DETAILED PASSENGER AIRBAG MODELING FOR EARLY STAGE EVENTS TRW Abstract LS DYNA FORUM 2012

Occupant restraint systems are an essential part of today’s vehicles to reduce the injury risk of occupants during collisions. Additionally to in position collisions, further requirements influence the performance and design of airbag modules. This can be integrity of airbag housings, IP opening forces or the FMVSS208 including Out-of-Position for driver and passenger airbags modules where a detailed modeling of the first milliseconds after TTF is necessary. Since virtual product development is an important part in vehicle development, predictability of airbag modules for In-Position, airbag and IP integrity simulation and Out-of-Position is required. In this paper we focus on modeling techniques for airbag simulations of passenger airbag modules during the first phase of deployment and the use of simulation methods in the development process. To reduce the number of hardware loops, the predictability and robustness of the simulation model has to be guaranteed. Changes in airbag folding or the inflator used have to be captured in the model. Standard simulation approaches are not sufficient to capture all loads and effects acting in an early state of deployment. Additional correlation tests and advanced modeling techniques have to be implemented to correlate the model at an early state, when first contact between airbag and neighboring parts occur. Basic modifications, for instance changes in inflator gas flow model, detailed airbag folding or airbag shape modeling are required. Recent developments of software tools allow a fast folding simulation of airbags, a pre-requisite for an efficient usage of simulation in product development process. Completed by fluid structure interaction methods, e.g. CPM in LS-Dyna, a realistic gas flow model and hence deployment of the airbag, which captures proper loadings on surrounding parts like airbag housings or dummies, can be achieved. First, the different test settings for a passenger airbag module correlation are summarized. Then modeling strategies of passenger airbag modules are discussed including detailed analyses of the airbag folding and its deployment. Benefits and limits of the airbag model are presented showing a stepwise increasing complexity of the model. Finally a variation of the airbag folding and the inflator performance are implemented to show their effects regarding deployment in the first milliseconds.