The influence of out-of-position displacement during emergency braking on occupant whiplash injury in subsequent rear-end collisions

During emergency braking condition, the occupant inside the vehicle will move forward due to the iner-tia, deviating from the standard upright seating posture assumed in the design of restraint systems. Pre-vious studies have focused on the influence of this out-of-position displacement on occupant injuries in frontal collisions, but few attention has been paid to the effect on whiplash injury during a subsequent rear-end collision. In this study, the MADYMO simulation platform and its active human body model were used to setup a vehicle interior sled test model for rear-end collision research. By setting different braking strength (0.8 and 1.1g), the trigger time of active pretensioning seatbelt (from 0.2s before to 0.2s after the braking initiation), and the pretensioning force (from 100N to 600N), various forward out-of-position displacements of the occupant were obtained. The corresponding whiplash injury met-rics including neck shear force, tension force, and neck injury criteria (NIC) in subsequent rear-end col-lisions were then recorded. The simulation results indicate that the occupant’s neck whiplash injury metrics are, to some extent, positively linear correlated with the out-of-position displacement. The ac-tive pretensioning seatbelt cannot eliminate the forward displacement caused by head and neck flexion, and the whiplash injury parameters generally exceed the capping limits defined in current mainstream evaluation protocols like Euro-NCAP.