Modeling and analysis of wet friction clutch engagement dynamics

• An extended reset-integrator friction model is proposed.
• Friction model incorporates Stribeck function for different phases of lubrication.
• Viscous effects and delay in pressure signal due to filling of ATF are considered.
• Model is verified with the experimental results in both time and frequency domains.
• In terms of amplitude Shudder vibration is independent of pressure fluctuation.

In recent years, there has been a significant increase in the usage of wet-friction clutches. Presently researchers across the globe are involved in improving the performance and lifetime of clutches through testing and simulation. To understand the clutch vibrational and dynamical behavior, an SAE#2 test setup mathematical model based on extended reset-integrator friction model is developed in this paper. In order to take into account the different phases of fluid lubrication during engagement cycle, the model includes the experimentally determined Stribeck function. In addition the model considers the viscous effect and the delay in the actuation pressure signal. The model is validated with the experiments performed on the SAE#2 test setup in both time and frequency domains. By analyzing the set of experimental results, we confirmed that the amplitude of shudder vibration is independent of the amplitude of applied contact pressure fluctuation.