Microscopic observation of behavior of magnetic particle clusters during torque transfer between magnetic poles

Abstract

The behavior of magnetic particles during the formation, fracture, and sliding of clusters was investigated. A setup, in which particles can be visualized and the torque between poles is measured simultaneously, was designed and built. In the case of flat poles, clusters were inclined in both the fracture and sliding mode areas. In the case of textured poles, the torque increased and varied with the cycle corresponding to the pitch of the texture. These clusters inclined by an angle less than that in the case of flat poles. The magnetic field distribution calculated by a finite element method supported this result, in which the field was concentrated at the concaves and their edges. These results will lead to the design of more efficient torque transfer devices using magnetorheological fluids.