Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Weiterentwicklung der Reverse Time Migration zur Anwendung auf Ultraschall-Echo-Daten in der zerstörungsfreien Prüfung
Ultrasonic measurements in non-destructive testing are used to determine the size of structural elements and to locate and characterise components and inhomogeneities. State of the art for reconstruction are methods like 3D-SAFT (Synthetic Aperture Focusing Technique). These algorithms require only direct reflections from objects. It is impossible to get reliable information on the diameter of tendon ducts or vertical boundaries of objects because these can only be imaged using multiple reflections. Reverse Time Migration is a commonly used imaging method in exploration geophysics. With this method, it is possible to image steep structures with an incidence angle larger than 70° like steps or the bottom of components. In this thesis, the capability of the Reverse Time Migration for non-destructive testing is shown using simulated data. It was possible to image the full perimeter of a hole in a simulated object. Ultrasonic measurements were performed on a polyamide specimen to verify the results of the simulations with low noise data. A hole was drilled into the specimen and the size of the hole was increased stepwise. Measurements were made for each step. Position, size and diameter were imaged accurately and the applicability of the Reverse Time Migration in non-destructive testing was proven. In the next step, laboratory measurements on a concrete model were performed. A tendon duct was imaged in position, size and diameter. First results of a measurement on a bridge show that it is possible to locate a rectangular tendon duct. Unfortunately it was impossible to image the bottom of it due to missing multiple reflections and attenuation. The results of the simulations and the measurements show a clear advantage over the SAFT algorithms used so far. Further work must be done to improve the quality of the measurements and the images. Especially on concrete the influences of noise because of the aggregates and the attenuation are high. This can be seen in the results of the measurements of the bridge.
Weiterentwicklung der Reverse Time Migration zur Anwendung auf Ultraschall-Echo-Daten in der zerstörungsfreien Prüfung
Ultrasonic measurements in non-destructive testing are used to determine the size of structural elements and to locate and characterise components and inhomogeneities. State of the art for reconstruction are methods like 3D-SAFT (Synthetic Aperture Focusing Technique). These algorithms require only direct reflections from objects. It is impossible to get reliable information on the diameter of tendon ducts or vertical boundaries of objects because these can only be imaged using multiple reflections. Reverse Time Migration is a commonly used imaging method in exploration geophysics. With this method, it is possible to image steep structures with an incidence angle larger than 70° like steps or the bottom of components. In this thesis, the capability of the Reverse Time Migration for non-destructive testing is shown using simulated data. It was possible to image the full perimeter of a hole in a simulated object. Ultrasonic measurements were performed on a polyamide specimen to verify the results of the simulations with low noise data. A hole was drilled into the specimen and the size of the hole was increased stepwise. Measurements were made for each step. Position, size and diameter were imaged accurately and the applicability of the Reverse Time Migration in non-destructive testing was proven. In the next step, laboratory measurements on a concrete model were performed. A tendon duct was imaged in position, size and diameter. First results of a measurement on a bridge show that it is possible to locate a rectangular tendon duct. Unfortunately it was impossible to image the bottom of it due to missing multiple reflections and attenuation. The results of the simulations and the measurements show a clear advantage over the SAFT algorithms used so far. Further work must be done to improve the quality of the measurements and the images. Especially on concrete the influences of noise because of the aggregates and the attenuation are high. This can be seen in the results of the measurements of the bridge.
Weiterentwicklung der Reverse Time Migration zur Anwendung auf Ultraschall-Echo-Daten in der zerstörungsfreien Prüfung
Müller, Sabine (Autor:in) / Niederleithinger, Ernst / Reicherter, Klaus
01.01.2023
Aachen : RWTH Aachen University 1 Online-Ressource : Illustrationen, Diagramme (2023). doi:10.18154/RWTH-2023-08382 = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2023
Hochschulschrift
Elektronische Ressource
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