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In this work, a parametric study is carried out on carbon fiber-reinforced plastic (CFRP) materials to investigate how the spatially varying fiber distribution influences the measured signal in an eddy current testing (ECT) configuration. The measurement setup was modeled using finite element method, while the fiber distribution is taken into account by an inhomogeneous anisotropic conductivity tensor. The study revealed a trade-off relation between the size of the ECT coil and the maximal dynamic range of the ECT signal, which contributes to the understanding of the connection between the fiber arrangement and the ECT signal and provides an opportunity for optimal ECT coil design. [ABSTRACT FROM AUTHOR]

Litz wires consist of many individual, isolated conductor strands. Certain litz wires are fabricated by simply twisting the bundle of strands, hence a wire pitch is realized. In this paper, the ac resistance of coils made of such twisted litz wire are calculated by combining two-dimensional finite element simulation and circuit laws. In so doing, the inherently three-dimensional problem can be solved at much lower computational cost. Results are presented for the current distribution, and for the alternating current resistance of coils, validated against measured data. [ABSTRACT FROM AUTHOR]

The inverse problem of electromagnetic (EM) non‐destructive testing (NdT) consists of reconstructing material defect parameters invoking EM field measurements. Uncertainties of the configuration (e.g. imprecise constitutive and geometrical parameters) are inevitably present; hence, the reconstructed defect parameters are also uncertain. In this study, the different sources of uncertainty are ranked by means of sensitivity analysis. The model‐based inversion (involving EM simulation) is computationally demanding; moreover, sensitivity analysis usually requires a vast number of repeated runs of the inversion. To overcome the computational complexity, surrogate models are applied at different levels. Interpolation on a sparse grid is used as a surrogate model of the EM simulation. The sensitivity of the reconstructed defect parameters concerning configuration uncertainties is characterised by means of Sobol indices. The Sobol indices are obtained from a polynomial chaos expansion surrogate model of the entire inversion scheme. A numerical example drawn from eddy‐current NdT is thoroughly analysed to illustrate the proposed methodology and to demonstrate its performance. [ABSTRACT FROM AUTHOR]

Magnetic flux simulations were utilized in a novel magnetic measurement method performed for the detection of local thinning of ferromagnetic plates. It was shown by numerical simulation, how parameters affect detectability of the defects. Linear relationship was found between the evaluated parameters and size of the artificial slot. Good correlation was found between theoretical and experimental results. [ABSTRACT FROM AUTHOR]

A nonlocal generalization of the IBC (impedance boundary condition) concept is introduced in this work for modeling the coil wires in resonant WPT (wireless power transfer) links. Such NLIBCs (nonlocal IBCs) can accurately account for the skin and proximity effects in the wires for all frequencies relevant to resonant WPT systems and can be utilized in both finite-element and surface-integral-equation numerical frameworks. The NLIBCs have run-time performance close to that of the IBC because the NLIBCs take advantage of the quasi-2D nature of the electromagnetic field inside the wires. The results for a typical WPT configuration illustrate the performance. [ABSTRACT FROM AUTHOR]

Scattering from propellers is investigated using the 3D Finite Element Method (FEM), alongside a simpler integral equation (IE) method using 1D discretization. It is shown that under certain conditions and near the propellers' resonant frequency, results using the two methods are in agreement, justifying the use of the IE method; this is advantageous because of smaller computation times, and for providing a physical insight to the scattering phenomena at hand. Anechoic chamber measurements are performed to validate the numerical results. [ABSTRACT FROM AUTHOR]

The wall, made of ferromagnetic steel, of a nuclear reactor pressure vessel is covered by an austenitic (very weakly ferromagnetic) cladding. In this work, we investigated how the base material and the cladding can be inspected separately from each other by nondestructive magnetic measurements. It was found that with the proper choice of the magnetizing yoke, these two different materials could be measured independently of each other. The effect of the yoke's size was studied by the numerical simulation of magnetic flux, pumped into the material during magnetic measurements. Measurements were performed by two different sizes of yokes on pure base material, on base material under cladding and on cladding itself. Experiments verified the results of the simulation. Our results can help for the future practical application of magnetic methods in the regular inspection of nuclear power plants. [ABSTRACT FROM AUTHOR]

The inverse problems of electromagnetic nondestructive testing are often solved via the solution of several forward problems. For the latter, precise numerical simulators are available in most of the cases, but the associated computational cost is usually high. Surrogate models (or metamodels)—which are getting more and more widespread in electromagnetics—might be promising alternatives to heavy simulations. Traditionally, such surrogates are used to replace the forward model. However, in this paper the direct use of surrogate models for the solution of inverse problems is studied and illustrated via eddy-current testing examples. [ABSTRACT FROM PUBLISHER]

Accurate numerical simulation of Eddy-Current Testing (ECT) experiments usually requires large computational efforts. So, a natural idea is to build a cheap approximation of the expensive-to-run simulator. This paper presents an approximation method based on functional kriging. Kriging is widely used in other domains, but is still unused in the ECT community. Its main idea is to build a random process model of the simulator. The extension of kriging to the case of functional output data (which is the typical case in ECT) is a recent development of mathematics. The paper introduces functional kriging and illustrates its performance via numerical examples using an ECT simulator based on a surface integral method. A comparison with other classical data interpolation methods is also carried out. [ABSTRACT FROM AUTHOR]