An Improvement And Study On Frontal Bumper System Of Vehicle In Low-Speed Frontal Impact

With the development of automobile industry and the increase of vehicle stockyear by year, it increases the frequency of traffic accidents and causes a large numberof casualties, vehicle damage and loss of property, therefore people pay more andmore attention to vehicle safety. Car collision from the impact speed can be dividedinto low-speed collision and high-speed collision. High-speed collision is the maincause of occupant injuries and death, which attracts the attention of Government. Thespeed of low-speed collision is generally slower than15km/h. Low-speed collisiongenerally does not cause casualties, therefore this kind of collision does not attractenough attention of manufacturers and consumers. However with the development ofvehicle-stock, especially the traffic condition is becoming more and more worse withthe rapid increase of vehicle in the city which increases the frequency of low-speedcollision.Many countries have established low-speed regulations and make it as one of theevaluation indexes of NCAP. Relevant parts of vehicle will be destroyed inlow-speed impact, we have to change or repair these parts, it is an economicburden for our consumers and insurance companies. Insurance companiesestimate the grade of a car according to the result of the low-speed impact,therefore improving the low-speed impact capacity has important significance inreducing vehicle maintenance costs.In this paper, a model based RCAR (Research Council for Automobile Repairs,Automotive Repair Association) regulations are improved. Based on the requirementof RCAR regulations, I intercept the frontal structure of the longitudinal beam anddesign and match the crash-box between the longitudinal beam and bumper and thenresearch the crash-box based on the quantity of trigger slot, finally the goodenergy-absorption and deformation is attained. At last making an overall improvementon bumper, crash-box and stringer by increasing bumper stiffness, filling aluminumfoam in crash-box, increasing longitudinal beam strength and adding reinforcing ribin weak place and which eventually meets RCAR test successfully. Finally,orthogonal experiment design and overall balance method are designed to discuss theeffect of parameters of crash-box thickness, bumper thickness and trigger slot depthon energy-absorption of bumper system. The paper proves the validation of improvement in theory, which provides areference to improve the safety of low-speed impact. The result shows that: improvedvehicle meets the requirement of RCAR test, the plastic deformation of longitudinalbeam of improved car decreases from81.58%to4.756%, the tank does not deformanymore. After optimization, the energy of crash-box increases from3485J to3775J,the energy of low-speed impact system increases from6067J to6123J, the energy oflongitudinal beam increases from237J to252J, plastic deformation from4.756%to4.962%through it increases it is still below5%which is still satisfy with RCAR test.The optimized result shows that reasonable match of bumper, crash-box thickness andtrigger slot depth can increases the energy-absorption capacity of bumper system,further more it can protect expensive parts such as longitudinal beam to reducemaintenance costs.