Synthesized micro-theoretical analysis of performance of magnetorheological fluids subjected to shear mode operation: transmission, slip and sedimentation characteristics

Abstract

Abstract This paper aims to formulate a synthesized micro-theoretical analysis that consists of transmission, slip and sedimentation characteristics for the evaluation of the performance of magnetorheological fluids (MRFs) subjected to the shear mode operation. To begin, based on the magnetic dipole theory and the typical micro-structure of MRFs, the shear yield stress of MRFs is analyzed considering the contribution of the magnetic force, excluded-volume force and viscous force. Then, an improve micro-structure of MRFs that is in correspondence with the actual observation is built, and the slip power of MRFs per unit area that takes into account the friction of the particles, walls and carrier liquid is investigated. Moreover, the sedimentation characteristic of MRFs described by the sedimentation velocity of the particles with the coating is analyzed based on the Stokes’ rule. The main influencing factors, such as the magnetic field intensity, the volume fraction of particles, the radius of particles, the coating thickness, the shear strain and the shear strain rate, etc, are taken into account in the micro-theoretical analysis, and the effects of these factors on the transmission, slip and sedimentation characteristics of MRFs are investigated respectively. It shows that the micro-theoretical analysis can describe these characteristics of MRFs accurately and reasonably, and can effectively be utilized for the initial design and optimization of the performance of MRFs and the useful guidance on the external control of magnetorheological transmission devices.