The Bumper Pedestrian Protection And Low-Speed Collision Performance Study And Improvement

On the one hand, as an important safety device, car bumper should protect pedestrians legs in one car collision accident and should as far as possible to protect the body parts in the low-speed collision, reduce the loss rate. Therefore, we must consider sufficiently the needs of the both when design it. On the other hand, the deformation of thin-walled metal structure with good yield form to efficiently absorb the impact energy, suitable for application in the collision energy absorption components. So we can consider use it on the car bumpers to improve its safety performance.In this paper, according to the relevant regulations about the pedestrian leg protection and low-speed collision regulations, by means of numerical analysis for a typical saloon car prototype build pedestrian leg protection and low-speed collision finite element model, to examine the vehicle’s pedestrian leg protection and low-speed collision performance. Through the analysis of the results show that the low-speed collision protection performance is good but the pedestrian leg protection performance still need to improve.Finally simulation to optimize the parameters of the model and with the original vehicle pedestrian leg protection performance and low-speed collision performance were analyzed, structure of the improved bumper system of pedestrian leg protection and low-speed collision safety performance than the original model has indeed improved. Thesis research results for the following bumper provided useful experience design and performance improvement.I design of elliptic cross section shape of thin-walled metal tubes preliminary according to the existing research materials and the original bumper energy absorption space of the bubble size.Based on a single elliptical thin-walled tube performance test, we can understand its deformation characteristics and the length and thickness of the two parameters effect on the properties of thin wall pipe collision.Then installe multiple elliptical endergonic structure composed of thin-walled metal tubes into the bumper energy absorption bubble position. Within a certain range is obtained by simulation experiment many times the length and the thickness of the oval thin-walled metal tube, of the two parameters and bumper small legs collision impact performance and the performance of low-speed collision data.Then the response surface method is used to fit the length and thickness of two parameters and the bumper of the lower leg experiment acceleration value, calf impact experiments of thin wall tube than the energy absorption value, low speed collision of beam displacement values of the approximate function relation.Further, with the goal of maximizing the value than the energy absorption function, to the calf acceleration value, the beam displacement, elliptical thin-walled tube thickness and length of scope as constraint value model, to optimize the parameters of the thin wall pipe.As the existing bumper structure should not be changed too much, This paper puts forward the scheme by using aluminum thin-walled metal tube instead of bumper original energy-absorbing foam structure.