A method for detecting through cracks in a railway wheel disc by thermal imaging has been developed. This technique was used to detect the time evolution of the temperature distribution on the wheel surface during heating by an infrared camera or a thermal imager operating in the wavelength range 8-12 or 2.8-3.05 micron. The wheel was heated from the rolling surface. It has been found that, during heating, the temperature jumps near the through crack and increases as the heating time increases. The temperature jump is caused by the high thermal resistance of the crack to the passing heat flow, which is due to the difference between the heat conduction coefficients of the wheel material and the air layer in the crack. The data confirm that 2- to 3-min heating at a heater power of ~270 W is sufficient for detecting a crack. In order to find the minimum heating time for crack detection, additional studies are required. During the experiments, it was found that external flare light of the object has a more significant effect on the images in the wavelength range 2.8-3.05 micron than in the range 8-12 micron.
Infrared diagnostics of cracks in railway carriage wheels
Infrarotdiagnose von Rissen in Personenzugrädern
Russian Journal of Nondestructive Testing ; 44 , 10 ; 664-668
2008
5 Seiten, 4 Bilder, 7 Quellen
Article (Journal)
English
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