| People pay more attention on automobile safety with the increase of Vehicle Population. People have been researching on safety of automobile occupant for decades and achieved many results which reduced casualties in traffic accident and saved many lives. However, people paid little attention on pedestrian safety.According to the statistics publicized by the Transportation Administration office of Police Ministry, the death toll of pedestrian and cyclist in traffic accident during 2000,2001 and 2002 in China are 6414, 7046, 6798. According to the statistics, head and leg are the most frequently injury position of pedestrians and knee injury is deemed to be the most serious among all the injuries because it probably can induce long-time disability for people, so leg injury mechanism and method of protection has an important role in pedestrian safety study. Pedestrian leg injury is mainly caused by the collision of lower limb and car bumper, so it's very important to research on parameter optimization method of bumper.Based on the analysis of characteristic of traffic accident, injury mechanism of pedestrian knee, bio-mechanics and according to the regulation of EEVC WG17 and the thesis advanced, this paper used UG NX2, PRO-E, Hypermesh to set up the 3D data model and finite element model of leg form and proved its validity according to test method of EEVC WG17. Then this paper carried through simulation analysis of pedestrian leg impact safety using Pam-crash and researched on parameter optimization method of bumper, then carried through simulation of some methods and improved pedestrian leg impact safety of a car to meet the demand the pedestrian safety regulations.The main contents of this paper are as follows:1. This paper introduced the present condition and the experiment methods of the pedestrian protects. Pedestrian safety regulations were analysed, then the theory of the explicit nonlinear finite element was introduced.2. Finite element model of legform impactor was established and carried through finite element analysis of static bending certification test, static shearing certification test and dynamic certification test according to test method of EEVC WG17 to establish its validity.3. Finite element model of pedestrian leg and automobile front structures was established and simulation analysis for pedestrian leg impact safety was carried through.4. The paper researched on parameter optimization method of bumper and carried through simulation of some methods, such as changing position of bumper and adding multi-storey ladder energy-absorbing block, so improved pedestrian leg impact safety of a car to meet the demand the pedestrian safety regulations.The innovations of this paper are as follows:1. keen joint finite element model was established which was simple and effective and meet leg movement laws. It met bio-mechanics regulations and improved speed of simulation.2. This paper creatively founded multi-storey ladder energy-absorbing block which improved the pedestrian leg impact safety of a car greatly.The finite element model of legform impactor established in this paper meet the demand of the pedestrian safety regulations and parameter optimization methods of bumper were effective, so this paper provids new methods for research of pedestrian safety, and can reduce costs of practical tests, shorten vehicle development cycle and avoid unnecessary injury caused by a live test. The paper provides reference for pedestrian safety research in our country vehicle designbased on pedestrian safety, and it's also valuable to establish pedestrian safety regulations in our country. |
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