Research Of Bus Roll-over Safety Improvement

In recent years, with the increasing requirements of passenger highway transport, the security problem of passenger vehicle becomes gradually increasingly prominent. In the United States, from 1999 to 2003, at average annual 40 people were killed and 18430 injured in the passenger traffic accidents, which inluding 75% of rollover, dicth falling, and river crashing. The scholars abroad research the security of rollover crash of passeger cars, according to the European ECE R66 requirements for analyzing structural strength of the upper bus body, which have studied deeply. While most of domestic passenger car manufacturers applicate CAE technology to study the passenger vehicles, which focus on passenger buses strength and stiffness analysis, modal analysis and road passenger response spectrum analysis, and has not fully carried out the security research of passenger car crash.According to some safety researches of domestic passenger car rollovers, there exsit the following three problems in research work: (1) most of the passenger vehicle rolling simulations only use the energy conservation theorem to calculate the initial angular velocityωin the process of passenger car rolling crash, not considering moment of inertia J of the passenger vehicles, and obtains the wrong initial angular velocity, which leads to an incorrect simulation results. (2) rarely use shell element modeling in the whole bus body skeleton, but use mostly beam element modeling and mixed modeling of beam elements and shell elements, which is not conform to the actual degree; moreover, the grid is not fine and thin enough, so the accuracy of the results is not high. (3) when improving the structures of passenger vehicles, the focus is thickening the whole beams or increasing the cross-sectional area, which is unfavourable to the structural lightweight.Aiming at the existing problems in the security research of passenger vehicle side turning, making use of the passenger buses CAD models provided by the manufacturer, this paper builds the finite element model with real vehicles (the bus body skeleton models are all used shell elements). Using energy conservation theorem and moment of inertia to calculate the initial angular velocityωin the process of passenger buses rolling collision. Using LS_DYNA to simulate the dynamic response of the vehicle body when it is side-turning, to find that the strength of bus body structure is small, and the car body side structural deformation is overpassed the survival space of the crew. Based on the simulation results, this paper proposes four improvement programs, by optimal designing the side wall structure, improving and experimental verifying of material parameters, to improving effectively the safety performance of rollover collision, and makes the weight of the upper bus body structure decreased 16.2%. At length the analysis of the caculation results of the improving programs is satisfied with the crew living space requirements of the ECE R66 regulations.