MODELING OF CRACK-GROWTH UNDER CYCLIC CONTACT LOADING

The paper describes a general computational model for modelling of sub surface fatigue crack growth under cyclic contact loading of mechanica l elements. The model assumes that the initial fatigue crack develops along the slip line in a single crystal grain at the point of the maxi mum equivalent stress. The position and magnitude of the maximum equiv alent stress are determined with the Finite Element Analysis of the eq uivalent contact model, which is based on the Hertzian contact conditi ons with the addition of frictional forces. The Virtual Crack Extensio n method is then used for simulation of the fatigue crack propagation from the initial to the critical crack length, when the surface materi al layer breaks away and a pit appears on the surface. The pit shapes and relationships between the stress intensity factor and the crack le ngth are determined for various combinations of contacting surface cur vatures and contact loadings. The computational results show that the model reliably simulates the subsurface fatigue crack growth under con tact loading and can be used for computational predictions of surface pitting for various contacting mechanical elements. (C) 1998 Elsevier Science Ltd. All rights reserved.