Nonlinear Finite Element Modeling of an Airbag During Inflation and Impact

Abstract : In this study, a nonlinear finite element method was applied to the simulation of airbag deployment and contact with a solid body in a crash situation. A finite element model of the folded airbag was modified and the forces generated by an unfolding airbag during its impact with a rigid wall were investigated using DYNA-3D code. The finite element model was verified by comparing results with those reported in the verification of PAM-CVS code which couples the PAM-CRASH finite element code with the crash victim simulator CAL3D. Having verified the finite element model, the effect of airbag parameters on the acceleration of a rigid sphere resulting from contact with an inflating airbag was investigated. The parameters considered were fabric density, bag elasticity, input gas temperature and extent of venting. The influence of these parameters on the contact was significant: lowering the fabric density resulted in higher bag velocity which in turn resulted in higher rebound velocity; the lower the input gas temperature, the longer was the contact time and the lower rebound velocity. The acceleration and rebound velocity had an inverse relationship with vent area. These observations with additional studies could be used in the development of better occupant safety systems.