the yielding passenger car seats are compared to the stiffer seat/cab, the passenger car seats offered improved protection. The results of dynamic Hyge rear impact sled tests indicated that stiffer seats do not have any consistent advantages over yielding seats for the complete range of speeds tested. When the production seats were modified to obtain higher seat back stiffness, higher responses were seen at the neck, thoracic spine, and lumbar spine. The other, stiffer production seats of different design also showed no consistent improvement in occupant protection across the speed range. Throughout the testing, the most sensitive response to seat design and crash severity was the lower neck extension moment. (A)
Samenvatting