The Research Of Anti-fatigue Ability For The Bogie Frame Of A Railway Vehicle

With the development of railway vehicle technology,China’s railway transportation is developing rapidly.Bogie is an important part of railway rolling stock and frame is the main bearing structure of bogie.Under the action of dynamic load,the welding seam of bogie frame is prone to fatigue crack,which threatens the safety and reliability of train operation.Whether the fatigue strength of welding seam of frame can meet the operation requirements will directly affect the safe operation of train.Therefore,the study of vehicle fatigue is an urgent need to ensure railway safety.This paper takes a railway bus bogie as the research object.Firstly,according to UIC515-4 standard,the static strength test is carried out for the bogie,and then the fatigue test is carried out according to the standard.Then,IIW standard,BS standard and weld fatigue software based on the equivalent structural stress method are used to calculate the fatigue life,Finally,the results are compared and the advantages of equivalent structure stress method compared with nominal stress method are obtained.Based on the fatigue assessment process and results of the bogie frame,the advantages and disadvantages of the nominal stress method and the equivalent structural stress method are analyzed.The nominal stress method has been widely used because of its high accuracy and simple application,but it has some limitations in practical engineering application.Because of the geometry discontinuity at the weld and the size of the finite element mesh,the results of the nominal stress calculation are not accurate enough;The welding joint form and load mode of the evaluation point are difficult to be in accordance with the standard,which will lead to the inaccurate calculation results of fatigue life.Equivalent structural stress method is one of the revolutionary results of fatigue analysis of welded structures.It is based on fracture mechanics and a large number of welding joint test data.It has the insensitivity of structural stress to finite element grid,and includes the influence of load mode and plate thickness on fatigue life.It can calculate the fatigue life of welded structure only by using one main S-N curve.