Effect of Modulation Frequency on Detecting Metal Materials with Microcracks Based on Ultrasound Infrared Lock-in Thermography
The non-destructive ultrasound infrared lock-in thermography (ULT) testing method was used to detect metal specimens with defects of micro cracks. An experimental platform was built based on the analysis of the ULT principle. Experiments had been carried out to Q235 plates with different testing parameters. The testing effect of thermography, amplitude and phase images was analyzed, and the relations between amplitude difference, phase difference, signal-to-noise ratio and modulation frequency were discussed.
Q. J. Tang et al., "Effect of Modulation Frequency on Detecting Metal Materials with Microcracks Based on Ultrasound Infrared Lock-in Thermography", Advanced Materials Research, Vols. 314-316, pp. 1387-1390, 2011