Fundamentals of Nondestructive Measurement of Biaxial Stress in Steel Utilizing Magnetoelastic Effect under Low Magnetic Field

Abstract

The relationship between magnetization and principal stress under a triaxial stress field is deduced theoretically from an equilibrium condition between magnetoelastic and magnetization energies calculated on polycrystalline iron. The relationship is expressed by a formula in which the intensity of magnetization parallel to the principal axis of the stress tensor decreases in proportion to the difference between the largest principal stress and the magnetizing-directional principal stress. A biaxial stress is developed in a cruciform testpiece made of mild steel, and then magnetizations in the direction of principal stress parallel and normal to the surface of the testpiece are measured using U- and C-shaped magnetic sensors, respectively. The measured results are revised considering the spread of magnetic flux. The experimental results fundamentally agree with theoretical predictions. The quantitative discrepancies are discussed.

Effect of Stress on Switched Reluctance Motors: A Magneto-Elastic Finite-Element Approach Based on Multiscale Constitutive Laws

“…Unfortunately, most magneto-elastic models are restricted to uniaxial mechanical loadings (e.g., [2]- [5]). Some authors proposed to define a magneto-elastic equivalent stress, namely a (fictive) uniaxial stress that would change the magnetic behavior in a similar manner than the multiaxial one [6]- [10]. These approaches can be suited for certain particular multiaxial configuration of stress but did not succeed in giving a general description of the effect of stress on magneto-elastic behavior.…”

Analysis of relationships between residual magnetic field and residual stress

“…of a fictitious uniaxial stress whose amplitude will lead to the same change in susceptibility as real multiaxial stress [17][18][19][20][21][22]. The problems related to the impact of a complex stress state on changes in magnetisation are issues whose description and modelling, due to potential application for stress measurements, are the subject of current research [17][18][19][20][21][22]. The residual magnetic field of a ferromagnetic element, also known as the Self Magnetic Flux Leakage, is the sum of the simultaneous effect of the geometry of the object and of the magnetic, electrical and mechanical properties of the material of which it was made in the magnetic field of the Earth.…”

Stress-Induced Anisotropy and Stress Dependence of Saturation Magnetostriction in the Jiles-Atherton-Sablik Model of the Magnetoelastic Villari Effect

“…This effect is connected with the changes of flux density B (achieved for a given value of the magnetizing field H) in the material subjected to mechanical stresses σ. The magnetoelastic Villari effect was observed in steel [2,3,4], soft ferrites [5] as well as amorphous [6,7] and nanocrystalline [8,9] soft magnetic materials.…”