Depth measurement of small surface-breaking cracks using the Half-Skip Total Focusing Method

Felice, Maria V.; Velichko, Alexander; Wilcox, Paul D.; Lane, Christopher

doi:10.1063/1.4914706

Cited by 11 publications

(8 citation statements)

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“…Such cases are especially noticed with regions beneath the defect, where scattered reflections never reach the receivers. For such points in few cases, the transmission time calculated in Equation (11) would not equate to the true instance of the reflected energy getting captured 22 …”

Section: Imaging Resultsmentioning

confidence: 99%

An ultrasonic wave‐based framework for imaging internal cracks in concrete

Kuchipudi

Ghosh

2022

Structural Contr & Hlth

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Nondestructive detection and sizing of internal cracks initiated in reinforced concrete have been critical problems. Geometric characterization of internal cracks and delaminations contributes to predicting their propagation path and failure pattern followed by structural prognostics. There have been limited studies on quantitative detection and characterization of vertical cracks in concrete using wave-based NDE techniques. This study focuses on solving the problem of imaging deep internal crack planes in the concrete medium by leveraging the ultrasonic shear horizontal (SH) waves from a transducer array. Postprocessing the array full matrix capture (FMC) data with both total focusing method (TFM) and plane wave imaging (PWI) reveals their efficiency in mapping planar defects inclined between 0 and 60 . However, their performance on vertical/near-vertical defects is found to be inferior with imaging limited to the tip of the defect planes. Further, half-skip modes of wave dispersion have been adopted in addition to the directly scattered pulses for imaging the vertical and near-vertical cracks. We propose an imaging framework based on the outcomes of our investigation on the best suitable methodology to detect and map planar defects like cracks inclined in the range of 0-90 . Statistical quantification of defect inclinations from the reconstructed images is compared to the ground-truth orientations, and they are found to be 94%-99% accurate. Besides accuracy, the computational efficiency of the proposed techniques makes them desirable and reliable for quick on-site inspections on built infrastructure.full matrix capture (FMC), total focusing method (TFM), half-skip total focusing method (HSTFM), plane wave imaging (PWI), shear horizontal (SH) waves, ultrasonic array, vertical cracks | INTRODUCTIONInternal cracks in reinforced concrete are a result of various factors including thermal, mechanical, and environmental deterioration. Cracking affects the performance of structural concrete at different stages in its lifecycle. Diagnosis of such defects is followed by retrofitting at early stages to mitigate the failure of structures. The non-homogeneity and highly attenuating nature of concrete medium poses a challenge for the nondestructive community to evaluate structures for thin underlying cracks.

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Section: Imaging Resultsmentioning

confidence: 99%

An ultrasonic wave‐based framework for imaging internal cracks in concrete

Kuchipudi

Ghosh

2022

Structural Contr & Hlth

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“…However, in the case of detecting a near backwall defect, there is additional complexity from the wave reflecting from the backwall, which is not accounted for in TFM. In response, Felice et al (Felice et al, 2015) developed the Half-Skip Total Focusing Method (HSTFM) to image and size the near backwall defects. Unlike TFM, HSTFM considers the 'half-skip' ray paths which are reflected on the backwall once, either before or after interacting with the defect, as shown in Fig.…”

Section: Half-skip Total Focusing Methodsmentioning

confidence: 99%

“…These cracks are commonly found near inaccessible interior surfaces, referred to here as 'backwalls', and are important to detect and characterise in safety-critical components under severe working environment (high pressure or high temperature) or cyclic loading, for example nozzles, piping components and vessel welds (Collins, 1993). Recently, the use of ultrasonic phased arrays to evaluate near backwall defects has attracted a lot of attention (Felice et al, 2014(Felice et al, , 2015Iakovleva et al, 2014;Zhang et al, 2016). A great advantage of using ultrasonic phased arrays is that this allows the acquisition of Full Matrix Capture (FMC (Holmes et al, 2005)) data.…”

Section: Introductionmentioning

confidence: 99%

Eliminating backwall effects in the phased array imaging of near backwall defects

Zhang

Huthwaite

Lowe

2018

The Journal of the Acoustical Society of America

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Ultrasonic array imaging is widely used to provide high quality defect detection and characterization. However, the current imaging techniques are poor at detecting and characterizing defects near a surface facing the array, as the signal scattered from the defect and the strong reflection from the planar backwall will overlap in both time and frequency domains, masking the presence of the defect. To address this problem, this paper explores imaging algorithms and relevant methods to eliminate the strong artefacts caused by the backwall reflection. The half-skip total focusing method (HSTFM), the factorization method (FM) and the time domain sampling method (TDSM) are chosen as the imaging algorithms used in this paper. Then, three methods, referred to as full matrix capture (FMC) subtraction, weighting function filtering, and the truncation method, are developed to eliminate or filter the effects caused by the strong backwall reflection. These methods can be applied easily with few tuning parameters or little prior knowledge. The performances of the proposed imaging techniques are validated in both simulation and experiments, and the results show the effectiveness of the developed methods to eliminate the artefacts caused by the backwall reflections when imaging near backwall defects.

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“…For this frequency, the wavelength in air is about 1.7 mm, so that in order to fulfill the half-wavelength criterion, the pitch d has to be smaller than approximately 0.8 mm. Currently, there are several examples described in the literature showing that it is possible to manufacture sensor arrays that meet this requirement [ 30 , 31 , 32 , 33 ]. Second, since the considered near-surface crack is very small (1 mm length), we may assume that, once excited, the defect will start to behave as a (secondary) point source.…”

Section: Inverse Model: Defect Localizationmentioning

confidence: 99%

Simulation Study of the Localization of a Near-Surface Crack Using an Air-Coupled Ultrasonic Sensor Array

Delrue

Aleshin

Sørensen

et al. 2017

Sensors

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The importance of Non-Destructive Testing (NDT) to check the integrity of materials in different fields of industry has increased significantly in recent years. Actually, industry demands NDT methods that allow fast (preferably non-contact) detection and localization of early-stage defects with easy-to-interpret results, so that even a non-expert field worker can carry out the testing. The main challenge is to combine as many of these requirements into one single technique. The concept of acoustic cameras, developed for low frequency NDT, meets most of the above-mentioned requirements. These cameras make use of an array of microphones to visualize noise sources by estimating the Direction Of Arrival (DOA) of the impinging sound waves. Until now, however, because of limitations in the frequency range and the lack of integrated nonlinear post-processing, acoustic camera systems have never been used for the localization of incipient damage. The goal of the current paper is to numerically investigate the capabilities of locating incipient damage by measuring the nonlinear airborne emission of the defect using a non-contact ultrasonic sensor array. We will consider a simple case of a sample with a single near-surface crack and prove that after efficient excitation of the defect sample, the nonlinear defect responses can be detected by a uniform linear sensor array. These responses are then used to determine the location of the defect by means of three different DOA algorithms. The results obtained in this study can be considered as a first step towards the development of a nonlinear ultrasonic camera system, comprising the ultrasonic sensor array as the hardware and nonlinear post-processing and source localization software.

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Depth measurement of small surface-breaking cracks using the Half-Skip Total Focusing Method

Cited by 11 publications

References 0 publications

An ultrasonic wave‐based framework for imaging internal cracks in concrete

An ultrasonic wave‐based framework for imaging internal cracks in concrete

Eliminating backwall effects in the phased array imaging of near backwall defects

Simulation Study of the Localization of a Near-Surface Crack Using an Air-Coupled Ultrasonic Sensor Array

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