POLYMODE

Faurecia Systèmes d'Intérieur, world leader in the design of instrument panels, has to meet safety performance constraints such as airbag deployment when sizing an instrument panel. Airbag simulation is used as a design aid by development teams. However, today's behavioral laws have mainly been developed for steels. The associated damage and fracture models are relatively simplistic, based solely on tensile tests. Compressive and shear stresses are not taken into account. Finally, temperature effects have been neglected, as calculations have so far been carried out at ambient temperature. However, the operating range of an airbag is between -30 and 85°C. Breakages observed in cap inserts and firing channels often occur both cold and hot. Vibration welding is the technology of choice for the assembly interface between the firing channel and the fairing insert.  During airbag deployment, adhesive or cohesive fractures are sometimes observed. On the simulation side, these welds are modeled without any real behavioral model. As a result, pull-out and delamination phenomena are not properly taken into account in our simulations. The current economic climate is forcing us to reduce development costs. It is therefore necessary to propose an optimized architecture at an early stage, and thus anticipate the risk of breakage before the tooling is launched, thanks to simulation tools. Improving our behavior laws is all the more important as we are working on developments without prototypes.