Influence of a multiaxial stress on reversible and irreversible magnetic behaviour of a 3% Si-Fe alloy

The research presented in this paper is motivated by the design of electrical devices submitted to mechanical stress. It aims at studying the magnetic behaviour of ferromagnetic materials submitted to biaxial stress. It deals with the evolution of the magnetic susceptibility, coercive field and magnetic losses with respect to stress, magnetic field level and frequency. These quantities are of primary importance in the design of rotors for high speed rotating machines. The work is focused on the magnetic behaviour of a standard grade of Iron-Silicon alloy under the form of thin sheet. Non conventional experiments are performed on cross-shaped samples in order to apply biaxial stress representative of the loadings experienced by rotors of rotating machines. These experiments are performed on a multiaxial testing machine, ASTREE. The magnetic loading is applied using a single U-yoke. The measurement of magnetic induction, magnetic field and strain is conducted by the means of needle-B sensor, H-coil sensors and Digital Image Correlation (DIC) respectively. Both anhysteretic and dissipative responses to magneto-mechanical loadings are considered. The results allow to identify the more critical stress configurations for this material.