Rapid computation of eddy current signals from narrow cracks

Theodoulidis, Theodoros; Poulakis, N.; Dragogias, Athanasios

doi:10.1016/j.ndteint.2009.08.005

Cited by 61 publications

(26 citation statements)

References 20 publications

(23 reference statements)

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“…For reference, the following expressions for the electromagnetic field are given. Firstly, the magnetic field is expressed as (4) and the components of the magnetic field are therefore (5) (6) and (7) The electric field in source-free regions is given by (8) and its components are therefore (9) (10) and (11) By using a scalar decomposition with as the preferred direction, Fig. 2, and selecting the truncation boundary condition judiciously we have avoided coupling of the TE and TM modes at the surface.…”

Section: B Scalar Decompositionmentioning

confidence: 99%

“…This has been done by approximating the flaw field using piecewise constant volume elements and the solution sought by using the fact that, in the quasi-static limit, the normal current at the surface of a crack is zero. Applying this condition at matching points on the crack surface each at the center of the face of a volume element in the form of a rectangular parallelepiped defines the matrix [4], [12]. Details of the incident field calculation for a coil near the edge of a truncated quarter space are given in [10].…”

Section: E Quarter-space Dyadic Green's Functionmentioning

confidence: 99%

“…A well-established scheme for finding the field of a flaw is one based on an electric field integral equation used to get numerically predictions via the moment method [1]- [4]. Provided an integral kernel is available that satisfies the appropriate interface condition for the homogeneous conductor, a solution can be sought by representing only the field at the flaw region in a discrete form.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Eddy Current Probe Signals Due to a Crack at a Right-Angled Corner

2012

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In eddy current testing, a flaw in a metal is detected when it gives rise to a change in the electrical impedance of the probe that induces current in the material. Theoretical models and computer codes have been developed to predict the probe signals as an aid to improving inspections and the interpretation of measurements. Model calculations can be efficient for a restricted class of problems in which the conductor geometry is simple, such as an infinite plate or tube. The computational cost is usually low in such cases because dedicated Green's kernels are available, allowing numerical approximations of integral equations to be found using only a few unknowns to represent the field in the flaw region. In this study, the aim has been to perform eddy current calculations on corner cracks efficiently using an approximate Green's function for a conductive quarter-space, thereby extending the class of problems that benefit from the use of a dedicated kernel. The properties of the kernel mean that numerical solutions based on boundary or volume elements can be found for an edge crack by rendering as a discrete approximation only the field at the surface of the flaw or the field within it respectively. Volume element calculations have been carried out to determine the field at a corner crack and from it the probe response. Comparisons of the calculated probe impedance due to edge notches show good agreement with experimental measurements.

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Section: B Scalar Decompositionmentioning

confidence: 99%

Section: E Quarter-space Dyadic Green's Functionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Eddy Current Probe Signals Due to a Crack at a Right-Angled Corner

2012

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“…Eddy current testing (ECT) technique is widely used with advantages of high sensitivity to surface or subsurface defects of conductive structure [1][2][3]. In conventional eddy current testing, a cylindrical coil carrying AC current is used to test the conductive specimen.…”

Section: Introductionmentioning

confidence: 99%

Calculation model for the induced voltage of pick-up coil excited by rectangular coil above conductive plate

Zhang

Tang

2015

2015 IEEE International Conference on Mechatronics and Automation (ICMA)

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The electromagnetic NDT method plays an important role in the nondestructive material test. In testing conductive structures, the send-receive coils probe has more advantage than the absolute coil probe. One rectangular excitation coil is located above and parallel to moving conductive plate, another cylindrical pick-up coil is located on the opposite side across the moving conductive plate. The accurate theoretical expression of the induced voltage in the pick-up coil is derived by analytical method, then the influences of the excitation frequency, plate thickness and the moving speed of conductor to the induced voltage are analyzed. The analytical calculation results are verified with the implementation of finite element method. Index Terms -Eddy current testing. Conductive plate. Rectangular excitation coil. Induced voltage. Finite element method.

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“…Eddy current testing (ECT) is widely used with advantages such as high sensitive to surface defects of conductive structure [1][2][3]. In conventional eddy current testing, a circular coil carrying current is placed proximity to the specimen (which must be electrically conductive).The alternating current in the coil generates changing magnetic field which interacts with specimen and generates eddy current in it.…”

Section: Introductionmentioning

confidence: 99%

The series calculation model for the magnetic field of coil above arbitrary layer conductive plates

Zhang

Yin

2014

2014 IEEE International Conference on Mechatronics and Automation

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In calculation the magnetic field of the coil above multilayer conductive plates, time consuming and implementation difficulties are the main problems. A series expansion method was proposed to calculate the magnetic field, based on the Maxwell equations, the magnetic vector potential and solution region truncation. The conductive plates were extended to arbitrary layers and the expression for the magnetic field change of the coil was derived in the form of series. When the radius of truncated region and the number of summation terms were selected properly, and some terms were precomputed, the computation time can be reduced considerably and at the same time preserve the computational accuracy. The magnetic field change of the coil above a conductive half space was calculated at different frequencies with series approach and finite element method respectively, the results agreed very well and confirmed the suitability of the proposed series expansion calculation model and its application prospect in forward model of eddy current testing for defect quantitative measurement.

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Rapid computation of eddy current signals from narrow cracks

Cited by 61 publications

References 20 publications

Eddy Current Probe Signals Due to a Crack at a Right-Angled Corner

Eddy Current Probe Signals Due to a Crack at a Right-Angled Corner

Calculation model for the induced voltage of pick-up coil excited by rectangular coil above conductive plate

The series calculation model for the magnetic field of coil above arbitrary layer conductive plates

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