| In recent years,High-speed trains are developing rapidly in China.It provides many convenience for people's daily travel.However,with the operating mileage and speed increasing,Its transportation safety has become a key issue.The safety of train operation is inseparable from the performance of the axle,Although the axle is unlimited life design based on the material durability limit,it does not guarantee the safety of the axle structure in the whole service life.The research on fatigue performance of axle steel materials has great significance,the methods of axle life prediction have not made breakthrough progress and on the macro scale.Therefore,applying the crystal plasticity finite element method commonly used in the field of materials science to the axle steel material can provide a new method for the fatigue study of the axle steel material,and the microscopic characteristics will be studied more.In this paper,the LZ50 axle steel is first tested to obtain the key data required for the simulation calculation;then write user material subprograms which can reflect the constitutive relationship of material;and then through comparative analysis to find the crystal Plasticity finite element modeling method which is suitable for LZ50 axle steel life prediction.combine the simulation results of the model with the formula of the energy method to predict the life of the LZ50 axle steel material on a microscopic scale;Finally,the traditional fatigue life prediction method is used to predict the life of the axle steel material on the macro scale and compare with micro methods,The main conclusions are as follows:(1)Through the material tensile test,the tensile strength of the material is 753 MPa,and the yield strength is 428 MPa.The stress-strain curve of the material is obtained,and the fatigue test of the LZ50 axle steel material is carried out by the lifting method to study the fatigue performance of the axle.The fatigue limit of the axle sample is283.9MPa.(2)The Neper software is used to establish the geometric model and by writing the ABAQUS user material subroutine which define the material constitutive relationship,to achieve the calculation of the crystal Plasticity finite element model,It is found that the model in this paper can well reflect the grain strengthening effect of the material and the influence of the grain boundary on the performance of the material.(3)The test results and crystal Plasticity finite element simulation results are substituted into the energy method life prediction formula,and the energy conversion rate of the LZ50 axle steel material crack initiation is 0.000197.According to the results obtained,when the stress level is 350 MPa,the life of the material is 478691 times.(4)The Hypermesh software is used to establish the macro model of the axle,and the analysis are performed through the ABAQUS software.It is found that the stress in the excessive arc area on the inside of the axle shaft contact is the largest,and the calculation result file is imported into the Fe-safe software for life prediction.At a stresslevel of 350 MPa,the life of the material is 495345 times.The location where the fracture occurs is the area of maximum stress.(5)Through the comparison of the two methods,it can be seen that the difference in life calculated by the two life prediction methods under the same working condition is3%.It shows that the model used in this paper can well predict the life of axle steel materials on the micro scale. |
PDF Full Text Request