| With the increasing number of cars in China,more and more families choose to travel by car,so road traffic safety accidents keep climbing.However,due to problems such as low utilization rate and serious misuse of child restraint systems in our country,more and more children are injured or even killed in traffic accidents.In recent years,domestic and international research on child safety seats for babies has become been attached to more importance,but the research on booster seats for middle-aged and older children is not yet perfect.In this paper,a booster seat was taken as the research object,and the different parameters of the booster seat and safety belt were studied and optimized to improve the protection effect for child occupants.This paper interpreted the content and requirements of various aspects of European ECE R129regulation in detail,and selected Q series 6-year-old child dummy for frontal impact sled test based on the regulation.Through the CATIA software,a three-dimensional model for simplifying the booster seat was established,and at the same time,the establishment of the entire frontal impact simulation model of the booster seat was completed in the HyperCrash software.The RADIOSS solver was used to calculate the model,and the test results were compared to verify the effective-ness of the simulation model in kinematic response and dynamic response.The four parameters as the shell thickness,cushion angle,headrest height and belt guide position of the booster seat were selected as the research objects,and the 3ms head resultant acceleration a_H,3ms chest resultant acceleration a_C,upper neck tension F_Z and head horizontal displacement x_H were selected as the main injury assessment criteria,the frontal impact protection effect of booster seat was researched by the single factor study method.The results show that,in frontal impact,the optimal height of the booster seat shell is 6.0mm,the optimal height of the seat cushion angle is 1°,the optimal range of the headrest height is 20-30mm,the optimal position range of the lap belt guide is 0-5mm.Orthogonal test and analysis of variance were used to filter the parameters with higher significance.The Matlab software was used to establish an approximate response surface model of the injury assessment criteria for children,and multi-objective optimization was performed based on the NSGA-II genetic algorithm.The results show that the shell thickness and headrest relative height of booster seat are two significant factors.The optimal optimization is to increase the seat shell thickness by 6mm and the headrest relative height by 29mm.Compared with the original model,after the optimization,the 3ms head resultant acceleration a_H of the child dummy decreases by18.9%,the chest resultant acceleration a_C of 3ms decreases by 20.1%,the upper neck tension F_Z decreases by 19.2%and head horizontal displacement x_H decreases by 10.1%.The three parameters of the safety belt webbing stiffness,shoulder belt restraint path and lap belt restraint path were selected as the research objects,and the weighted injury criterion WIC was determined.The research results through simulation test and sled test show that during the frontal impact,the factors when the belt stiffness of the belt is 0.7 times the original model,the restraint path of shoulder belt on booster seat is path B(the shoulder belt passes above the lap belt guide)and the lap belt is restrains the thigh,all injury assessment criteria are the smallest;while the restraint path of the shoulder belt on the child dummy has no significant effect on the protection effect.Finally,the risk assessment criterion of submarining and neck injury of child dummy were pro-posed.The risk of submarining can be assessed by the relative position of the lap belt and the horizontal displacement of dummy head and pelvis;the risk of neck injury can be assessed by the tension the bending moment of the upper neck. |
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