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Title: Fundamentals of rail-wheel interaction : adhesion and rolling contact fatigue
Author: Arnall, Andrew David
ISNI:       0000 0004 7964 5636
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2019
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How do rolling contact fatigue cracks within the rail interact? Formed by the wheel-rail contact, rolling contact fatigue cracks within the rail tend to occur as a series of closely spaced cracks. These do not occur as a row of identically sized or spaced cracks, as is commonly modelled. Within this thesis investigations are conducted on how the relative size and separation between these cracks affects the stress intensity factor found at the crack tip. Through improvement in the understanding of how cracks of similar sizes interact, the crack size and separation combinations that are more likely to lead to rail failure from rolling contact fatigue can be better identified. This will permit a more condition based approach for determining maintenance schedules, with cracks more likely to lead to rail failure prioritised. The two dimensional and three dimensional boundary element approaches used within this thesis demonstrate that the greatest shielding effect is found when the cracks are of similar sizes, with the least shielded case being a large crack surrounded by cracks many times smaller. The overlying crack is found to have a greater influence on the shielding effect experienced by the central crack than the underlying crack. As expected the shielding effect decreased as the crack spacing increased. In addition the locations of rolling contact fatigue sites that are not generated by cornering forces are compared to the locations of low adhesion events and underbridges. Particular correlation is found with underbridge locations. Further investigations found that abrupt support stiffness changes leads to an increased degree of whole rail bending, which would be expected to lead to increased damage within the rail. However, the increased degree of whole rail bending is not found for gradual support stiffness transitions.
Supervisor: Fletcher, David ; Lewis, Roger Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available