A Study On Forecasting Of Fatigue Life For Aluminium Alloy Car Body Including The Potential Welding Defects

With China’s high-speed rail technology rapid development and high speed multiple units is widely put into operation,fatigue of the railway locomotive and vehicle products is becoming important.Once the key parts of the high-speed trains have a fatigue fracture, it will lead to extremely serious consequences. Therefore, during the design stage, the scientific prediction for the fatigue life of welded structures of railway vehicles, has become an essential part of the reliability of rail vehicle structural design.First of all, to carry out a study for different welding defects which affect the fatigue properties of aluminum alloy welded joints.Under the test conditions of iterative dynamic load, to research on welding defects including imperfect penetration, incomplete fusion impact on aluminum alloy welded joint fatigue performance.Based on structural stress method, to transform different welding defects as the initial crack and calculate the ratio of initial crack depth and the thickness of the specimen.Through the use of numerical simulation technology, the test results were compared and analyzed which is potential welding defects aluminum alloy welded joint fatigue performance.By making use of structural stress method, we obtain the theoretical prediction methods of aluminum alloy welded joints with potential welding defects.Secondly, the middle EMU body of CRH380BL is the research object, based on the basic theory of finite element, HyperWorks10.0software as the platform, established finite element model of the middle EMU body of CRH380BL, by using ANSYS solver, static strength of the middle EMU body of CRH380BL can be analysed.Loaded the body in accordance with BS EN12663-1:2010standard requirements, on the basis of the data of the body strength, use the United States ASME2007standard structural stress method and based on the master S-N curve of welded structures fatigue life prediction technology, according to Miner linear cumulative fatigue damage theory, fatigue life of the car body welding line can be predicted. Finally, use the front of the paper "the theoretical prediction methods of aluminum alloy welded joints with potential welding defects",so fatigue life of the aluminum alloy body with potential welding defects can be assessed,what verifies the reliability of product design.