Assessing risks of subsurface initiated rolling contact fatigue from field measurements

A previous simplification of the Dang Van equivalent stress measure for cases of wheel–rail contact is modified. The new criterion for subsurface initiated rolling contact fatigue is suited for real-time assessment of measured wheel–rail contact forces. The only parameters in the new expression for the equivalent stress are the vertical force and the wheel and rail radii. Comparisons between the new and the original criterion are carried out and show good agreement for the studied cases of tangent track operation. By employing principles of vehicle dynamics the criterion is further extended to the case of operations in curves. Finally the influence of transient loads on the growth of RCF cracks in wheels was investigated. It was demonstrated that transients need to be spaced closer than roughly 10 meters to give any substantial increase in crack growth rates