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Acoustic emission for fatigue crack monitoring in nuclear piping system

Mohd, Shukri 2013. Acoustic emission for fatigue crack monitoring in nuclear piping system. PhD Thesis, Cardiff Univeristy.

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Accurate Acoustic Emission (AE) source location is crucial for monitoring the thermal fatigue crack in nuclear piping systems. Conventional Time of Arrival (TOA) location techniques can provide estimated location of fatigue cracks but are not accurate enough to allow crack size estimation. This thesis examines the role of AE as a Non-destructive Testing (NDT) tool for thermal fatigue damage monitoring in nuclear piping system. The work focuses on developing an accurate AE source location technique. The works is divided into three main areas of research: 1. Development of Wavelet Transform analysis and Modal Location (WTML) method A novel location method was successfully developed using modal location theory and wavelet transform analysis. Source location was performed on a steel plate of 790 x 300 mm with nominal thickness of 5 mm under a planar location setup using H-N sources. The accuracy of the new technique was compared with the major location methods (the time of arrival (TOA) technique, triple point filtering and DeltaT location methods). The result of the study shows that the WTML method produces more accurate location result compared with other AE location methods. 2. Validation of WTML method for accurate location of fatigue crack growth in steel plate Laboratory fatigue tests were conducted on steel plate in order to monitor and locate fatigue crack growth, and validate the workability of WTML method. WTML was successful in locating the AE signal released from fatigue crack growth. The accuracy of WTML is much better than TOA, DeltaT and triple point filtering location methods. 3. Crack size measurement using WTML method The capability of the WTML location method to measure crack length due to fatigue crack growth under tensile-tensile loading is investigated. The WTML method successfully used to determine the crack length in the steel pipe with the maximum measurement error of 5 mm. Key Words: Acoustic Emission, Damage detection, Fatigue Crack Growth, Source location, Modal Analysis, Wavelet Transform Analysis, Crack-length measurement

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Engineering
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Last Modified: 19 Mar 2016 23:20

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