Optimizing the rear seat environment for older children, adults, and infants
Authors: Jingwen Hu, Jun Wu, Kathleen D. Klinich, Matthew P. Reed, Jonathan D. Rupp, Libo Cao
Objective: Our recent rear seat safety research found that more-forward and higher lap belt anchorage locations and much shorter and stiffer seat cushions can improve the protection of older children from 6 to 12 years old who are using the vehicle belt without a booster. The objective of this study was to investigate whether the optimal rear seat restraint systems for adults and infants are consistent with those for older children. Methods: We conducted sensitivity analyses and design optimizations for adults and for infants in a rear-facing child restraint system (CRS) using a set of MADYMO models, an automated simulation framework, and occupant belt-fit and posture prediction models from our previous studies. A series of 12 sled tests was also used to validate the computational models. Results: The optimal belt anchorage locations and the seat cushion length for older children, adults, and rear-facing CRS-seated infants conflict with each other. In particular, more-forward lap belt anchorage locations that prevent submarining for older children would reduce the protection to both adults and CRS-seated infants, although the protection is still acceptable based on regulated injury criteria. A shorter seat cushion could provide optimal protection to older children and adults but would significantly increase the CRS rotation. Conclusions: The findings of this study suggested that adaptive/adjustable restraint systems are necessary to simultaneously improve the rear seat occupant protection for all age groups.