FINITE ELEMENT ANALYSIS OF FRACTURE MECHANICS OF WHEEL-RAIL

In this paper, wheel-rail contact problem in the presence of rail surface crack is investigated. The reason for investigating this problem is significant effect of wheel-rail contact on stress intensity factors. In this research, by using finite element method and a commercial software, wheel-rail is modeled under partial slip rolling condition. Contact elements are used to model the interactions between the wheel-rail contact surfaces and the crack surfaces. Stress intensity factors are calculated through a numerical displacement extrapolation method. The effects of crack orientation, crack length, friction coefficient and contact on the stress intensity factors are studied. The results indicate that KII has greater values than KI. Therefore, shear mode may dominate the tip behavior in this wheel-rail contact problem. As the wheel passes over, the complicated crack edge deformation changes the direction of interfacial shear stress and this causes variation in KII. Fluctuation in KII is the main factor of fatigue crack propagation in the wheel-rail contact problem.