Pitting of the rolling bodies contact surface

Abstract

A calculational model for investigation of the fracture processes and durability of the surface contact zones of rolling bodies has been proposed within the framework of the fatigue fracture mechanics concepts. Unidirection rolling in conditions of dry friction and boundary lubrication has been investigated. The model basis is the algorithm step-by-step construction of the crack growth paths developed with application of singular integral equations of two-dimensional problem of the elasticity theory for bodies with curvilinear cracks and local fracture criteria for a complex stress-strain state. The paths calculation algorithm also takes into account redistribution of stresses, caused both by crack growth and mutual motion of contacting bodies. In the case of rolling with lubrication, that can fill the crack, its action is modeled by stresses, additionally distributed on the crack faces. Propagation paths of edge cracks have been constructed. The dependence of path form on friction coefficient between contacting bodies, the length and orientation of the initial crack, and in the presence of lubrication, on the intensity of its pressure on the crack faces, has been investigated. In calculations the generalized mode I fracture criterion ( σ θ -criterion) has been used. An attempt has been made to explain the mechanism of development of such crack-like defect as pitting and ‘squat’, often met during rolling contact fatigue. As an example, the residual durability of the ShH-15 bearing steel presurface layer under boundary lubrication has been estimated.