Friction Plate Fatigue Testing

Dual Clutch Transmission

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In a DCT one clutch drives odd numbered gears and the other clutch drives the even numbered gears.
In a DCT an odd gear can be preselected while the vehicle is in an even gear and vice versa, which makes it quite fast for gear shifts.

Clutch Pack

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Clutches are the interface between engine and transmission in vehicle drivetrains.
During the development of the wet clutch system in the Dual Clutch Transmissions, there is a need to know the durability and the friction behaviour of the clutch packs.

Drive Cycle

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The first task is to implement a drive cycle to test the durability of the clutches. This cycle is repeated until the theoretical lifetime has been reached.
For this task: three vehicle launches with increasing road slope are defined as a drive cycle. In co-operation with the Test Rigs Software Engineer, this cycle on the vehicles is converted to a cycle that is suitable to be implemented on ETR.

Life cycle calculation using thermal SN curve

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Based on the thermal model and the measured clutch interface temperature, and looking up on the thermal SN curve provided by the friction plate supplier (Borg-Warner),the number of cycles to achieve full life and damage of each cycle is calculated.

FPD Tests on ETR

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The second task is to investigate friction deterioration. To this end- a number of friction plate durability (FPD) tests and friction characterization tests are to be performed on Endurance Test Rigs (ETR) at different stages of the transmission development.

Friction Characterization

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a number of friction characterization tests were executed on the ETR on different transmissions that had undergone a different type of endurance tests.
During these tests, the friction measurement cycles are executed to be able to plot the friction coefficients for a wide range of slipping speed, nominal surface pressure, interface temperature and oil contamination.
The clutch lifetime achieved and the plots of the friction coefficients at the different stages of the clutch lifetime were reported to the clutch domain owner.

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