Development of Plastic Fracture Simulation Technology for Passenger Airbag Tear Line 2015-01-1341

The explicit methods analysis solver LS-DYNA was used to create technology for simulating airbag deployment and plastic airbag lid tear-away in the front passenger seat. The present study clarified the mechanical properties and the transitions in fracture pattern of the material at low temperature plastic this way, an appropriate modeling method was developed and the prediction accuracy of the simulation of airbag lid tear-away on deployment was increased.

Tensile testing of the material was carried out where there were differences in thickness of the tear-away section and the fracture characteristics were determined. A material model was created by analyzing changes in fracture characteristics and collapse patterns, taking into consideration the effects of strain and strain rate localization on fracture strain as well as ductile-brittle fracture transition. Next, airbags were subjected to the impactor testing. It was confirmed that the reaction force characteristics with that impactor had a good correlation with the simulation model. Finally, the airbag that matched the reaction force characteristic and the instrument panel model were combined. The simulation result was compared with the experimental results of the tear-away deployment, leading to good correlations with the tear-away process in simulations and experiments. It was also found that the two factors were important with regard to the reproducibility of the progressive tear-away process. They were changes in fracture mode due to the strain rate and strain rate dependence of fracture strainIn addition, it is necessary to pay careful attention to the modeling method due to the varying material thickness. More over prototypes with various significant parameters were created and subjected to accuracy verification. These prototypes also yielded good results for reproducibility. The sufficient accuracy aimed to reduce the number of prototypes in the vehicle development was confirmed.