Small Female Upper Extremity Interaction with a Deploying Side Air Bag

This paper presents a study characterizing the interaction between a small female upper extremity and a deploying side air bag. The results are based on 12 tests with small female cadavers, and 15 tests with the instrumented SAE 5^th percentile female upper extremity attached to the 5^th percentile Hybrid III female dummy. The upper extremity was loaded by a deploying seat mounted thoracic side air bag in a static test environment. Three types of inflators were used that varied in peak pressure and pressure onset rate. Three upper extremity positions where chosen that maximized loading to the humerus and elbow joint. Upper extremity instrumentation for both the cadaver and dummy tests included accelerometers and angular rate sensors on the forearm, humerus, and upper spine. Additional instrumentation on the cadavers included strain gage rosettes on the anterior and posterior humerus. The SAE 5^thpercentile female instrumented upper extremity included six axis load cells in both the forearm and humerus. Using pre-test CT images and the humerus strain gage data, peak humerus moments were calculated for the cadaver tests and compared to the peak humerus moments recorded by the dummy in similar positions. Despite kinematic differences between the dummy and cadaver, the moments recorded in the cadaver and dummy were similar.

Chondral and osteochondral fractures in the elbow joint were recorded for seven of the twelve cadaver tests, while a simple fracture of the distal humerus head was observed in one test. A linear regression was performed to correlate occurrence of recorded injury and the test parameters. Injury risk functions were constructed for age, forearm acceleration, elbow moment, and air bag inflator level. Given the similarity between the dummy and cadaver humerus responses, the dynamic injury tolerance for the 5^th percentile female humerus of 128 Nm was recommended for use with the dummy.