Optimizing Seat Belt and Airbag Designs for Rear Seat Occupant Protection in Frontal Crashes

Jingwen Hu, Matthew P. Reed (University of Michigan), Jonathan D. Rupp (Emory University School of Medicine), Kurt Fischer, Paul Lange, Angelo Adler (ZF TRW Automotive Holdings Corp)

CHALLENGE - Recent field data have shown that the occupant protection in vehicle rear seats failed to keep pace with advances in the front seats likely due to the lack of advanced safety technologies. The objective of this study was to optimize advanced restraint systems for protecting rear seat occupants with a range of body sizes under different frontal crash pulses. 

SOLUTION - This study included three series of sled tests and two series of computational simulations focusing on model validation and design optimization. modeFRONTIER, a multiobjective optimization software program, was coupled with MADYMO to conduct the optimizations. Model parameters optimized in the model validation process against the baseline tests included rear seat parameters (cushion stiffness, damping, and friction), front seat parameters (back stiffness and damping), seat belt parameters (shoulder and lap belt slacks), and ATD parameters (chest and abdomen contact characteristics of the old-THOR 50th model).

BENEFITS - Good correlations between the tests and simulations were achieved through a combination of optimization and manual fine-tuning, as determined by a correlation method. Parametric simulations showed that optimized belt-only designs (3-point belt with pre-tensioner and load limiter) met all of the injury assessment reference values (IARVs) under the soft crash pulse but not the severe crash pulse, while the optimized belt and SCaRAB design met all the IARVs under both the soft and severe crash pulses.​