Crack propagation in rails under rolling contact fatigue loading conditions based on material forces

Artikel i vetenskaplig tidskrift, 2012

Tools for the prediction of crack growth in rails are of vital importance for the railway industry. In this paper, numerical simulations of crack growth in rails are presented. More specifically, the focus is on short surface head check like cracks, often observed at the rail gauge corner. A fatigue crack propagation model expressed in terms of a crack driving force, derived from the concept of material forces, is presented. It is shown that only the component parallel to the crack tip of the crack driving force is a reliable quantity that can be used in numerical simulations of a Rolling Contact Fatigue (RCF) situation. In addition, it is shown that one term in the expression of the crack driving force (Gsur) is dependent on the computational mesh. The propagation model has been used for parametric studies of crack propagation to investigate key parameters such as loading and crack geometry. Results from these studies suggest that anisotropic effects from the highly deformed surface layer may need to be included in order to simulate head check growth in rails accurately.