Effects of Nonmagnetizable Particles on the Structure of Magnetorheological Fluids

E-ISSN： 2405-4666|1|1|35-48

ISSN： 2405-4658

Source： Current Smart Materials, Vol.1, Iss.1, 2016-10, pp. : 35-48

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Abstract

Background: Addition of nonmagnetizable particles to a magnetorheological(MR) suspension causes an increase in the magnetic field-induced yieldstress. The goals of this paper are to determine how the suspension microstructurechanges when the nonmagnetizable particles are added, and whether or not suchchanges can cause the changes in rheological properties.lt;/pgt< pgt;Methods: We employed particle-level simulations to investigate the structural andrheological properties of MR suspensions containing a mixture of magnetizable andnonmagnetizable spheres. We demonstrate that nonmagnetizable spheres cause theyield stress to increase in monolayers and three-dimensional simulations, as is observedin three-dimensional experiments. We examine the role of nonmagnetizablespheres in the suspension structure for monolayer and three-dimensional suspensions. Structuremeasures examined included the fluctuations in volume fraction, the pair distribution functions, and theeigenvalue ratio of the mass moment tensor of clusters.lt;/pgt< pgt;Results: The nonmagnetizable spheres cause only minor changes to the microstructure of the magnetizablesphere component of the suspensions. Furthermore, the nonmagnetizable spheres cause structuralchanges to monolayers that differ from the changes in microstructure of three-dimensional suspensions.lt;/pgt< pgt;Conclusion: The results suggest that the small structure changes caused by the addition of nonmagnetizableparticles do not cause the increase in yield stress.