Thermomechanical Effects in a Single-Sided Multidisk Clutch/Brake Design

In the single-sided design of a multidisk clutch or brake, each disk is composed of a steel core with a single layer of friction material bonded to one side. Each disk in the pack faces in the same direction so that the rubbing surface of friction material slides against the bare metal surface of the adjacent disk. This design has been known for years and can be considered an alternative to the much more common double-sided design. In the paper, thermomechanical effects in the single-sided clutch are studied. Finite element simulation shows characteristic pattern of thermal deformations of friction disks, peculiar to that design. The pattern is accompanied by non-uniform contact pressure at some sliding interfaces and high thermal stresses in the disks. The stresses may exceed the yield limit and this results in the known permanent conical distortions of the disks. The theoretical predictions were confirmed in experimental tests performed on inertia-type test stand. A good agreement in the pattern of thermoelastic deformation and disks' coning was obtained. The major mechanism causing excessive thermal stresses in single-sided design was identified in this study. As a result, the clutch design was modified in order to better accommodate the thermal deformations of the disks. Both the calculations and experimental tests showed that the design improvements significantly reduce maximum temperature, thermal stresses, and thereby the coning problem. This single-sided design was proved to be suitable for high-energy power-shift applications.