Lamb mode diversity imaging for non-destructive testing of plate-like structures

Prado, Vander Teixeira; Higuti, Ricardo Tokio; Kitano, Cláudio; Martínez-Graullera, Óscar; Adamowski, Júlio C.

doi:10.1016/j.ndteint.2013.06.001

Cited by 66 publications

(31 citation statements)

References 24 publications

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“…The group velocity is defined in terms of a narrowband signal [38], and consequently for the signals considered in this work the group velocity is more adequate to characterize the pulse propagation than the phase velocity. In the case of dispersive signals, there are techniques for dispersion compensation [39] that have been employed by the authors in a previous work [40], where a high-dispersive A1 mode was used. In the noncompensated image, the defects appeared at wrong positions, even using a correct group velocity.…”

Section: Ultrasonic Imaging Of Immersed Platesmentioning

confidence: 99%

Ultrasound imaging of immersed plates using high-order Lamb modes at their low attenuation frequency bands

Takiy

Kitano

Higuti

et al. 2017

Mechanical Systems and Signal Processing

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This paper focuses on the use of a Lamb wave-based methodology for ultrasound imaging of immersed plate structures. In these cases Lamb waves can be strongly attenuated due to leaky waves and viscous losses in the liquid, but there are low attenuation frequency bands that may be used for NDT applications. Experimental measurements were conducted to validate the existence of these low attenuation frequency bands, which were also theoretically predicted for some propagation modes, between the frequencies-thickness products of 0.5 MHz mm and 9.0 MHz mm. Using a 5 MHz linear-array and phased-array techniques, A1 and S1 modes are used to obtain images of an immersed aluminum plate with artificial defects. The signals are post-processed in order to select the desired propagation mode and to obtain an image with dynamic focusing in reception. While the A1 mode is strongly attenuated, the S1 mode, at 3.4 MHz mm, can be used to detect and localize defects in the immersed plate.

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Section: Ultrasonic Imaging Of Immersed Platesmentioning

confidence: 99%

Ultrasound imaging of immersed plates using high-order Lamb modes at their low attenuation frequency bands

Takiy

Kitano

Higuti

et al. 2017

Mechanical Systems and Signal Processing

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“…Camacho's results showed that PCF can improve the resolution and contrast of ultrasound images. Based on analyses of SCF, Prado proposed a compounding method [11] that used A0 and S0 mode Lamb waves to detect artificial defects in an aluminum plate. These two sets of detected signals were combined in an image with amplitudes weighted by SCF.…”

Section: Introductionmentioning

confidence: 99%

Instantaneous Phase Coherence Imaging for Near-Field Defects by Ultrasonic Phased Array Inspection

Zhang

Zeng

Fan

et al. 2020

Sensors

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This paper describes an imaging method for near-field defect detection in aluminum plates based on Green’s function recovery and application of instantaneous phase coherence weighting factors. The directly acquired acoustic information of near-field defects is usually obscured by the nonlinear effects due to the physical limitation of the acquisition system. Using the diffuse field to recover the Green’s function can effectively retrieve the early time information. However, averaging operations of finite number in this process produces an imperfect imaging result. In order to improve the image quality, two kinds of instantaneous phased coherence weighting factors are used to weight the Green’s function to reduce the background noise and improve the signal-to-noise ratio: the instantaneous phase coherence factor (IPCF), and the instantaneous phase weighting factor (IPWF). Experiments are conducted on two aluminum plates with two and four near-field defects, respectively. As a result, the background noise of amplitude images weighted by IPCF and IPWF is less than that of the conventional total focusing method (TFM). In addition, the IPCF image achieves a better signal-to-noise ratio (SNR) than that of IPWF, and the phase discontinuity in an IPWF image is suppressed through the IPCF.

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“…Prado V T, Higuti R T researched TFM imaging by Lamb wave. Dead zone was reduced, resolution and contract were improved of the image obtained from Sign Coherence Factor (SCF) [11].…”

Section: Introductionmentioning

confidence: 99%

Defect detection study on total focus method of sound field imaging based on parallel processing

Zhang

Guo

Luo

et al. 2014

2014 IEEE Far East Forum on Nondestructive Evaluation/Testing

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Abstact:In order to process real-time phased array ultrasound imaging, to improve imaging resolution, and achieve on-line defect detection, total focusing method (TFM) imaging algorithm is used for the complete data, thrust reversers the focus and algorithm in different positions, the computational problems of large data can be solved by the FPGA parallel algorithms. After that, the total focusing method imaging algorithm can be realized in the real-time detection.

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Lamb mode diversity imaging for non-destructive testing of plate-like structures

Cited by 66 publications

References 24 publications

Ultrasound imaging of immersed plates using high-order Lamb modes at their low attenuation frequency bands

Ultrasound imaging of immersed plates using high-order Lamb modes at their low attenuation frequency bands

Instantaneous Phase Coherence Imaging for Near-Field Defects by Ultrasonic Phased Array Inspection

Defect detection study on total focus method of sound field imaging based on parallel processing

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