Challenges in improving the performance of eddy current testing: Review

Abdalla, Ahmed N.; Faraj, Moneer A.; Samsuri, Fahmi; Rifai, Damhuji; Ali, Kharudin; Kée, D. De

doi:10.1177/0020294018801382

Cited by 124 publications

(63 citation statements)

References 126 publications

(121 reference statements)

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“…The ECT probe plays roles as the actuating source and also the receiving sensor for damage detection. Throughout the literature, different ECT probe types have been reported and their operation modes are generally classified into four categories-absolute, differential, reflection and hybrid [1][2][3]. Reflection probes have separate excitation and detection sensors, which can be individually optimized for their intended applications [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…As the ECT probe's capability and accuracy for defect detection correlate with the noise level of eddy current signals, one main objective in the ECT probe design is to achieve an output with high signal-to-noise ratio (SNR) [8][9][10]. This can be achieved by improving the probe coil configurations and excitation modes, examples of which have been extensively reported in previous studies [2,[10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Rotating Focused Field Eddy-Current Sensing for Arbitrary Orientation Defects Detection in Carbon Steel

Wang

Deng

2020

Sensors

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This paper presents a rotating focused field eddy-current (EC) sensing technique, which leverages the advantages of magnetic field focusing and rotating magnetic field, for arbitrary orientation defects detection. The sensor consists of four identical excitation coils orthogonally arranged in an upside-down pyramid configuration and a giant magneto-resistive (GMR) detection element. The four coils are connected to form two figure-8-shaped focusing sub-probes, which are fed by two identical harmonic currents with 90 degrees phase difference. A finite element model-based study of arbitrary orientation defects detection was performed to understand the probe operational characteristics and optimize its design parameters. Probe prototyping and experimental validation were also carried out on a carbon steel plate specimen with four prefabricated surface-breaking defects. In-situ spot inspection with the probe rotating above the defect and a manual line-scan inspection were both conducted. Results showed that the probe has the capability of detecting defects with any orientations while maintaining the same sensitivity and the defect depth can be quantitatively evaluated by using the signal amplitude. Compared with the existing rotating field probes, the presented probe does not require additional excitation adjustment or data fusion. Meanwhile, due to its focusing effect, it can generate a strong rotating magnetic field at the defect location with a weak background noise, thus yielding superior signal-to-noise ratio.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rotating Focused Field Eddy-Current Sensing for Arbitrary Orientation Defects Detection in Carbon Steel

Wang

Deng

2020

Sensors

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“…The fine fraction may however contain more stainless steel than the quantities retrieved. The lift-off for stainless steel in ECSs is the lowest of all NFMs (76 times lower than Al), with small pieces tending to remain in the waste when impurities have adhered to the scraps (AbdAlla et al, 2019;Kristian Kahle, Ramboll et al, 2015;Spencer and Schlömann, 1975). In general, the fine fractions contained more impurities than coarse fractions (Figure 7).…”

Section: Category Name Detailsmentioning

confidence: 98%

Quality Assessment of Nonferrous Metals Recovered From Landfill Mining: A Case Study in Belgium

Lucas

López

Parrodi³

et al. 2019

Detritus

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Nonferrous metals (NFMs) provide a major contribution to potential revenues generated by the implementation of landfill mining (LFM). However, metals present in landfills undergo stronger degradation than during regular use, likely resulting in a lower quality compared to conventional scrap. Nowadays, information relating to the most common metals found in LFM projects is readily available, although no consistent quality data can be attained. In general, excavated landfill material is processed mechanically through a series of different steps, including screening and metal separation by magnetic and eddy current separators. This study focuses on the characterisation of NFMs recovered from a specific landfill site in Belgium, with the aim of assessing the quality of each NFM for marketing purposes. The study also addresses the issue of metal concentration and defilements detected, with a preliminary evaluation indicating a total of 5 kg of NFMs per ton of excavated material processed at the Mont-Saint-Guibert landfill. In addition, the application of thermal treatment enabled the observation that, on average, only 70 wt% of the nonferrous fraction is metallic. The majority of surface defilements (30 wt%) are represented by a combination of organic and inorganic impurities that are strongly bound to NFMs. Consequently, the different scraps extracted and the eventual destination of each were technically assessed using two separate approaches. The first approach facilitated the potential recovery of seven types of scraps from NFMs, including two different qualities of Al scrap, two of Cu, one of Pb, one of Zn, and one of stainless steel. In line with the second, and perhaps more realistic approach, NFMs may be directly marketable from the landfill as mixed nonferrous scrap. FIGURE 9: Concentration of metal and defilements in marketable NFMs [wt%].

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“…The excitation coil is wound on the MnZn-ferrite yoke with 500 turn enameled wires whose diameter is 0.15 mm. The detection sensor is a 2-axis tunnel magneto resistance (TMR) sensor that is set at the bottom center of the yoke [27,28]. The 2-axis TMR sensor (Type: TMR2303, Capacity: ±80 Oe, Sensitivity: 3 mV/Oe, made by MULTI DIMENSION, China), is used to measure the Bx and Bz at the same time.…”

Section: System Set Upmentioning

confidence: 99%

Identification of Tiny Surface Cracks in a Rugged Weld by Signal Gradient Algorithm Using the ACFM Technique

Yuan

Chen

et al. 2020

Sensors

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It is still a big challenge to identify tiny surface cracks in a rugged weld due to the lift-off variations using the nondestructive testing (NDT) method. In this paper, the signal gradient algorithm is presented to identify the tiny surface crack in the rugged weld using the alternating current field measurement (ACFM) technique. The ACFM simulation model and testing system was set up to obtain the insensitive signal to the lift-off variations. The signal gradient algorithm was presented to process the insensitive signal for the identification of the tiny surface crack in the rugged weld. The results show that the Bz signal is the insensitive signal to lift-off variations caused by the rugged weld. The signal to noise ratio (SNR) of the crack identification signal was greatly improved by the signal gradient algorithm, and a tiny surface crack can be identified effectively in the weld and the heat affected zone (HAZ).

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Challenges in improving the performance of eddy current testing: Review

Cited by 124 publications

References 126 publications

Rotating Focused Field Eddy-Current Sensing for Arbitrary Orientation Defects Detection in Carbon Steel

Rotating Focused Field Eddy-Current Sensing for Arbitrary Orientation Defects Detection in Carbon Steel

Quality Assessment of Nonferrous Metals Recovered From Landfill Mining: A Case Study in Belgium

Identification of Tiny Surface Cracks in a Rugged Weld by Signal Gradient Algorithm Using the ACFM Technique

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