Prediction of fatigue crack paths including crack-face friction for an inclined edge crack subjected to mixed mode loading

Abstract

Accurately describing the fatigue crack growth rate and fatigue crack growth direction is crucial in determining the residual fatigue life of steel structures in general and for railway rails in particular. The crack growth rate and crack growth direction depend on the crack driving force. The stress intensity factor (SIF) is often considered as crack driving force and it depends on the applied load, the crack length and geometry. This paper concerns a numerical investigation on an inclined edge crack in a rail subjected to a moving patch load to evaluate its growth rate and direction including both normal and tangential stress components. A 2D finite element (FE) model is created including friction between the crack faces. The crack is incrementally extended in the predicted direction after each passage of the moving load. A parametric study is conducted to study the effect of the friction and traction coefficients. The results are compared in terms of predicted crack paths and SIF characteristics. It is shown that both friction and traction have a significant influence on the fatigue crack growth rate and path.