Design and Development of Magnetorheological Fluid Actuator

Magnetorheological Fluid, MR-fluid, normally consist of magnetic particles suspended in some carrier fluid. The physical characteristics of MR-fluid can be controlled by the applied magnetic field, thus the usual applications of MR-fluid are breakers and dampers. In weak magnetic field, the magnetic particles of the carrier fluid would have attractive interaction and be magnetization, the viscosity and the yield stress also substantial promotion. In strong magnetic field, MR-fluid would follow the magnetic field lines and become chain formation. By utilizing the characteristics of MR-fluid, magnetorheological fluid actuator is designed and developed in the thesis. The main actuating system is controlling the driving current, could adjustment the magnetic field in horizontal direction of the square helical coil. Through the magnetic field vector changed, which combined by the horizontal magnetic field and the vertical magnetic field of permanent magnet, the chain formation of MR-fluid pushed the actuating component, to make the actuator product the actuation force. Due to the magnetic field of permanent magnet is a constant, the magnetic field of the square helical coil would be varying magnetic field. By exploiting the square wave to offer the signal to the square coil in this thesis, the frequency of square wave, duty cycle could transform the velocity. In this paper, experiment with different volume percentage of magnetic particles of Magnetorheological Fluid, respectively MRF-144CG, MRF-132DG, and MRF-122-2ED. Via experiment, we can found that using MRF-122-2ED as the working fluid, operated at a frequency of 10Hz and duty cycle of 80%, the magnetorheological fluid actuator have the maximum speed for 3.2 mm/s. By experiment we also can found the magnetorheological fluid have the maximum actuator force for 8.4x10-3 N.