Simulation of an Airbag Deployment in Out-of-Position Situation

C. Ruff (Kompetenzzentrum - Das virtuelle Fahrzeug (vif)) The common used “Uniform Pressure Method” (UP) is a well-tried method to simulate an airbag deployment in accident cases. Nevertheless, this method indicates rather heavy inadequacies at the examination of the airbag deployment in the first milliseconds. A solution is the airbag deployment calculation by using CFD methods, wherein the calculated gas flow pressure may be applied “correctly” to the airbag shell elements. This CFD simulation is integrated in LS-Dyna with the so-called Arbitrary Lagrangian Eulerian (ALE) method and in this review the result’s accuracy will be discussed. According to the FMVSS 208, an OoP model will be built-on and comparisons with simulations and tests are done. Another important detail in this labour is the airbag cover examination and the tear seam modelling, as a trivial FE modelling cannot be done due to the very fine mesh. So two possible solutions for tear seam modelling are introduced and discussed. Furthermore considerations concerning the gas generator combustion will also be revealed and an analysis about the impossibility of the direct comparison between gas generator tank test and airbag deployment will be done. At least, some parameters, which take effects in the simulation, are researched and evaluated, so finally an optimized simulation model can be made available for further examinations.