Numerical investigation of the effects of pre-crash braking on occupant neck whiplash injury

Abstract Among vehicle collisions, rear-end collision is the main injury source of neck whiplash injury. With the increasing prevalence of autonomous emergency braking systems in new vehicles, occupant postures during rear-end collisions have become more diverse. Thus, it is imperative to study the occupant kinematics of out-of-position (OOP) passengers during rear-end collisions. This paper integrated both volunteer tests and computer-aided engineering methods to analyse the occupant kinematics and main whiplash injury indexes for OOP passengers among the braking-induced rear-end collision scenarios. The research results indicated that a larger velocity change of braking resulted in greater occupant head and chest displacements. In rear-end collisions of the same impact severity, the main injury indexes of the OOP occupants were worse when compared with those of the standard seated occupants, among which the lower neck Fz forces were 624% and 411% of the base model, respectively. Furthermore, the relative displacement increased both head and chest peak accelerations. These research results are beneficial for the development of active restraint systems, as well as the update of the whiplash test protocol.