Application of Reverse-Time Migration to Ultrasonic Echo Data in Nondestructive Testing

  • Ultrasonic echo testing is widely used in non-destructive testing to investigate concrete structures as well as to locate built-in components or inhomogeneities. Currently, Synthetic Aperture Focusing Technique algorithms (SAFT) are used for imaging. These algorithms are highly developed but have some limitations. It is not possible to image the lower boundary of tendon ducts or vertical reflectors. We adopted a geophysical imaging technique, the Reverse Time Migration (RTM), to non-destructive testing in order to improve the imaging of complicated structures in concrete. By using the entire wavefield there are fewer limitations compared to SAFT. In a first step, simulations for polyamide and concrete structures were performed by using a 2D acoustic finite difference code. The simulations were followed by experiments at a polyamide specimen. Here we were able to determine shape and size of boreholes with a sufficient accuracy. After these successful tests we carried out experimentsUltrasonic echo testing is widely used in non-destructive testing to investigate concrete structures as well as to locate built-in components or inhomogeneities. Currently, Synthetic Aperture Focusing Technique algorithms (SAFT) are used for imaging. These algorithms are highly developed but have some limitations. It is not possible to image the lower boundary of tendon ducts or vertical reflectors. We adopted a geophysical imaging technique, the Reverse Time Migration (RTM), to non-destructive testing in order to improve the imaging of complicated structures in concrete. By using the entire wavefield there are fewer limitations compared to SAFT. In a first step, simulations for polyamide and concrete structures were performed by using a 2D acoustic finite difference code. The simulations were followed by experiments at a polyamide specimen. Here we were able to determine shape and size of boreholes with a sufficient accuracy. After these successful tests we carried out experiments at a reinforced concrete foundation slab. The reconstruction of the structure of the lower boundary of the slab was improved and vertical reflectors inside the slab were imaged clearly. These tests on polyamide and concrete showed that RTM is a step forward for ultrasonic testing. However we observed migration artifacts and difficulties in imaging 3D structures. In a second step we implemented a 2D elastic RTM code, since for our ultrasonic measurements elastic waves are emitted. The modeling code is included in the Madagascar software package. The required computing power for performing elastic RTM is significantly high. Thus we need appropriate computer hardware to obtain meaningful results within an adequate time frame. Using our hardware RTM of an ultrasonic data set takes far too long (3 months). We applied the elastic code to ultrasonic data acquired on a concrete specimen which contains vertical reflectors. A comparison of the acoustic RTM results with those obtained by elastic RTM showed an improvement in the image quality. Future work includes the analysis of RTM artifacts and the expansion of the algorithm to three dimensions. Another topic to be addressed is to how to account for the size of the ultrasonic transducer arrays which we are using.zeige mehrzeige weniger

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Metadaten
Autor*innen:Maria Grohmann
Koautor*innen:Ernst Niederleithinger
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2017
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Nondestructive Testing; Ultrasonic Echo Technique
Veranstaltung:Future Soc Lab Day am Hasso Plattner Institut
Veranstaltungsort:Potsdam, Germany
Beginndatum der Veranstaltung:25.04.2017
Enddatum der Veranstaltung:25.04.2017
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:02.05.2017
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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