Speaker
Description
Rolling contact fatigue in railheads develops under complex, non-proportional multiaxial loading. However, crack-initiation predictions typically depend on a single fatigue criterion applied at a fixed or preselected location. This approach does not account for changes in the material response caused by repeated wheel passages, making it difficult to distinguish the influence of the loading history from that of the selected fatigue formulation. To address this limitation, a classical multiaxial fatigue model and two deformation-dependent modifications were evaluated within a unified framework for pearlitic R260 rail steel. The wheel–rail contact model defined the pressure and traction distributions applied to the railhead. At a reference wheel load of 85 kN, the finite-element model predicted a peak surface pressure of 1427 MPa, only 3.0% higher than the Hertzian value of 1386 MPa. An initial elastic analysis produced a maximum subsurface von Mises stress of approximately 851 MPa at a depth of 2.46 mm. This value exceeded the R260 proof stress by about 59%, confirming the need for an elastic–plastic analysis. A moving pressure–traction distribution reproduced a complete wheel passage. Stress, total-strain and plastic-strain tensor histories were evaluated throughout the subsurface rail region, while residual stress, back stress and plastic strain were retained between successive passages. A three-dimensional critical-plane search was then performed at each investigated location. The criteria were compared in terms of fatigue-damage distribution, crack-initiation depth, critical-plane orientation and predicted initiation life. Deformation-dependent formulations changed the severity and size of the critical region during repeated loading.
| Topic Area | Fatigue, Corrosion and Structural Integrity of Engineering Structures and Mechanical Systems |
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