Analysis of Factors Affecting the Growth of Rail Bottom Cracks
[Objective]In terms of the rail material,residual stress,temperature stress and other factors,work conditions are respectively designed to explore the influences of rail bottom crack expansion.[Method]Based on the theory of fracture mechanics,combined with rail bottom measurement,the model of rail bottom crack ex-pansion has been established and indicators such as critical crack size,average crack extension rate as well as re-maining life has been quantified.[Result]It is found that there exists positive correlation between the fracture toughness of rail material and the remaining life.The remaining life of U95Cr H is less than U78CrV H,which is less than U75V H.Taking U78CrV H,used in the line under test,as an example,when the residual stress grows from 0 to 300 MPa,the critical crack size grows by about 2.5%and the remaining life decreases by about 6%;and when the residual stress is 200 MPa,with the temperature stress from 0 to 200 MPa,the critical crack size does not change much and is within 1%.[Conclusion]The research results of the article can provide reference for the research and maintenance of rail bottom crack propagation.
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