Reference-free crack detection under varying temperature

Abstract

A new paradigm for damage diagnosis is proposed by developing a damage detection technique that eliminates the need for initially collected baseline data. Traditional techniques often identify damage by comparing the current data set with the reference data collected from the pristine condition of the structure being monitored. However, this conventional pattern comparison approach is shown to be vulnerable to other changes such as temperature variation that may not be relevant to defects of interest. One of potential advantages of the proposed reference-free approach is that false-alarm due to these undesirable variations could be minimized particularly for field applications where varying structural and environmental conditions impose significant challenges for damage diagnosis. In this paper, the effect of varying temperature on the previously developed reference-free crack detection technique is investigated using an aluminum plate with an increasing crack depth.

Data normalisation for Lamb wave–based damage detection using cointegration: A case study with single- and multiple-temperature trends

“…Various approaches have been developed to deal with the undesired temperature effect in Lamb wave responses, as discussed in Sohn (2007Sohn ( , 2011. The early proposed approaches are based on soft computing (Lee et al, 2003;Sohn et al, 2002).…”

Second-order harmonic generation of Lamb wave in prestressed plates

“…This study showed that the data processing becomes much easier when only one Lamb wave mode exists. Moreover, the excitation of S0 can be easily generated by using a common dual-transducer excitation method [54].…”

Bolted joint integrity monitoring with second harmonic generated by guided waves

“…17,18 In recent years, many studies using linear or nonlinear guided waves have been carried out and they focused on different damage types and materials. 19,20 For linear guided waves, Sohn 21 used the mode conversion technique to detect a notch on an aluminium plate. A reference-free damage detection method was introduced.…”