SIMULATION OF SURFACE PITTING DUE TO CONTACT LOADING

A computational model for simulation of surface pitting of mechanical elements subjected to rolling and sliding contact conditions is presen ted. The two-dimensional computational model is restricted to modellin g of high-precision mechanical components with fine surface finishing and good lubrication, where the cracks leading to pitting are initiate d in the area of largest contact stresses at certain depth under the c ontacting surface. Hertz contact conditions with addition of friction forces are assumed and the position and magnitude of the maximum equiv alent stress is determined by the finite element method. When the maxi mum equivalent stress exceeds the local material strength, it is assum ed that the initial crack develops along the slip line in a single-cry stal grain. The Virtual Crack Extension method in the framework of fin ite element analysis is then used for two-dimensional simulation of th e fatigue crack propagation under contact loading from the initial cra ck up to the formation of the surface pit. The pit shapes and relation ships between the stress intensity factor and crack length are determi ned for various combinations of contacting surface curvatures and load ings. The model is applied to simulation of surface pitting of two mes hing gear teeth; Numerically predicted pit shapes in the face of gear teeth show a good agreement with the experimental observations. (C) 19 98 John Wiley & Sons, Ltd.