Out-of-position occupant phenomenon: how to de-power your airbags

The topic of this study is the problem of out-of-position children being hit by a deploying passenger airbag. BMW in Germany and TNO in the Netherlands joined their efforts to tackle this very serious problem. A number of out-of-position airbag deployment experiments have been performed using the P3 child dummy. In addition a in-position frontal-impact crash-test has been performed using the 50th percentile Hybrid III dummy. The experimental results show that the in-position adult will not sustain any serious injury in a frontal impact crash. The out-of-position child, however, runs a higher risk of being seriously injured by the airbag. To study this problem MADYMO simulation models of the experimental set-ups have been created, using a sophisticated finite element airbag model capable of simulating the airbag deployment in detail. The simulation results of these models have been correlated with their specific experiments. The correlation showed the finite element airbag model was equally capable of simulation out-of-position occupant behaviour, as well normal in-position behaviour. Two simulation models, one of the out-of-position child models and a low severity frontal-impact in-position model, have been subjected to an optimisation study. The inflator mass flow and the airbag vent were optimised in order to obtain acceptable injury results for both the adult and the child simultaneously. The optimisation results showed there is a theoretical possibility to maintain a proper level of safety for an in-position adult, while significantly reducing the injury criteria for an out-of-position child, by adjusting the mass flow of an inflator