In Situ Observation of Behavior of Magnetic Particle Clusters During Torque Transfer Between Textured Magnetic Poles

The viscosity of a magnetorheological fluid (MRF) changes with the magnetic field; however, the behavior of magnetic particles in an MRF under the application of a magnetic field has not been fully clarified. In our previous work, we proposed a real-time observation system in which the torque is simultaneously measured. Textured poles concentrated on a magnetic field, increasing the transfer of torque. In this paper, the behavior of magnetic particles, such as the formation, fracture, and sliding of clusters, in the presence of textured poles as well as the transfer of torque was investigated by in situ observation using our torque measurement system. With increasing depth of the pole texture, the magnetic-field gradient increased, the magnetic field at the edges of the texture increased, the clusters became concentrated in a narrower region, and the maximum torque increased. These results are expected to lead to the design of more efficient torque transfer devices using MRFs.