Experimental evaluation of electromagnetic-thermal non-destructive inspection by eddy current thermography in square aluminum plates

The performance of electromagnetic-thermal non-destructive inspection is investigated experimentally by eddy current thermography. The experiments concerned the detection of the crack in ten square aluminum plates at various positions and orientations. For the excitation are employed two circular coils with an outer diameter either smaller or comparable to the plate side. Crack detection is based not only on the thermograms, but on data processing techniques as well. Despite the fact that the performance of the infrared camera used is relatively low and the exciting frequency was only 50 Hz, the coil with small section detected effectively the nine cracks out of the ten while the coil with large section detected effectively seven out of ten. ► Detection of cracks in square aluminum plates by eddy current thermography. ► Coil diameter either smaller or comparable to the plate side; exciting frequency low. ► Crack detection based on the thermograms and on data processing techniques as well. ► The small coil detects nine cracks out of ten, the large coil seven out of ten.