A Study On Head And Lower Extremities Injury Prevention In Car To Pedestrian Impact

Pedestrians are the most vulnerable road users, and frequently involved in vehicle traffic accidences. Statistical data indicates that head and lower extremities are the main injury parts,So extensive researches on head and lower extremities protection have been carried out by vehicle safety experts and researchers both home and abroad.The current paper is to analyze influence of front structure of a car on pedestrian's head and lower limbs injury. And many corresponding improvement measures are put forwards.Child finite element head-form from ARUP Company is employed to develop the simulation model of head-form impacting with the hood based on the EURO-NCAP testing regulation, and validation is performed base on the literature. The relationship between the change of bonnet structural and material with the child head-form acceleration and intrusion is studied. The new type inner hood with multi-truncated cone or wave is designed and the classic steel for the hood is replaced by aluminum alloy.The real accident is reconstructed to understand the thigh kinimatics response. Based on the front geometry of a car production of Europe, a passenger car model is developed and the thigh protection airbag parameters are analysed.Based on the finite element method, a FE model which simulates the leg form impacting on the bumper is built to analyze the influence of design of bumper on the pedestrian leg injuries. The bumper is improved by changing absorption materials, adding an additional lower bumper and attaching a steel bar behind the bumper front.The study results indicate that the stiffness of the new type hood inner with multi-truncated cone or wave with aluminum alloy is more uniform. So force distribution is more dispersed and deformation area is broader. The two types of hood add the effective inertia mass to increase the energy absorption in the first impact. Accident reconstruction method can effectively simulate the process of an accidental collision and analysis dynamic response. The stiffness of absorption materials is the most significant effects on the injury parameters in the lower legform test. With the increase of stiffness, all three injury parameters will increase. Adding the lower stiffener can decrease the knee bending angle. This study provides an effective approach and simulation method for research on injury biomechanics and development of protection measures for pedestrian head and lower limbs.