The Research Of Ability Of Anti-fatigue For Aluminum Alloy Car Body

Railway is a national important infrastructure, which not only plays an important role in military, but also is the premise of social and economic development. Railway is the artery of national economy and popular means of transportation and Railway plays an important role in the modern various transportation, So it is a mainstay of all transportation industry. With the development of railway enterprise, lightweight body, quick running speed and running into the safety became the development direction of railway transportation. High-speed emu become the representative of the high-speed railway, however in the process of high speed and light car body, there’s often some safety hidden trouble, which needs high requirement for car body stiffness and strength. One of the core issues is fatigue life problem in design and manufacture of high-speed emu. In order to be able to better realize the reliability and safety of high-speed emu, fatigue resistance of the high-speed emu car body is considered in this paper.First of all, on the basis of high-speed CRH3emu car body structure, a head finite element model of the aluminum alloy car body was established by virtual simulation method. According to EN12663-2010standards,±0.2g acceleration was exerted on the car body vertically and±0.15g acceleration on the horizontal and vertical direction. Also, for safety consideration, an extra pressure of3kpa was put on the car body both inner and outside. The fatigue strength was calculated under seven conditions with the analysis software ANSYS11.0. The whole car body fatigue performance was analyzed with infinite life design method.Second, given the IIW standard of International Institute of Welding basing on the nominal stress method, the car body’s finite element model was analyzed, and the weld seams which we care about were found referring to the welding drawings. Six welds were chosen to extract the corresponding observation points of the first principal stress in the strength analysis results. Then, according to the ⅡW standard, appropriate welding joint and the corresponding parameters were selected, the weld fatigue damage and life was evaluated using the linear cumulative damage theory.Third, the most accurate of American ASME standard equivalent structural stress method was used to analyze the car body finite element model again. The equivalent structure stress and the cumulative damage ratio of the finite element model were gained from the independent research and development of FE-WELD fatigue analysis software. When the three methods were compared, namely the infinite life design method, the IIW standard of International Institute of Welding basing on the nominal stress method and American ASME standard equivalent structural stress method, the accuracy of the standard was evaluated from the advantages and disadvantages of each method, as well as the calculation results.Finally, considering the influence of the corrosion fatigue of high speed emu car body, the car body finite element model was analyzed under the most accurate of American ASME standard equivalent structural stress method. The result was reached that the corrosion fatigue is very important for the influence of car body in comparison with that of the no corrosion condition fatigue.