Simulation for Propagation of Horizontal Fissures in Rail Squats

Abstract

Rail squats are surface initiated rolling contact fatigue cracks due to the repeated passage of the train wheels. In this study, numerical simulations were performed of propagating horizontal fissures in squats. The growth was based on boundary element analyses of stress intensity factor (K-value) for a two-dimensional (2D) inclined surface crack under a Hertzian contact patch. By arranging several such 2D cracks in parallel and connecting their tips, K-values for a three-dimensional (3D) semi-elliptical horizontal crack can be obtained approximately. This approach can give the great speed advantages over fully 3D methods. A Paris-type crack growth law with an equivalent K-value range proposed by Richard was obtained using data from mode I/II and mode I/III non-proportional mixed-mode experiments. The direction of branching was predicted according to the Hourlier-Pineau criterion.