A novel magnetorheological (MR) fluids transmission device for high-power applications is designed, simulated and experimented. The transmission device is implemented of multi-hollow drive disc with magnetic conductive columns and adopts water cooling method to heat dissipation. In this paper, firstly, a novel hollow transmission disc with magnetic conductive columns is proposed, and the structure of the high-power MR fluid transmission device is determined. And then, the magnetic circuit is designed in detail, and the magnetic field distribution of the transmission device is analyzed by the method of finite element. Finally, a prototype of the transmission device is fabricated and several tests are carried out to evaluate the torque transmission, time response and temperature rise of the prototype. The results show that the proposed MR transmission device can produce a maximum output torque of 1880 N m and possesses a high slip power of up to 70 kW.

We report the preparation of a high-performance magnetorheological (MR) fluid by using silane coupling agent and bentonite as additives at appropriate contents determined by a series of experiments. We also adopted a new preparation process that was optimized through an orthogonal experimental design. The effects of process parameters on the sedimentation stability of the MR fluid were determined. Sedimentation ratio, apparent viscosity, and yield stress were measured to evaluate the performance of the MR fluid prepared by the optimized process. Results indicated that the MR fluid exhibited enhanced sedimentation stability when the silane coupling agent and bentonite mass fractions were 2.88% and 3.60%, respectively. Moreover, the effect of the second stirring process on sedimentation stability was found to be more important than the first. The optimal preparation parameters determined for the high-performance MR fluid are as follows: first and second stirring temperature of 20°C, first stirring time of 5 min, second stirring time of 5 h, and first and second stirring rotation speed of 2000 rpm.

Aiming to obtain the influence mechanism of temperature on the torque transmission stability of magnetorheological fluid, firstly, a magnetorheological transmission device and its test-bed are established, and then, the thermal expansion, temperature pressure effect, heat volatilization, viscosity temperature characteristic, magnetic temperature characteristic and other related temperature characteristics were experimented systematically. The results indicate that the thermal expansion rate of 30 wt% magnetorheological fluid is 6 % and 18 % respectively at 120 degrees C and 220 degrees C, and the working space pressure is 13 kPa when the temperature rises from 32 degrees C to 63 degrees C. The thermal volatilization rate is still lower than 1 % at 200 degrees C for 8 hours. The viscosity of the silicone oil based magnetorheological fluid decreases by 78 % when the temperature increases from 20 degrees C to 240 degrees C, and the saturation magnetization decreased by 6.2 %, 13 % and 23 % respectively at 150 degrees C, 250 degrees C and 350 degrees C. Furthermore, the temperature field distribution experiment shows that the highest temperature region is at the outer diameter of the disk and expands slowly along the radial direction. Moreover, compared with rotational speed, temperature is the main factor affecting the torque fluctuation of magnetorheological fluid.

The transmission interface deformation for a disk-type magnetorheological clutch appears unavoidably due to machining error, assembling error, and thermal stress. To study the transmittable torque variation due to interface deformation, the common deformation forms of a disk-type magnetorheological clutch are summarized. And then, an experimental test-bed is designed and established. After this, the experiments of transmittable torque due to deformed disks are carried out in the test-bed. The research results indicate that interface deformation has certain influence on the transmittable torque of magnetorheological clutch. For the skew deformation, the transmittable torque will increase approximately linearly with the increment of deformation value. For the warping deformation, when the deformation value is positive, the torque variation rule is the same as skew deformation. While the deformation value is negative, the torque decreases first as the absolute deformation value is smaller and then increases as the absolute deformation value becomes larger.

Aiming to solve the problem of high-power magnetorheological fluid transmission heat dissipation, a new type of magnetorheological fluid drive disk is designed. The characteristics of the flow field and temperature field of high power MR fluid transmission devices are analyzed. Meanwhile, the influence of factors, such as rotating speed, inlet velocity, inlet position, diameter and number of magnetic columns, on the flow field are also investigated. Furthermore, the distribution characteristics of the ultimate slip power and the transient temperature field are obtained. The experimental platform of an MR fluid transmission device was established, and the torque transfer performance and heat dissipation performance were tested. The experimental results show that the device has good heat dissipation performance and can transfer high-power torque.

On the basis of shear working mode of magnetorheological fluid, in this article, a novel temperature controllable yield stress measurement device is designed, and the double magnetic circuit structure and the heating structure are proposed. And then, the magnetic field and temperature field of the measurement device are simulated, respectively, by the finite element method. Furthermore, several experiments are carried out to evaluate the magnetic field, measurement precision, and repeatability of the self-designed device. The results indicate that the proposed measurement device has uniform magnetic field distribution and controllable temperature and also has high yield stress testing accuracy and repeatability.