ABSTRACT
Ferromagnetic materials are liable to be magnetized in the magnetic field owing to their magnetic characteristic which is similar to iron. Permeability of this type of material will change when it is under the effect of external stress[1]. The relationship between the change of the permeability and the stress is:
Δμ μ
λ σ= 2 2 S
SB (2)
where μ is the material permeability. λs is the saturation magnetostriction coefficient, and Bs is the saturation flux density. Usually, Km represents the stress sensitivity coefficient of the material, which has the relation Km = 2/Bs2.
