An investigation into eddy current pulsed thermography for detection of corrosion blister

This letter reports an investigation into eddy current pulsed thermography (ECPT) for detecting corrosion blister in mild steel. The detection mechanisms for various types of damage were addressed based on their interaction with eddy current distribution and heat conduction. Experimental studies showed that the blister and ruptured blister area can be easily monitored using conventional thermograms from an infrared camera. Signal processing algorithms were investigated to obtain new features. Principal components analysis (PCA), independent components analysis (ICA) and fast Fourier transform (FFT) were compared in the performance of blister detection. It was found that peak time was the best way to detect the blister and the extent of peak time increase was in the following sequence: blister ≫ intact area > ruptured blister. Several features can be specially used to separate the ruptured blister.