Magnetorheology in an aging, yield stress matrix fluid
Name
McKinley_Magnetorheology.pdf
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1.58 MB
Format
Adobe PDF
Checksum (MD5)
3e5a21622488e6f4c2ab86d3955c2313
Author(s)
Rich, Jason P.
Doyle, Patrick S
McKinley, Gareth H
Date Issued
May 2012
Journal
Rheologica Acta
Publisher
Springer Science + Business Media B.V.
Citation
Rich, Jason P., Patrick S. Doyle, and Gareth H. McKinley. Magnetorheology in an Aging, Yield Stress Matrix Fluid. Rheologica Acta 51, no. 7 (July 8, 2012): 579-593.
Version
Author's final manuscript
Abstract
Field-induced static and dynamic yield stresses are explored for magnetorheological (MR) suspensions in an aging, yield stress matrix fluid composed of an aqueous dispersion of Laponite® clay. Using a custom-built magnetorheometry fixture, the MR response is studied for magnetic field strengths up to 1 T and magnetic particle concentrations up to 30 v%. The yield stress of the matrix fluid, which serves to inhibit sedimentation of dispersed carbonyl iron magnetic microparticles, is found to have a negligible effect on the field-induced static yield stress for sufficient applied fields, and good agreement is observed between field-induced static and dynamic yield stresses for all but the lowest field strengths and particle concentrations. These results, which generally imply a dominance of inter-particle dipolar interactions over the matrix fluid yield stress, are analyzed by considering a dimensionless magnetic yield parameter that quantifies the balance of stresses on particles. By characterizing the applied magnetic field in terms of the average particle magnetization, a rheological master curve is generated for the field-induced static yield stress that indicates a concentration–magnetization superposition. The results presented herein will provide guidance to formulators of MR fluids and designers of MR devices who require a field-induced static yield stress and a dispersion that is essentially indefinitely stable to sedimentation.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Hatsopoulos Microfluids Laboratory
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Creative Commons Attribution-Noncommercial-Share Alike 3.0
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DOI of Published Version
https://doi.org/10.1007/s00397-012-0632-z
