Ultrasonic Imaging in Solids Using Wave Mode Beamforming

Scalea, Francesco Lanza di; Sternini, Simone; Nguyen, Thompson V.

doi:10.1109/tuffc.2016.2637299

Cited by 15 publications

(5 citation statements)

References 36 publications

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“…Such an aspect is crucial, as has also been noted by recent reviews of research on guided-wave-based structural health monitoring [ 3 , 4 ]. Moreover, a detailed knowledge of the displacement field can be used to improve the focus in defect image reconstruction when using wave mode beamforming and compounding strategies [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Interaction of Shear and Rayleigh–Lamb Waves with Notches and Voids in Plate Waveguides

Pau

Achillopoulou

2017

Materials

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This paper investigates the interaction of different shear- and Rayleigh–Lamb-guided waves in plates with a discontinuity such as a notch or an internal void. The problem was solved numerically using a finite element model and by exploiting an analytical solution obtainable for the double sharp changes of the cross-section that served as a reference. We aimed to elucidate the relation between the size and shape of the discontinuity and the reflection and transmission coefficients of the scattered field. Different sizes and profiles of the discontinuity were considered, with the shapes ranging from step changes of the height to ellipses, both symmetric and nonsymmetric. Regimes related to low and high values of the product frequency multiplied by the height of the plate were investigated. These showed how the mode conversion was related to the symmetry between the incident mode and the discontinuity, and to the actual existence of multiple propagating modes. The analysis presented was motivated by the need to set up procedures that exploit propagating waves not only to detect the presence of a notch, but also to characterize its size and shape.

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Section: Introductionmentioning

confidence: 99%

Interaction of Shear and Rayleigh–Lamb Waves with Notches and Voids in Plate Waveguides

Pau

Achillopoulou

2017

Materials

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“…The theoretical considerations of dual-output systems and causality are taken to maximize the SNR of the passive IRFs. The wave mode compounding technique is exploited to enhance array gain in Delay-and-Sum (DAS) beamforming of the virtual FMC data [17]. Experimental results are shown by the passive imaging of a drilled hole in an aluminum block.…”

Section: Introductionmentioning

confidence: 99%

Passive ultrasonic beamforming for fast and efficient imaging

Lanza di Scalea,

Huang,

Hosseinzadeh

2024

Health Monitoring of Structural and Biological Systems XVIII

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This work explores the opportunity for utilizing ultrasonic arrays in a passive manner to increase imaging speed and accuracy, compared to conventional ultrasonic beamforming approaches. While conventional beamforming requires the use of many transmitters as well as receivers, the possibility exists to minimize the number of transmitters and exploit the normalized cross-power spectrum operator to extract "virtual" Impulse Response Functions between pairs of (only) receivers. In principle, this possibility would allow, for example, the use of a single transmitter element and processing the remaining elements as receivers (passively) to obtain similar image quality as using each element as both transmitter and receiver (as done, for example, in a Full Matrix Capture mode). By minimizing the number of transmitters, it would be possible to significantly increase imaging speed (ultrafast imaging) and simplify multiplexer hardware (few highvoltage output channels). The normalized cross-power spectrum could eliminate the distortion in the phase of the Impulse Response Functions which is commonly seen in active transmission modalities. These exciting possibilities are explored in the case of imaging defects in structural components.

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“…The authors introduce a modified Green's function based on considerations of the direction of arrival of each wave mode on the array 14 . In analogy to the adaptive weights the authors proposed in time domain beamforming 15 , the replica modeled with wave structure aims to reduce side lobe levels as well as increase the spatial resolution in MFP images.…”

Section: Introductionmentioning

confidence: 99%

Ultrasound time reversal imaging of extended targets using a broadband white noise constraint processor

Huang

Scalea

2023

Medical Imaging 2023: Ultrasonic Imaging and Tomography

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High resolution ultrasound time-reversal imaging typically requires adequate signal strength. The multiple signal classification (TR-MUSIC) algorithm can produce images of point scatterers with subwavelength resolution when a clear separation of the signal space and the noise space exists. When the size of the scatterers is on the order of the wavelength or larger, the TR-MUSIC algorithm suffers from poor image quality due to a tangled eigenstate spectrum. In this study, we use a coherent broadband white noise constraint (B-WNC) matched-field processor that requires zero knowledge of the eigenspace in the interrogated medium to obtain high quality ultrasound images. The WNC algorithm enhances the robustness to model mismatch of matched-field beamformers in poor signal conditions. The multi-tone broadband beamformer offers additional gain over a single-tone by augmenting the dimension of the physical array and exploiting the cross-frequency terms in the time reversal operator. The dynamic range bias obtained from a rank-deficient covariance matrix benefits the B-WNC images to retain better contrast than the TR-MUSIC images. This study also proposes improvements in modeling the replica vectors for the virtual time-reversal process. The transverse mode is combined with the longitudinal mode in the formulation using the free-field Green’s function. The resolution is further improved by exploiting the transverse mode information in the multistatic data. Adaptive spatial windows are applied to the replica vectors according to the displacement structure of the wave mode at medium-array interface. Numerical simulations and experimental testing demonstrate the potential for accurate sizing of extended targets that have a size comparable to the dominant wavelength using the proposed B-WNC algorithm.

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Ultrasonic Imaging in Solids Using Wave Mode Beamforming

Cited by 15 publications

References 36 publications

Interaction of Shear and Rayleigh–Lamb Waves with Notches and Voids in Plate Waveguides

Interaction of Shear and Rayleigh–Lamb Waves with Notches and Voids in Plate Waveguides

Passive ultrasonic beamforming for fast and efficient imaging

Ultrasound time reversal imaging of extended targets using a broadband white noise constraint processor

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