Occupant/airbag interactions involving fully deployed airbags are routinely simulated today by representing the effect of inflator gas as a uniformly distributed pressure inside the bag.
Accurate simulation of the gas/airbag/occupant interactions requires a fluid-structure capability. In this case, inflator gas flow within the partially deployed bag plays a primary role in the severity of the occupant/airbag interaction. Recently, interest has focused on out-of-position occupant scenarios, wherein the occupant contacts the airbag prematurely, before it is fully deployed. Typical airbags reach a fully inflated state in about 50 milliseconds, ideally prior to contact with the vehicle occupant. Airbags provide occupant safety in automotive crashes by deploying at an extremely high rate upon impact.
