Effect of seat belt and head restraint on occupant’s response during rear-end collision

Current neck injury criteria used to evaluate whiplash injuries are based on the kinematics or kinetics of the occupant’s head and neck during rear impacts. The occupant’s response is affected by many factors including impact severity, seat design and occupant related factors such as gender and posture. Most of the current finite element models are concerned with modeling the head and neck, ignoring the interaction of the seat with the occupant during rear collision. In this work the Global Human Body Model Consortium (GHBMC) finite element model was used to study these interaction effects with emphases on the effect of seat belt, headrest and seat stiffness on the occupant’s response during rear-end collisions and evaluate the response using three neck injury criteria. The study shows the dramatic importance of the occupant’s seat restraint and head rest upon occupant safety. Specifically, the occupant ramping during rear impacts can be prevented by using the seat belt. Furthermore, the headrest reduces the head displacement and rotation. Our work further reveals that the head displacement reduction can lead to higher moments, axial and shear forces at the neck, especially for cases involving poorly adjusted or stiffer headrest.