Abstract
Abstract Within the framework of materials fracture mechanics the computational model for investigation of fracture processes and prediction of rolling bodies residual lifetime under their cyclic contact has been formulated. The step-by-step calculation of crack propagation paths using solutions of the singular integral equations of two-dimensional contact problems for solids with curvilinear cracks and also local fracture criteria under complex stress–strain state are the basis of the model; calculation takes into account the fatigue crack growth resistance characteristics of materials and tribojoints performance parameters. The algorithms of cracks propagation paths construction in the contact zone take into account a change of the stress–strain state, that is caused both by the cracks extension and a counterbody movement (load change) in a contact cycle. They also take into consideration the possible change of fracture mechanism in the cracks propagation process and friction between cracks faces. Taking into account the published experimental data on crack initiation and propagation under cyclic contact of solids, two criteria of material local fracture have been included in the calculation model: the criterion of generalized normal opening ( σ θ -criterion) and the criterion of generalized transverse shear. Conditions for evaluation of pitting particles sizes in dependence on the service parameters and characteristics of fatigue crack growth resistance have been formulated. Realization of the model is given for a wheel–rail pair under boundary lubrication in contact. Using the fatigue crack growth resistance characteristics of RSB 12 and 75KhGST (75ХГСТ) rail steels, their residual lifetime has been evaluated by pitting development. The corresponding curves of contact fatigue have been constructed.
Published Version
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