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This thesis addresses the current lack of specification of magnetic fields currently used in the physical testing of Magnetorheological Elastomers MREs as well as providing the first comparative test results for MREs subject to both biaxial and uniaxial cyclic loading in the same magnetic field. In order to design an electromagnetic array capable of generating a suitable magnetic field for the cyclic biaxial testing of MREs, a review of currently used magnetic fields for uniaxial testing of MREs was carried out and a suitable array was modelled and evaluated with both 2D and 3D FEA software. Once the FEA analysis of the modelled arrays was completed, a final electromagnetic array was proposed and constructed. A detailed field map of the magnetic field generated by the constructed array to determine the overall magnitude, direction, and uniformity of the flux density is presented. This physically measured and mapped magnetic flux density is compared to both 2D and 3D FEA models highlighting the need for actual field mapping as well as modelling of magnetic fields. Currently there is no standard accepted method for specifying the magnetic field applied during MRE testing. This thesis presents a proposed standard method for specifying an applied magnetic field. This study also provides the first comparative results for MREs tested under both uniaxial and biaxial high strain fatigue conditions using the same applied magnetic field. This high strain data for both test conditions is important as mathematical and FEA modelling of elastomers requires comparative inputs for a range of test modes, and no previously published study has provided both for the same samples tested in the same magnetic field. This also allows a direct comparison between the biaxial results and the uniaxial results under a number of different strain and flux conditions as well as allowing a comparison of these results with previously published uniaxial results of other authors.
Gorman, D. (2017) The Evaluation and Implementation of Magnetic Fields suitable for Biaxial Cyclic Testing of Magnetorheological Elastomers. Doctoral thesis, DIT, 2017.