INVESTIGATION INTO THE EFFECTIVENESS OF ADVANCED DRIVER AIRBAG MODULES DESIGNED FOR OOP INJURY MITIGATION

摘要

In accordance with National Highway Traffic Safety Administration (NHTSA) regulations and, in particular the Federal Motor Vehicle Safety Standard (FMVSS) 208 for the protection of vehicle occupants from a deploying airbag, the development of frontal restraint systems is driven by new technologies and technical solutions to cover the challenging out-of-position (OoP) load case. Considering the subject of the driver airbags, traditional module technology addressed only the energy absorption capability to protect the driver occupant while in-position for a severe frontal crash load case. The early unfolding characteristics of the deploying airbag and its physical effects on the environment did not therefore form part of the engineering focus at that time. This paper will discuss an advanced driver airbag (DAB) module devised to deploy in an initially less aggressive mode, thereby exposing occupants seated OoP and close to the airbag's effective working area to less risk. The airbag inflation is divided into a primary and a secondary deployment phase by chambering the cushion with internal gas deflection fabric walls. After reaching an internal threshold pressure, these walls fail at a predetermined enervated split line. This leads to full bag deployment to ensure full energy absorption potential for the occupant seated in-position during the crash loading. This sophisticated deployment characteristic is simulated using a numerical approach to represent the actual fluid flow within the airbag to reproduc the airbag's initial unfolding process. Initial simulations recreate a simple physical (pendulum) laboratory test scenario. Further consideration of the OoP performance of the advanced airbag module is provided by replacing the simple pendulum with the more complex digital female frontal dummy positioned in accordance with the FMVSS 208 standard. Finally, the results obtained using the advanced airbag occupant simulation methodology are compared with the results of OoP occupant tests.