Influences of the uneven contact pressure and the initial temperature on the hot judder behavior in a multi-disc clutch

This paper presents an investigation of the hot judder behavior in a multi-disc clutch with the uneven contact pressure and the initial temperature taken into account. Considering the actual structure of clutch, the pressure function is achieved to describe the uneven contact pressure distribution due to the circlip constraint. Moreover, the pin-on-disc test is conducted to obtain the formula of the coefficient of friction with the contact pressure, surface temperature, and rotating speed involved. The thermal and dynamic models are established and coupled to evaluate the hot judder behavior. The results demonstrate that the uneven contact pressure has a slight influence on the clutch hot judder, but it expands the radial temperature difference on the friction surface; meanwhile, the friction torque generated on the friction surface closer to the circlip is larger. Although the increase of initial temperature can shorten the clutch engagement time, the clutch hot judder will be shriller, as verified in the SAE#2 bench test. Furthermore, in order to reduce the clutch hot judder, the circlip should be optimized to smooth the radial contact pressure, and the advanced thermal management method should be applied to strengthen the clutch heat dissipation.