An investigation of friction-induced vibration in automatic transmission wet clutches
Abstract
The study of wet clutch torque transmission characteristics is a problem of both theoretical and practical interest. In this dissertation, the topic is examined from two parallel viewpoints; the fundamental approach involves detailed dynamic modeling of the contacting surfaces, while the applied approach includes a computationally efficient model for the gross features of clutch engagement. The model for torque transfer is validated with experimental data from the Wet Clutch Dynamic Test Rig. The torque transfer model accurately predicts wet clutch engagement performance over a wide range of input parameters. The results demonstrate the importance of accurately determining such parameters as friction material permeability, applied force, and friction coefficient. It is shown that the success of the predictions is closely related to the precise characterization of the friction coefficient. The fundamental study involves the interaction of velocity-dependent friction coefficient and time-varying normal forces. A new type of friction-related dynamic instability is predicted using a perturbation analysis, and simulation results are presented to corroborate the predictions. A finite element model of the contact is developed, and stick-slip before lockup of the clutch disks is shown to produce torque oscillations under non-constant normal forces.
Degree
Ph.D.
Advisors
Sadeghi, Purdue University.
Subject Area
Mechanical engineering|Automotive materials
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