Search

In order to reveal the influence of rotating speed on the stability of torque transmission by magnetorheological fluid, magnetic force, centrifugal force, gravity, stokes resistance and buoyancy of particles are calculated and analyzed. Besides, the rule of particles distribution is simulated by the Fluent software. On this basis, experiments are carried out based on magnetorheological transmission device. The results indicate that the centrifugal force due to rotating speed has greater effect on particles concentration as there is no magnetic field, and particle concentration mainly appears at the outer diameter of disk, but its effects are concentrated only in a smaller area, which will enhance the local working magnetic field. When the particles are subjected to a strong magnetic field, the magnetic force between the particles is much greater than the centrifugal force; thus, the influence of rotating speed can be ignored. The relationship between transmittable torque and rotating speed is not linear due to the hydraulic torque at the speed of 0–80 r/min.

We report the preparation of a magnetorheological fluid with a high working temperature by using fluorocarbon surfactant and titanate coupling agent as additives at appropriate contents determined by a series of experiments. The sedimentation ratio, apparent viscosity, and yield stress are measured to evaluate the performance of the prepared magnetorheological fluid. Results indicate that AES dispersants, titanate coupling agents, and fluorocarbon surfactants all have improved dispersion properties, and that the compounding fluorocarbon surfactants and titanate coupling agent can further improve the settlement stability of magnetorheological fluid, with < 7 % one-week settlement rate. Diatomite has a good thixotropic effect, and the antisettling effect enhanced with increased content. The types of carrier fluid have no significant effect on the performance of MR fluids. The prepared MR fluid can also work at 180 °C, which is higher than most commercial fluids, and the shear yield stress can reach 50 kPa.

Although the need to belong, or the desire for interpersonal attachments, is a basic human motivation, understanding of how and when it influences workplace ostracism is notably limited. Based on belongingness theory, this study examines the negative relationship between the need to belong and exposure to workplace ostracism by focusing on the mediating role of organizational deviance and the moderating role of in-role performance. Data from 108 supervisor-subordinate dyads in China were collected at three time points. The results reveal that organizational deviance mediates the relationship between the need to belong and workplace ostracism. Additionally, in-role performance alleviates the negative relationship between the need to belong and organizational deviance. The implications for management theory and practice are discussed. 基于归属感理论，本研究通过聚焦于组织越轨行为的中介效应和角色内绩效的调节效应，探讨了归属感的需求对职场排斥的作用机制。通过分析三个阶段收集的108份领导-下属配对数据，研究结果表明：归属感的需求对职场排斥具有显著的负面作用；组织越轨行为在归属感的需求与职场排斥之间起中介作用，角色内绩效缓解了归属感的需求与组织越轨行为之间的负向关系。

On the basis of orthogonal experiment, a novel transmission magnetorheological fluid with synthetic ester chain oil as carrier fluid is prepared. The effect of single additive content on the apparent viscosity and settling stability of magnetorheological fluid is analyzed, and the characteristic evaluations are also carried out. The results indicate that the magnetorheological fluid containing 60 wt% carbonyl iron powder has an apparent viscosity of 2.15 Pa·s and can attain the shear yield stress of 36 kPa when the magnetic field strength is 0.5T. Furthermore, the settlement rate of the MRF is less than 3% after two weeks. In comparison with the silicone oil and mineral oil, the synthetic ester chain oil-based magnetorheological fluid has the lowest thermal expansion rate.

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...

To obtain high-performance magnetorheological fluid, first, the effectiveness of single surfactant including oleic acid, sodium dodecyl benzene sulfonate, OP4 emulsifier and Tween80 are analyzed by testing the sedimentation stability and viscosity. And then, according to the research results, a novel preparation process, that is the compounding of different surfactants, is proposed. Finally, the effect of surfactants compounding type and content on the properties of magnetorheological fluid are also researched. It is found that the properties of MR fluids can be improved effectively by compounding of oleic acid and sodium dodecyl benzene sulfonate, and the most appropriate compounding content relationship is 4.0 g: 4.0 g.

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.