Assessing Arm Injury Potential From Deploying Air Bags

A study of the National Accident Sampling System (NASS) found an increase in upper extremity injuries when drivers were restrained by a seat belt and air bag as opposed to a seat belt alone. These injuries were attributed to forces from the air bag deploying or the air bag projecting the arm into vehicle components or the upper body of the driver. Two evaluation methods were used to assess the extent of injury and aggressiveness of different driver side air bags. The RAID, developed by Conrad Technology, and the Hybrid III instrumented arm, tested at the Vehicle Research and Test Center, were used in static testing to evaluate the effect of air bags on the arm.

The positions of the RAID and the Hybrid III arm simulated the arm in four different turning positions with the forearm across the center of the wheel. Both devices recorded arm moments and accelerations. Film analysis determined the cause of the peak resultant moment for each bag in the four configurations. The Hybrid III was able to attribute half of the moments that surpassed the Injury Assessment Reference Values (IARV) to forces from the air bag when deployed in close proximity to the forearm, while the other half of the moments that surpassed the IARV were from contact with the head, neck and chest of the dummy. In contrast, the RAID only recorded accelerations and moments due to the air bag but was unable to account for contact between the arm and the occupant or vehicle's interior. The Hybrid III instrumented arm and the RAID gave similar rankings of the severity of the different air bags.