Modeling surface rolling contact fatigue crack initiation taking severe plastic shear deformation into account

摘要

A new model for the prediction of rolling contact fatigue crack initiation at the surface of railway rails and wheels has been developed, which takes contact-related plasticity effects into account. The model assesses the propensity towards fatigue crack initiation based on microstructural crack paths in the severely shear-deformed, anisotropic material near the surface. The key to differentiate between situations favoring crack initiation accompanied by wear and situations where only wear prevails, is the distribution of plastic shear strain in combination with stress in a crack initiation layer at the surface, rather than the maximum values of the plastic strain or stress. The model predicts the formation of head checks at the gauge corner of rails and the corresponding damage pattern on wheels. It is parameterized based on results from a full-scale test rig experiment. The model can be coupled to multi-body systems simulations of railway vehicles to account for the effect of plastic shear deformation on rolling contact fatigue crack initiation in such simulations. This allows systematic studies of contact conditions, material properties and railway vehicle dynamics behavior with regard to rolling contact fatigue crack initiation. (C) 2016 Elsevier B.V. All rights reserved.