Guided wave diffraction tomography within the born approximation

Bélanger, Pierre; Cawley, P.; Simonetti, F.

doi:10.1109/tuffc.2010.1559

Cited by 110 publications

(108 citation statements)

References 25 publications

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“…O b can be obtained from the ray tomography reconstruction, and equation (2.14) can be rewritten as 19) where p b and G b are estimates of the incident wavefield and Green's functions, respectively, in the background O b ; complete details of how they are calculated are in [21]. As before, this forms a linearization, provided p b and G b remain constant, which enables O δ to be calculated directly.…”

Section: (Iii) Harbutmentioning

confidence: 99%

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Evaluation of inversion approaches for guided wave thickness mapping

Huthwaite

2014

Proc. R. Soc. A.

111

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Accurate inversion is vital for quantitative imaging, including ultrasonic guided wave tomography, where thickness maps of plate-like structures are reconstructed to quantify corrosion damage. The dispersive properties of guided waves are often exploited to enable thickness maps to be produced from wave speed reconstructions. Ray tomography, diffraction tomography and a hybrid algorithm combining their features were investigated to reconstruct wave speed. Test data produced from simple defects of different sizes using a realistic full elastic guided wave model and the equivalent idealized acoustic model were passed to the imaging algorithms, generating wave speed maps, and, from these, thickness maps. For both datasets, ray tomography exhibited poor resolution. Diffraction tomography performed better, but was limited to shallow, small defects. The hybrid algorithm achieved the best results, giving a resolution around 1.5-2 wavelengths from the realistic test data compared to half wavelength from the idealized case. These results were validated with experimental data, and also extended to a realistic corrosion patch confirming the trends demonstrated with simple defects. The resolution loss with realistic data compared with idealized data indicates the acoustic model cannot accurately capture guided wave scattering and an alternative approach is necessary for better resolution reconstructions.

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Section: (Iii) Harbutmentioning

confidence: 99%

“…For this, a piezoelectric transducer was used to excite the A 0 wave; this transducer is as described in [19]. This is around 10 mm in diameter (i.e.…”

Section: (E) Experimental Validationmentioning

confidence: 99%

Evaluation of inversion approaches for guided wave thickness mapping

Huthwaite

2014

Proc. R. Soc. A.

111

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“…The study showed that Lamb wave diffraction tomography could further improve image quality and resolution. Belanger et al (2010) proposed a time-of-flight diffraction tomography within the Born approximation using low frequency Lamb waves. Their study employed a transducer network with 64 transducers to evaluate reduction in plate thickness.…”

Section: Background Of the Proposed Methodsmentioning

confidence: 99%

A two-stage approach for quantitative damage imaging in metallic plates using Lamb waves

Ng¹

2015

Earthquakes and Structures

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March, 2016Earthquakes and Structures, Vol. 8, No. 4 (2015) (Received April 18, 2014, Revised October 16, 2014, Accepted October 17, 2014 Abstract. This paper proposes a two-stage imaging approach for quantitative inspection of damages in metallic plates using the fundamental anti-symmetric mode of (A 0 ) Lamb wave. The proposed approach employs a number of transducers to transmit and receive A 0 Lamb wave pulses, and hence, to sequentially scan the plate structures before and after the presence of damage. The approach is applied to image the corrosion damages, which are simplified as a reduction of plate thickness in this study. In stage-one of the proposed approach a damage location image is reconstructed by analyzing the cross-correlation of the wavelet coefficient calculated from the excitation pulse and scattered wave signals for each transducer pairs to determine the damage location. In stage-two the Lamb wave diffraction tomography is then used to reconstruct a thickness reduction image for evaluating the size and depth of the damage. Finite element simulations are carried out to provide a comprehensive verification of the proposed imaging approach. A number of numerical case studies considering a circular transducer network with eight transducers are used to identify the damages with different locations, sizes and thicknesses. The results show that the proposed methodology is able to accurately identify the damage locations with inaccuracy of the order of few millimeters of a circular inspection area of 100 mm 2 and provide a reasonable estimation of the size and depth of the damages.

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“…As shown in the dispersion curves of figure 1, the guided wave velocity is a function of the frequency-thickness product, so by fixing frequency, wave velocity can be shown to be a function of thickness. This is a widely used assumption which has been used for 20 years in guided wave tomography [3][4][5][6][7][8][9][10][11][12] but relies on a key approximation. The dispersion curves are derived for infinite plates of constant thickness [13]; therefore, the assumption is made that any local thickness variations are sufficiently gradual that they can be neglected.…”

Section: Introductionmentioning

confidence: 99%

Guided wave tomography with an improved scattering model

Huthwaite¹

2016

Proc. R. Soc. A.

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Guided wave diffraction tomography within the born approximation

Cited by 110 publications

References 25 publications

Evaluation of inversion approaches for guided wave thickness mapping

Evaluation of inversion approaches for guided wave thickness mapping

A two-stage approach for quantitative damage imaging in metallic plates using Lamb waves

Guided wave tomography with an improved scattering model

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