Vibration Instabilities in Clutch System

Clutch vibro-acoustic phenomena may be modeled with unidirectional simulation tool. For some situations as squeal noise, this modeling is not sufficient. Therefore a tridimensional finite element model is necessary. Current literature reveals a large number of works with this method on brake system. However, very few investigations have been conducted on clutch system. In this paper, a tridimensional finite element model of dry automotive clutch for manual transmissions is developed to offer for the design phase, a tool to predict clutch squeal. This model has been validated in static and dynamic thanks to test bench, impact hammer and electrodynamic shaker measurements. Instability mechanism investigated with complex eigenvalue analysis has shown that some modes can become unstable due to coupling by friction. These unstable modes are considered as resonances with negative damping ratio, which is likely to produce clutch squeal. Moreover, the impact of two key parameters, namely friction coefficient and contact pressure distribution, on clutch instabilities is studied.