Investigating occupant safety through simulating the interaction between side curtain airbag deployment and an out-of-position occupant

The objective of this research is to elucidate the effect of side curtain airbag deployment on occupant injuries and safety when the occupant is either in-position or out-of-position (OOP). We used side impact vehicle collision simulations with a 1996 Dodge Neon model, which was further modified to include a side curtain airbag, a seatbelt, and a 50th percentile Hybrid III dummy. The airbag used in the study was inflated using both the uniform pressure (UP) and smooth particle hydrodynamics (SPH) methods. In-position and OOP simulations were performed to assess and establish guidelines for airbag aggressivity thresholds and occupant position versus risk of injury. Three different OOP scenarios (OOP1, OOP2, OOP3) were initially setup following the work of Lund (2003), then modified such that the dummy's head was closer to the airbag, increasing the chance of injury caused by the airbag. The resultant head acceleration as a function of time for in-position and OOP simulations shows that both UP and SPH methods produce similar peak accelerations in cases where the airbag is fully inflated prior to impact. In all cases, the head peak accelerations and the head injury criteria for simulations with an airbag were significantly lower when compared with the no airbag case, which would typically indicate that the use of an airbag results in improved occupant protection during side impact. However, in the case of OOP2 and OOP3, the neck flexion forces actually increase significantly when compared with the no airbag case. This finding indicates that the HIC and neck flexion forces criterion are in conflict and that there may be a tradeoff in terms of occupant injury/safety with a side curtain airbag that is strongly correlated to the occupant position. Consequently, this study shows that safety devices result in a significant effect on occupant injury/safety when the occupant is in OOP conditions. Moreover, in some cases, simulation results show that the side curtain airbag may not make the occupant safer. This study requires further investigation of the vehicle-specific airbag and its interaction with an occupant in various OOP conditions.