The influence of different parameters on surface pitting of contacting mechanical elements

The paper describes a general computational model for simulation of surface pitting of mechanical elements subjected to contact loading conditions. In the model it is assumed that the initial crack of length 0.015 mm is initiated at the contacting surfaces due to previously running in process or thermal and/or mechanical treatment of the material. The discretised model with the initial crack is then subjected to normal contact pressure, which takes into account the elastohydrodynamic lubrication conditions, and tangential loading due to friction between contacting surfaces. The model accounts also for the influence of fluid trapped in the crack and residual stresses due to heat treatment of the material on crack propagation. The virtual crack extension method in the framework of finite element analysis is then used for two-dimensional simulation of fatigue crack propagation from the initial crack up to the formation of the surface pit. The pit shapes and relationships between the stress intensity factor and crack length are determined for various combinations of contacting surface curvatures and loadings. The comparison of computational and available experimental results shows that the proposed model reliably simulates the surface fatigue crack growth under contact loading and can be used for computational predictions of surface pitting for various contacting mechanical elements.