Modelling a squat form crack on a rail laid on an elastic foundation

Farjoo, Mohammadali, Daniel, William and Meehan, Paul A. (2012) Modelling a squat form crack on a rail laid on an elastic foundation. Engineering Fracture Mechanics, 85 47-58. doi:10.1016/j.engfracmech.2012.02.004


Author Farjoo, Mohammadali
Daniel, William
Meehan, Paul A.
Title Modelling a squat form crack on a rail laid on an elastic foundation
Journal name Engineering Fracture Mechanics   Check publisher's open access policy
ISSN 0013-7944
1873-7315
Publication date 2012-05
Sub-type Article (original research)
DOI 10.1016/j.engfracmech.2012.02.004
Volume 85
Start page 47
End page 58
Total pages 12
Place of publication Oxford, United Kingdom
Publisher Pergamon
Collection year 2013
Language eng
Abstract Rolling contact fatigue cracks in railway track called squats are studied in this paper. In the first part, the effects of an elastic foundation (sleepers and the ballast) on stress intensity factors obtained at a crack tip are studied. A simplified finite element model (FEM) and an extended finite element model (XFEM) were created to investigate these effects, the XFEM model being limited in geometrical size, but more able to model crack growth. Both FEM and XFEM confirmed that an elastic foundation leads to an additional bending stress which increases the crack growth rate significantly. Field results also authenticate that squat form cracks appear on timber sleepers more commonly than on concrete ones. These results indicate that considering these bending stresses in a FE model, is important to achieve a more realistic model of squat development. In the second part, a short crack of 250 μm length is simulated to investigate how variations of traction ratio (TR), friction coefficient between the crack faces (FC) and the crack angle affect SIFs when the rail is mounted on an elastic foundation. Simulations show that a crack on a rail laid on elastic foundation (clips, sleepers and ballast) can lead to significantly higher SIFs in many conditions and consequently raises crack growth rate. This indicates that foundation stiffness is as important as water entrapment and friction coefficient between the crack faces.
Keyword Rolling contact fatigue cracks
Squats
FE analysis
XFE analysis
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online 18 February 2012.

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mechanical & Mining Engineering Publications
Official 2013 Collection
 
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Citation counts: TR Web of Science Citation Count  Cited 12 times in Thomson Reuters Web of Science Article | Citations
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