Detection Probability Improvement for Nondestructive Evaluation Using a Magnetic Camera

Lee, Jin Yi; Hwang, Ji Seoung; Choi, Se Ho; Lim, Jae Kyoo

doi:10.4028/www.scientific.net/kem.306-308.241

Cited by 14 publications

(10 citation statements)

References 3 publications

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“…The LMF measurement system such as a magnetic camera is useful for detection and evaluation of cracks because the quantitative LMF distribution and its processed images such as ∂B/∂x and ∂B/∂y can be obtained. Especially, the differential LMF to the magnetization direction, ∂B/∂x, can eliminate the inclined magnetic field of the magnetizer, and estimate the crack position and size [3,4]. Fig.…”

Section: Analysis and Experimental Results And Discussionmentioning

confidence: 99%

Development of Numerical Analysis Software for the NDE by Using Dipole Model

Lee

Jun

Hwang

et al. 2007

KEM

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The magnetic field distribution around a crack can be calculated more easily and quickly by using a dipole model than finite element method (FEM). This paper reports the development of numerical analysis software that uses an improved dipole model to analyze the magnetic field around cracks. The preprocessor in this software includes the crack formation software, which can distribute the magnetic charge per unit area, m, on the crack section area. Also the lift-off, measurement area and sensor interval, and magnetization direction can be considered in the preprocessor. Also, the postprocessor presents functions, such as the natural magnetic field distribution and ∂B/∂x, ∂B/∂y, as results. Also, the physical characteristics of the magnetic optical sensor and the Hall sensor are included in the postprocessor, and the magnetic field distribution can be changed to optical intensity and electrical signal distribution. The experiment results, which are obtained by using the magnetic camera on the crack, are compared with analysis results obtained by using the dipole model analysis software.

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Section: Analysis and Experimental Results And Discussionmentioning

confidence: 99%

Development of Numerical Analysis Software for the NDE by Using Dipole Model

Lee

Jun

Hwang

et al. 2007

KEM

Self Cite

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show abstract

“…Magnetic camera was designed as real-time quantitative visualization of the distribution of 2D static LMFD by magnetizing the specimen using a magnetic source with approximately 5 -100 fps of frame rate [8]- [13]. The magnetic camera consists of a magnetic source, sensor array, magnetic lens, signal processing, and user interface for the inspection display (Figure 1) [19].…”

Section: Magnetic Cameramentioning

confidence: 99%

“…On the other hand, magnetic camera works by utilizing semiconductor-based sensors such as Hall sensor, magnetoresistive (MR) sensor, and giant MR sensor to measure distorted magnetic flux density owing to the presence of crack [8], [9]. Magnetic camera provides real-time visualization of the distribution of LMFD using integrated signal processing consisting of magnetic source, sensor array, magnetic lens, signal processing, and user interface for the inspection display [10]- [13]. Magnetic camera can extend the measurement area up to 3 meters on one cycle which is very beneficial for actual industrial inspections [14].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Magneto-Optical Faraday Effect Method and Magnetic Camera for Imaging the 2-D Static Leakage Magnetic Flux Density

Dharmawan¹,

Lee²,

Wang³

2022

eJNDT

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Magnetic flux leaks around the defect on the magnetized ferromagnetic specimen. The magnetic flux leakage testing (MFLT) use the magnetic sensor to measure the leaked magnetic flux density (LMFD). The high sensitivity of sensor need to increase the probability of detection (POD). Also the small size and high spatial resolution of sensor need to increase POD and to sizing defect. Uniform and small lift-off are another necessary to increase POD and sizing ability. Also, the real time imaging of magnetic flux density can increase the inspection time. So the period of planned preventive maintenance could reduce. Two dimensional semiconductor-based magnetic sensor array with high spatial resolution satisfies these requirements. Projection of magnetic flux density on a sensor itself would be another method. We compare the magnetic camera and the magneto-optical Faraday effect (MOE) for MFLT. Magnetic camera uses the two dimensional Hall sensor arrays to imaging the LMFD. And the MOE project LMFD. The plane of polarized light rotates inside of magneto-optical film (MOF). The Faraday rotation angle proportional to direction and intensity of magnetic flux density. Sensitivity, spatial resolution, magnetic hysteresis, repeatability, full-scaled operational range compared. Also shape of target specimen compares too.

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“…The specimen was magnetized by using a yoke type magnetizer, which had a 250mm of poles interval and 4,000 turns of coil at 0.34A input current. Also, the differential magnetic field to the magnetization direction, ∂H Z /∂x, was used in the experiment and analysis results because the ∂H Z /∂x data can eliminate the bad influence of the magnetic field from the poles of the magnetizer and the leaked magnetic field from the crack can be extracted efficiently by using ∂H Z /∂x [7][8][9].…”

Section: Improvement Of the Dipole Modelmentioning

confidence: 99%

A Study of Magnetic Charge per Unit Area of Dipole Model for the NDE

Hwang

Jun

Choi

et al. 2007

KEM

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Nondestructive testing using magnetic field is useful for detection of a crack on ferromagnetic material. The magnetic field distribution has to be obtained for quantitative evaluation of crack direction, size, and shape. Also, a crack can be evaluated by using the inverse problem analysis. However, an analysis method using a dipole model can be used to analyze the magnetic field distribution around a crack at a higher speed than the finite element method (FEM). Therefore, a dipole model simulation can provide useful information which can be used for the inverse problem analysis. However, the magnetic charge per unit area, m, and the permeability, μ, has been treated as constants. Therefore, analyzed results have been different from experimental results in most cases. This paper proposes the improved dipole model simulation method, which assumes that the magnetic charges per unit area exist at the section areas, edge lines and summits of a crack. Also, the magnetic charges per unit area were assumed to depend on the square of the crack depth. The improved method is validated by comparing its results with the experiment results obtained with the use of the magnetic camera.

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Detection Probability Improvement for Nondestructive Evaluation Using a Magnetic Camera

Cited by 14 publications

References 3 publications

Development of Numerical Analysis Software for the NDE by Using Dipole Model

Development of Numerical Analysis Software for the NDE by Using Dipole Model

Comparison of Magneto-Optical Faraday Effect Method and Magnetic Camera for Imaging the 2-D Static Leakage Magnetic Flux Density

A Study of Magnetic Charge per Unit Area of Dipole Model for the NDE

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