Rheological model of solid layer in rolling contact

Hou, Keping; Kalousek, J; Magel, Eric

doi:10.1016/s0043-1648(97)00097-5

Cited by 49 publications

(39 citation statements)

References 7 publications

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“…Size, shape, and structure of the particles will influence their rheological behavior. For example, the ability of the particles to form a 'compact' layer under the effect of normal load and shear stress, also called 'cohesion' [27,28], will determine if the behavior of the transfer film will be solid-or fluidlike [29]. In fact, all attempts to use phosphate powders as anti-wear additives have been unable to reproduce the antiwear behavior of ZnDTPs [21,30].…”

Section: Formation and Functionality Of The Transfer Filmmentioning

confidence: 99%

Effect of Chain-Length and Countersurface on the Tribochemistry of Bulk Zinc Polyphosphate Glasses

2012

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Zinc polyphosphate glasses are considered to be chiefly responsible for the anti-wear efficiency of ZnDTP tribofilms. In this work, the tribochemical properties of amorphous bulk zinc polyphosphates of different chain lengths (ranging from zinc metaphosphate to zinc pyrophosphate) have been investigated. Tribological tests on bulk polyphosphate discs have been carried out using steel and quartz balls as counter-surfaces in a poly-a-olefin (PAO) bath at room temperature. The composition in the wear track and on the contact region of the balls has been monitored by small-area and imaging X-ray photoelectron spectroscopy (i-XPS). The XPS analysis revealed that the composition of short-chain-length polyphosphates remained unchanged following tribological stress. Long-chain-length polyphosphates are depolymerized in the wear track as a consequence of a tribochemical reaction. By comparing the results obtained using quartz and steel balls, it could be observed that while the reaction of iron oxide with the polyphosphates certainly plays a role in the depolymerization of the samples under sliding conditions, pressure and shear stress alone and also in the presence of water or oil-oxidized species are able to depolymerize the glass when an inert material is used as counterpart; the composition of the wear track, in this case, is dependent on the applied load. All samples were able to form an adhesive, glassy transfer film on both steel and quartz balls, but the short-chain-length polyphosphates showed a lower friction coefficient and wear coefficient. The results suggest a third-body mechanism with the polyphosphates acting as a solid lubricant. Differences in tribological behavior of the different-chain-length polyphosphates are attributable to their mechanical and rheological properties.

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Section: Formation and Functionality Of The Transfer Filmmentioning

confidence: 99%

Effect of Chain-Length and Countersurface on the Tribochemistry of Bulk Zinc Polyphosphate Glasses

2012

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“…Adhesion and factors influencing it have mainly been investigated using experimental techniques, although some attempts have been made to model so called third body layers in the wheel/rail contact [16,17] and Chen et al [18] have produced theoretical models to investigate the effect of water in a contact.…”

Section: Introductionmentioning

confidence: 99%

Twin disc assessment of wheel/rail adhesion

Gallardo-Hernández

Lewis

2008

Wear

157

118

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Loss of adhesion between a railway wheel and the track has implications for both braking and traction. Poor adhesion in braking is a safety issue as it leads to extended stopping distances.In traction it is a performance issue as it may lead to reduced acceleration which could cause delays.In this work wheel/rail adhesion was assessed using a twin disc simulation. The effects of a number of contaminants, such as oil, dry and wet leaves and sand were investigated. These have been shown in the past to have significant effect on adhesion, but this has not been well quantified.The results have shown that both oil and water reduce adhesion from the dry condition.Leaves, however, gave the lowest adhesion values, even when dry. The addition of sand, commonly used as a friction enhancer, to leaves, brought adhesion levels back to the levels without leaves present. Adhesion levels recorded, particularly for the wet, dry and oil conditions are in the range seen in field measurements.Relatively severe disc surface damage and subsurface deformation was seen after the addition of sand. Leaves were also seen to cause indents in the disc surfaces.The twin disc approach has been shown to provide a good approach for comparing adhesion levels under a range of wheel/rail contact conditions, with and without contaminants.

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“…The typical value of r a is 10 -5 (m) [20]. Furthermore the results of layer observation from [12] showed that the thickness of oxide layer on the surface of disc is about 20 (µm). Therefore the l f can be selected as 20 (µm).…”

Section: The Flash Temperaturementioning

confidence: 98%

“…When the influence of the oxide layer on the contact surface can be neglected, selecting λ = λ s , equation (10) is produced on the contact surface [12]. This oxide layer increases the asperities temperature by increasing the resistance to heat flow [20].…”

Section: The Flash Temperaturementioning

confidence: 99%

Wear transitions in a wear coefficient model

Vuong

Meehan

2009

Wear

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Abstract:The frictional-work wear model has been used popularly for the prediction of wear phenomena such as rai l corrugation. The accuracy of such model s depends on the value chosen for the empirical wear coefficient in this wear model. Experimental results have widely shown that this wear coefficient is strongly dependent upon the type of wear process involved.The wear coefficient in the frictional-work wear model under two-disc contact and dry friction conditions proposed is a multi-step function of the friction power density corresponding to three types of wear. However, at present there is no clear means of predicting the transitions between wear types. This paper investigates wear transitions between the wear types are predicted using analytical models based on the wear mechanics involved.

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Rheological model of solid layer in rolling contact

Cited by 49 publications

References 7 publications

Effect of Chain-Length and Countersurface on the Tribochemistry of Bulk Zinc Polyphosphate Glasses

Effect of Chain-Length and Countersurface on the Tribochemistry of Bulk Zinc Polyphosphate Glasses

Twin disc assessment of wheel/rail adhesion

Wear transitions in a wear coefficient model

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