Wireless power transfer-based eddy current non-destructive testing using a flexible printed coil array

Abstract

Eddy current testing (ECT) has been employed as a traditional non-destructive testing and evaluation (NDT&E) tool for many years. It has developed from single frequency to multiple frequencies, and eventually to pulsed and swept-frequency excitation. Recent progression of wireless power transfer (WPT) and flexible printed devices open opportunities to address challenges of defect detection and reconstruction under complex geometric situations. In this paper, a transmitter–receiver (Tx–Rx) flexible printed coil (FPC) array that uses the WPT approach featuring dual resonance responses for the first time has been proposed. The dual resonance responses can provide multiple parameters of samples, such as defect characteristics, lift-offs and material properties, while the flexible coil array allows area mapping of complex structures. To validate the proposed approach, experimental investigations of a single excitation coil with multiple receiving coils using the WPT principle were conducted on a curved pipe surface with a natural dent defect. The FPC array has one single excitation coil and 16 receiving (Rx) coils, which are used to measure the dent by using 21 C-scan points on the dedicated dent sample. The experimental data were then used for training and evaluation of dual resonance responses in terms of multiple feature extraction, selection and fusion for quantitative NDE. Four features, which include resonant magnitudes and principal components of the two resonant areas, were investigated for mapping and reconstructing the defective dent through correlation analysis for feature selection and feature fusion by deep learning. It shows that deep learning-based multiple feature fusion has outstanding performance for 3D defect reconstruction of WPT-based FPC-ECT. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.

Machine-Learning-Based Evaluation of Corrosion Under Insulation in Ferromagnetic Structures

“…Machine learning, including its latest development known as deep learning, has embraced countless applications in various sectors of industry. Non-destructive testing (NDT) is not an exception to this current trend, and eddy NDT current techniques have also seen the applications of machine learning, such as the works reported in [12,13]. In this study, the use of machine learning in processing PEC signals obtained without signal averaging is presented.…”

Characterization of Angular RCF Cracks in a Railway Using Modified Topology of WPT-Based Eddy Current Testing

“…The demonstrated idea of a non-radiative WPT operation at maximum energy transfer efficiency in [12] over a certain distance and its modified response with multiple resonances while in an over-couple region of operation [15] has been explored in previous research for sensing application. Previously, WPTECT research has applied the idea to quantify the depths and width of cracks and reconstruct natural corrosion through multiple feature extraction, selection, and fusion [16,17]. Each of the two implemented basic topologies (SS and PP) has a distinct response and quality factor expressions due to their individual unique impedance matching, leading to different measurement performances of WPTECT systems [10,11,20].…”

“…It uses WPT series-series (SS) compensation topology because of its low input and output impedance for a maximum current at resonance, which leads to maximum field generation. Subsequently, a parallel-parallel (PP) topology has been applied in the second WPTECT [17] because of its higher transfer response to metal and defect with less sensitivity to noise influence [18], resulting from its current source nature and higher input and out impedance at the resonance point. The second WPTECT investigated multiple feature extraction, selection, and fusion to characterize and map the 3D natural dent-area due to metal loss and corrosion on a pipeline sample.…”

“…Different from the WPTECT circuits topologies of [16,17], our proposed PS-PS topology has series (Ca) and shunt (Cb) capacitors in each Tx and Rx network. Ca reduces the coil's effective reactance, shares the total reactive power with Cb to maintain oscillation, and serves as impedance matching [19].…”

A Novel Planar Differential Koch Fractal Eddy Current Probe with Parallel Wound Topological Structure

“…In this way, the shortcomings, which include the area that is hard to reach and the sensors that are easily influenced by lift-off noise in the conventional rigid sensors, can be improved [17]. Daura et al [18] proposed using the wireless power transfer to efficiently acquire the defect signal of the transmitter-receiver flexible printed coil. She et al [19] proposed the flexible floral eddy current probe, which is a differential exciting eddy current probe to suppress the lift-off noise and to detect the flaws in the metal plate.…”