Detection and characterisation of short fatigue cracks by inductive thermography

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung


Inductive thermography can be excellently used to detect surface cracks in metals. A short induction heating pulse (0.1-1s) induces eddy currents in the sample and an infrared camera records the surface temperature distribution. As cracks disturb the eddy current distribution and the heat diffusion, they become visible in the infrared images. In this paper it is investigated, how different parameters influence the surface pattern around short cracks (0.5-12mm length). The main emphasis is on finite element simulations, but some experimental results are presented, too. The influence of crack geometry, as crack depth, length, inclination angle and crack shape below the surface are investigated for ferro-magnetic and austenitic steel. Around the crack tips high temperature ‘hot spots’ can be observed, which intensity increases with the crack depth. But this intensity is strongly affected by the crack shape, whether it is rectangular, trapezoid or half-penny shape. For longer cracks (6-8mm length) simulation results show, that in the middle of the crack the phase distribution can be used to estimate the crack depth. Furthermore, the effect of experimental parameters, as excitation frequency, heating pulse duration and the angle between crack line and induction coil are investigated in order to optimize an experimental setup.
FachzeitschriftQuantitative InfraRed Thermography Journal
Frühes Online-Datum28 Juli 2021
PublikationsstatusElektronische Veröffentlichung vor Drucklegung. - 28 Juli 2021

Bibliographische Notiz

Funding Information:
This project has received funding from the Clean Sky 2 Joint Undertaking (JU) under grant agreement Nº. 101007699. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Clean Sky 2 JU members other than the Union.

Publisher Copyright:
© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

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