Modelling the three-dimensional behaviour of shallow rolling contact fatigue cracks in rails

• Published in: Wear Vol. 253; no. 1-2; pp. 17 - 25
• Main Authors: Bogdanski, S, Brown, M W
• Format: Journal Article
• Language: English
• Published: 25.07.2000
• ISSN: 0043-1648

A model of the fatigue behaviour of three-dimensional (3D) semi-elliptical shallow-angle rolling contact fatigue (RCF) cracks was developed by combining numerically obtained (3D FEM) linear elastic fracture mechanics (LEFM) crack front loading histories with mixed-mode fatigue crack growth rate data. The model was applied for the 'squat' type of crack - typical of rail RCF failure, to predict (i) shape development, (ii) co-planar extension, (iii) spalling, and (iv) branching to transverse defects. The model demonstrated that propagation of 'squats' under the rail surface is feasible when a fluid entrapment mechanism is introduced, encouraging a mixed-mode shear dominated growth. However, cracks may branch to a Mode I direction when the residual stress, crack inclination and braking force create favourable conditions.