Particle-chain evolution and constitutive model of magnetorheological polishing fluids based on hexagonal close-packed structure

Abstract

This paper proposes a novel constitutive model of magnetorheological polishing fluids (MRPFs) to predict field-dependent properties such as yield shear stress. First, the invasion of polishing particles to carbonyl iron particle (CIP) chains is analyzed in terms of the destructive effect on the distance of particles and the enhancement of chain structures. Subsequently, the hexagonal close-packed structure of magnetorheological fluids (MRFs) is utilized to formulate a constitutive model of MRPFs after examining the reconstructed distance and the proportional property of carbonyl iron particle chains affected by the polishing particles. According to the constitutive model, several factors that may affect the performance of MRPFs are considered, and experiments are carried out to prove these conjectures. A series of experiments explore the influencing mechanism of the radius and volume fraction of the polishing particles on the field-dependent properties of MRPFs such as the yield shear stress. The results, which are highly consistent with the simulation data based on constitutive model, show that the radius and volume fraction of polishing particles significantly affect the field-dependent properties of MRPFs. In addition, at a given magnetic field intensity the optimum radius and volume fraction of the polishing particles can be obtained to enhance the field-dependent yield shear stress of MRPFs.