Ultrasonic defect characterisation-Use of amplitude, phase, and frequency information

Long Bai*, Alexander Velichko, Bruce W. Drinkwater

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

13 Citations (Scopus)
388 Downloads (Pure)


This paper studies ultrasonic defect characterisation with the aim of reducing the characterisation uncertainty. Ultrasonic array data contain a mixture of responses from all reflecting features, and the scattering matrix for each defect can be extracted in post-processing, which describes how ultrasonic waves at a given incident angle are scattered by a defect. In this paper, it is shown that defect characterisation performance can be improved by the inclusion of phase and frequency information relative to current single-frequency-amplitude approaches. This superior characterisation performance is due to the increased number of informative principal components (PCs) and higher signal-to-noise ratios in the PC directions. Scattering matrix phase measurement is very sensitive to localisation errors, and an effective approach is proposed, which can be used to reliably extract phase from experimental data. Nine elliptical defects having different aspect ratios and orientation angles are characterised experimentally. The complex multi-frequency defect database has achieved up to 90.60% reduction in the quantified sizing uncertainty compared to the results obtained using only the amplitude at a single frequency.

Original languageEnglish
Pages (from-to)349-360
Number of pages12
JournalJournal of the Acoustical Society of America
Issue number1
Early online date23 Jan 2018
Publication statusPublished - Jan 2018


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