Prediction And Analysis Of Welding Fatigue Life Of EMU Bogie Frame

At present,China’s railway transportation is developing towards the direction of high speed and heavy load.The bogie frame is the key operating and load-bearing parts of the locomotive and vehicle.The welding parts of the bogie frame are facing the double tests of safety and lightweight.Therefore,it has become an important research topic to use scientific and reasonable methods to predict the fatigue life of the welded parts of the bogie frame and optimize the frame structure.In this paper,combined with the methods of locomotive multi-body dynamics simulation,finite element dynamics analysis and structural fatigue analysis,life prediction and analysis are carried out on the danger points of the welded parts of the bogie frame.The specific research contents and work are as follows:The multi-body dynamics analysis method is used to analyze the external excitation of bogie frame.Firstly,the multi-rigid body modeling of the EMU train is carried out,and then the vertical and transverse load time history of the two-series spring of the bogie frame is obtained through simulation analysis.Analysis of previous study on welding joint sums up the influence of stress concentration coefficient of the weld parameters,then use notch stress method to establish each welding joint under different parameters of geometric model,is obtained by the finite element simulation of weld parameters on the stress concentration coefficient of the gap,and analyzes the architecture is most suitable for fatigue life prediction of weld parameters.Three dimensional modeling software is used to model the bogie frame,simplify and repair it.Then the transient dynamic simulation of the whole bogie frame is carried out by using the finite element analysis method to determine the welding fatigue risk points.Finally,the sub model technology is used to model the welded joint at the fatigue risk point,and the simulation analysis is carried out to calculate the stress variation history with time.Fatigue life analysis software is used to predict the life of the welded joints at the dangerous points of the frame,and the obtained life is compared with the standard life of the bogie frame.Finally,the life analysis of different frame parameters of the welded joints at each dangerous point is carried out,and the optimization suggestions of the frame structure are given.In the process of prediction and analysis of the fatigue life of the welded parts of the bogie frame,this study applied the notch stress method,taking the weld parameters and frame parameters into account,further improved the fatigue life prediction process of the frame,so as to improve the accuracy of the life prediction,and provided a reference for the fatigue strength assessment of the bogie frame.