Magnetostrictive effect


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.


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