Analysis of Residual Stress Distribution in the ESCO Rail Profile ۶۰E۱ by Contour Method

The residual stresses have an undeniable effect on the fatigue life, fatigue crack growth rate and fracture toughness of the rails. The aim of this research was study the longitudinal residual stresses in the rail profile ۶۰E۱ cross-section by the contour method. To this aim, a sample of the rail profile ۶۰E۱ having a length of ۰.۵m was taken from ۳m of the rail end. The cutting process of the contour method was performed by wire electro discharge machining (EDM), skim cut settings, using ۲۵۰μm diameter brass wire and cutting rate of ۴۰ mm۲/min. The contour of both sides of the sample after the cut was measured in ~۱۰۰۰۰ point in each side by using the mechanical contact coordinate measuring machine (CMM). To minimize the multiple possible error sources, the average of two contours was considered. The surface contour was smoothed by MATLAB software and using the bivariate fourth grade spline. The peak-to-valley amplitude of the displacement contour was about ۱۰۰μm. FE analyze of the contour method was performed by ABAQUS package. The cutting plane was modeled as a flat surface and the measured contour was introduced to the node locations as displacement boundary conditions. The results present the C-shape pattern of the longitudinal residual stresses across the rail cross-section which is in good agreement with the previous results in this field. The magnitude of the residual stresses in the head, web and foot were about ۱۸۰, -۱۰۰ and ۱۶۰ MPa respectively. The uncertainty of the results is less than ±۱۵%.