Inverse wave field extrapolation: a different NDI approach to imaging defects

Pörtzgen, Niels; Gisolf, Dries; Blacquière, Gerrit

doi:10.1109/tuffc.2007.217

Cited by 81 publications

(44 citation statements)

References 16 publications

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“…Malcolm et al ͑2009͒ demonstrate this property for the deterministic case of one known horizontal reflector that was used to image a complex area from below. Also, in the field of nondestructive testing, such as inspection of welds in pipelines, this is a known technique where the back wall is used for secondary illumination ͑see, e.g., Pörtzgen et al, 2007͒. …”

Section: Discussionmentioning

confidence: 99%

Seismic migration of blended shot records with surface-related multiple scattering

2011

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This paper focuses on the concept of using blended data and multiple scattering directly in the migration process, meaning that the blended input data for the proposed migration algorithm includes blended surface-related multiples. It also means that both primary and multiple scattering contribute to the seismic image of the subsurface. Essential in our approach is that multiples are not included in the Green's functions but are part of the incident wavefields, utilizing the so-called double illumination property. We find that complex incident wavefields, such as blended primaries and/or blended multiples, require a reformulation of the imaging principle in order to provide broadband angle-dependent reflection properties.

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Section: Discussionmentioning

confidence: 99%

Seismic migration of blended shot records with surface-related multiple scattering

2011

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“…When all phases are equal, C=1, maintaining pixel intensity, whereas when they approach a uniform distribution C→0, reducing pixel intensities. This operation has shown promise [12] to inspect structurally noisy materials as backscatter signals are expected to exhibit greater phase variability than flaw signals. In this case I is given by:…”

Section: Imaging Algorithmsmentioning

confidence: 99%

“…Since its onset, numerous algorithms are available to post-process FMC data into an image, including wave-field extrapolation (IWEX) [12], the wavenumber algorithm [13], and what is regarded in the NDE community as the most established algorithm: the Total Focusing Method (TFM) [8,10]. Advanced imaging algorithms are currently emerging in attempts to further improve inspection of difficult materials such as coarse grained metals.…”

Section: Introductionmentioning

confidence: 99%

A methodology for evaluating detection performance of ultrasonic array imaging algorithms for coarse-grained materials

Pamel

Brett²,

Lowe

2014

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-Improving the ultrasound inspection capability for coarse grain metals remains of longstanding interest and is expected to become increasingly important for next generation electricity power plants. Conventional ultrasonic A, B, and C-scans have been found to suffer from strong background noise due to grain scattering which can severely limit the detection of defects. However, in recent years, array probes and Full Matrix Capture (FMC) imaging algorithms have unlocked exciting possibilities for improvements. In order to progress and compare these algorithms we must rely on robust methodologies to quantify their performance. This article proposes such a methodology to evaluate the detection performance of imaging algorithms. For illustration, the methodology is applied to some example data using three FMC imaging algorithms; Total Focusing Method (TFM), Phase Coherent Imaging (PCI), and Decomposition of the Time Reversal Operator with Multiple Scattering Filter (DORT MSF). However it is important to note that this is solely to illustrate the methodology; this article does not attempt the broader investigation of different cases that would be needed to compare the performance of these algorithms in general. The methodology considers the statistics of detection, presenting the detection performance as Probability of Detection (POD) and probability of False Alarm (PFA). A test sample of coarse grained INCONEL 625, manufactured to represent materials used for future power plant components and containing some simple artificial defects, is used to illustrate the method on the candidate algorithms. The data is captured in pulse-echo mode using 64 element array probes at centrefrequencies of 1MHz and 5MHz. In this particular case, it turns out that all three algorithms are shown to perform very similarly when comparing their flaw detection capabilities.

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“…Using ultrasonic array imaging methods such as the: total focusing method [1], synthetic aperture focusing technique [2], [3], inverse field wave extrapolation [4] or wavenumber algorithms [5], a range of defects can be detected and accurately located. If the defects are large, i.e.…”

Section: Introductionmentioning

confidence: 99%

A numerical database for ultrasonic defect characterisation using array data: Robustness and accuracy

Malkin

Caleap

Drinkwater

2016

NDT & E International

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. AbstractElastodynamic scattering matrices are known to contain geometrical information about a given scatterer, such as its size and shape. Here, the extent to which this scattered information can be retrieved using an ultrasonic array and used to characterise defects for Non-Destructive Evaluation is explored. Experimentally measured defect scattering matrices are compared to a database of possible scatterers and the nearest neighbour used to characterise the defect's geometry in terms of crack length and orientation. As an example, a database of scattering matrices for small (lengths 0.2-2.0mm) cracks at a range of frequencies (2-20MHz) is formed. The short range similarity (i.e. that between close neighbours) and the long range similarity (i.e. uniqueness) are used to understand the uncertainties inherent in this approach. In addition, the effect of spatially coherent noise, such as grain scattering in a polycrystalline metal, on the scattered information content is quantified. It is shown that as the noise level or frequency increases, so the information retrievable from a given crack is reduced, setting bounds on the accuracy of characterisation possible from a given ultrasonic dataset.

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Inverse wave field extrapolation: a different NDI approach to imaging defects

Cited by 81 publications

References 16 publications

Seismic migration of blended shot records with surface-related multiple scattering

Seismic migration of blended shot records with surface-related multiple scattering

A methodology for evaluating detection performance of ultrasonic array imaging algorithms for coarse-grained materials

A numerical database for ultrasonic defect characterisation using array data: Robustness and accuracy

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