In this paper the stress intensity factors (SIFs) around a 3D semi-elliptical squat form crack on a rail surface are investigated and the results are compared with the same crack on a flat surface.Elastic foundation effects are also considered in this modelling as a key factor in crack propagation. It is found that due to the curved geometry of the rail head surface and the elastic foundation effects, the opening mode and shear modes show different behavior compared withformer models. Also the lateral load due to an angle of attack between a wheel and the rail can change the SIF pattern significantly. In addition, it is shown how the rail surface curvature can change the SIF pattern and why equivalent SIF at both sides of the crack are higher than at the crack's front midpoint. So the amplitude of equivalent SIF at an elliptical crack front plots as a curved shape around the crack tip,indicating that the crack can grow at a higher rateat some locations of the crack front than at other locations. Traction ratio is considered as well as lateral load and it is shown the superposition of a lateral load with lateral load ratio of 0.5 and traction ratio of 0.2 can increase the equivalent stress intensity factor at some points by up to 200%. This may explain why squats have a greater chance of appearing on transverse curved rails.
Stress intensity factors around a 3D squat form crack on a rail surface laid on an elastic foundation
2012
16 Seiten, 13 Bilder, 2 Tabellen, 17 Quellen
Aufsatz (Konferenz)
Englisch
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