Optimizing the thermal properties of clutch facings

Abstract The tribological contact under sliding situation taking place in the friction surfaces during dry clutch engagement process is strongly affected by heat transfer occurring in the clutch system. Heat is produced due to dissipation mechanisms of mechanical work which is developed by the frictional forces acting in the contact paths yielding the interfacial temperature to increase. The magnitude of temperature rise depends to a large extent on the thermal properties of clutch facings fitting the friction disk. This paper gives a modeling of the thermal properties of general organic clutch facings which are manufactured according to the scatter wound procedure. Starting from the material formulation, the rule of mixtures approach is used to determine the local thermal properties for an elementary yarn segment embedded in a matrix shell taken to be a representative volume element. Then, estimates for the thermal properties of the whole facing are obtained through a homogenization technique where global averaging over the facing surface of the directional contributions set by these individual segments are performed. Optimization of the facing thermal properties is conducted after that with regard to material formulation of the clutch facings and key parameters of the fabrication process.