Carbon Fiber for Wet Friction Applications

Kearsey, Andrew; Wagner, Dagobert

doi:10.4271/972754

Cited by 7 publications

(10 citation statements)

References 2 publications

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“…The use of Carbon and PAN (polyacrylonitrile) fibers, on the other hand, makes friction composites less sensitive to dynamic fluctuations in brake pressure and sliding speed [10,11]. According to Kearsey and Wagner [11], the influence of additives on the friction behavior of Carbon friction surfaces is comparable to that of paper friction linings, but less pronounced, which is confirmed by Stockinger et al [12].…”

Section: Introductionmentioning

confidence: 86%

“…Several studies show that the use of Carbon fibers in composites results in a lower coefficient of friction and increases the risk of shudder (self-induced vibration), especially at high temperatures [6][7][8][9]. The use of Carbon and PAN (polyacrylonitrile) fibers, on the other hand, makes friction composites less sensitive to dynamic fluctuations in brake pressure and sliding speed [10,11]. According to Kearsey and Wagner [11], the influence of additives on the friction behavior of Carbon friction surfaces is comparable to that of paper friction linings, but less pronounced, which is confirmed by Stockinger et al [12].…”

Section: Introductionmentioning

confidence: 99%

“…The wear resistance of Carbon friction linings is higher than that of paper friction linings [4,7,11,[21][22][23][24][25]. The combination of adhesive wear, abrasive wear and thermal degradation is considered to be the main wear mechanism in wet Carbon friction plates over their entire service life [8].…”

Section: Introductionmentioning

confidence: 99%

“…A polymer matrix with excellent heat resistance enables safer and more comfortable shifting operations and extends the service life of a Carbon-based wet clutch [8]. The thermal conductivity of the friction material can be increased by incorporating Carbon fiber in a composite material [11,24].…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigations of spontaneous damage to wet multi-plate clutches with carbon friction linings

Groetsch

Stockinger

Schneider

et al. 2021

Forsch Ingenieurwes

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Safety and comfort, while ensuring torque transfer capability, are essential for wet multi-plate clutches. The safety of the torque transmission process largely depends on the endurance of the tribological system against spontaneous and long-term damages. Modern Carbon friction linings in wet multi-plate clutch applications offer superior wear resistance compared to other friction materials, but there is hardly any published data on their spontaneous damage behavior. This article therefore presents results from experimental studies on the spontaneous damage of innovative Carbon friction linings carried out on a component test rig. Furthermore, the influence of different steel plate thicknesses (3.5 mm vs. 6 mm) was investigated. 16 step tests, including visual assessments of the clutches, were performed with Carbon-fiber reinforced plastic (CFRP) and Carbon-fiber reinforced Carbon (C/C) linings in brake operations.The results of the step tests are documented in friction work over friction power diagrams. Results show excellent endurance of modern Carbon friction linings against spontaneous damage and thus makes them suitable for safety relevant high-performance applications. There was no clear influence of the steel plate thickness on spontaneous damage. However, the C/C friction lining ran at a specific energy of up to 5.26 J/mm2 in combination with sliding velocities of up to 67 m/s (high speed application) without failure. This is the highest published spontaneous damage resistance identified for wet clutches.

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Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental investigations of spontaneous damage to wet multi-plate clutches with carbon friction linings

Groetsch

Stockinger

Schneider

et al. 2021

Forsch Ingenieurwes

View full text Add to dashboard Cite

show abstract

“…Since friction materials are porous and heat cannot be conducted across the voids in the material, the heat must be conducted through the fibres, which are predominantly cellulose and themselves good heat insulators. Recently, carbon fibre has been used to partially or fully replace the organic fibres in friction materials so as to help improve the thermal conductivity [13]. The carbon fibres can be oriented in the direction of the friction material thickness, helping to conduct the heat away from the surface into the steel base plate to which the friction material is bonded [14].…”

Section: Introductionmentioning

confidence: 99%

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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Friction behavior of innovative carbon friction linings for wet multi-plate clutches

Stockinger

Groetsch

Reiner³

et al. 2021

Forsch Ingenieurwes

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The torque transfer capability as well as long-term endurance are essential for wet multi-plate clutches. The quality of the torque transmission process largely depends on the tribological system consisting of friction pairing, lubricant and applied loads. The requirements on friction linings in wet multi-plate clutches increase continuously due to stricter CO2 reduction regulations and the demand of higher power densities.There is a lack of published data and information about the friction behavior of modern Carbon friction linings in wet multi-plate clutch applications, although these friction materials have successfully proven their performance capabilities over the last two decades in synchronizers. Therefore, this article presents results from experimental studies on the friction behavior of innovative Carbon friction linings carried out on a component test rig. Friction screening tests were performed with Carbon-fiber reinforced plastic (CFRP) and Carbon-fiber reinforced Carbon (C/C) linings in brake and constant slip operation. Furthermore, our research included long-term tests with different lubricants (engine/marine/tractor oil).Results show that modern Carbon friction linings can offer advantages over other materials. In the friction screening (brake and constant slip operations) and long-term tests, the torque transfer capability of both friction linings is very stable, even at high specific loads—sliding velocities near 30 m/s and axial pressures of 2.5 MPa. Influences of sliding velocity, pressure and lubricant on the friction performance are presented. Furthermore, the gradient of the Coefficient of Friction (CoF) curve usually decreases at the end of the engagement to enable good control and shift comfort.

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Carbon Fiber for Wet Friction Applications

Cited by 7 publications

References 2 publications

Experimental investigations of spontaneous damage to wet multi-plate clutches with carbon friction linings

Experimental investigations of spontaneous damage to wet multi-plate clutches with carbon friction linings

Thermal Behaviour of a Slipping Wet Clutch Contact

Friction behavior of innovative carbon friction linings for wet multi-plate clutches

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