FRED II Quasistatic Seat Testing Rearward: An Improved Method Based on the SAE H-point Manikin

Various methods have been used to load a seat in the rear direction, including FMVSS 207, assorted body blocks and QST (quasistatic seat test). However, each method lacks some critical aspect of occupant loading of the seat or is too complex for routine development work. A new method is presented to determine the strength and energy transfer of a seat to an occupant in rear impacts that reflects how an occupant interacts with the seat in a rear impact. A metal-cast H-point manikin, called FRED II, was modified to support a loading bar and was pulled rearward into the seatback by a hydraulic ram. The force and displacement of the loading and the inboard and outboard seatback angle were measured. The response of the seat was recorded by video. The moment about the recliner pivot at peak force was determined by aligning the center of the recliner in side views of the seat position initially and at peak load. The height of the cable above the center of the recliner was determined giving the moment arm at peak load. The force was integrated with displacement to determine energy transfer to the seat. Twelve tests were performed with FRED II and twelve with a traditional body block used by CRA. There were nine matched tests with identical seats. With FRED II, the average peak moment was 2,407 ± 460 Nm and the energy transfer was 2,046 ± 531 J. With the body block, the average peak moment was 2,534 ± 297 Nm using the same method to determine the moment at peak force and the energy transfer was 1,740 ± 379 J. FRED II loads the seatback as the Hybrid III dummy does in sled tests. It measures the energy transfer capability of the seat in a manner that is similar to occupant loading in a rear impact. FRED II is a simple and improved quasistatic method for seat testing. FRED II provides the H-point location and can be used to measure head restraint position.