Towards Guided Wave Robotic NDT Inspection: EMAT Size Matters

Trushkevych, Oksana; Dixon, S.; Tabatabaeipour, Morteza; Dobie, Gordon; Potter, M. D. G.; MacLeod, Charles N.; Gachagan, Anthony; Pierce, S. Gareth; Edwards, R. S.

doi:10.1109/ultsym.2019.8925875

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…A periodic force structure which generates an SH wave can be obtained through the Lorentz force or magnetostriction. Magnetostrictive effects can be significant on magnetite [16] [17], but are negligible in the tested samples. The Lorentz force is the force on particles of charge q moving with velocity v in a magnetic field B, given by F=qv×B.…”

Section: A Emat Design Considerationsmentioning

confidence: 92%

“…This may be required in some applications, in particular on small or narrow samples. The expected trade-off for using EMATs with a width of the wavelength or smaller is reduced directivity of the EMAT [17]. This may not be significant in applications where travel distance of the signals of interest is under 40 cm, but may not be acceptable where signals need to travel longer distances.…”

Section: A Emat Design Considerationsmentioning

confidence: 99%

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Miniaturised SH EMATs for Fast Robotic Screening of Wall Thinning in Steel Plates

et al. 2021

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Electromagnetic acoustic transducers (EMATs) are well suited to generating and detecting a variety of different ultrasonic wavemodes, without the need for couplant, and they can be operated through some coatings. EMATs can be used to generate shear horizontal (SH) waves, which show promise for fast screening of wall thinning and other defects. However, commercial SH-wave EMATs are not suitable for robotic implementation on ferritic steel due to the large magnetic drag force from the magnets. This paper describes the design and characterisation of miniaturised SH guided wave EMATs, which significantly reduce the magnetic drag and enable mounting onto a small crawler robot for sample scanning. The performance of the miniaturised EMATs is characterised and compared to a commercial EMAT. It is shown that signal to noise ratio is reduced, but remains within an acceptable range to use on steel. The bandwidth and directivity are increased, depending on the exact design used. Their ability to detect flat bottomed holes mimicking wall thinning is also tested.

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Section: A Emat Design Considerationsmentioning

confidence: 92%

Section: A Emat Design Considerationsmentioning

confidence: 99%

Miniaturised SH EMATs for Fast Robotic Screening of Wall Thinning in Steel Plates

et al. 2021

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“…Fig. 13 shows the experimental setup on a rectangular 10 mm steel sample with dimensions of 2 x 1 m. EMAT signals were measured at 5 cm intervals using the miniaturised EMAT generator and two receivers [58] with the set-up on the robot shown in Fig. 13.…”

Section: Experimental Validation Of Gw-ogmmentioning

confidence: 99%

Application of ultrasonic guided waves to robotic occupancy grid mapping

Tabatabaeipour

Trushkevych

Dobie

et al. 2022

Mechanical Systems and Signal Processing

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“…Typically, the first higher order mode, such as A1 for Lamb waves or SH1 for SH waves, is selected. SH1 is usually preferred because it does not leak into nonviscous fluids that may be in contact with the sample, and it can be excited using non-contact electromagnetic acoustic transducers (EMATs) [2,3].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Complex Corrosion Profiles on Remaining Wall Thickness Quantification Using Shear Horizontal Guided Waves

TZAFERIS,

TABATABAEIPOUR,

DOBIE

et al. 2023

Proceedings of the 14th International Workshop on Structural Health Monitoring

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Corrosion of plate and pipe structures is a major concern to many key industries, including power, maritime, and oil and gas. When there is a need to inspect large areas quickly or when access to the structure is limited, guided wave testing is often preferred over bulk wave measurements. In this work, shear horizontal guided waves are employed for wall thickness quantification. Specifically, the interaction of modes SH1 and SH0 with complex corrosion defects is investigated. The guided wave mode are selectively generated using a phased array-based approach. A pair of identical phased array probes are positioned before and after the simulated corrosion profile, to monitor the reflected and transmitted waves. The targeted mode is excited selectively using a 32-element 3 mm pitch array and guided wave modes are decomposed after a 2DFFT is performed. The cut-off frequency technique using mode SH1 is shown to be adequate when smooth wall thinning defects are considered. When sharp pits are present, mode SH0 proved sufficient to determine the pits depth.

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Towards Guided Wave Robotic NDT Inspection: EMAT Size Matters

Cited by 6 publications

References 11 publications

Miniaturised SH EMATs for Fast Robotic Screening of Wall Thinning in Steel Plates

Miniaturised SH EMATs for Fast Robotic Screening of Wall Thinning in Steel Plates

Application of ultrasonic guided waves to robotic occupancy grid mapping

The Effect of Complex Corrosion Profiles on Remaining Wall Thickness Quantification Using Shear Horizontal Guided Waves

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