Abstract
Nonlinear ultrasonic imaging methods for non-destructive testing have shown sensitivity to early damage formation. Among those, the Fundamental wave Amplitude Difference (FAD) technique has been proposed in the literature as a nonlinearity mapping method for defect visualisation. It does so by calculating the residual between a low and high nonlinearity image, which is achieved by some modulation of the focal spot amplitude. This is realised either through different input voltages or alternating the element-wise firing scheme. This paper assesses the sensitivity of FAD through different techniques used for the generation of the low nonlinearity images, using both theoretical and experimental approaches. These techniques include (1) Different-Voltage FAD (DV-FAD); (2) Odd-Even FAD (OE-FAD) and; (3) Parallel–Sequential FAD (PS-FAD). Formulae are derived that allow the different firing sequences and image corrections to be compared. The FAD techniques are then experimentally evaluated against the theory, showing a 50% amplitude gain at the crack tip when comparing PS-FAD to OE-FAD and DV-FAD. Additionally, the instrument behaviour is assessed by considering the image correction required to improve the image contrast for the visualisation of the crack tip. Finally, it is shown that all FAD techniques are equivalent in terms of nonlinear detection but additional work is required in comparing the performance of other array controllers when using FAD.
Original language | English |
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Article number | 103107 |
Number of pages | 12 |
Journal | NDT & E International |
Volume | 145 |
Early online date | 10 Apr 2024 |
DOIs | |
Publication status | Published - 1 Jul 2024 |
Bibliographical note
Publisher Copyright:© 2024 The Author(s)
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Dive into the research topics of 'Characterisation of coherent ultrasonic nonlinear imaging'. Together they form a unique fingerprint.Student theses
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Nonlinear Ultrasonic Non-Destructive Evaluation: Understanding the limitations and improving the metrology of nonlinear ultrasound
Ebrahim Saib, Z. M. (Author), Drinkwater, B. (Supervisor) & Croxford, A. (Supervisor), 7 May 2024Student thesis: Doctoral Thesis › Doctor of Philosophy (PhD)
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