Rheology of Perfluorinated Polyether-based MR Fluids with Nanoparticles

F. Jonsdottir, K.H. Gudmundsson, T.B. Dijkman, F. Thorsteinsson, O. Gutfleisch

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    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.
    Original languageUndefined
    Pages (from-to)1051-1060
    JournalJournal of intelligent material systems and structures
    Issue number11
    Publication statusPublished - 2010


    • IR-73287

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