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Surface cracks and wear of rail: a full-scale test on a commuter train track
KTH, Superseded Departments, Machine Design.ORCID iD: 0000-0003-2489-0688
KTH, Superseded Departments, Machine Design.
2002 (English)In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 216, no 4, 249-264 p.Article in journal (Refereed) Published
Abstract [en]

Damage mechanisms such as surface cracks and wear on a rail can reduce the service life of a railway track. The purpose of this investigation was to study the development of these two damage mechanisms on new and 3-year-old rails in a commuter railway track over a period of 2 years. Four curves were studied with radius between 303 and 616 m. In two of the curves, two different kinds of rail steel grade (UIC 900A grade with ultimate strength 900 N/mm2 and UIC 1100 grade with ultimate strength 1100 N/mm2) were used in each curve. In the other two curves, only the lower-strength rail was used. Four pieces of new rail, each 20 m long, were inserted in the two curves with both UIC 900A and UIC 1100 grade rail. Lubrication was applied on the high rail of one of the curves with both UIC 900A and UIC 1100 grade rail and on one of the curves with only UIC 900A grade rail. The two remaining curves were not lubricated. Surface cracks in the form of headchecks could be noted on the surface of the new 1100 grade rails after 1 month of traffic. By contrast, the surface of the UIC 900A grade rails showed visible surface cracks in only two of four curves and that after approximately 2 years of traffic. Both materials seemed to be similarly sensitive to crack initiation but the 1100 grade rail was more sensitive to crack propagation and also more sensitive to the formation of headcheck cracks. Lubrication, as expected, reduced the profile change. A less expected outcome was that lubrication also reduced the rate of crack propagation; however, the lubricated UIC 1100 grade rail was as sensitive to crack initiation as the unlubricated UIC 1100 grade rail. By comparing the wear depth in the headcheck zone with the crack length, equilibrium between these two damage mechanisms was found for the lubricated UIC 1100 grade rail. Both the crack length and the wear depth showed low values. By using a lubricant with friction modifiers the stresses was low enough to prevent crack propagation; at the same time, the rail was hard enough to reduce the wear rate. This is probably the most favourable state in terms of rail maintenance cost.

Place, publisher, year, edition, pages
2002. Vol. 216, no 4, 249-264 p.
Keyword [en]
Lubrication, Rail, Surface cracks, Wear
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-4915DOI: 10.1243/095440902321029208ISI: 000180190500003OAI: oai:DiVA.org:kth-4915DiVA: diva2:7014
Note
QC 20100930Available from: 2005-02-09 Created: 2005-02-09 Last updated: 2017-12-05Bibliographically approved
In thesis
1. On wear in rolling/sliding contacts
Open this publication in new window or tab >>On wear in rolling/sliding contacts
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The aim of this thesis is to increase the understanding of wear in rolling/sliding contacts such as the wheel-rail contact for railroads and the roller-washer contact for roller bearings.

The Stockholm commuter train network has been the subject of papers A and B in this thesis in which the wear and surface cracks on rails has been observed for a period of three years. By comparing the wear depth with the crack length, equilibrium between these two damage mechanisms was found for a lubricated rail. By using a lubricant with friction modifiers the stresses was low enough to prevent crack propagation; at the same time, the rail was hard enough to reduce the wear rate. This is probably the most favourable state in terms of rail maintenance cost.

Roller bearings subjected to lubricant borne particles have been the subject of papers C, D and E in this thesis. Particles in the lubricating oil can have a significant impact on the wear in lubricated contacts. Even at low concentration levels can self-generated particles cause significant wear. The here presented results shows that filtration during run-in can significantly reduce both the mass loss and the number of self generated particles. A series of experiments has been carried out to study the wear of roller bearings by ingested lubricant borne hard particles. The form of the worn profile and the length of wear scratches correspond closely to the sliding within the contact. A count of the number of wear scratches on the rolling element surface indicates that the contact concentrates particles. A novel wear model based on the observation of a single point on the contacting surface when a concentration of particles passes through it has been developed and the necessary data for the model has been determined from the experiments. Comparison of the simulation results with the experimental results shows good qualitative agreement for the form change of the washer surfaces.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. x, 20 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2005:03
Keyword
Technology, wear, rolling, sliding, contact, environment, TEKNIKVETENSKAP
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-122 (URN)
Public defence
2005-02-11, Kollegiesalen, Valhallavägen 79, Stockholm, 09:30
Opponent
Supervisors
Note
QC 20101015Available from: 2005-02-09 Created: 2005-02-09 Last updated: 2012-01-27Bibliographically approved

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Olofsson, Ulf

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