Magnetostrictive stress sensor

Any ferromagnetic material is able to be subjected to magnetostriction. It means that there is a coupling between the mechanical and magnetic states of the material. Because of the “direct magnetostrictive effect”, the material displays a mechanical anisotropic deformation when it is put under a magnetic field. Conversely, the magnetic permeability of such a material changes as a function of the applied mechanical stress. This is called the “inverse magnetostrictive” effect.

Therefore, under appropriate magnetic conditions, a measurement of the material’s magnetic permeability gives an indication of its internal mechanical stress state.