Abstract: The Hertz theory and finite element software ANSYS are used to analyze the contact fatigue problem of wheel/rail with surface crack. Under the condition of different axle loads and operating states, the stress intensity factors of crack tip at different locations are obtained. The results show that, the stress intensity factor KI increases with the increase of axle load, but the variation of KII differs greatly for different operating states. The stress intensity factor KI and KII increase significantly with the effect of the friction, and it changes the variation trend of KII. In the state of fraction free, KII accounts for 5% of KI. In the pure rolling state, KII accounts for 20% of KI. In the full sliding state, KII accounts for 55% of KI. It means that the KII cannot be ignored when analyzing the fatigue and fracture mechanism of rail. Hertz theory has the following defects, narrow scope of application, larger result and error accumulation because of the Hertz theory does not consider the plasticity of material and the friction between wheel and rail. The finite element method is an effective method to solve the complex contact fatigue problem of wheel/rail.

Key words: ANSYS, axle load, fatigue crack, friction, Hertz theory, wheel/rail contact