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@PHDTHESIS{Mller:967999,
author = {Müller, Sabine},
othercontributors = {Niederleithinger, Ernst and Reicherter, Klaus},
title = {{W}eiterentwicklung der {R}everse {T}ime {M}igration zur
{A}nwendung auf {U}ltraschall-{E}cho-{D}aten in der
zerstörungsfreien {P}rüfung},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2023-08382},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2023},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2023},
abstract = {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.},
cin = {532610 / 530000 / 080052},
ddc = {550},
cid = {$I:(DE-82)532610_20140620$ / $I:(DE-82)530000_20140620$ /
$I:(DE-82)080052_20160101$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2023-08382},
url = {https://publications.rwth-aachen.de/record/967999},
}
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