If magneto strictive strain is a linear function of the field \(H\), what strain would appear in a Galfenol rod if it was subjected to a field of \(100 \mathrm{~A} / \mathrm{m}\) ? Use data read from the chart of Fig. 3.19 to find out.

\(2.5 \times 10^{-4}(0.025 \%)\). A field of \(100 \mathrm{~A} / \mathrm{m}\) might produce a strain of \(1 / 8\) of this, or about \(0.003 \%\).

Fig. 3.19

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Saturation magnetostriction (ustrain) 1000 100 10 10 1 0.1 Magnetostriction and coercive field Amorphous, iron alloys Permalloy Ni-75% Fe Soft ferrites Permalloy Ni-45% Fe 10 Silicon iron Galfenol- Terfenol-D 100 1000 Coercive field Hc (A/m) MFA 15 10,000