A Theoretical and Numerical Study of an Additional Viscosity Term in a Modified Elasto-Plastic Friction Model for Wet Friction Clutch Simulations

Abstract

This paper deals with a theoretical and numerical study of various viscosity terms in the modified elasto-plastic friction model and their influence on the resulting friction force-torque, transmitted through the contact of the friction clutch. Various simple viscous definitions for fluids considering shear rate dependent viscosity were investigated. The Carreau fluid model was chosen as a basis for the research, since it can describe Newtonian, dilatant, and pseudo plastic fluids. In addition to theoretical investigations, numerical simulations under realistic friction clutch operation conditions were carried out. The results were compared to the results of a validation case for a dry friction clutch simulation using the modified elasto-plastic friction model. This research showed significant differences between various viscosity definitions and revealed the drawbacks of such approach, were simple viscous models were used.In addition to viscosity, calculating the heat generated due to friction and its influence on the contact temperatures are discussed briefly. The basic theory and equations are given along with the directions for future work. The requirements for an accurate temperature calculation in the friction contact are outlined.

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“…Therefore, the flow and volume of oil in the hydraulic control cylinder can be controlled via the proportional flow valve, so as to control the speed and displacement of the clutch [29]. When the proportional flow valve works, its resistance can be considered constant, so the current can be controlled by adjusting the voltage [30]. The voltage of the proportional flow valve is controlled by the duty ratio of pulse width modulation (PWM).…”

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“…Marn et al [10] had a biological focus on working with aortic valves. Petrun et al [11] engaged various viscosity parameters in a modified elasto-plastic friction model and discussed their effect on the final friction force-torque, transmitted through the contact of the friction clutch. Another example of application of non-Newtonian fluids is in the drilling industry, studied by Safaiy et al [12].…”