Prediction of the Service Life of Rolling Bodies According to the Development of a Subsurface Crack

Within the framework of the fracture mechanics of solid bodies under the conditions of rolling-contact fatigue, we study the paths of propagation of a subsurface crack and determine the residual service life of the rolling surfaces (in terms of their crack resistance) under the conditions of dry friction. The stress intensity factors and growth paths of an initially rectilinear crack are analyzed depending on its orientation, location, and length and on the friction coefficient f (f = 0.2–0.4) for the rolling bodies in contact under the assumption that the crack propagates according to the mode-I mechanism. We establish the ranges of the indicated parameters in which the crack is completely open (its lips are not in contact). Some features of propagation of horizontal cracks and formation of spalling in the rolling bodies are discovered. It is shown that it is difficult for a horizontal crack to appear on the surface according to the (mode-I) mechanism of normal tension. The residual service life of the subsurface layers of rolling bodies made of 75KhGST rail and 9KhF roll steels and weakened by subsurface cracks is evaluated.