| In China,traffic injuries have become the second cause of death in China from 0-17 children.Children's accidental injury studies showed that when the child's chest was damaged in a frontal collision,it was easy to result in serious injuries with a high mortality rate.Studies have shown that the use of child restraint systems is the most effective way to reduce the risk of child occupant traffic accidents.Dynamic performance testing is an important indicator for evaluating the safety of automotive child restraint systems.Currently,there is no literature on the relationship between chest acceleration and internal and external forces in child restraint systems for child occupants.Based on previous research,in order to clarify the relationship between the acceleration of the chest of the child occupant and the internal and external forces in the frontal collision,and the risk of injury to the internal organs under different CRS constraints,the Sled-CRSs numerical FE model was established by using Hybrid ? 3-year-old dummy and Total Human Model for Safety 3YO(THUMS 3YO)Occupant Model Academic Version 4,based on the ECE R44 frontal impact test regulation.The establishment of the sled FE model and child safety seat FE model are introduced in detail.And a method of reproducing crash pulse using the combination of thin-walled circular tubes to satisfy acceleration interval requirements of ECE R44 regulation.Finally,the simulation model is verified.Then the equation of motion on the chest of Hybrid ? 3-year-old dummy was established and the relationship between chest acceleration and the internal and external forces that exerted on the chest were analyzed.And the comparative analysis of the risk of THUMS 3YO occupant's thoracic soft tissues injury in two CRSs.The simulation result shows that the chest acceleration is related to the external and internal forces,and the external force is the key factor.By analyzing the dynamic response of the Hybrid ? 3-year-old child dummy and child FE model,it is found that the torso pose and the contact behavior of the chin and chest were different between the dummy and child human FE model.The stress and strain distribution of chest visceral organs of THUMS 3YO in the two CRSs were both exceeded the injury threshold,and the damage value in the impact shield CRS was larger than that in 5-point harness CRS.The research clarifies the kinematics equations of children's chest and the risk of thoracic soft tissues injury under different dynamic loadings.Hope that this research can be a good reference for the design of the child restraint system.Based on the five-point CRS verification model,this paper analyzes the influence of the constraint system design parameters on the child dummy injury parameters.The results show that the five-point seat belt stiffness,the five-point seat belt and the friction coefficient between the child's dummy,the position of the safety shoulder strap opening,and the position of the buckle have different effects on chest acceleration,chest compression and head displacement.Therefore,the rational design of the parameters of the restraint system has an important impact on the child occupant injury parameters.In this research,based on FE simulations and tests,the behavior,responses and injury parameters of the child occupant restrained by different types of CRSs were analyzed. |
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