Finite Element Simulation of Driver Folded Air Bag Deployment

Finite element simulation of air bags as part of the automotive occupant restraint system is rapidly evolving as a new CAE tool in support of car product development. The majority of occupant computer simulations are concentrated around the study of occupant impact into the air bag when the air bag is substantially inflated. Further, the initial air bag representation in the simulation prior to deployment is of an unfolded configuration. These simplifications do not compromise simulation of crashes wherein the dummy comes in contact with the air bag after it is substantially full. The situation wherein the dummy interacts with the air bag early during the inflation is of interest when the occupant is located close to the air bag prior to deployment. In such cases the predeploy-ment geometry of the air bag in the model needs to be representative of the actual air bag folded configuration and the unfolding of the air bag needs to be simulated. This paper includes simulations of interactions between a hemispherical solid object and an air bag under different conditions with an increasing order of complexity. Finite element simulation of the events was performed to compute the accelerations and velocities of the impacting objects and the air bag pressure. Laboratory experiments of analogous events were done independently to validate the simulation. The answers predicted by finite element simulation correlated to the experimental results with sufficient accuracy therefore, can be a useful design tool for most driver air bag crash applications.