Investigation of Cluster Formation in MR Fluid under Compression Using Ultrasonic Measurement

Abstract

This paper reports measurement results of ultrasonic propagation velocity in MR fluid under compression. Experiments were conducted by applying different pressures in MR fluid at constant magnetic flux density. At low magnetic flux densities (100 and 200 mT), the ultrasonic propagation velocity in MR fluids changes when subjected to pressure. This change is related to cluster formation in MR fluid. The ultrasonic propagation velocity change is smaller when higher pressures are applied, indicating that cluster size in MR fluid becomes thinner under higher pressures. However, at higher magnetic flux densities (300 and 400 mT), ultrasonic propagation velocities under different pressures are nearly similar. These results indicate that at higher magnetic flux densities, pressures do not affect cluster formation in MR fluids.

Comparison of different magneto-rheological fluids’ stability

“…The main thing for increasing stability of the MR fluid is to control the sedimentation rate. To determine sedimentation level in the MR fluid ultrasonic sensors can be used [4]. Velocity of the ultrasonic sensors differs under magnetic field and when sedimentation occurs.…”

The sedimentation of magneto-rheological fluid monitoring system based on resistivity measuring

“…Most of them are based on the evaluation of the inductance of a coil surrounding the test tube containing the MR sample [10]. The others are using ultrasonic sensors to determine the level of sedimentation [11]. Ultrasonic propagation velocity in MR fluid changes dependent on magnetic field and is strongly related to sedimentation in this fluid.…”