Influence of a Combo Side Airbag on the Risk for Basilar Skull Fracture in a Far-Side Occupant

Objective: The impact force to the head and neck were measured in sled tests with and without inflation of a combo airbag for a far-side occupant to determine the risk for basilar skull fracture.

Methods: Sled tests were run at 24 and 32 km/h (15 and 20 mph) with and without inflation of a combo side airbag to analyze the effect of cross-car diving into the side interior. The matched tests involved one pair at 24 km/h and another at 32 km/h. The 24 km/h pair involved a lap–shoulder-belted 5th percentile female Hybrid III and the series at 32 km/h involved an unbelted 5th percentile Hybrid III. The dummy was ballasted to 69.5 kg (153 lb) and laid on the right side. The dummy was positioned 30.5 cm (12) from the far-side interior to ensure the full sled delta V occurred before head impact. The buck consisted of a 2001 Ford Taurus. The combo thorax–head side airbag was stored in the seatback. The airbag was triggered about 120 ms before the head impact. The head, chest, and pelvis were instrumented with triaxial accelerometers and the upper and lower neck, thoracic spine, and lumbar spine had transducers measuring triaxial loads and moments. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared to study the influence of inflating the side airbag on the head and neck.

Results: The top of the head impacted the far side. The force of impact was similar with and without the airbag as the head compressed the airbag and loaded the vehicle interior trim behind the airbag. The peak force on the head was primarily from neck load as torso augmentation occurred. For the 24 km/h (15 mph) tests, the peak force was 4.7 kN (1055 lb) without and 4.8 kN (1088 lb) with the airbag and there was over 2.67 kN (600 lb) of lap belt load. The peak head acceleration was 93 g without and 72 g with the airbag. For the 32 km/h (20 mph) tests, the force on the head was 15.3 kN (3433 lb) without and 15.2 kN (3406 lb) with the airbag, although the instrumentation saturated. The peak head acceleration was 236 g without and 262 g with the airbag.

Conclusion: The airbag reduced head acceleration in the belted test but did not influence the diving forces from torso augmentation through the neck of the far-side occupant. The side airbag did not reduce the risk for basilar skull fracture due to high neck compression loads in either the belted or unbelted tests.