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Seat Back Strength Analysis & Design



Ford Explorer (4-Dr) Rear Impact

Crash Test




Jeep Grand Cherokee

New 301 Rear Impact Test Conditions

50 mph w/30% offset

(click to enlarge)



Ford Explorer (2-Dr) Rear Impact

Crash Test

(click to enlarge)



David J. Biss was the Seat Back Strength and Failure Analysis Engineer for three full-scale crash tests at the National Crash Analysis Center



Rear Impact HYGE Sled Test at 18.7 mph of

1998 Ford Explorer



Reverse Engineering Tear-Down of

Explorer Seats

(click for slide show)



Reverse Engineering Tear-Down of Sebring Convertible ABTS Seats

(click for slide show)



Forensic and Design Analysis of Seat Tracks

(click for slide show)






Time-Line Of The Evolution Of

Seat Back Strength

(click to enlarge)



  • For comparative reference purposes in this analysis, the occupant loading on the seat back will be assumed as 52.5 Kg (115 lb) [ = 70% of the Hybrid-III dummy weight] at 33cm (13 inches) above the SRPt/H-point.

  • There have been a number of petitions and rulemaking considerations regarding FMVSS 207 Seat Back Strength over the years. However, in 2004 NHTSA terminated Rulemaking, and the wording of the justification for doing so was essentially similar to the justification for the (fundamentally non-dynamic) standard set forth in the original REPORT ON THE DEVELOPMENT OF THE INITIAL [FMVSS] in 1967. Over the past 38 years, with NHTSA not furthering rear impact safety standards through Rulemaking, car manufacturers like Volvo, Mercedes, BMW and Saab have gone ahead and voluntarily applied the Basic Occupant Protection Principles of DeHaven, Stapp, Bohlin and others to upgrade dynamic rear impact occupant protection performance to become orders of magnitude improvements over the minimum FMVSS 207 which, in the final analysis, turns out not to be a dynamic crash standard at all.

The Euro-NCAP Program includes a rear impact seat restraint assessment test that has significantly improved the rear impact safety of passenger vehicles in that market.






Rear Impact [whiplash] Test


The Euro-NCAP Rear Impact [Whiplash] Assessment System is far more advanced than any Federal requirements in the U.S. For more information, refer to: