The detection of flaws in austenitic welds using the decomposition of the time reversal operator

Laura J. Cunningham, Anthony J. Mulholland, Katherine M. M. Tant, Anthony Gachagan, Gerry Harvey, Colin Bird

Research output: Contribution to journalArticle

13 Citations (Scopus)
121 Downloads (Pure)

Abstract

The non-destructive testing of austenitic welds using ultrasound plays an important role in the assessment of the structural integrity of safety critical structures. The internal microstructure of these welds is highly scattering and can lead to the obscuration of defects when investigated by traditional imaging algorithms. This paper proposes an alternative objective method for the detection of flaws embedded in austenitic welds based on the singular value decomposition of the time-frequency domain response matrices. The distribution of the singular values is examined in the cases where a flaw exists and where there is no flaw present. A lower threshold on the singular values, specific to austenitic welds, is derived which, when exceeded, indicates the presence of a flaw. The detection criterion is successfully implemented on both synthetic and experimental data. The datasets arising from welds containing a flaw, are further interrogated using the decomposition of the time reversal operator (DORT) method and the total focussing method (TFM) and it is shown that images constructed via the DORT algorithm typically exhibit a higher signal to noise ratio than those constructed by the TFM algorithm.
Original languageEnglish
Number of pages18
JournalProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume472
Issue number2188
DOIs
Publication statusPublished - 1 Apr 2016

Keywords

  • imaging algorithms
  • austenitic welds
  • flaw detection

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