Crash Performance Evaluation Of LB565 Child Restraint System

A study of emulating of LB565 child seat using the software of MADYMO （Mathematical Dynamic Model） was carrried out in this thesis.According to the European ECE R44/04 standards and combined with 9-month-old child dummy,set up a simulation trolley model of LB565 child seat.Though the comparison trolley test results,verified the correctness of the model.On the basis of these,analyzed the sensitivity of protecting performance parameters,used the three factors and three levels of the orthogonal optimization,so that LB565 child seat greatly improves protection performance of children.Finally,simulated and analyzed two kinds of misusing the child seat,then compared the changes of child injury.The main research content is as follows:1.After read many related materials,we made the induction and the summary to the child constrained system’s research content and the research technique,Outlined the CRS research content and the method,introduced the present research situation,the trend of development of overseas,the European ECE R44/04 regulations of the relevant provisions of CRS and compared with the difference between the United States FMVSS 213;2.According to the ECE R44/04 laws in relevant provision,established CRS finite element model and trolley chair model,the adult safety belt and child harness system model and the P3/4 child stuffed dummy.Then the simulations of the positive trolley impact to the child seat have been done.The analysis simulation obtained the child stuffed dummy chest synthesis acceleration curve and forehead synthesis acceleration curve and chest spinal column direction acceleration curve and forehead HIC value, explained that this CRS conforms to the European laws standard in the head-on collision to the protection of 9 month big child.Introduced that trolley test equipment and flow,compared with the computer simulation and trolley test results discovered each kind of injury curve basically tallies,except HIC the other error is in 15%,has confirmed the simulation model accuracy.3.According to the laws and regulations requirements of Europe and the USA,C-WIC formula was obtained on the basis of Adult-WlC.The stiffness of child seat,the feature of child seat material,the position of the point child belt wearied around,the stiffness of adult seat belt,the angle of the child seat cradle,the stiffness of seat belt furl device,the coefficient of friction between child dummy and child seat,the amount slack of child belt,we change upper and lower limits of these 8 parameters to observe the change of C-WIC after simulation.The aim is to find out which is the most sensitive parameter for the quality of child protection.4.Three levels of three factors in orthogonal test is applied to analysis the performance of CRS in Tab L₉（3⁴）.At last the optimal condition is that we increase cradle angle and the vertical angle 20°,increase the stiffness of the child seat by 50%, choose 0.3 as the coefficient of friction between child dummy and child seat.Through range analysis,we find the main factor is the angle of child seat cradle,then are the coefficient of friction between child dummy and child seat and the stiffness of child seat material.Comparing the original injury indexes with the improved injury indexes,we find that the effect of children protection is modified a lot.5.Two misuse situations were researched:（Ⅰ）,Child seat belt off;（Ⅱ）,Adult seat belt was not clamped on the child seat.The simulation results showed the child head injury was increased in the child seat belt off condition,but the second situation has little affection compared with the CRS was used correctly.