Ferromagnetic materials have the interaction between mechanical and magnetic fields which is called magnetoelastic coupling. Also it is known that magnetic properties of ferromagnetic materials depend on plastic deformation. There are various kinds of Non-Destructive Testing (NDT) based on these phenomena for estimation of stress and plastic deformation. We propose a new analytical method of magnetic hysteresis curve, in which the saturation magnetic hyste resis curve is decomposed to neutral magnetization...
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Estimation of Stress and Plastic Deformation of SS400 SteelUsing Magnetic Properties

There are various inspection methods using Magnetic Flux Leakage Testing. In this paper, we attem pt to apply Thin-Film Flux Gate magnetic sensor to measure weak leakage flux density induced by s urface or back surface defects like cracks or notches. And it is shown that the measured magnetic flux density near the specimen surface indicates the pattern reflecting the shape of the defects....
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Non-destructive Evaluation Based on Measurement of Leaked Magnetic Flux by TFG sensor

There are few works using 2-dimensional measurement in Magnetic Flux Leakage testing. We attempt to estimate the flaw depth and distinguish front or back surface flaw by estimating horizontal component Bx and vertical componen t B, of the magnetic leakage flux density from magnetic structural material. We first calculate the distribution of magnetic flux density near a specimen surface by use of FEM analysis. The distribution is assumed to be approx imated by exponential function according to the dipole mo...
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Evaluation of Depth and Location of Defects Based on 2-Axis Sensing with Amorphous MI Sensors and Parameter Evaluation of Leakage Flux Density Function

Austenitic stainless steel SUS304 is typically classified as a paramagnetic material, but it forms ferromagnetic martensite phase due to plastic deformation, stress or fatigue. This martensitic transformation can be applied to magnetic Non-Destructive Evaluation (NDE) technics. In this paper, we attempt to detect and estimate the artificially introduced notch, fatigue crack and fatigued part in SUS304 steel by measuring the Magnetic Flux Leakage (MFL) near the specimen surface. It is fo und that the notch ...
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Evaluation of Fatigue and Damage in SUS304 using Magnetic Flux Leakage

Magneto-Acoustic Emission (MAE) is stress pulses observed during dynamic magnetization process of ferromagnetic material, which is caused by abrupt and discontinuous motion of magnetic domain wall pinned by inclus ions, voids, dislocations, grain boundaries etc. The characteristics of MAE change with the applied stress, plastic deformation and fatigue since the stress, dislocation and residual stress influence the structure of the magnetic domains and the pinning effects. Therefore, MAE is potential techni...
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Fatigue Estimation of SUS304 Stainless Steel by Magneto-Acoustic Emission

Ferromagnetic materials have the interaction between mechanical and magnetic fields which is called the magnetomechanical coupling. Typical examples of such couplings are the magnetostriction and dependen ce of the stress strain relation on the magnetic field. The magnetoacoustic effect focused in this paper is also one of the magnetomechanical couplings. It has been shown that from the effect there exists the correlation of the plastic strain and the ultrasonic velocity change due to the magnetization. Th...
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Non-Destructive Evaluation of Plastic Deformation of Steelusing Magnetoelastic Coupling Effect

This study attempt to detect cracks in austenitic stainless steel by Magnetic Flux Leakage Technique with a high sensitive magnetic sensor. If a specimen is subjected to the stress, the magnetic properties change or the martensite phase is formed due to the plastic deformation or the stress induced phase transformation.. When the generated phase is martensite, this local change of magnetic property can be detected by measuring the Magnetic Flux Leakage with a sensitiv e magnetic sensor. In order to verify ...
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Detection of Crack in Austenitic Stainless Steel with High Sensitive Magnetic Sensor

In this paper, we propose new inverse analysis method for reconstruction of magnetic permeability distribution using 2D magnetostatic analysis with Genetic Algorithm. We use Finite Element Method for 2D magnetostatic analysis, where the array of material number of each element is considered as genetic code. First, we produce genetic codes, i.e., individuals, randomly. We perform the FEM analysis to obtain the distribution of magnetic flux density near the specimen surface with respect to each individual. ...
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Study on Inverse Analysis Method for Reconstruction of Magnetic Permeability Distributionusing 2D Magnetostatic Analysis with GA

Magneto-Acoustic Emission (MAE) is stress pulses observed during dynamic magnetization process of ferromagnetic material, which is caused by abrupt and discontinuous motion of magnetic domain wall pinned by inclusions, voids, dislocations, grain boundaries etc. It is known that the incidence of MAE has significant correlation with the rate of magnetization change, so that the characteristics of MAE depend on the applied stress because of Magneto-Elastic Coupling (MEC). In this paper, we examine the cor...
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Study on Relation between Magnetization Curve and Magneto-Acoustic Emission of SM490A Steel