Pattern-Changing Instabilities and Giant Magnetostriction in Periodic Magnetoelastic Composites

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The research objective of this grant is to elucidate the effect of a certain type of "pattern-changing" instabilities in magneto-elastic composites with periodic microstructures in order to achieve much larger magnetostrictive strains than have been possible to date in these systems. In the purely mechanical context, it is known that these pattern-changing instabilities, where the deformation in the composite abruptly changes (or bifurcates) from the usual one-cell periodic pattern to a new, lower energy deformation pattern involving collective interactions between the cells, is typically associated with a "soft" mode of deformation, where small changes in the applied stress can lead to large strains. Building on earlier work, theoretical tools will be designed for modeling efficiently the possible appearance of these instabilities and the macroscopic response of the composite in the post-bifurcation "soft" regime. These tools will then be used to design magneto-elastic composites that are capable of significantly larger ("giant") magnetostrictive strains than have been possible to date. This research will result in novel and highly efficient multi-field modeling techniques, which will be of broad application to large classes of active material systems, and will lend themselves to numerical implementation in FEM codes. Improvements in the modeling of magneto-elastic composites and in the design of microstructures leading to large magnetostrictive strains should lead to enhanced performance of these materials in many industrial applications, ranging from adaptive tuned vibration absorbers in automotive suspension systems to artificial muscles in the robotics industry, as well as phononic and photonic bandgap switches. The research will be conducted synergistically with educational and outreach activities.