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- Talebi, Nasrin, 1992, et al.
(författare)
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CRACK INITIATION CRITERIA FOR DEFORMED ANISOTROPIC R260 RAIL STEEL
- 2022
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Ingår i: CM 2022 - 12th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, Conference Proceedings. ; , s. 857-864
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Konferensbidrag (refereegranskat)abstract
- Rail material selection and maintenance planning require accurate material failure criteria. While many of these criteria consider low-cycle fatigue of virgin materials, rail failure is known to occur after severe plastic deformations. It is, therefore, relevant to consider the applicability of such criteria during large plastic deformations. In this study, we simulate previously performed high-shear tension-torsion experiments using finite strain theory to evaluate the local stresses and strains. Based on these results, failure criteria are calibrated and validated. The Jiang-Sehitoglu criterion accurately fits and predicts failure. However, the identified parameter values are different from literature values for similar materials.
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| 2. |
- Talebi, Nasrin, 1992, et al.
(författare)
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Evaluations and enhancements of fatigue crack initiation criteria for steels subjected to large shear deformations
- 2024
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Ingår i: International Journal of Fatigue. - 0142-1123. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- While large accumulated plastic deformations occur in the rail surface layer where rolling contact fatigue cracks initiate, many available Low Cycle Fatigue (LCF) crack initiation criteria focus on small plastic strains. Accordingly, this paper evaluates available fatigue crack initiation criteria for highly shear-deformed R260 steels, reflecting the conditions in the surface layer of rails. Furthermore, modified crack initiation criteria are suggested. The evaluation is based on three different experiments: Large shear strain increments under varying axial loading (predeformation), strain-controlled LCF tests after some predeformation, and axial High Cycle Fatigue (HCF) experiments. For the predeformation, Finite Element (FE) simulations, with a large-strain plasticity model for cyclic and distortional hardening, provide predictions of the local stress and strain histories. A cross-validation procedure is used to assess the accuracy and reliability of both established and modified fatigue crack initiation criteria. The proposed modifications to one of the criteria show an improved fit to the experimental data. However, there is a tendency to overfitting, which can be improved by including more experimental data.
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