Mode-converted waves and D-scans for flaw sizing and characterisation in ultrasonic time-of-flight diffraction (TOFD)

摘要

Ultrasonic time-of-flight diffraction (TOFD) is known as a reliable non-destructive testing technique for the inspection of weld defects in steel structures. However, the critical stages of data processing and interpretation in TOFD are still performed manually and offline. This is subject to inevitable human errors due to reduced alertness arising from operator fatigue and visual strain when processing large volumes of data. Manual interpretation focuses only on the compression wave portion of the collected TOFD data and overlooks the mode-converted region. Even automatic or semi-automatic TOFD interpretation methods still consider the mode-converted data as irrelevant and redundant. This paper shows some possible employments and utilisations of the data included in the mode-converted returns for accurate sizing and characterisation of weld flaws in D-scans. The results achieved so far have been promising in terms of accuracy, consistency and reliability, and the devised methods are now under thorough investigation to explore their potential further.