The generation of strain induced by a magnetic field.
The magnetostrictive effect is that the strain of a ferromagnetic material
is produced by rotation of the magnetizing direction of each magnetic domain
in the material in the direction of the magnetic field. Recently it was
discovered that alloys of iron and rare-earth metals (Sm, Tb, Dy, Ho, Er,
Tm, and so on) exert intense magnetostriction of about 100 to 1,000 times
greater than that generated by conventional Co-Fe-Ni alloy magnetostrictive
materials, and since then these alloys have been drawing attention as supermagnetostrictive
materials. The strain produced by the effect is said to be 1,650×10-6 to
2,400×10-6, which is greater than the 670×10-6 to 950×10-6 of a piezoelectric
device. A magnetostrictive actuator utilizing magnetostrictive effect is
driven by external magnetic field. Therefore a magnetic circuit is necessary,
but the advantage of the actuator is that it can be driven by wireless.
Super-magnetostrictive actuators have been applied on an experimental basis
to a wireless robot and a robot that moves through pipes. This effect can
also be refered as Joule effect.