Simulation Study On Active Seat Parameters For 50th Percentile Occupant Protection Under Frontal Impact

Seat is an important part of occupant restraint system. It pays an important role in reducing the injury risk of the occupant in an accident. If the seat parameters are adjusted, the seated posture of the occupant will be changed. So occupant kinematics and dynamics response during the impact will be effected. Moreover, the protection effect of the occupant restraint system will be effected. If the active seat can be adjusted to the optimal parameters before the collision occurs, the occupant restraint system can offer optimal protection to the occupant. Thereby, the injury risk of the occupant under frontal impact can be reduced effectively. In order to study on the protection effect of active seat for the 50 th percentile occupant under frontal impact, the active seat parameters were studied in this paper.Firstly, a simplified sled restraint system experimental device was designed based on the relative size of the front passenger area of a production car. According to C-NCAP 2015 test requirements, a sled impact experiment was conducted using Hybrid Ⅲ 50 th dummy in vehicle crash laboratory in Hunan University. Then, the sled restraint system finite element model was established according to the experimental condition, and the simulation results and experimental results were compared to verify the effectiveness of the finite element model.Secondly, the effect of single seat parameter to the 50 th percentile occupant injury was studied by univariate analysis. Based on the univariate analysis, the ranges of seat position, cushion height, cushion angle and backrest angle were determined. The Optimal Latin Hypercube was used for sampling in design space. The sampling points were simulated Using LS-DYNA software respectively. Based on the simulation results, the Kriging surrogate model which has high credibility was established. Based on Kriging model, the Multi-Island Genetic Algorithm was used to determine the target area. Then, the NLPQL Algorithm was used to determine the optimal seat parameters. The optimal seat parameters for the 50 th percentile occupant under frontal impact were obtained. The weighted injury criteria was decreased by 15.77% after optimization.Finally, the Kriging models of HIC₃₆, C3 ms, and C_comp were analyzed. The analysis shows that for the 50 th percentile occupant, when the seat height is greater than 45 mm, and backrest angle is between 15°and 35°, the HIC₃₆ and C3 ms can be reduced by moving the seat backwards before the collision, but the C_comp will be increased. When the cushion height is adjusted between 0mm and 60 mm, the HIC₃₆ and C_comp can be effectively reduced by increasing the cushion height. When the cushion height is between 35 mm and 45 mm, the C3 ms is small. When the cushion angle is adjusted between 15°and 30°, the C3 ms and C_comp can be reduced by increasing the cushion angle, but the influence on the HIC₃₆ is not obvious. When the backrest angle is adjusted between 15°and 35°, the HIC₃₆ can be reduced by increasing the backrest angle, but the C_comp will be increased slightly. The results show that the comprehensive injury risk of the 50 th percentile occupant can be effectively reduced by adjusting the seat position, cushion height, cushion angle and backrest angle before the collision.