The Study On Coach Energy-absorbing Characteristics And Injury Mechanism Of Occupant Under Frontal Crash

Coaches are the ma in transport for passengers with the characteristics of large passenger capacity, but it also can lead to lot s of deaths if accident happen s. In recent years, serious traffic accidents associated with coaches happened occasi onally, therefore more and more attention was paid to the safety of coaches. Due to the lack of energy absorbing structure and space in the front of the common coaches, the collision energy is almost entirely absorbed by the body in frontal impact. Consequently, high acceleration and severe deformation of front passenger cabi n will be generated, which is a great threat to passenger ’s safety. At present, the regulations of vehicle frontal crash in China are not perfect, and the existing occupant protection laws and regulations are based on the specific size of dummy under normal riding position. T herefore, the existing occupant restraint system is designed for specific dummy. With the widely application of the occupant restraint system, traffic accident investigation and analysis show that the common occupant restraint system has the obvious limitations when dealing with the complicated actual collision.In order to make up the shortness of coaches researches about different body types occupant restraint system at home and abroad, and to provide some reference to the establishment of collision regulations for coaches frontal crash in the future, this paper mainly studies and analyzes the influence of passenger restraint system parameters on different body types occupants. T he main work and research in this paper is as follows:1) Build the finite element simulation model of coach for 50km/h frontal crash. Based on the test of sled car, design energy absorption structure in the front of the coach and re-design the frame of coach to improve its poor crashworthiness and the energy absorption ability. Perform simulation of the improved finite element model, and get the 50km/h frontal crash acceleration pulse waveforms and the invasion curve of steering wheel.2) Use MADYMO to build some occupant restraint system model s, which contain 5 percentile, 50 percentile, 95 perc entile female dummy, 50 percentile, 95 percentile male dummy, and simulate the occupant restraint system model by inputting the collision acceleration pulse waveforms and the invasion curve of steering wheel.3) Select occupant restraint system parameters in MODEFRONTIER which have a significant impact on occupant’s injury by the uniform Latin method. Use the MOGA-II module to build the response surface of system parameters, ge t the optimized restraint system parameters. Then verify the exactness of the agent model by putting the optimization parameters into the madymo model.This paper shows that the restraint system parameters which are designed for 50 percentile male dummy are not suitable for other body types occupants. It is also found that in the study of the parameters of the airbag and seatbelt, seatbelt and airbag parameters need to be matched to achieve the best occupant protection; the pretension of belt ha s no significant effect on every type occupant’s safety, and the limit ed strength of seat belts ha s significant effect on occupant chest injury; As the size of dummy increases, the diameter of airbag, airbag initiation time, gasbag drawstring length and belt limits strength should be increased accordingly.