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A research program was initiated to evaluate the performance of prototype dual stage passenger air bags in terms of both restraint system performance and deployment aggressivity for different size occupants. Variations in inflator partitions, vent hole diameter sizes, and deployment timing were examined. High speed unbelted sled tests were conducted with both 50th percentile male and 5th percentile female Hybrid III adult dummies at 48 kmph; and belted sled tests were conducted at 56 kmph. Low risk deployment tests with child dummies were conducted to evaluate air bag aggressivity. Overall, it was concluded that the dual stage air bag systems under evaluation had improved performance over the baseline single stage systems in terms of providing high speed protection while reducing aggressivity to out-of-position occupants; however, some dual stage systems may require additional occupant detection methodologies to suppress or control inflation.

NHTSA uses a variety of computer modelling techniques to develop and evaluate test methods and mitigation concepts, and to estimate safety benefits for many of NHTSA's research activities. Computer modeling has been particularly beneficial for estimating safety benefits where often very little data are available. Also modeling allows researchers to augment test data by simulating crashes over a wider range of conditions than would otherwise be feasible. These capabilities are used for a wide range of projects from school bus to frontal, side, and rollover research programs. This paper provides an overview of these activities. NHTSA's most extensive modeling research involves developing finite element and articulated mass models to evaluate a range of vehicles and crash environments. These models are being used to develop a fleet wide systems model for evaluating compatibility issues.