Rheology of Perfluorinated Polyether-based MR Fluids with Nanoparticles

Motivated by the use of magneto-rheological (MR) technology in prosthetic devices, the goal of this study is to develop a MR fluid composition that is tailored for the requirements of a prosthetic knee actuator. A MR fluid composition is sought with a suitable balance between the field-induced shear...

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Bibliographic Details
Published in:Journal of intelligent material systems and structures 2010-07, Vol.21 (11), p.1051-1060
Main Authors: Jonsdottir, F., Gudmundsson, K.H., Dijkman, T.B., Thorsteinsson, F., Gutfleisch, O.
Format: Article
Language:English
Subjects:
Computational fluid dynamics
Cross-disciplinary physics: materials science
rheology
Electro- and magnetorheological fluids
Exact sciences and technology
Fluid dynamics
Fluid flow
Fluids
Fundamental areas of phenomenology (including applications)
Inelasticity (thermoplasticity, viscoplasticity...)
Magnetorheological fluids
Material types
Multiphase and particle-laden flows
Nanomaterials
Nanoparticles
Nanostructure
Nonhomogeneous flows
Physics
Rheology
Solid mechanics
Structural and continuum mechanics
Viscosity
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Summary:Motivated by the use of magneto-rheological (MR) technology in prosthetic devices, the goal of this study is to develop a MR fluid composition that is tailored for the requirements of a prosthetic knee actuator. A MR fluid composition is sought with a suitable balance between the field-induced shear stress, the off-state viscosity, and sedimentation stability for the proposed application. Rheological characteristics are investigated for samples with monodisperse micron-sized particles and bidisperse fluids with a mixture of micron- and nanosized particles. Two types of nanosized particles are used. All fluid samples employ a novel perfluorinated polyether oil as carrier liquid which enhances stability. The samples are investigated with respect to both field-induced and off-state characteristics. The results are compared to analytical and empirical models that exist in the literature. The monodisperse fluids are shown to give a favorable trade-off between field-induced strength and off-state viscosity. The addition of a small concentration of nanoparticles is found to moderately increase the field-induced shear-yield stress. However, for a larger concentration of nanoparticles, the yield stress begins to decrease. Nanoparticles exhibit an undesirable effect on the off-state viscosity. The results reveal valuable information for the designers of MR fluids and designers of prosthetic actuators.
ISSN:1045-389X
1530-8138
DOI:10.1177/1045389X10376844