Application of Lorentz force eddy current testing and eddy current testing on moving nonmagnetic conductors

Carlstedt, Matthias; Porzig, Konstantin; Uhlig, Robert P.; Zec, Mladen; Ziółkowski, Marek; Brauer, Hartmut

doi:10.3233/jae-141872

Cited by 19 publications

(4 citation statements)

References 9 publications

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“…The distances between the observation points are d x = d y = 1 mm in x-and y-direction. In LFE, small velocities are used for the relative movement to reduce mechanical oscillations (Mengelkamp et al, 2016a) and to reduce the skin effect (Carlstedt et al, 2014). In consequence, the secondary magnetic field from the induced eddy currents can be neglected and the weak reaction approach is applied (Zec et al, 2014).…”

Section: Reference Forward Solution: Finite Element Methodsmentioning

confidence: 99%

Single voxel approach for Lorentz force evaluation

Dölker

Petković

Schmidt

et al. 2019

COMPEL

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Purpose Lorentz force evaluation is a non-destructive evaluation method for conducting specimens. The movement of a specimen relative to a permanent magnet leads to Lorentz forces that are perturbed in the presence of a defect. This defect response signal (DRS) is used for defect reconstruction. To solve a linear inverse problem for defect reconstruction, an accurate and fast forward computation method is required. As existing forward methods are either too slow or too inaccurate, the purpose of this paper is to propose the single voxel approach (SVA) as a novel method. Design/methodology/approach In SVA, the DRS is computed as a superposition of DRSs from single defect voxels, which are calculated in advance, by applying the boundary element source method. This research uses a setup of an isotropic conducting specimen, a spherical permanent magnet and defects of different shapes at different depths. With the help of simulations, this study compares the SVA to the previously proposed approximate forward solution (AFS) and the extended area approach (EAA) using the normalized root mean square error (NRMSE). Simulated data using the finite element method serve as the reference solution. Findings SVA shows across all simulations NRMSE values <2.5 per cent compared to <8 per cent for EAA and <12 per cent for AFS. Originality/value The superposition principle of SVA allows for the application of linear inverse methods for defect reconstruction while providing sufficient accuracy of the forward method.

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Section: Reference Forward Solution: Finite Element Methodsmentioning

confidence: 99%

Single voxel approach for Lorentz force evaluation

Dölker

Petković

Schmidt

et al. 2019

COMPEL

Self Cite

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show abstract

“…B. Feng, T. Rocha, and F. Yuan all studied the motion-induced eddy current testing method and used magnetic field sensors to pick up the defect signals [ 51 , 67 , 68 , 69 , 70 , 71 , 72 ]. Researchers from Technische Universität Ilmenau proposed a new Lorentz force NDT method for conductive specimens, which is also based on motion-induced eddy current [ 73 , 74 , 75 , 76 , 77 ].…”

Section: Factors Influencing Mfl Signalmentioning

confidence: 99%

A Review of Magnetic Flux Leakage Nondestructive Testing

Feng

et al. 2022

Materials

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Magnetic flux leakage (MFL) testing is a widely used nondestructive testing (NDT) method for the inspection of ferromagnetic materials. This review paper presents the basic principles of MFL testing and summarizes the recent advances in MFL. An analytical expression for the leakage magnetic field based on the 3D magnetic dipole model is provided. Based on the model, the effects of defect size, defect orientation, and liftoff distance have been analyzed. Other influencing factors, such as magnetization strength, testing speed, surface roughness, and stress, have also been introduced. As the most important steps of MFL, the excitation method (a permanent magnet, DC, AC, pulsed) and sensing methods (Hall element, GMR, TMR, etc.), have been introduced in detail. Finally, the algorithms for the quantification of defects and the applications of MFL have been introduced.

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“…Thess et al proposed a new method known as 'Lorentz force eddy current testing' [14][15][16][17]. The main innovation of this method relies on the observation that according to the principle of electromagnetic induction, an eddy current is induced, and a Lorentz force is generated by the interaction between the magnetic field and the eddy current that acts on the electric conductor in accordance with Newton's third law.…”

Section: Measurement Science and Technologymentioning

confidence: 99%

A magnetostatic force inspection method for monitoring the oscillation marks of continuous casting

Chen¹,

Wang²,

Ren³

et al. 2015

Meas. Sci. Technol.

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Based on the well-known fact that ferromagnetic materials can be significantly attracted by a permanent magnet (PM), we develop an innovative magnetostatic force inspection method to monitor the oscillating marks formed during continuous casting. A small PM produces a static magnetic field that penetrates into the ferromagnetic material slab formed via continuous casting. This magnet forms a localized magnetic sensing zone (MSZ) within the ferromagnetic material. The magnetostatic force acting on the ferromagnetic material can be expressed as the Maxwell tensor integral over the surface of the ferromagnetic material within the MSZ. This force provides local surface profile information. The reaction force of the magnetostatic force acting on the PM can be measured using a laser-cantilever system (a high force resolution method), and thus the profile features of the oscillation marks can be obtained. A measuring device with a laser-cantilever system is designed, constructed, and applied in a series of prototypes and a static experiment. A numerical model is simultaneously constructed to validate the measurement results. The differences between the actual and measured profiles are analyzed. An actual steel specimen with oscillation marks is measured using this device, and the accuracy is evaluated. In summary, the potential for the application of this method in the metallurgy industry is demonstrated.

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Application of Lorentz force eddy current testing and eddy current testing on moving nonmagnetic conductors

Cited by 19 publications

References 9 publications

Single voxel approach for Lorentz force evaluation

Single voxel approach for Lorentz force evaluation

A Review of Magnetic Flux Leakage Nondestructive Testing

A magnetostatic force inspection method for monitoring the oscillation marks of continuous casting

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