Research On Magneto-rheological Fluids Preparation And Performance

Magnetorheologcial Fluids （MRF）, which is composed of soft magnetic particlessuspended in carrier fluid and stabilizer, is a new type intellectual material with attractiverheological properties upon the application of an external magnetic field, and has awidespread use in the occasions of damping control and power transmission recent years,Magnetorheological Transmission Device （MRTD）, with superior transmissionperformance and application prospect, is an important application of MRF. According to theexisting problems, the following aspects are thoroughly researched in the dissertation.According to the special requirements of transmission MRF, of which each componentis chosen and the performance is analyzed. MRF is prepared according to its sedimentalstability. The best addition of surfactant and thixotropic agent is selected. The optimumprocess parameters to prepare MRF were determined by orthogonal experiment.The characteristic of MRF is analyzed to select MRF which is most suitable in theapplication of MRTD. The influential factors on sedimental stability, SaturationMagnetization, viscosity, density, thermal expansion of MRF were researched, and theinfluences of size of soft magnetic particle, content, base carriers the fluid and temperatureon the characteristic of MRF were analyzed experimentally.The method of testing yield stress of MRF is summarized, and the problems existing inthe process of testing yield stress are pointed out. A disk type yield stress measurementinstrument with temperature control function is designed, and the simulation andexperimental analysis on the magnetic circuit of the instrument is performed. Shear yieldstresses of MRF we prepared with different size of soft magnetic particle, content and shearrate were all tested and the change of shear yield stress of MRF with the temperatureincreasing. After heat treatment at different temperatures, shear yield stresses of MRF weretested.