The Effect Of Cracks In The Subsurface Of Rail

Compared with others transportation,railway transportation has the advantages of good efficiency,large transport volume and safety,etc.Rail transport has been playing a very big role in promoting the rapid economic development.The rails will be damaged during the operation of the railway.Wheel-rail contact fatigue refers to the process of wheel-rail contact.In the contact zone,due to the effect of the wheel's cyclic force on the rails,micro-cracks are formed on the surface or sub-surface of the rails.As the micro-cracks expand,the rails generate large-scale peeling or even fracture.Therefore,the study of crack interactions on the surface or subsurface of rails can help to clearly understand the damage and failure mechanism of rails.This will ensure the safety of railway transportation and reduce the economic losses caused by the damage of rails.In this paper,through the simplification of the rail model,the influence of internal cracks in the rail is calculated through theoretical derivation.The finite element method is used to simulate the rail to verify the correctness of the theoretical calculation.These calculations provide theoretical support for explaining the damage of rails.This article studies the following conclusions:?1?Using the Kachanov's simplification method based on elastic mechanics,it is studied that the interaction between cracks in the subsurface of a semi-infinite plane.?2?Based on the Hertz's theory and Coulomb's friction law,the law of interaction between cracks in the subsurface is obtained when the wheel is fully sliding on the rail.?3?The cracks in the subsurface of rails are slip-open cracks when the cracks are under the contact patch.The magnitude of the stress intensity factor K_I is basically zero.Therefore,K_II is obviously very important when analyzing the damage and fracture mechanism of rails.?4?The stress intensity factor K_II of the cracks in the subsurface of the rails tends to increase when the axle weight the increases,the crack length,the crack length increases,the distance between the cracks decreases,and the distance from the rail surface decreases.?5?By taking into consideration of the interaction between cracks,the stress intensity factor of two cracks at the same horizontal position is significantly greater than the stress intensity factor of a single crack at the same position.