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@PHDTHESIS{Martens:851034,
author = {Martens, Ulrike Silke},
othercontributors = {Schröder, Kai-Uwe and Widemann, Martin},
title = {{T}owards a reliable fatigue life prediction in metallic
crack patching},
volume = {4/2021},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Düren},
publisher = {Shaker Verlag},
reportid = {RWTH-2022-07896},
isbn = {978-3-8440-8691-1},
series = {Aachener Berichte aus dem Leichtbau},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2022},
note = {Druckausgabe: 2022. - Auch veröffentlicht auf dem
Publikationsserver der RWTH Aachen University; Dissertation,
RWTH Aachen University, 2021},
abstract = {The topic of "Ageing Aircraft" is one of the big issues in
today's operational aircraft. Fatigue cracks for instance
are of great concern when looking at old metallic aircraft
structures. [1, 2] Increasing the aircraft's operational
service life in terms of flight hours and flight cycles is
of great interest not inly from a financial point of view.
Contemporary demands for sustainability are of great concern
in aviation industry. The aim to the delay the replacement
of cracked components and to reduce inspection times and
effort results in the need for effective and lasting repair
methods. Adhesively bonded repair patches made of fibre
reinforced polymers (FRP) can restore the component's
structural integrity without structural degradation.
Research into metallic crack patching goes back to the
1980s. Since then, effective design methods have been
developed and improved to a very high level of accuracy. The
majority of today's research still focuses on the general
verification of patch efficiency and the improvement of the
preliminary patch design methods. But, the actual difficulty
is the reliable service life prediction. Cyclic mechanical
loading combined with continuously changing environmental
influences can significantly detract the repair's
functionality over time. Hence, fatigue life assessments
using the initial repair properties is limited due to their
degrading characteristics. However, a full exploitation of
the potential on the other hand can only act up with a
reliable fatigue life prediction. In a comprehensive
analysis of the design process the present study reveals
effective starting points for prospective research. It shows
why additional studies on patch effectiveness cannot lead to
improve the reliability of bonded patches. With a coupon
test series the theory is supported that the effect of even
more precise preliminary patch design methods is
insignificant concerning service life extension and that the
focus of future studies has to be set on the assessment of
service loads and their impact on the structural integrity.
To this, a concluding test series shows how the method of
infrared thermography enables significant improvements in
the comprehension of the fatigue behaviour of a crack
patched metallic structure.},
cin = {415610},
ddc = {620},
cid = {$I:(DE-82)415610_20160301$},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2022-07896},
url = {https://publications.rwth-aachen.de/record/851034},
}
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