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Appl. Sci. 2018, 8(2), 257;

Induction Thermography for Surface Crack Detection and Depth Determination

Institute for Automation, University of Leoben, Leoben A-8700, Austria
Received: 15 December 2017 / Revised: 2 February 2018 / Accepted: 6 February 2018 / Published: 9 February 2018


In the last few years, induction thermography has been established as a non-destructive testing method for localizing surface cracks in metals. The sample to be inspected is heated with a short induced electrical current pulse, and the infrared camera records—during and after the heating pulse—the temperature distribution at the surface. Transforming the temporal temperature development for each pixel to phase information makes not only highly reliable detection of the cracks possible but also allows an estimation of its depth. Finite element simulations were carried out to investigate how the phase contrast depends on parameters such as excitation frequency, pulse duration, material parameters, crack depth, and inclination angle of the crack. From these results, generalized functions for the dependency of the phase difference on all these parameters were derived. These functions can be used as an excellent guideline as to how measurement parameters should be optimized for a given material to be able to detect cracks and estimate their depth. Several experiments on different samples were also carried out, and the results compared with the simulations showed very good agreement. View Full-Text
Keywords: thermography; induction heating; crack detection; crack depth thermography; induction heating; crack detection; crack depth

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Oswald-Tranta, B. Induction Thermography for Surface Crack Detection and Depth Determination. Appl. Sci. 2018, 8, 257.

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