The Mechanism Of Fatigue Damage And Fatigue Life Prediction Of High-speed Emu Welded Bogie Frame

Bogie is one of the high-speed EMU's key components. It's functions include supporting bodywork, operation and steering, etc. It must keep good performance status to ensure the safe and reliable of the high-speed train. With the continuous development of Chinese high-speed railway, the reliability of the product structure of vehicles has become increasingly demanding. The fatigue strength of welded bogie has become a universal hotspot of railway vehicle industry. As the the most advanced bogie in China, CRH3 high-speed EMU bogie has more strickly requirements on its safety performance.This paper focused on the following research:First of all, according to the development of domestic and the international backgrounds, the situation of fatigue problems is briefly summarized. The paper discusses the fatigue characters of the welded structures and the main methods applied to the analysis of the welding structures. Nominal stress method, hot stress method and fracture mechanics method are discussed in the paper, as well as equivalent structural stress, which is not sensitive to element size.Then, the refined finite element model is established based on the analysis of atigue performance requirements, load mode (including the vertical force and transverse force, etc), and corresponding calculation conditions of the frame of CRH3 high-speed EMU welded bogie. The stress distribution of 15 conditions of the static strength of the bogie are calculated according to EN13749 loading criteria. The analysis'results show the bogie can meet the demand of static strength.Finally, according to selection principle of fatigue assessment point, the fatigue prediction position of the trailer bogie frame were determined. The frame's fatigue life was predicted by applying the Goodman curve, International Institute of Welding standard and the structural stress method respectively. It also analyzes the characteristics and application areas of these types of assessment methods. Enough anti-fatigue capability is shown in the calculated results of welding structure. By analyzing the comparison of the calculated results of these methods, we can observe that the structure stress method is more reliable than other methods in predicting the fatigue of welded structures.