Characterization of Tensile Stress-Dependent Directional Magnetic Incremental Permeability in Iron-Cobalt Magnetic Sheet: Towards Internal Stress Estimation through Non-Destructive Testing

Abstract

Iron-Cobalt ferromagnetic alloys are promoted for electrical energy conversion in aeronautic applications, but their high magnetostrictive coefficients may result in undesired behaviors. Internal stresses can be tuned to limit magnetostriction but must be adequately assessed in a non-destructive way during production. For this, directional magnetic incremental permeability is proposed in this work. For academic purposes, internal stresses have been replaced by homogenous external stress, which is easier to control using traction/compression testbench and results in similar effects. Tests have been limited to tensile stress stimuli, the worst-case scenario for magnetic stress observation on positive magnetostriction coefficient materials. Hysteresis cycles have been reconstructed from the incremental permeability measurement for stability and reproducibility of the measured quantities. The directionality of the sensor provides an additional degree of freedom in the magnetic response observation. The study reveals that an angle of π/2 between the DC (Hsurf DC) and the AC (Hsurf AC) magnetic excitations with a flux density Ba at HsurfDC = 10 kA·m−1 constitute the ideal experimental situation and the highest correlated parameter to a homogeneous imposed tensile stress. Magnetic incremental permeability is linked to the magnetic domain wall bulging magnetization mechanism; this study thus provides insights for understanding such a mechanism.

The Two-Domain Model Utilizing the Effective Pinning Energy for Modeling the Strain-Dependent Magnetic Permeability in Anisotropic Grain-Oriented Electrical Steels

“…The yoke was driven by the Kepco BOP-100-2M power supply (6), which operates as a highly efficient voltage-to-current converter. The relative magnetic permeability of the sample was measured by a Lakeshore 480 fluxmeter (7) with digitally corrected characteristics. The results of the measurements were visualized and archived in text files to simplify further processing.…”

“…It should be highlighted that recently developed advanced experimental setups for testing the 2D mechanical stress dependence of relative magnetic permeability in electrical steels [6][7][8] have brought a fresh impetus into the process of understanding the magnetoelastic phenomena in strongly anisotropic soft magnetic materials. On the other hand, it should be highlighted that the interaction between magnetocrystalline anisotropy and stress-induced anisotropy requires an explanation on the basis of quantum physics phenomena.…”

Magnetostrictive energy conversion ability of Iron Cobalt Vanadium alloy sheet: Experimental and theoretical evaluation

“…Permendur has a high yield strength (σ c = 1000 MPa) and a quasi-isotropic magnetic behavior in the sheet plane in no-stress conditions. Its low magnetocrystalline anisotropy induces no naturally preferred crystallographic orientation (Fagan et al, 2021; Rekik, 2014; Toutsop et al, 2022). All tested specimens were extracted from the same batch.…”

Measurement Criteria for the Magnetic Characterization of Magnetic Materials

“…Such a problem can be split into two categories: (a) uniaxial (the applied uniaxial stress is in the direction of the applied magnetic field) and (b) multiaxial (multiaxial stress is applied or the uniaxial stress is not in the direction of the applied magnetic field). The uniaxial problem does not generally suffer from stress non-uniformity and was the subject of numerous works [23][24][25][26][27][28][29][30][31][32][33][34][35]. The sample shapes can be parallelepipedal [23], [27], [28], [32], [35] or cylindrical [31].…”