Post Hatfield rolling contact fatigue: the effect of residual stress on contact stress driven crack growth in rail: part 2: data

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Rolling contact fatigue | Fletcher, D. I. | Report

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Title: Post Hatfield rolling contact fatigue: the effect of residual stress on contact stress driven crack growth in rail: part 2: data
Author(s): Kapoor, A.; Fletcher, D. I.
Abstract: Runs of the model developed and described in the previous report were undertaken to investigate the effect of residual stress and continuously welded rail (CWR) stress on crack growth in rails. The areas investigated were: Prediction of crack growth rates and directions, and how residual stress affects these; The effect of CWR stress on crack growth rate, including when it acts in combination with residual stress; The way in which initial crack angle affects the influence residual stresses have on crack propagation rates; The effect of contact pressure, surface friction and crack face friction on the crack growth rate in the presence of residual stress. It was found that: The inclusion of residual stress in the modelling of a crack at 30° below the rail surface produced a tendency for the crack to branch down into the rail, but this effect does not begin until the crack exceeds 20-25mm in length. Tensile CWR stress (cold rails) could produce around a 70% rise in crack growth rate over that of no CWR stress. Compressive residual stresses (hot rails) had almost no effect on crack growth rates. Without residual stresses crack growth rate was predicted to increase with increasing crack angle. With residual stresses present this trend was reversed, with 30 cracks showing the highest growth rates, and the growth rate of cracks of 60° or above showing insensitivity to crack angle. Trends in crack growth rate with variations in contact pressure, crack face friction and surface friction levels were largely similar for cases with and without residual stresses applied. This report contains revised information on the residual stress input data, and supersedes earlier versions of the report.
Publication type: Report
Source: NewRail, report WR061106-3 (Nov 2006)
Publication year: 2006
Keyword(s): Continuously welded rail stress; Crack growth; Hatfield; Rail; Residual stress; Rolling contact fatigue
Publisher: NewRail, Newcastle University
Publisher URL: http://www.rail-reg.gov.uk/server/show/nav.1184