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Portable Generator to Detect Cracks on Large Steel Structures: An Application of Inductive Thermography

Toasa Caiza, Paul Dario; Schwendemann, Rüdiger 1; Calero, Paola 2; Ummenhofer, Thomas 2
1 Karlsruher Institut für Technologie (KIT)
2 Versuchsanstalt für Stahl, Holz und Steine (VAKA), Karlsruher Institut für Technologie (KIT)

Abstract:

The demand of non-destructive methods to detect cracks caused by fatigue or brittle behavior in large steel structures has increased in the last years. Thermography based on electromagnetic induction is a promising method to detect cracks in weld seams and notches. This paper presents a portable experimental setup, which allows to perform in situ crack detection tests on large steel structures. The success of this configuration is based on the use of a highly efficient switched H-Bridge circuit, which can generate a square-wave output voltage with a fundamental frequency up to 100 kHz. Due to the low losses and the low necessary DC-link voltage, the circuit can be supplied by a lithium-ion battery, which allows a small and light setup. The generated square-wave output voltage supplies an air coil resulting in a high frequent triangle current. The induced electromagnetic field caused by the current signal generates eddy currents in the steel structure. Due to an increased current density of the eddy currents in the crack area, there is a measurable temperature increase near the crack. The resulting temperature field is visualized and recorded with an infrared (IR) camera, which shows in real time the occurrence of cracks.


Verlagsausgabe §
DOI: 10.5445/IR/1000136096
Veröffentlicht am 09.08.2021
Cover der Publikation
Zugehörige Institution(en) am KIT Elektrotechnisches Institut (ETI)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 0195-9298, 1573-4862
KITopen-ID: 1000136096
Erschienen in Journal of Nondestructive Evaluation
Verlag Springer
Band 40
Heft 3
Seiten 63
Nachgewiesen in Dimensions
Scopus
Web of Science
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