Continuous acoustic emission source location in pipeline using time reversal signal processing

0519749 - ÚT 2020 RIV CZ eng A - Abstract
Převorovský, Zdeněk - Krofta, Josef - Chlada, Milan - Kober, Jan
Continuous acoustic emission source location in pipeline using time reversal signal processing.
NDT in Progress 2019. Praha: Ústav termomechaniky AV ČR, v. v. i., 2019 - (Převorovský, Z.). s. 125. ISBN 978-80-87012-72-7.
[NDT in Progress 2019 /10./. 07.10.2019-10.10.2019, Praha]
R&D Projects: GA ČR(CZ) GA17-22615S
Institutional support: RVO:61388998
Keywords : continuous AE * source location * pipe elbow, waveguides * time reversal
OECD category: Materials engineering

Reliable location of Acoustic Emission (AE) sources is one of the most important inverse problems in non-destructive testing (NDT) and structural health monitoring (SHM) of engineering structures.
Standard AE source localization procedures often fail at more complicated structures with wave dispersion, velocity or geometry changes, etc. Localization of continuous AE signals generated by
leakage, i.e. random noise is much more difficult than that of short burst signal sources. Eeffective tool for all such situations is time reversal (TR) signal processing [1], which results in space - time
wave focusing, partial source signal reconstruction and more precise source location than other used techniques (up to 1 mm). After artificial AE source location tests on various plates, reported in
[1], we applied TR technique on large steam pipeline (4140 x 245 x 37.5 mm) and small pressure vessels to prove its practical use under real industrial conditions. Leakages were simulated with
random noise signals emitted by piezoelectric transducers. AE signals were recorded during the real leaks on power plant. Those signals were overlapped with other more intensive signals reproducing
real large background noise on power plant (water flow in the pipe). Noise mixture was detected by AE transducers mounted on 1m long waveguides welded to the tested structure. Long signals from two transducers were recorded, time reversed and rebroadcast to the structure using reciprocal TR method. Maximum of their cross-correlation denotes the leakage source on structure surface. More
detailed surface scanning around roughly pre-localized source was necessary to precise localization. Scanning can be realized e.g. by scanning laser interferometer or numerically in a perfect computer model of the structure.
Permanent Link: http://hdl.handle.net/11104/0304939