Design and Development of Cylindrical MR Fluid Brake with Multi-Coil Structure

Magnetorheological fluids (MRF) are functional fluids which respond to an applied magnetic field with a change in rheological behavior. The objective of this study is to clarify an effective design method to develop the cylindrical MR fluid brake (cylindrical MRB). Before getting into the design, a testing cell to evaluate rheological properties of the MRF was developed. The experimental result was modeled as a characteristic curve which is independent of the shear rate. This model was utilized as fundamental data for design. A cylindrical MRB whose maximum torque is 10 Nm was also designed, and its braking torque was compared with the estimated torque with finite elemental method software for a magnetostatic analysis and proposed mathematical model of the MRF. Although the results show errors at off-state of the brake that come from a friction of an oil seal, the cylindrical MRB whose maximum torque is about 10 Nm was developed.