Air Bag Deployment Characteristics

Sullivan, Lisa K.; Kossar, Jerome M. · 1992 · ROSA P / United States. Department of Transportation. National Highway Traffic Safety Administration

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Summary

This 1992 report by the National Highway Traffic Safety Administration (NHTSA) examines the inflation characteristics of production driver-side air bags to assess factors contributing to secondary injuries, particularly for smaller occupants. The study was motivated by concerns that while air bags reduce crash fatalities, they can cause residual injuries such as facial abrasions and burns, especially in 5th percentile female occupants who sit closer to the steering wheel. The research focused on static, non-crash deployments to isolate the effects of bag design and inflation dynamics without the complexity of crash forces. The study employed a two-phase experimental design. Phase I involved the high-speed filming (5,000 frames per second) of nine different air bag systems to analyze deployment characteristics. Researchers digitized the footage to determine peak velocity, maximum displacement, and inflation time. Phase II selected four representative systems (two tethered, two untethered; various folding patterns) and deployed them against a seated 5th percentile female Hybrid III dummy. To visualize contact patterns, the dummy’s face was coated with a tri-color powdered chalk scheme. The dummy was positioned based on actual vehicle measurements, with some tests conducted with the dummy moved 3 inches closer to the steering wheel to simulate occupant movement during a crash. Phase I results identified four distinct folding patterns: accordion, modified accordion, pleated accordion, and overlapped. Peak velocities ranged from 98 to 211 mph, with an average of 144 mph. Tethering significantly affected displacement and inflation time: tethered bags displaced 12–15 inches (mean 14 inches) and inflated in 21–29 milliseconds (mean 25 ms), whereas untethered bags displaced 17–20 inches (mean 19 inches) and inflated in 21–47 milliseconds (mean 34 ms). Peak velocities were similar between tethered and untethered systems. Phase II findings demonstrated that tethering and folding patterns critically influenced facial contact. Untethered bags tended to engulf the dummy’s face, resulting in broader chalk removal. Tethered bags, constrained in displacement, contacted primarily the lower jaw and chin, avoiding the upper face. When the dummy was positioned closer, tethered bags exhibited sliding contact along the jawline and chin, while untethered bags showed more extensive facial engagement. The study concluded that air bag tethering and folding geometry are significant determinants of occupant interaction and potential injury mechanisms during deployment.

Key finding

Tethered air bags exhibited significantly lower maximum displacements (mean 14 inches) and shorter inflation times (mean 25 msec) than untethered bags (mean 19 inches and 34 msec), resulting in distinct facial contact patterns where tethered bags primarily contacted the lower jaw and chin while untethered bags tended to engulf the face.

Methodology

lab_experiment

Sample size: 9

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• seat belt use