Recent developments in vibrothermography

Due to the sensitivity of fluorescent penetrant inspection to surface roughness of the inspected material, researchers have been investigating alternative inspection methods. Vibrothermography is one of the contactless non-destructive testing methods in which vibration pulses with high frequencies (typically 20-40 kHz) are used in a part for a short period of time to produce thermal gradient at the defect. In this technique, thermographic or infra-red cameras are used for radiation detection due to thermal gradient in the range of 0.9-14 µm electromagnetic spectrum. This paper focuses on the recent developments in vibrothermography. It covers basics, history, equipments used, types, materials, probability of detection, principle of heat generation mechanism and factors that affect detectability in vibrothermography.