A Novel Magnetorheological Fluid with High-Temperature Resistance.

A magnetorheological fluid (MR fluid) is mainly composed of soft magnetic particles, surfactants, and the base carrier fluid. Among these, soft magnetic particles and the base carrier fluid influence the MR fluid significantly in a high-temperature environment. Therefore, a study was carried out to investigate the changes in the properties of soft magnetic particles and base carrier fluids in high-temperature environments. On this basis, a novel magnetorheological fluid with high-temperature resistance was prepared, and the novel magnetorheological fluid had excellent sedimentation stability, of which the sedimentation rate was only 4.42% after heat treatment at 150 °C followed by one-week placement. At 30 °C, the shear yield stress of the novel fluid was 9.47 kPa under the magnetic field of 817 mT: higher than the general magnetorheological fluid with the same mass fraction. Moreover, its shear yield stress was less affected by the high-temperature environment, reducing by only 4.03% from 10 °C to 70 °C. The novel MR fluid can be applied to a high-temperature environment, effectively expanding the application range of MR fluid.

Preparation of a novel magnetorheological fluid for high temperatures.

Magnetorheological fluids, especially those in high-power magnetorheological devices, inevitably work at high temperatures because of the wall slip, energized coils and frictions between particles. In order to prepare a magnetorheological fluid for high temperatures, this work investigates the properties of three main components (soft magnetic particles, surfactants and base carrier fluids) for a magnetorheological fluid at high temperatures. On this basis, a novel magnetorheological fluid for high temperatures is prepared. Its sedimentation stability, viscosity and shear yield stress are investigated at high temperatures. The results show that the novel magnetorheological fluid has acceptable sedimentation, suitable viscosity and stable shear yield stress at high temperatures. The novel magnetorheological fluid for high temperatures can be applied to most magnetorheological devices, especially high-power magnetorheological devices.

Design, experiment, and performance analysis of magnetorheological clutch with uniform magnetic field distribution along the radial direction for tension control.

High-precision tension control is very important for industrial production. Benefit from the unique property of magnetorheological (MR) fluid, a MR clutch is a potential device in a tension control system due to its fast response and large output dynamics. In this paper, based on the detailed analysis of axial magnetic induction intensity generated by the coil along the radial distribution, a shear-mode MR clutch with uniform magnetic field distribution along the radial direction is proposed for the tension control system. A theoretical model of torque transmission and a magnetic circuit were derived, and a magnetostatic simulation was carried out to validate the effectiveness of the proposed circuit design. Experimental evaluation was conducted to investigate the static and dynamic transmission torque property. Finally, a proportional-integral-differential controller was designed to regulate the output torque. Experimental testing demonstrated the effectiveness and practical feasibility of the MR clutch in tension control.