Friction in wheel–rail contact: A model comprising interfacial fluids, surface roughness and temperature

Tomberger, Christoph; Dietmaier, Peter; Sextro, Walter; Six, Klaus

doi:10.1016/j.wear.2010.10.025

Cited by 47 publications

(39 citation statements)

References 14 publications

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“…Recently a numerical model was developed to study wheel-rail adhesion under contaminated conditions. However, due to the complexity of some types of wheel-rail contamination, the adhesion model accounted only for water and oil lubricated conditions [84][85][86][87]. These numerical models were based on some simplifications such as: an infinite half space, static conditions and a constant friction coefficient which is fully used by the adhesion in the longitudinal direction.…”

Section: Adhesion Modelingmentioning

confidence: 99%

Tribology of the wheel–rail contact – aspects of wear, particle emission and adhesion

Olofsson

Zhu

Abbasi

et al. 2013

Vehicle System Dynamics

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The wheel-rail contact is a safety critical interface. Wear, particle emission and adhesion are all wheelrail contact phenomena and are discussed here. All three phenomena are material and system parameters and are linked together. Different countermeasures to one phenomenon such as adhesion enhancement with a friction modifier can increase the wear in the contacting bodies. The wear of railway wheel and rail are linked to the number of airborne particles generated, but the exact number and size distribution of the aerosols is unknown. The main objective of this study is to review recent work in this field and to discuss future trends.

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Section: Adhesion Modelingmentioning

confidence: 99%

Tribology of the wheel–rail contact – aspects of wear, particle emission and adhesion

Olofsson

Zhu

Abbasi

et al. 2013

Vehicle System Dynamics

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“…The latest one is the model of Tomberger et al [33]. The calculation is based on the Hertzian contact model and it computes the local mechanical and thermal stress distributions and resulting traction curves.…”

Section: Tomberger Et Almentioning

confidence: 99%

“…In Fig. 2.10, the k r parameter is defined in [33] as a so-called roughness-parameter ranged between 0 and 1. The 0 value corresponds to very 'smooth' surfaces and 1 value to very 'rough'.…”

Section: Tomberger Et Almentioning

confidence: 99%

Friction in wheel - rail contacts

Popovici¹

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SummaryIn the autumn, railroad traffic is often interrupted due to the occurrence of slippery tracks. The Dutch main operator (NS) and the infrastructure manager (ProRail) struggle with repeated delays. The layer between wheel and rail causing this phenomenon has not yet been identified, but can be quantified by rheological properties determined by correlating the measured friction between wheel and rail and the developed friction model. To this end, the research described in this thesis is twofold: theoretical; in which the wheel -rail contact is modelled in terms of contact and friction, and experimental; in which the friction between wheel and rail is measured to validate the developed model. The contact model between wheel and rail is approximated to be elliptical, which is shown to be accurate for the described purpose. The low friction situation is assumed to be caused by an interfacial layer, which is acting like a lubricant. Combining the previous two assumptions, a mixed lubrication friction model is developed for the Hertzian elliptical contact situation in which the interfacial layer is acting as a lubricant governed by the Eyring model. The mixed lubrication friction model results in the so-called Stribeck curve and/or the traction curve, which both take frictional heating and starved conditions into consideration. In addition, the changes in attack angle are also taken into account and a general viscoelastic model is proposed for both interfacial and boundary layers. In this way, most of the situations occurring in the wheel -rail contacts are covered, with the recommendation that future research should include the effect of spin. The validation of the friction model was performed by conducting laboratory experiments on general elliptical contacts in the presence of a lubricant. Field experiments are conducted for extracting the rheological properties of the interfacial layer causing the low friction by using the presented model. For the field experiments, two pioneer devices were developed and successfully used on the real track. One is a sliding sensor which measures the coefficient of friction between a curved shaped specimen pressed against and sliding along the rail, i.e. simple sliding conditions. A second device is developed and mounted on a train for measuring traction curves between a measuring wheel and the head (top) of the rail, i.e. rolling/sliding conditions, at velocities of up to 100 km/h. The measuring campaign was scheduled over 20 nights during the autumn of 2008 on three tracks of the Dutch rail network (Hoekselijn, Zeeuwselijn and UtrechtArnhem -Zwolle). Five characteristic traction curves were identified by the use of a statistical approach and rheological properties were extracted for the layer causing the low friction situation. Most of the approximately 6000 measured traction curves showed good agreement with the friction model, in which the viii Summary interfacial layer is represented by the Eyring behaviour. However, for some of them, viscoelasticity had to be taken into ...

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“…Nevertheless, the literature shows cases of numerical errors associated with continuity problems in the tangential traction distribution for high creepages when the entire contact patch slides (full-slip) [116,[146][147][148]. These continuity problems become more important when adopting Kalker's Simplified Theory [97] to solve the tangential problem.…”

Section: Numerical Issuesmentioning

confidence: 99%

Advanced Techniques for Time-Domain Modelling of High-Frequency Train/Track Interaction

Navarro¹

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The aim of the present Thesis is to develop models for the study of very highfrequency phenomena associated with the coupled dynamics of a railway vehicle with the track. Through these models, this Thesis intends to address squeal noise as a particular case of rolling noise when the train negotiates a small radius curve.Wheel/rail interaction is the predominant source of noise emission in railway operations. Rolling contact couples the wheel and the rail through a very small area, characterised by strongly non-linear and non-steady state dynamics that differentiates rolling noise from any other noise problem. Wheel/rail contact problem is studied based on Kalker's variational theory and the local falling behaviour of the coefficient of friction is introduced by means of a regularisation of Coulomb's law. Its implementation shows that the influence of the falling friction on the creep curves can be assumed negligible, thus rolling contact is finally modelled using a constant coefficient of friction.Flexibility is introduced in railway substructures through the Finite Element (FE) method in order to cover the high-frequency range. This work adopts a rotatory wheelset model that takes computational advantage of its rotational symmetry. It also develops a cyclic flexible rail model that fixes the translational contact force in a spatial point of the mesh through a technique called Moving Element (ME) method. A modal approach is used to reduce significantly the number of degrees of freedom of the global problem and a diagonalisation technique permits to decouple the resulting modal equations of motion in order to reduce the computational requirements of the time integrator.Simulations in curving conditions in the time domain are carried out for constant friction conditions in order to study if the proposed interaction model can reproduce squeal characteristics for different curve radii and coefficients of friction.Keywords: train/track dynamic interaction, rotatory wheelset, cyclic track, wheel/rail rolling contact, falling friction, regularisation of Coulomb's law, Moving Element Method, decoupling techniques, curve squeal. iii ResumenEl objetivo de la presente Tesis es desarrollar modelos para el estudio de fenómenos de muy alta frecuencia asociados a la dinámica acoplada de un vehículo ferroviario con la vía. A través de estos modelos, esta Tesis pretende abordar el fenómeno de los chirridos como un caso particular de ruido de rodadura en condiciones de curva cerrada.La interacción rueda/carril es la fuente predominante de ruido en las operaciones ferroviarias. El contacto es el responsable del acoplamiento entre la rueda y el carril a través de un área muy pequeña caracterizada por una dinámica fuertemente no lineal y no estacionaria. El problema de contacto rueda/carril se estudia mediante la teoría variacional de Kalker y la caída local del coeficiente de fricción se introduce por medio de una regularización de la ley de Coulomb, que muestra que su influencia sobre las curvas de fluencia se puede despre...

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Friction in wheel–rail contact: A model comprising interfacial fluids, surface roughness and temperature

Cited by 47 publications

References 14 publications

Tribology of the wheel–rail contact – aspects of wear, particle emission and adhesion

Tribology of the wheel–rail contact – aspects of wear, particle emission and adhesion

Friction in wheel - rail contacts

Advanced Techniques for Time-Domain Modelling of High-Frequency Train/Track Interaction

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