Research And Application Of Motor-bus Collision Accident Reconstruction Oriented To Occupant Injury

With China's industrialization and urbanization entering into the stage of rapid development, implementing public transit priority has become the primary strategy for current urban construction. As one of public transit system's important carriers, motor-bus has been receiving more and more attention in the research of its accident safety from both domestic and foreign scholars. The computer simulation based bus collision accident reconstruction takes fully advantage of high accuracy, strong objectivity and comprehensive analysis, etc, which can provide scientific basis for the research of accident survey, accident prevention and occupant injury mechanism, etc. Thus, this kind of accident reconstruction has crucial social meaning and practical utility. Considering the existing research and practical demand, this paper presents studies in the field of two main accident collision processes, which are outer vehicle collision and inner bus secondary collision. Through connecting the two collision processes with vehicle impact kinematical parameters, comprehensive analysis of whole bus collision accident can be achieved. As for outer vehicle collision process, the trajectory optimization based momentum-impulse exchange and deformation vs. collision method are adopted to establish the vehicle and surrounding coupled model, which is based on the investigating information of skip marks, road surface debris and vehicle outer body deformations, etc. The post-crash information of vehicle rest position can be used to reveal the impact process and then find pre-crash situation. The most coherent simulative process can be obtained by making repeated adjustments according to the difference between simulative vehicle trajectory and real road track, or the inconformity between simulative vehicle body deformation and real measurement result.As for inner bus secondary collision, the multi-body dynamics method is used to reconstruct the movement state and collision process of occupant, which is based on the investigating information of occupant position, human body evidence and inner bus structure deformation, etc. Through the inner bus impact simulation, the cause of human body injury and severity level can be analyzed. Considering the characteristics of coupling method between occupant and inner bus structure and related part deformation, hybrid occupant dummy model with hand grip force and fine inner bus structure model were established by introducing multi-body and finite element coupled method. With contact definitions, spatial location adjustments and joint restraint configurations, the coupling model between inner bus structure and occupant was built. Due to the fact that the cause of occupant injury is complicated, this paper analyzes the influence of several factors on the simulation results of human body injuries through a series of simulation tests. The occupant impact movement and injury characteristics under three standard impact working conditions were discussed so as to provide reference and guide for the application of real accident case study.Finally, the foresaid research result is applied to the reconstructions of real accident cases. Through studying three real bus collision accidents, the research methods and simulation process were described in detail. Due to lack of physical experiments, the results of these reconstructions are proved by accident investigation data. The purpose of these applications is to evaluate the feasibility and practicability of the numerical models and research methods studied in this paper.