Head And Lower Extrmeties Injury Analysis And Research On Protection Measures In Car To Pedestrian Impact

In car to pedestrian accidents, pedestrian becomes to be vulnerable due to lacking of passenger protection space, and leads to high frequency. As statistical data indicates that head and lower extremities are the main injury parts. So extensive researches on head and lower extremities protection havs been carried out by vehicle safety experts and researches both home and abroad.This paper is to analyze influence of front structure of a car on pedestrian's lower limbs and head injury, and discuss the protection measures for the two key part injury.It has improved the shoulder of 50 percentage mathematic pedestrian model developed by Charmels Technical University in multi-body code MADYMO. Through adding Sternoclavicular joint,acromioclavicular joint and glenohumeral joint, defining the joints machenical characters to the shoulder and employing the biomechanical experiment results to validate this model, so the bio-fidelity of the its shoulder has been improved by a degree. The modified model is used as a tool for the bio-fidelity study and parameter analysis in car to pedestrian impact. Identifing the range for the main design variable of front structure referring to geometry of front structure from statistic data, and developing the following passenger car model based on the front geometry of a car production of Europe: (1) the car model for analyzing the influence of front structure parameter on lower limbs and head injury, (2) the car model for head protection airbag parameter analysis and front structure parameter optimization, (3) the car model for bumper design based on pedestrian lower limbs protection.By adopting the orthogonal experiment design method to assign the value of every parameter, drawing the trend picture and ANOVA to analyze the influence and importance of front structures of passenger car on pedestrian head and lower extremities injuries. It has discussed the protection measures for head, built head protection airbag model, and gained the best answers through optimization method, finally studied bumper design method to reduce risk of knee injury.The study results indicate that knee injury will benefit from lowering height of the bumper, increasing bumper vertical width and distance between the bumper leading and hood leading. Reducing the windscreen angle relative to level and height of hood leading edge, increasing the hood angle will improve head protection. During lower limbs impact with bumper, fitting the plastic energy absorber on the bumper beam can reduce the value of the tibia acceleration by 37.6%, and knee bend angel by 12%. Supplying the stiff support at the low end of tibia can reduce the bending angel of knee by 12%, and so reduce the risk of knee injury.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.