Study On The Dynamic Response Of Child Occupant And The Design Parameters Of CRS In Frontal Crash Based On ECER129 Test

With the rapid growth of the Chinese private cars quantity, more and more parents take their children to take a private car to travel, and then the children's safety problem has gradually aroused the attention of parents and society. The car safety belt, safety airbag and other restraint systems are designed for the protection of adult occupants, and not only cannot well protect children whose body is not mature enough and stature is short, but also may be more serious injury to children. Child safety seat is a protective restraint device which can protect the child occupant, in a vehicle accident, it can effectively reduce the injury degree and death probability of child occupant by restraining the body's movement, and its crash safety is one of the core issues in the study of child restraint system(CRS).Finite element method is one of the most important links in the designing of CRS, the use of child dummy is the most important one in simulation calculation. At present, there are certain limitations of child dummy in application for the simulation of CRS in frontal impact sled test, and cannot completely take the place of real children. Therefore, studying the child dummies' motion response and their similarities and difference have a great significance, and also have a vital role in the field of child safety. In addition, in order to improve the safety of children, it is necessary to study the parameters of CRS.In this paper, by using Q3 dummy FE model, FE simulation of frontal sled tests for three types of domestic child safety seat(vehicle safety belt fixed type, 5-point harness type,ISOFIX CRS(without the strap)) were conducted under the condition of ECE R129 test,results of dummy's kinematics and damage value in simulation were compared and validated with the results in sled test, analyzing the protective performance of child safety seat on occupant injury. After verification, we can see that Q3 FE dummy model can be protected effectively in the three child safety seat, and the simulation results all meet the good agreement with the sled test results, which can be used as the basic model for the future study.To study the impact of the deference between 3-year old child occupant dummy models on the performance evaluation of CRS, this paper uses Q3 dummy FE model and THUMS3 YO Human FE model to establish FE simulation model of frontal sled tests for three types of domestic child safety seat under ECE R129 test. The kinematic behavior of the FE modelswere compared, as well as the injury parameters of neck bend angle, chest deflection and chest resultant acceleration. The results show that, in front-impact- shield CRS, Q3 were flipped upward, while THUMS 3YO with a motion of declination. The injury parameters of neck bending angle, chest deflection and resultant acceleration of the THUMS 3YO were larger than that of Q3, but the head acceleration and the upper neck force of THUMS 3YO were less than that of Q3. The research results show that the neck and chest of THUMS 3YO FE model are more flexible and less stiffness than Q3 dummy FE model. This conclusion can be as reference for the future application and development of child dummies.After verification for the FE simulation of the Q3 dummy FE model constraint on the ISOFIX CRS, the influences of the key design parameters of CRS, such as the friction coefficient between children's safety belt and child dummy, the stiffness of children's safety belt, the location of shoulder strap of children's safety belt and the friction between child seat and car seat on injury parameters were studied. The results show that the impact of these four design parameters on child occupant is relatively large, and it can reduce the children's death probability in a collision accident by properly adjusting these parameters. Injury parameters,such as head injury criterion(HIC15) values, head and chest resultant acceleration, were analyzed by using orthogonal experimental design, and the main design parameters of the above parameters are analyzed, and the optimum design is obtained.