High Retention Seat Performance in Quasistatic Seat Tests 2003-01-0173
A new generation of seats has been designed to specifications for high retention (HR) in a Quasistatic Seat Test (QST). The QST involves occupant loading of the seat in a rearward direction and targets peak H-point moment to >1700 Nm giving an energy transfer capability of 2000 J. QST tests from 1998-2000 were compared to results from pre-HR seat designs of the late 1980s and early 1990s to determine performance improvements.
Twenty-seven QST tests of HR seats were randomly selected from a larger series and were evaluated for strength and seat deformation under occupant loading. They represented 20 different seat types from four suppliers. Averages and standard deviations in QST results were computed. In addition, eight repeat tests were conducted with one seat to determine repeatability of the QST. These data were compared to an earlier repeatability study of the 1994 W pre-HR seat, which was evaluated at two facilities. Finally, 12 QST tests were conducted where variability was introduced in the seat back angle, track position, offset and orientation, and in the seatback angle transducers.
The average H-point moment of the HR seats was 2537 ± 703 Nm and represented a 2.3-times higher moment than pre-HR designs. This was achieved with a 35% reduction in seatback angle change at the 1700 Nm target, but a similar initial stiffness or “yield” behavior of the seats. A 2.9-times higher energy transfer capability was achieved by the seats to 3659 ± 1140 J providing calculated rotations <60° for crashes up to 42.5 km/h on average with the 50th percentile male, a 69% increase over pre-HR seats. The repeatability tests demonstrated a coefficient of variation below 3% for the peak force and seatback angle change at the 1700 Nm target moment. The comparable result from the earlier study was within 12%. In conclusion, the new generation of high retention seats provides occupant retention to a significantly higher rear crash delta V than pre-HR designs. These improvements were refined by QST testing and were achieved while reducing the mass and cost of the conventional (non-ABTS) seat designs.
Recent Developments in Automotive Safety Technology-PT-119, The Debate Between Stiff and Yielding Seats-PT-106, Advances in Vehicle Aggresivity & Compatibility, Side & Rear Impact, & Rollover Protection-SP-1775, SAE 2003 Transactions Journal of Passenger Cars - Mechanical Systems-V112-6