Equivalent circuit vs. finite element method approach in designing and modelling of magnetorheological clutch

The magnetorheological (MR) clutch, thanks to the properties of the MR fluid (Smart Material), generates viscous torque TC, which can be controlled electromagnetically. The design and the modelling process of the MR clutch consist of different calculations: magnetic, mechanic, fluid flow, thermal. However, the first step of the process should be magnetic calculations, because the basic mechanical parameter TC depends mainly on the magnetic field. Magnetic calculations using both the equivalent circuit (EC) and the finite element method (FEM) for the multi-disc MR clutch are compared in the paper. For the EC calculation, different EC methods (methods of determining magnetic circuit reluctances) are put together. The EC calculations are very quick, but the researcher needs to have vast experience in EC modelling to choose the proper EC method. The FEM calculations, although about 10,000 times slower, give a greater opportunity to make the model agree with the real MR clutch.