Frequency Response of a Magnetostrictive Ferromagnet-Polymer Composite

A magnetostrictive ferromagnet-polymer composite was previously found to exhibit large, reversible magnetostrictive strain, with a maximum strain of about 60%, upon application of DC magnetic fields on the order of 5kOe.¹ The composite consisted of steel wires suspended in a polymer matrix with random orientation. Reported here are the results of a study of the frequency response of the magnetostriction of samples from the above mentioned research. The amplitude of the magnetostrictive oscillation was measured as a function of the applied AC magnetic field frequency from 1.5Hz to 35Hz, with a constant AC magnetic field magnitude of 85Oe rms. This magnetic field had a magnitude less than that necessary to reach the linear response regime found in the DC magnetostriction study.¹ For each sample that was measured, a resonant peak was observed at approximately 20Hz. The low frequency response differed from that expected of a damped simple harmonic oscillator.

1. Thomas I. Richardson, Austin Schleusner, and E. Dan Dahlberg, “Giant reversible magnetostriction in a ferromagnet–polymer composite,” J. Appl. Phys. 128, 055109 (2020); doi: 10.1063/5.0018245.