Constant Force Restraints for Frontal Collisions

This paper presents a model demonstrating the concept of a constant force restraint (CFR) system for frontal collisions. A three-bodied dynamic model of a 50th percentile anthropometric test dummy (ATD) in a 35 mile/h frontal collision was made using Lagrangian dynamics and verified with test data from the NHTSA. The model was used to compare visco-elastic and constant force seatbelt models in a 1998 Chevy Malibu. The viscoelastic seatbelt simulation was able to reproduce accurately the shape and magnitude of pelvis, chest, and head accelerations when compared to test data. The constant force seatbelt simulation showed reductions in pelvis, chest, and head accelerations by 56, 62, and 63 per cent respectively. The peak lap belt force was reduced by 60 per cent. Relative head rotation was reduced by 16°. A CFR system has the potential to reduce the risk of injury significantly by reducing forces and accelerations on the occupant. These results show great potential to reduce head injury criteria and could be applied to adaptive restraint systems by tuning the CFR to the occupant and crash.