A simplified index for evaluating subsurface initiated rolling contact fatigue from field measurements

A previous simplification of the Dang Van equivalent stress measure for assessment of subsurface initiated rolling contact fatigue (RCF) related to wheel–rail contact is modified. The new criterion is intended for real-time assessment of subsurface RCF from measured wheel–rail contact forces. The only needed 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 operations. By employing principles of vehicle dynamics the criterion is further extended to the case of operations in curves. Reasonable consistency was found for curve radii down to approximately 2000 m.