Stress intensity factor for a semi-elliptical rail head crack under traction

Abstract

The complex loading conditions in rails induce stress and deformations in the material which keep on accumulating and evolve to rolling contact fatigue (RCF) cracks as soon as ductility exhaust. The cracks can occur at the surface or at the sub-surface level. Generally occurring surface crack is of semi-elliptical shape. Here, we consider a semi-elliptical crack located in such a way that its major axis is perpendicular to the rail axis and minor axis is in the depth direction. Stress intensity factor (SIF) of the crack is evaluated for friction and traction force by varying the speed of the train. A three-dimensional finite element analysis is carried out using ANSYS 14.0. UIC 60 rail profile cross-section is used for the simulation purpose. Results are evaluated by taking two values of coefficient of friction (0.1 and 0.35) at the wheel-rail interface. From the outcomes it is seen that the stress intensity factor value is maximum at the deepest point of the crack front. SIF estimation method of Tada, Paris and Irwin also gives analogous values.