Influence of Crack Geometric Properties on Its Propagation Tendency of Rail Surface Crack under Rolling Contact Fatigue for the Port Machines

With the development of the loading capacity of the port machines, rail cracks have become a safety problem during operation. As rail cracks' geometric properties change, load distribution is rearranged at the crack tips, which affects the propagation tendency of the crack. In this study, simulations of rail surface crack growth under rolling contact fatigue (RCF) were presented based on a 3D finite element model. More specifically, the focus was on the calculation of the stress intensity factors at the crack tip fronts of short surface crack as well as the variation of the crack geometric properties such as the crack's size, inclination angle and shape, etc. The results showed that with the increase of the crack size, the propagation rate increases to a maximum and then decreases when the crack extends away from the domination of RCF loadings. Moreover, with the increase of the crack inclined angle, the crack propagation rate decreases, but this is only true when the crack size is small. Under RCF, the propagation rate at the rail surface in lateral direction was higher than that at the deepest crack tip, which leads the crack to develop from semi-circular into semi-elliptical, and the propagation rate of semi-elliptical crack is higher than the semi-circular one with the same crack size.