Simulation And Research Of Car Child Restraint System In Rear End Impact And Side Impact

In recent years, a growing emphasis has been placed on child safety in car. Child car safety seats can reduce injuries of child occupants effectively in the accident. However, their quality varies greatly in the market.Although the ECE\R129 legislation contains requirements for child occupant restraint in side impact, it is used in parallel with ECE\R44 regulations and has not been enforced yet. Relevant enterprises and organizations have not carried out these regulations strictly in side impact. However, the degree of child occupant injury in a side impact is higher than the frontal and rear impact. It is of great significance in engineering to improve the side impact performance of the child safety seat, and it will be a hot pot in the research of child car safety seat.According to the requirements of European child restraint system regulations(ECE/R44), a finite element model including the trolley seat, the child seat, the child dummy and the safety belt is established with Hypermesh, Ls-prepost, and Oasys Primer. Referring to the front and rear impact experiments, the simulation of the impact process is performed with Ls-dyna.The consistency of the dummy movement patterns, the dummy’s head and thorax acceleration in impact process with the experimental results shows that the simulationmodel is effective.On this basis, a side impact model is built by replacing the side door with side steel plate. Referring to the related side impact acceleration waveform, the side impact process of the child safety seat is simulated and analyzed. The validity of the simulation analysis method is confirmed by comparing with the experimental results. Then the effect of design parameters including the seat belt and back plate stiffness and friction coefficient, the usage parameters such as handle positions and seat belt preload of the child safety seat on child dummy’s injury are analyzed. The results show that: the increase of the safety belt stiffness results in the increase of dummy neck injury; the back plate stiffness is important to its buffering effect for dummy’s head and thorax; the friction coefficient between the seat and the dummy have a significant influence not only on the chest but also on the head; A proper seat belt preload and an intermediate-state basket handle can alleviate the damage degree of child passenger in side impact.With the continuous improvement of relevant regulations of motor vehicles safety, more strict requirements of car child safety seat in impact will be put forward. The simulation analysis method and research results in this paper will be of great significance to improve the design level, to reduce the development cost, and to provide a safe and reliable automobile child seat for the society.