Contact properties of a wet clutch friction material

Ingram, M.; Spikes, H. A.; Noles, J.; Watts, Raymond F.

doi:10.1016/j.triboint.2009.11.008

Cited by 50 publications

(34 citation statements)

References 6 publications

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“…On a microscopic scale, these reductions can be translated into the fact that the real contact area and the number of asperities making contact ac increase in size, as experimentally investigated both in dry and lubricated conditions [14,23]. Hence, at given normal load, the and ac of a worn surface are larger than those of a fresh surface.…”

Section: Resultsmentioning

confidence: 99%

“…However, the respective in�uences of adhesive wear and thermal degradation occurring in the material on the frictional characteristics during its lifetime still remain unclear and are subject to further investigation. Several researchers [14,23], by ignoring the thermal degradation effect, have attempted to understand the adhesive wear effect on the contact properties of a paper-based material during the run-in tests, namely, the real contact area and the number of asperities making contact. ey reported that the two contact parameters increase as the wear progresses.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Adhesive Wear and Thermal Degradation on the Frictional Characteristics of Paper-Based Friction Materials: A Comparative Study

2013

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is paper discusses the effects of adhesive wear and thermal degradation on the dry frictional characteristics of paper-based friction materials against steel material. Some commercial paper-based friction materials typically used for clutch applications were subjected to adhesive wear and thermal degradation and the dry frictional characteristics were then measured at different states on a rotational tribometer. e experimental results reveal that both adhesive wear and thermal degradation have opposite effects on the frictional characteristics, where the static and kinetic coefficients of friction increase due to adhesive wear but decrease due to thermal degradation.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Adhesive Wear and Thermal Degradation on the Frictional Characteristics of Paper-Based Friction Materials: A Comparative Study

2013

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“…The contact properties of the SD1777 material have been studied in a previous publication [4]. It was found that the real contact area increased approximately linearly with applied load, while the mean contact pressure at the contact units remained relatively constant at *60 MPa.…”

Section: Friction Materials and Fluidsmentioning

confidence: 98%

“…The latter was found simply by dividing the nominal pressure by the fraction of real area of contact. The fraction of real area of contact for the clutch pad loaded against the disc was measured in previous research [4]. Under a nominal pressure of 0.25 MPa, the fraction of real area of contact is 0.003, giving an average Similarly, the width of the contact can be estimated from the fraction of real area of contact and the number of contacts per mm 2 .…”

Section: Theoretical Flash Temperaturementioning

confidence: 99%

“…The resin-coated fibres, which typically have diameter 10-50 lm, partially protrude from the friction material surface and produce a very rough surface, with much steeper slopes than normally finished engineering surfaces. This means that when the friction disc is loaded against the relatively smooth steel separator disc, the real area of contact is only a small percentage of the nominal area and the contact actually consists of many small and independent 'contact units' [1][2][3][4]. The authors and others have shown that these contact units are typically 20 lm in diameter and comprise about 1-5% of the nominal contact area [2,4].…”

Section: Introductionmentioning

confidence: 99%

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Thermal Behaviour of a Slipping Wet Clutch Contact

2010

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Wet clutches are used in automatic transmissions to enable gear changes and also to reduce energy loss in the torque converter. These friction devices are susceptible to stick-slip effects, which result in the vehicle giving an unsteady ride. Stick-slip effects can be avoided by ensuring the wet clutch and lubricant combination produces a friction coefficient that increases with sliding speed. Although wet clutches have been studied throughout the industry for many decades, the mechanism of the generated friction is still not fully understood. It is known that, because of the fibrous nature and thus very large roughness of friction material, the overall contact between clutch plates actually consists of many small, independent, contact units, which are the sites of the generated friction. Some authors have suggested that a temperature rise due to friction either at these contact units or of the overall clutch plate may be important in controlling friction behaviour. In this study, the flash temperatures at the contact units formed in the wet clutch contact have been measured using an infrared camera. Three friction materials have been tested. It was found that measured flash temperature in a pure sliding system similar to that present in a slipping clutch remain well below 5°C, and are therefore unlikely to play a major role in the observed friction-speed dependency of slipping wet clutches at speeds below 2 m/s.

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Effects of Fluid Properties on Rod Seal Stick‐Slip Mechanical and Sound Vibrations

2022

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The effect of fluid properties on hydraulic cylinder rod seal stick‐slip friction was studied. Breakaway and stick‐slip forces were measured for three ISO VG 32 fluids with slipper, U‐cup, and Vee‐pack seals. Breakaway forces increased exponentially with dwell time. Stick‐slip friction produced audible low‐frequency noise. Differences in the stick‐slip behavior of the fluids were observed. Fast Fourier transform analysis of sound, force, and mechanical vibrations was conducted. Stick‐slip friction increased the amplitude of low‐frequency vibrations in all three domains. Micro stick‐slip movement was elucidated via motion amplification technology. These findings provide a basis for the development of fluids that improve the control and safety of hydraulic equipment.

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Contact properties of a wet clutch friction material

Cited by 50 publications

References 6 publications

Influence of Adhesive Wear and Thermal Degradation on the Frictional Characteristics of Paper-Based Friction Materials: A Comparative Study

Influence of Adhesive Wear and Thermal Degradation on the Frictional Characteristics of Paper-Based Friction Materials: A Comparative Study

Thermal Behaviour of a Slipping Wet Clutch Contact

Effects of Fluid Properties on Rod Seal Stick‐Slip Mechanical and Sound Vibrations

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