The Design And Analysis Of MRF Clutch

Magnetorheological(MR) fluids consist of stable suspensions of particles in a carrying fluid such as silicone oils, responding to an applied magnetic field in their rheological behavior. In the absence of applied magnetic field, MR fluids exhibit Newtonian-like behavior. Upon application of a magnetic field, the suspended particles in the MR fluids become polarized and aligned in the direction of the magnetic field. The fluids behave as a semi-solid having a controllable yield stress. The yield stress of MR fluids increases as the applied magnetic field increases. The feature provides reversible, quiet, rapid response interfaces between electronic controls and mechanical systems.An MR fluid clutch device achieves braking by shear force of the MR fluid. An MR fluid clutch has the property that its torque changes quickly in response to an external magnetic field. In the absence of an applied magnetic field, the torque is the viscous force of MR fluids in liquid state. When the external magnetic field is applied, the suspended particles in the MR fluids become polarized and gathered to form chain-like structure. These chain-like structures restrict the movement of the MR fluids, thereby increasing the yield stress of the fluids. The clutch can be achieved by utilizing the shear stress of the MR fluids. The torque can be adjusted continuously by changing the magnetic field strength.In this paper, the rheological behavior of MR fluids are introduced and the the constitutive equation is analyzed, then, the design method of the MR fluids clutch is investigated theoretically. The equation of the torque transmitted by the MR fluids in the clutch is derived to provide the theoretical foundation in the design of the clutch. The results of the experiment of the MRF clutch show that the MR fluid could transmit torque in response to an external magnetic field.