Fatigue Life Assessment Of Key Welds Of Bogie Frame Based On Master S-N Curve Method

With the rapid development of urban rail transit in our country,the running speed of vehicles continues to increase,and the issue of vehicle fatigue strength has become more and more important.As the main load-bearing structure of rolling stock,the bogie not only bears the force given by the car body,but also bears various excitations caused by uneven track.The welded structure in the frame is prone to fatigue problems.Therefore,it is particularly important to evaluate the fatigue life of the weld on the bogie frame.This paper takes the bogie of a certain intercity EMU as the research object and the master S-N curve method as the research method to evaluate the fatigue life of the key welds on the bogie frame.This article first studies the fatigue assessment theory and methods,analyzes the limitations of traditional fatigue life assessment methods,and introduces the master S-N curve method and its advantages,explains the reason why the master S-N curve method is selected as the fatigue assessment method for the key welds of the bogie frame in this article;this article then takes the bogie of a certain intercity EMU as the research object,determines the operating conditions according to the UIC615-4 standard,uses Ansys to evaluate its static strength,and then combines the revised Goodman fatigue limit Figure for its fatigue strength evaluation.The results show that the static strength and fatigue strength of the frame meet the requirements.Finally,the fatigue load value and the loading method of the frame is determined according to the fatigue test load provided by the UIC615-4 standard.Then,the fatigue life evaluation platform Fe-weld based on the master S-N curve method is used to calculate the fatigue life of the key welds of the bogie frame The results show that the minimum fatigue life of the welded frame appears at the weld between the air spring seat and the upper cover plate,which is 1.30E+07,which is greater than 1.0E+07 required by the standard.Therefore,the fatigue strength of the welded frame meets the design requirements.This article uses two different fatigue evaluation methods to evaluate the fatigue strength of the bogie frame.Under the two evaluation methods,the fatigue strength meets the requirements,thus verifying the reliability of the results.In addition,this article predicts the position of the most dangerous welds of the bogie frame,which can provide reference for maintenance personnel to a certain extent.