The frequency-dependent magnetostriction of five samples of a ferromagnetic steel wire-polymer composite was investigated from 3 to 70 Hz. The volume fractions, or "loadings,"of steel wires in the samples were 0.02, 0.05, 0.07, 0.10, and 0.20. All samples exhibited a resonance at about 40 Hz, with damping and magnetostriction that generally increases with increased wire loading. A decrease in the overall magnetostriction of the 0.20 loading sample is attributed to mechanical blocking of the wire rotations in the polymer. The loading-dependent damping and an unexpected low-frequency behavior were explained by the time-dependent magnetic response of the wires.
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The authors thank Jason Cleveland and Peter Saulson for useful discussions. This work was supported by NSF (Grant No. DMR 1609782) and the University of Minnesota’s Undergraduate Research Opportunities Program.
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