Tension and torsion magnetic sensors based on frequency harmonic content analysis of induced signal in perpendicular fields

Design of a new generation of tension and torsion magnetic sensors is proposed. The approach. experimental and theoretical. of frequency harmonic content of induced signal is described. In the case of magnetization in perpendicular fields, the signal obtained in a coaxial pickup coil with the easy axis of magnetization of the sample is computed and a spectral analysis is provided. A spectral analysis of the signal induced in a coaxial pick-up coil is made up by a spectrum analyser and numerically. Harmonic content dependency on magnetostrictive response of the sample versus frequency and intensity of ac perpendicular magnetic field on de parallel magnetic field, on stress and torsion is presented. Different signal behaviours for various samples are discussed. (C) 1997 Elsevier Science S.A.