Investigation of cluster growth in MR fluids using ultrasonic wave propagation

This research reports the experimental results of a study on cluster growth in Magneto-rheological (MR) fluid. The experiments were conducted by applying different magnetic field (M/F) sweep rates to MR fluid. A magnetic field was swept from 0 to 400 mT at different times. Since the MR fluid is opaque, an ultrasonic measurement method was applied. Ultrasonic propagation velocity (V) in MR fluid is dependent on magnetic field and is strongly related to cluster formation in this fluid. Therefore, ultrasonic propagation velocity was measured and the change of ultrasonic propagation velocity (Delta V/V-0) was calculated. Based on the experimental results, cluster growth in MR fluids can be analyzed experimentally. Effect of volume fraction in MR fluid on cluster growth is presented. Furthermore, the relation between the change of ultrasonic propagation velocity and M/F sweep rate is discussed.