@article{Cawley:2020:10.1177/1475921719882330,
author = {Cawley, P and Chua, C},
doi = {10.1177/1475921719882330},
journal = {Structural Health Monitoring: an international journal},
pages = {1311--1322},
title = {Crack growth monitoring using fundamental shear horizontal guided waves},
url = {http://dx.doi.org/10.1177/1475921719882330},
volume = {19},
year = {2020}
}

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TY  - JOUR
AB  - Monitoring cracks in critical sections of steel structures is a topic of growing interest. Existing high frequencyultrasonic techniques have good detection sensitivities but poor inspection coverage, requiring an impractical numberof transducers to monitor large areas. Low frequency guided waves are used for corrosion detection in pipelines,but are insufficiently sensitive for many crack detection applications. The sensitivity can be improved by using higherfrequencies and by placing the receiving transducers closer to the defect. This study evaluates the monitoringperformance of an SH0 mode system at frequencies just below the high-order mode cut-off. Baseline subtractionwith temperature compensation was applied to experimental data generated by a ring of transducers on a 6-inchdiameter pipe. It was found that the residual signals after baseline subtraction were normally distributed so therandom fluctuations could be reduced by coherent averaging; it was thereby possible to reliably detect a 2x1 mmnotch simulating a crack located one pipe diameter along the pipe from the transducer ring. The damage detectionperformance at different locations along the pipe was assessed by analysing receiver operating characteristic (ROC)curves generated by adding simulated defects to multiple experimental measurements without damage. At a fixedstandoff distance, the damage detection performance increases with the square root of the number of averaged signals,and is also improved by averaging the signals received by transducers covering the main lobe of the reflection fromthe defect. When the defect is located more than about one pipe circumference from the transducer ring, the optimalperformance is obtained by averaging across all the transducers in the ring, corresponding to monitoring the T(0,1) pipemode. Therefore, an SH0 mode monitoring system has great potential for crack monitoring applications, particularly forwelds in pipes.
AU  - Cawley,P
AU  - Chua,C
DO  - 10.1177/1475921719882330
EP  - 1322
PY  - 2020///
SN  - 1475-9217
SP  - 1311
TI  - Crack growth monitoring using fundamental shear horizontal guided waves
T2  - Structural Health Monitoring: an international journal
UR  - http://dx.doi.org/10.1177/1475921719882330
UR  - https://journals.sagepub.com/doi/10.1177/1475921719882330
UR  - http://hdl.handle.net/10044/1/73665
VL  - 19
ER  - 

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