The role of high positive friction (HPF) modifier in the control of short pitch corrugations and related phenomena

Eadie, Donald T.; Kalousek, J; Chiddick, Kelvin C.

doi:10.1016/s0043-1648(02)00098-4

Cited by 120 publications

(94 citation statements)

References 7 publications

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“…In recent years industry focus has been on the separate control of friction at (a) the gauge face / flange interface (traditional lubrication) and (b) the top of rail (TOR) / wheel tread interface. The latter requires special materials known as friction modifiers that provide (a) a controlled intermediate coefficient of friction (average µ = 0.35 [4] as measured by a Salient Systems push tribometer) considered safe for braking and adhesion, and (b) a positive slope to the creepage / creep force curve beyond the point of creep saturation (referred to as positive friction) [5]. This paper describes modeling work aimed at better understanding the role and mechanisms of TOR friction control in reducing train energy requirements, and continues previous work presented in [6].…”

Section: Wheel / Rail Frictionmentioning

confidence: 99%

A predictive model of energy savings from top of rail friction control

VanderMarel

Eadie

Oldknow

et al. 2014

Wear

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In this paper the authors present a predictive model of train energy requirements due to the application of a top of rail friction modifier (TOR-FM) versus dry wheel / rail conditions. Using the VAMPIRE® Pro simulation package, train energy requirements are modeled for two sets of TOR-FM frictional conditions, one using full Kalker coefficients and the other by using a Kalker factor of 18%. Both scenarios use a top of rail saturated coefficient of friction of 0.35.Under both TOR-FM frictional conditions, train energy savings are shown for complete laps of the Transportation Technology Center Inc.'s (TTCI) Transit Test Track (TTT) loop, and also when isolating only the tangent section of the loop. However, the magnitude of energy savings varies greatly depending on the Kalker coefficient factor used, highlighting the need to model this relationship as accurately as possible. These simulation results are compared with data obtained from a field study, in which train energy savings of 5.3% (lap) and 7.8% (tangent) are shown due to the application of TOR-FM.

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Section: Wheel / Rail Frictionmentioning

confidence: 99%

A predictive model of energy savings from top of rail friction control

VanderMarel

Eadie

Oldknow

et al. 2014

Wear

Self Cite

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“…The application of HPF is mainly to reduce short pitch corrugation and squeal by introducing a positive slope after the saturation point on the creep curve as shown in Figure 29 [76]. The positive slope is introduced in order to avoid stick-slip oscillations.…”

Section: Measures To Improve Wheel-rail Adhesionmentioning

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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“…These experimental quantities are fundamental for the validation both of the degraded To reach this goal and to effectively exploit the measured data, in this phase the wheelset is supposed to be placed in its centred position; in this way the position of the single contact point P c can be supposed to be known and nearly constant and the surface curvatures in the contact points, the semi-axes of the contact patch a, b and the contact shear stiffness C can be easily calculated [29]. Moreover the following simplified expressions for the sliding s sp j , for the creepage e sp j and for C hold: (20) in which J w = 160 kg m 2 is the wheel inertia. Subsequently Eq.…”

Section: The Tangential Contact Problem and The Degraded Adhesion Modelmentioning

confidence: 99%

“…More particularly the analyses have been performed both on laboratory test rigs and through on-track railway tests by considering natural and artificial external contaminants and friction modifiers [7,8,16,18,20,24,36,50].…”

Section: Introductionmentioning

confidence: 99%

An innovative degraded adhesion model for railway vehicles: development and experimental validation

2013

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The realistic description of the wheel-rail interaction is crucial in railway systems because the contact forces deeply influence the vehicle dynamics, the wear of the contact surfaces and the vehicle safety. In the modelling of the wheel-rail contact, the degraded adhesion represents a fundamental open problem. In fact an accurate adhesion model is quite hard to be developed due to the presence of external unknown contaminants (the third body) and the complex and highly non-linear behaviour of the adhesion coefficient; the problem becomes even more complicated when degraded adhesion and large sliding between the contact bodies (wheel and rail) occur.In this work the authors describe an innovative adhesion model aimed at increasing the accuracy in reproducing degraded adhesion conditions. The new approach has to be suitable to be used inside the wheelrail contact models usually employed in the multibody applications. Consequently the contact model, comprising the new adhesion model, has to assure both a good accuracy and a high numerical efficiency to be implemented directly online within more general ve- The model studied in the work considers some of the main phenomena behind the degraded adhesion: the large sliding at the contact interface, the high energy dissipation, the consequent cleaning effect on the contact surfaces and, finally, the adhesion recovery due to the external unknown contaminant removal.The new adhesion model has been validated through experimental data provided by Trenitalia S. p. A. and coming from on-track tests carried out in Velim (Czech Republic) on a straight railway track characterised by degraded adhesion conditions. The tests have been performed with the railway vehicle UIC-Z1 equipped with a fully-working Wheel Slide Protection (WSP) system.The validation showed the good performances of the adhesion model both in terms of accuracy and in terms of numerical efficiency. In conclusion, the adhesion model highlighted the capability of well reproducing the complex phenomena behind the degraded adhesion.

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The role of high positive friction (HPF) modifier in the control of short pitch corrugations and related phenomena

Cited by 120 publications

References 7 publications

A predictive model of energy savings from top of rail friction control

A predictive model of energy savings from top of rail friction control

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

An innovative degraded adhesion model for railway vehicles: development and experimental validation

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