Geometry optimization of a magnetorheological clutch operated by coils

Magnetorheological uids (MRFs) are smart materials responsive to magnetic eld, widely applied in dampers and shock absorbers but also in clutches and brakes. The MRF gap shape is a very important topic in the design of clutches, since it directly in uences the transmissible torque and the power loss. In this paper an approach to MRF clutch design based on optimization is proposed and tested on four dierent layouts. Starting from a given available volume, two MRF gap shapes, namely single cylinder and multi-disc, and two coils positions, i.e. internal or external, were considered. A lumped parameter model was developed to analytically compute the magnetic ux along the clutch magnetic circuit and to calculate the transmissible torque of the clutch. The optimal geometry of the clutch for maximum transmissible torque, in terms of number and dimensions of the coil sectors, was determined for each shape and coil conguration and the results were validated by nite element models.