| As the most vulnerable road users, the pedestrians had high risk of injury and death in car to pedestrian accidents. Accordingly, the researches of improving vehicle frontal structures or developing combination of active and passive technologies to protect pedestrians were carried out one after the other. In China, bull bars were wildly installed on one-box and SUV type vehicles to reduce vehicles frontal structures damage in low-speed crashes. But the various bull bar designs haven’t been taken into account pedestrian safety; meanwhile, vehicle safety engineers paid little attention to brain injury caused by windshields because of the low stiffness in windshields region. So, researching the influences of bull bars and windshields on pedestrian injuries in pedestrian crashes has important practical significance.The aim of this paper is to analyze influences of bull bar structure on pedestrian injuries in vehicle-pedestrian crash and then propose a pedestrian-friendly bull bar design. Moreover, study on brain injury caused by windshields via accident analysis.First, five vehicle-pedestrian accidents reconstructions were carried out by MADYMO using selected accident data from an in-depth study. The whole accident involved cars were one-box type, and three of them were installed with steel bull bars. Comparing the injury output parameters from simulations between cars with bull bar and cars without bull bar, it found that the rigid bull bar caused high risk of lower extremity fracture.Second, several bull bar finite element models were developed, including metal bull bar for one-box, metal and ABS plastic bull bar for SUV. Lower legform to bumper tests and lower legform to bull bar tests were implemented according to the631/2009/EC. The simulation results indicated that bull bar benefit to reduce the knee bending angle and shear displacement of lower legform compared with original bumper. But metal bull bar (including steel and aluminium bull bar) increased tibia deceleration significantly in crash. Considering the three injury parameters of lower leg, ABS plastic bull bar on SUV could prevent lower leg injury better than original bumper.And then, a simplified vehicle/bull bar-pedestrian collision model was set up in MADYMO, and the height and leading length of bull bar were defined in this study. The influences of bull bar structures on50th pedestrian’s head and lower extremity injuries were analyzed. The results showed that as the overall height or slope forwards of bull bar increased, the risk of head injury increased. It’s suggested that reasonable bull bar design might reduced the extra injuries to pedestrian by addition of bull bar.Finally, to investigate the brain injuries caused by windshields, eleven real world car-pedestrian accident reconstructions were conducted using human head FE model and EEVC adult headform. In these accidents, the pedestrian’s heads impacted with windshields. The research showed that windshield frames were prone to cause severe brain injuries; head impact with middle region of windshield rarely resulted in skull injury, but it might cause brain injuries with different severities.This study provided some effective measures for standardizing installation of bull bar and designing pedestrian-friendly bull bar. The research results obtained by head-windshields accidents reconstructions could be used as improvement of windshield frame reference. |
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