| The number of traffic accident grows rapidly in China lately. The child occupants, without proper protection via restraint system, often suffer much more injuries than adults in accidents. Studies have shown that it could effectively protect the child occupant from the accident or reduce the injury risk to use the child restraint system (CRS) correctly. However, few Chinese families use CRS. Since there had been no testing and standards of CRS in China till July1,2012, the CRS in the market were of varying qualaties. This paper chose a rear-facing child seat which was designed for children under7years old to out imaze the structure in order to fit the requirement of Economic Commission for Europe (ECE) R44.FE simulation could be used to precisely simulate the deformation of the object in the crash. It is usually too complicated to build the model and takes too much time to carry out the results, however. On the contrary, rigid multi-body dynamics, which is able to anlyse the large displacement motion system, makes the modeling easy and takes less time to carry out the results. But it coulden’t observe the deformation. Lsdyna-Madymo coupling method takes advantages of the first two methods, then it is chosen to set up and simulated the model of frontal impact sled test with the child seat referring to the Regulation No.44by Economic Commission for European and the model validation was completed.According to the validation, the simulated thorax resultant acceleration matched the test results in the trend of the whole. They both had two peaks and grown rapidly in the last. Meanwhile the two peaks occurred on the same time. The simulated thorax viticle component acceleration matched the test results in the trend of the whole. They both developed into slight oscillation. The fact the simulation matches the test means the simulation model of the sled test with Lsdyna-Madymo coupling method is correct and reliable. This is the basis of the following studies.The sled test model was simulated and the simulation results were analysed. The study shows that the mainly bearing component was the body part of CRS, the stress concentration occurred around the mounting hole of the connecting pipe, the thorax resultant Acc.3ms exceedence was61.43g which is above the criterion, the CRS deformed partly and the dummy head path exceed the head excursion limit. Based on these studies, this paper proposed to improve the design of connecting pipe to solve the problem that the CRS would fly away from the ECE seat in the sled test. Compare the simulation results of the improved CRS to the originals’and find out that the mainly bearing component has changed to the base part of CRS, the value of maximum stress has reduced to50MPa, the dummy head path was under the head excursion limit and the returning path was obvious, the thorax resultant Acc.3ms has reduced to49.9g, and the thorax vertical component Acc.3ms has increated to17.73g, which are both under the criterion. That shows the crashworthiness of the improved CRS has been better.The sled test results show that the dummy head path hasn’t exceeden the excurtion limiti using the improved CRS. The values of the thorax resultant Acc.3ms exceedence and the thorax vertical component Acc.3ms exceedence are both less than the criterion value, which was further evidence of the crashworthiness improvement of the CRS and that the improved CRS could protect the children occupant effectivly. |
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