The effect of anisotropy on crack propagation in pearlitic rail steel

One of the main sources of damage in railway components is the large plastic deformations that accumulate in the surface layer under rolling contact loading. Large irreversible deformations in components made of pearlitic steel induce anisotropy in mechanical properties of the material in the surface layer. In the present work the influence of the anisotropic layer on propagation of cracks in rail head is investigated. Based on the concept of material forces, a computational framework for simulation of propagation of planar cracks is formulated where the propagation rate is linked to a crack-driving force. An anisotropic fracture surface model is employed to capture the effect of changes in the resistance against crack propagation in different directions and depths in the surface layer. Results of simulations for cases with different characteristics in the surface layer show that the anisotropic layer has a substantial influence on the crack path.