Side impact motor vehicle crashes pose unique challenges for occupant protection, particularly with regard to torso injury mitigation. The minimal crush distance between the vehicle exterior and the occupant torso has necessitated advanced passive safety technologies in response to tightened regulatory requirements and increased public awareness of safety issues. In particular, lateral airbag restraints (side airbags) have undergone a rapid and unregulated introduction in recent years, with US availability increasing to over 90% of new vehicles in 2010. As with frontal airbag restraints, the propensity for injury to occupants in close proximity to side airbag deployment remains a concern. Test protocols have been proposed to evaluate occupant injury risk from airbag deployment with mechanical occupant surrogates. Yet few studies have attempted to characterize thoracoabdominal responses to close-proximity airbag contact in actual crashes, leaving unaddressed the relevance of test protocols and occupant surrogates currently employed.

To address this issue, the present study sought to identify and characterize injury and biomechanical responses of the thoracoabdominal region to torso-interacting side airbag restraints. A novel biological experimental approach was developed from a multibody analysis and from an evaluation of documented restraint performance. Biomechanical responses of deflection, deflection rate, the Viscous Criterion, and deformation obliquity with respect to subject anatomy were quantified. Further, tissue-level material response was examined through a comparative finite element analysis of subject-specific loading. Results indicated that traumatic visceral injury specific to the posterolateral region was associated with close-proximity airbag interaction. Deformation response was uniquely oblique with respect to anatomy, necessitating the refinement of existing injury metrics. Biomechanical tolerances were also determined for risk of trauma to posterolateral viscera. These results are useful for the development of mechanical occupant surrogates and reductions to injury risks from close-proximity side airbag loading.