Research On Testing Technology And Device For Magnetorheological Fluids

Magnetorheological fluids (MRF) is a kind of intelligent materials, and can transform its statebetween liquid and solid under the action of a magnetic field in millisecond. It has found a wideuse in the mechanical transmission, structure vibration, medical devices and other fields. Thismagnetorheological property of the MRF is important and is the condition of designningmagnetorheological device. However, the testing technology of the MRF is still immature, only afew kinds of commercial magnetorheometers are available in the market, and related research hasjust started in China. Therefore, the development of a special magnetorheometer is of theoreticalsignificance and engineering value to provide a facility for the research and application of the MRFand its devices.In this paper, learning from the domestic and overseas testing technology of MRFcharacteristics, a novel circular-disk type of magnetorheometer was put forward based onrheological test theory. we can get the relationship of shear stress, shear strain rate, shear yieldstress, magnetic flux density by detecting motor speed, torque, magnetic flux density andtemperature.First of all, the stress of the MRF in the damping gaps was analyzed, the static and dynamicmechanics model in the shearing process was established, the theoretical relationship betweenshear yield stress and magnetic flux density was deduced by the Bingham model. the MRF dampershear device and magnetic circuit were introduced, analyzed and discussed based on thecharacteristics and function of magnetorheometer.Based on the electromagnetic theory and finite element theory, a novel method was putforward to design and optimize the magnetic circuit structure by uniting equivalent circuit ofmagnetic circuit and finite element numerical analysis. This method simplifies the calculation ofmagnetic resistance and coil number of circle, and improves the designning and optimizationefficiency of magnetorheometer. The optimization results show that the magnetic field is mainly inthe vertical direction of MRF in the MRF, the magnetic field evenly distributed and have sufficientmagnetic field intensity. the simulation is consistent with goal and the result of designningmagnetic circuit, the simulation is consistent with goal and the result of designning magnetic circuitthe relative deviation of simulation results is10%on average, confirm the designning of magneticcircuit for magnetorheometer is correct. The hardware and software were designed base on the characteristics and function ofmagnetorheometer, MRF were test by this paper developed magnetorheometer, the relativedeviation is10%on average compared with results of MCR301rheometer, and repeat error is8.3%, it confirm that the principle, model, theory test design and simulation analysis formagnetorheometer is correct.