Low-Energy Seat Compression: Characterizing Stiffness in Different Vehicles 2020-01-0527
In rear-end collisions, occupants move rearward relative to the vehicle and into their seats. In low energy impacts, the stiffness of the non-frame seat components may influence the kinematic response of an occupant. Previous research has reported seat stiffness from experiments for a limited number of seats. Because passenger vehicle seats have evolved, this current work reports the range of seat stiffnesses for modern passenger vehicles. A portable measuring device to characterize vehicle seat stiffness was built to accommodate a wide range of vehicle types. The device measured simultaneously the force applied to the seat and the average deflection. Seats of a sedan, sports utility vehicle, minivan, pickup truck, and a utility van were tested using the device. For each seat, three measurements were taken for four different seat regions: lower seatback, upper seatback, fore seat bottom and aft seat bottom. The seat stiffness for each region was determined using a linear fit of the force-deflection curve generated during testing. The range of seat stiffness across all seat types was 6,588 to 22,215 N/m. The average stiffness was 9,821 N/m (SD 2516 N/m) for the seatback and 12,563 N/m (SD 4,237 N/m) for the seat bottom. For 60% of the seats, the seat stiffness was significantly different for the seatback when compared to the seat bottom. Further, seat stiffness was significantly different between the two regions of the seatback (80% of seats) and between the two regions of the seat bottom (60% of seats). The results indicate that seat stiffness may vary with seat region. These data may be useful in modeling a subject specific low-energy vehicle accident and predicting the kinematics for an occupant.
Bethany L. Suderman, Denise R. Cruise, Nicholas H. Yang, Edmund Lau, Lenka Stepan, Irving Scher