The factors that influence airbag-induced upper-extremity injuries sustained by drivers were investigated in this study. Seven unembalmed human cadavers were used in nineteen direct-forearm-interaction static deployments. A single horizontal-tear-seam airbag module and two different inflators were used. The observed injuries were largely transverse, oblique, and wedge fractures of the ulna or radius, or both, similar to those reported in field investigations. Forearm fractures occurred within 5 to 10 ms of the onset of airbag pressure. The occurrence of forearm fractures is a function of both human tolerance and proximity of the forearm to the airbag module at the time of deployment. Human tolerance to fracture is a function of bone mineral content. Forearm fractures are associated with reductions in distal forearm acceleration and plateaus of distal forearm speed. Distal forearm speed appears to be a good predictor of the likelihood of forearm fracture. The study results suggest that airbag-module-to-forearm spacing has a substantial influence on airbag-induced upper-extremity injuries sustained by drivers. A simple airbag aggressivity assessment tool for the prediction of forearm fracture might be based upon peak or average distal forearm speed of a biofidelic, surrogate arm. (A)
Abstract