RUI: Magneto-Mechanical Coupling in Isotropic vs. Anisotropic, Hard- vs. Soft- Magnetic Magnetorheological Elastomers

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Magnetorheological elastomers (MREs) are composite materials, made from rubber (?elastomers?) and magnetic particles, whose mechanical behavior (?rheology?) changes in a magnetic field. Theories on MRE behavior assign this change to magnetic torques developed within the particles. This work, however, addresses the fundamental difference in behavior between MREs formed from soft-magnetic particles like iron, which do not develop internal torques, and those formed with hard-magnetic particles (e.g. permanent magnets) that do generate magnetic torques. The objectives of this work are to study the effective modulii in shear and compression, magnetization induced strain (or magnetostriction), and microstructure of different material compositions. Effective modulii will be determined by measuring the material?s response to vibration. Magnetostriction will be measured using optical microscopy. And, the microstructure will be characterized using x-ray tomography. Finally, the ability of the material to perform work will be measured by determining the amount of force that can be generated.MREs are technologically important because they are expected to perform better over their working lifetimes than their closest competitors, magnetorheological fluids. This study is important because the fundamental difference between soft-magnetic and hard-magnetic particles leads to definitions of several magneto-mechanical symmetries which may be exploited. For example, the authors have found that MREs using hard-magnetic particles can serve as reversible actuators whereas MREs using soft-magnetic particles cannot. This work will engage 10+ undergraduates through Rowan?s Engineering Clinics and Physics Research courses. Topics from this project will find use in Materials Science, Computational Materials Science, and (Advanced) Solid Mechanics courses. K-12 students participating in the Summer Institute in Materials Science, R.U.M.E./C.H.A.M.P. Saturday Academy, and the EOF/MAP Precollege Institute will also be exposed to this research.