Friction has been made use of in various kinds of mechanical systems and sometimes induces unexpected vibration or noise such as 'shudder' in clutch systems and 'squeal' in brake systems in automobile applications. The studies to decrease vibration in wet friction have been performed mainly in the tribology field by developing lubricants filling sliding surfaces. Although the development of appropriate lubricants is very effective prevention of friction vibration, it may occur due to degradation of lubricants and be amplified according to structure of clutch systems. In addition, even a little vibration energy can induce loud noise when it transmits to thin elements in clutch systems and modes of out-of-plane vibration predominantly comes out. There are not so many studies of vibration in the structure of clutch systems as brake systems. In this paper, vibration in wet friction systems with paper-based materials as seen in wet clutches in automatic transmissions was investigated theoretically and experimentally. The experimental setup was designed simply and essentially in order to investigate vibration phenomena themselves due to friction on sliding surfaces filled with a lubricant. The experiments were conducted in detail under various conditions of lubricating oils, surface velocities and normal loads. It was shown that the vibration phenomena in this wet friction system depended greatly on the relationship of the friction force to the relative velocity characterizing lubricating oils. It was suggested that the vibration phenomena could be classified using the relationship of the relative velocity between the sliding surfaces to the surface velocity of one sliding surface. In addition, the actual vibration phenomena according to the actual structure of wet clutch system were investigated by modal analysis using a finite element method. As a result, some of the modes and natural frequencies to likely lead to noise were shown.
Investigation of vibration in wet clutch systems with paper-based friction materials
2008
8 Seiten, 6 Quellen
Conference paper
English
Friction Materials for Slip Clutch Applications
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