PSI - Issue 42

Guilherme Saldanha et al. / Procedia Structural Integrity 42 (2022) 631–638 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 5. Experimental setup for the NDT.

2.3. Thermography In relation to thermographic analyses, active thermography was considered using Joule effect; therefore, a direct current was furnished to the defective endodontic file in its extremities and the instrument was painted black, using a spray paint, in order to maximize its emissivity. The camera used was a Fluke Ti 400, with a precision of ± 2ºC, and a focal length of 8 cm (Fig. 6). Moreover, to isolate the thermal noise created by the clamps and the environment, cardboard plates were used to create a test window. In addition, SmartView software was used to process the thermal data obtained. This software allows, among other things, viewing and editing the thermograms frame by frame, selecting the most appropriate colour

scale and finding the pixels where the highest and lowest temperatures are found. The thermograms obtained at 3 moments of the test were analyzed (Fig. 6), namely: (1) - Heating Phase (2) - Thermal Equilibrium Phase (3) - Cooling Phase

Fig. 6. Experimental set-up: thermographic camera, thermal noise insulators; endodontic file, excitation source. Thermal cycle showing the three moments when the thermograms were analysed.