Separability of Multiple Deep Crack Defects With an NDE Eddy Current System

Finite element simulation was carried out to characterize the separability of an eddy current nondestructive testing (EC-NDT) system in the case of the detection of deep cracks located in an aluminum plate. The interaction among multiple cracks was also analyzed. The results show that the separability of the EC system not only depends on the sensitive element dimensions but also on different parameters of the system, such as the sensor lift-off, the excitation frequency and the cracks depth. Furthermore, the simulations show that under some conditions, the magnetic response sensed for multiple cracks can be calculated as the superposition of the signals obtained for each crack. This point essentially simplifies the solution of the inverse problem of crack reconstruction.