Plasticity in wheel–rail contact and its implications on vehicle–track interaction

Six, Klaus; Meierhofer, Alexander; Trummer, Gerald; Bernsteiner, Christof; Marte, Christof; Müller, Gabor; Luber, Bernd; Dietmaier, Peter; Rosenberger, Martin

doi:10.1177/0954409716673118

Cited by 15 publications

(10 citation statements)

References 25 publications

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“…Wedge model [3,12] is a 'local sub-surface' approach that has been developed for improving the prediction of head check crack initiation by considering the influence of severe plastic shear deformation at the surfaces of wheels and rails. Such layers are frequently observed in railway operation and exceed the thickness of deformed surface layers in many other classical tribological problems [16]. Severe plastic shear deformation leads to microstructural alignment with the shear plane.…”

Section: Wedge Modelmentioning

confidence: 99%

Rail RCF damage quantification and comparison for different damage models

et al. 2021

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There are several fatigue-based approaches that estimate the evolution of rolling contact fatigue (RCF) on rails over time and built to be used in tandem with multi-body simulations of vehicle dynamics. However, most of the models are not directly comparable with each other since they are based on different physical models even though they shall predict the same RCF damage at the end. This article studies different approaches to quantifying RCF and puts forward a measure for the degree of agreement between them. The methodological framework studies various steps in the RCF quantification procedure within the context of one another, identifies the ‘primary quantification step’ in each approach and compares results of the fatigue analyses. In addition to this, two quantities—‘similarity’ and ‘correlation’—have been put forward to give an indication of mutual agreement between models. Four widely used surface-based and sub-surface-based fatigue quantification approaches with varying complexities have been studied. Different operational cases corresponding to a metro vehicle operation in Austria have been considered for this study. Results showed that the best possible quantity to compare is the normalized damage increment per loading cycle coming from different approaches. Amongst the methods studied, approaches that included the load distribution step on the contact patch showed higher similarity and correlation in their results. While the different approaches might qualitatively agree on whether contact cases are ‘damaging’ due to RCF, they might not quantitatively correlate with the trends observed for damage increment values.

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Section: Wedge Modelmentioning

confidence: 99%

Rail RCF damage quantification and comparison for different damage models

et al. 2021

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“…Figure 10 shows a typical example of the cross section of a rail taken from service. Severe plastic shear deformation is observed near the surface ('tribological' plasticity layer) decreasing with depth (transition to 'global' plasticity layer to undeformed material) [113,143,[161][162][163]. This is strongly influenced by the normal and tangential stress distribution within the contact patch.…”

Section: Near Surface Plastificationmentioning

confidence: 99%

“…Figure10. Example of the cross section of a rail taken from service showing severe plastic shear deformation near the surface (by assessing the alignment of the microstructure) as well as initiated micro-cracks[161].…”

mentioning

confidence: 99%

Challenges and progress in the understanding and modelling of the wheel–rail creep forces

Vollebregt¹,

Six

Polách³

2021

Vehicle System Dynamics

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This paper surveys advances in the understanding and modelling of wheel-rail creep forces. The main focus is placed on tribological aspects, for which significant progress was made in the past two decades. We emphasise the role played by the surface conditions, i.e. the presence of liquid and solid layers, surface roughness, and nearsurface plastic deformation. As these surface conditions may change over time, transient changes may be obtained in the creep force characteristic. This brings feedback into the picture, with consequences and opportunities for optimised adhesion recovery, traction control, and braking systems.

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“…When talking about surface-initiated RCF cracks like head checks on rails, severe plastic deformations in the near-surface layer play a key role. 12–19 Such plastic deformations lead to a change in the original microstructure of the material with regard to an alignment of the pearlite lamellas. These changes cause material damage ending up in preferred crack growth paths parallel to this alignment.…”

Section: Rcf Modelsmentioning

confidence: 99%

Rolling contact fatigue behaviour of rails: Wedge model predictions in T-Gamma world

Six

Mihalj

Marte

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part F:

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In this study, T-Gamma and Wedge models have been compared with each other for the prediction of surface-initiated rolling contact fatigue cracks on rail surfaces. Both models are able to account for different observed rolling contact fatigue-wear regimes in tracks, but with very different physical backgrounds. The T-Gamma model uses empirically determined damage functions by introducing a relationship between the wear number (T-Gamma) and the rolling contact fatigue damage increment. Different rolling contact fatigue-wear regimes are considered in this empirical approach based on the idea that initiated cracks get partially or fully removed by the wear mechanism, not accounting for the full complexity of the occurring tribological phenomena. The Wedge model represents a physical approach, where contact stresses and its impact on plastic deformations and related material anisotropy are considered. Thus, the prediction of different rolling contact fatigue-wear regimes is based on these physical relationships, where plastic shear deformations in the near-surface layer play a key role. For comparison, the wheel–rail contact data from stochastic multibody dynamics simulations of a metro vehicle with conventional bogie technology running in three curve radii have been used. While the T-Gamma model always predicts the same rolling contact fatigue damage increment for a given T-Gamma value, the Wedge model shows a scattering of the predicted rolling contact fatigue damage increments when plotting them over T-Gamma because of the explicit consideration of contact stresses. Thus, each scenario consisting, for example, of certain vehicles, curve radius, wheel–rail profile combination, friction conditions, rail material, etc. needs its own damage function in the T-Gamma world. This should be kept in mind when applying the standard T-Gamma model to scenarios which differ significantly from the scenario it has been parameterised for.

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Plasticity in wheel–rail contact and its implications on vehicle–track interaction

Cited by 15 publications

References 25 publications

Rail RCF damage quantification and comparison for different damage models

Rail RCF damage quantification and comparison for different damage models

Challenges and progress in the understanding and modelling of the wheel–rail creep forces

Rolling contact fatigue behaviour of rails: Wedge model predictions in T-Gamma world

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