Research Of Lower Extremity And Head Protection In Pedestrian-Vehicle Collision

With the growing of vehicle population and the heavy road transportation, traffic accidents has become one of the most dangerous threats to human's life. Pedestrian accounts for a large proportion in the accident fatality population. According to the statistics, lower extremity and head are most vulnerable body parts. When pedestrian-vehicle collisions happen, the lower limb contacts with the front part of the vehicle first, and the injury are caused by the aggressiveness of the bumper structure. Most of the fatal damages result from skull fracture or brain injury caused by the head impacts with the rigid underhood parts. Active hood is an effective way to minimize head injury. When active lifting system acts, the space formed between the hood and rigid parts in engine compartment is a buffer zone to absorb impact energy to protect pedestrian's head.This thesis includes studies on the lower limb and head protection in pedestrian-vehicle collision.For lower limb protection study, a CAE model of a target vehicle is established. Tests are carried out with the legform impacting the real vehicle and compared with finite element simulations. Based on the CAE model, foam-energy-absorbing structure is analyzed. A spoiler is designed to improve the tibia injury response. By bumper improved design based on the corrugated stucture and the design of spoiler, the target vehicle got full scores in the legform model-vehicle impact according to the EuroNCAP criterion. Low speed impact and frontal full vehicle impact were also considered as the original structure was revised.For head protection study, a novel reversible active hood lifting system is designed. If the underhood space is not enough, head will inevitably have an abrupt impact with rigid parts such as engine block beneath the hood. Before pedestrian collides with driving vehicle, the initiative hood will be elevated. Three concept design of active hood lifting system is brought forward and compared. The most promising design is selected and optimized. Real parts are made and test rig is established to demonstrate the design. The front part of the hood can be elevated by 30mm and the rear part of the hood can be elevated by 100mm. the active hood lifting system is revisible and have no impeding effect for the normal open and close of the hood if engine compartment in need of maintenance.