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A mathematical simulation of the operation of a compressed-gas airbag system is developed. A system was built and tested, and the analysis is evaluated on the basis of these tests. Included in the study are nonideal gas effects, manifold and diffuser effects, bag stretch, bag leakage, and overpressurization of the passenger compartment. Interaction between a single rigid object and the bag is also considered. A correlation between bag pressure and the force it generates is obtained. This allows the development of an analytic model for determining the motion of a single rigid mass interacting with a dynamically inflating airbag mounted in a moving vehicle. An application of the model to study rebound of the occupant from the airbag is presented.

A coupled engine-block and crankshaft model is developed and applied to predict the engine block vibration and radiated noise. Block surface vibration which is excited by combustion pulses and inertia loads is investigated as the source of radiated noise. The predicted response shows the dominant engine harmonics, resonant frequencies, global modes and local surfaces which participate to produce the radiated noise. A structural modification is evaluated which reduces the transmission of the loads through the bulkheads, and significant vibration and noise reduction is predicted.