Fluid Durability in a High Speed Electro-Rheological Clutch

The durability of an electro-rheological (ER) fluid was investigated by running a high speed ER clutch under different conditions and periods of operation. The tests involved running the clutch at 3000 rpm for a total period of twelve hours over a five day period. The tests subjected the fluid to a centripetal acceleration of 3000 m/s ² , and were conducted with and without an excitation field of 2 kV/mm, and with and without shearing the fluid at shear rates up to 9500 s ^-1 . The condition of the fluid was assessed periodically by measuring the torque response of the clutch to a step ap plication of voltage in respect of both magnitude and speed of response. Results at the two pole 50 Hz synchronous speed of 3000 rpm indicated that the particles in the fluid were centrifuged over the prolonged test periods. The application of a voltage across the fluid had a negligible effect on this particle migration. The effect of particle migration due to centrifugal and electro-static effects indicate future development requirements for these smart materials.