A Study of High Refinement Simulation Prediction on the CAB Development for FMVSS226 Ejection Mitigation Performance

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A Study of High Refinement Simulation Prediction on the CAB Development for FMVSS226 Ejection Mitigation Performance

Wang, Cheng / Shan, Jinhui / Xue, Lele

NHTSA released the FMVSS226 Standard in 2011, and defined the requirements for ejection mitigation systems, which limit the linear travel of headform by 100mm. In China regulations, there are similar requirements starting in 2021. Therefore, on the basis of the existing airbag design, adding the rollover protection function becomes a challenge for the airbag development. During the development of the curtain airbag, the cushion design, inflator type, and the fold pattern, all have an important influence on the airbag unfolding direction, the airbag positioning time and the airbag internal pressure, and then significantly affect the occupant protection performance afterwards. In order to reduce the cost and shorten the development time, it is necessary to predict the process of cushion deployment kinematics and the internal pressure of the airbag with high refinement, and based on it to predict and evaluate the FMVSS226 ejection mitigation performance. In this paper, a set of complete simulation development process is proposed and developed with FEA simulation method. Based on the step-by-step simulation and test validation of the tank test, fabric material mechanical properties test, airbag folding test, airbag static deployment test, drop tower validation test, the high accuracy curtain airbag simulation model could be established. With this model, the airbag internal pressure and deployment shape at 1.5s and 6s were calculated. Based on the test validation at the specified target point of A4, the proper friction coefficients were obtained and validated. Then, the delicate FMVSS226 ejection mitigation simulation model was generated, afterwards the remained target points simulations were performed. According to the comparison between the calculated results and test results, the total discrepancy of the distance between head form and window glass was within 4.4%, which has high accuracy.