Durability test device for MR fluids with permanent magnet and V-shaped groove

Abstract

Magnetorheological fluids (MRFs) are functional fluids whose viscosity changes when magnetic fields are applied. Therefore, these fluids are used in force and torque controllable devices. However, particle sedimentation is one of the drawbacks of conventional MRFs. To solve this problem, Kurimoto Co. Ltd developed a new fluid with sub-micron order Fe particles and a silicone-based solvent known as NanoMRF. The particle distributions of this material are stable over several months. However, its durability has not yet been fully discussed. Therefore, we developed new equipment to test endurance and examined the durability of the magnetorheological effect of the NanoMRF as well as a commercially available MRF. Our results show that the durability of the fluids was affected by the stability of the solvent. In particular, the durability is drastically improved when the solvent is supplemented by the peripheral sealing oil. The oxidation of particles is remarkably varied by the kind of solvent as well as the stability of the oxidation film on the surface of the particles. The energy of the collapse and reproduction of the particles was used not only to generate friction among the particles but also to decompose the solvent molecules.

Low inertia torque controllable device using magnetorheological fluid & umbrella-shaped rotor

“…On the other hand, the flow characteristics on-state were measured with an originally developed testing machine with V-shaped groove [12] (figure 4). The shear rate was controlled from 30-1000 s −1 .…”