Study Of Bumper Energy Absorber Considering Pedestrian Low-extremities Protection And Low-Speed Collision

Pedestrians are often in a weak position during traffic accidents and lead to serious injuri es. Therefore, the structure design of a car front bumper system needs to meet the requirement s of pedestrian protection regulations. At the same time, the front bumper system needs to me et the requirements of low-speed crash regulations. But because of a certain contradiction bet ween pedestrian protection and low-speed collision, through the proper design of the front bu mper system to take into account the requirements of pedestrian and low speed collision have a great significance. It is of great significance to design a proper front bumper system to meet the requirements of both pedestrian and low speed collision.In this paper, based on the research results in literatures, modular redesign and optimization of the structure parameters are carried out for energy absorber of car front bumper system, so that it can adaptively select different energy absorption mode by its own structural characteristics, and form a better balance between two kinds of impact protection performance.Firstly, the front bumper energy absorbing unit is designed. The modular X-shape energy absorbing unit, which based on the size of impact energy, can gradually improve energy absorbing ability by changing deformation modes. Furthermore, based on an existing domestic car model, a modular car bumper energy absorber is designed by using unit assembled in the form, and its performance is evaluated and compared with traditional foam energy absorber during two different collisions according to the rules of GB/T24550-2009 pedestrian protection and CMVSS215 low-speed impact. The results show that new energy absorber can deal with pedestrian and low-speed impact respectively in different deformation modes. Therefore the modular car bumper energy absorber can better meet requirements for both vehicle impact conditions compared to traditional foam bumper absorber.Secondly, a new plastic Xenoy alloys with stable and strong energy absorbing performance has been applied to the designed front bumper energy absorber. This study compares two different types of Xenoy alloys(PC / PET XL1339 and PC / PBT1103),and conduct tensile mechanical tests. The results show that PC / PBT1103 Xenoy alloys has more stable performance and reproducible results, and the material parameters of the PC / PBT1103 Xenoy alloys are obtained by experiments.Furthermore, a multi-objective optimization is conducted for structure parameters of car front bumper energy absorber. Three levels are set up in three structural parameters in this study to conduct a full factorial experiment. Based on the results, a multi-objective optimization of structure parameters is carried out with particle swarm method. The results show that the tolerance between the errors of optimization model and simulation model are controlled within 15%, and the performances of pedestrians and low-speed collision have been improved.This study has a significant effect for improving pedestrian and low speed impact performance and car bumper energy absorber design.