Numerical study on rolling contact fatigue in rail steel under the influence of periodic overload

Fatigue crack is one of the most common defects in railway system. Fatigue crack growth may lead to wheel and rail failure and damage to other components. In this paper, by applying the including service conditions of the railway system, first, a 3D nonlinear stress analysis model has been applied to estimate stress fields of the rail under the influence of periodic overloads. For this purpose, an UIC60 rail with accurate geometry using finite element method (FEM) is studied. Next, the results of this model are used for fatigue crack growth and also to estimate the fatigue life in rails using boundary element method (BEM). In this regard, first, the types of cracks and the corresponding factors which cause them were analyzed. In addition to performing stress analysis for different positions of the wheel, different values of the stress intensity factors (SIFs) were also obtained. Using these stress intensity factors, two characteristics of fatigue crack propagation namely, crack growth and direction of its development, were obtained. In this study, Paris Equation is used as a criterion of fatigue crack growth rate and the maximum tangential stress was considered as the crack growth direction. The numerical analysis results showed that the effect of periodic overloads on the fatigue life in rails was significant and could not be ignored.