Research Topic: Wet Clutches.
Research Project: Simulation of Wet Clutch Engagement and Failure Analysis of Wet Clutch Plates.
University: LSU, Mechanical Engineering.
Principal Investigator: Professor Michael Khonsari.
Graduate Student: Mongi Mansouri.
Contact Information: Professor Michael Khonsari.

Project description:
A wet clutch mechanism in the transmission system is so designed as to provide adequate torque transmission during operation by means of squeeze action between surfaces wetted by a lubricant, ATF. The wet clutch pack is composed of a series of metallic separator discs and core discs to which friction-lining materials are bonded. See Figure 1. In a typical engagement cycle, the
lubrication regime undergoes a transition from the hydrodynamic regime to the mixed or boundary lubrication regime. The time scale of the first stage of the engagement process is typically on the order of one second during which the squeeze action is of paramount importance (cf. Jang and Khonsari, 1999a). The research aims at investigating the effect of operating conditions on wet clutches dynamic, thermal and thermoelastic behavior, and the underlying frictional process. The goal is to develop designs that minimize failure, improve smoothness of operation, and extend component life. Preliminary 2D and 3D simulations of the dynamic and heat transfer behavior have been carried out based on FEM model (cf. Mansouri et. al., 2001), and systematic analyses have been developed, in order to quickly and accurately predict key performance parameters, such as developed energy, maximum power requirement, maximum temperature rise, engagement time, and maximum brake torque (cf. Mansouri et al., 2002). In order to investigate the failure phenomenon of coning, preliminary simulations of the thermoelastic problem have been carried out. As illustrated in Figure 2, temperature gradients developed in the separator disc during engagement produce deformation, which, under severe engagement condition and after many cycles of use, can lead to coning and fatigue failure as thermoelastic loading builds up, and stress reversal takes place.

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