Detection of short fatigue cracks by inductive thermography

Oswald-Tranta, Beate; Feistkorn, Sascha; Rössler, Gerd; Tuschl, Christoph; Scherrer, Michael

doi:10.21611/qirt.2020.033

Cited by 1 publication

(5 citation statements)

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“…In Figure 19a, the sample is ferro-magnetic and the crack length is about 12 mm long and has approximately a depth of 1 mm [20]. In Figure 19b the sample is austenitic steel and the fatigue crack has approximately a half-penny shape and a depth of 1.5 mm [19].…”

Section: Resultsmentioning

confidence: 99%

“…The whole crack side is selectively heated, causing a higher temperature along the line of the crack. Additionally, around the tip of the crack a high current density occurs, hence here a hot spot can be observed in the temperature image, see Figure 2b [20].…”

Section: Simulation For Short Cracks and Phase Imagesmentioning

confidence: 88%

“…This dependency on the crack depth has been intensively investigated in the last years for long cracks [14,18], which were simulated in 2D models, neglecting the influence of the crack length at the surface. Short, vertical cracks were investigated in austenitic steel [19] and in ferromagnetic steel [12,20], but this paper presents an extensive study of short cracks using finite element simulations. First a short introduction about induction thermography is given.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 3. Temperature distribution after 0.1 s heating around a 10 mm long and 1 mm deep crack in ferro-magnetic steel (a) and in austenitic steel (b); phase images for the same cracks: (c) in ferromagnetic steel and (d) in austenitic steel; phase images for a short crack with 2 mm length and 1 mm depth in ferro-magnetic steel (e) and in austenitic steel (f)[20].…”

mentioning

confidence: 99%

“…Figure19. a: Phase image of a 12 mm long crack in ferro-magnetic steel sample after 0.1 s heating pulse duration; b: phase image of a 6 mm long fatigue crack in austenitic steel after 0.5 s heating pulse duration[19,20].…”

mentioning

confidence: 99%

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Detection and characterisation of short fatigue cracks by inductive thermography

Oswald-Tranta

2021

Quantitative InfraRed Thermography Journal

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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.

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Section: Resultsmentioning

confidence: 99%

Section: Simulation For Short Cracks and Phase Imagesmentioning

confidence: 88%