Diffusion effects in eddy current nondestructive evaluation

NDE data fusion using phenomenological approaches

“…One group of scholars had chosen to treat eddy currents as an electromagnetic wave phenomenon and process the signal using wave based approaches [4,5,7,8,9]. The other side of the debate treats eddy currents as a diffusion process [12]. The discussion presented in this section reinforces the statement that the eddy current process is a diffusion process and that the use of wave based approaches to process eddy current signals can lead to erroneous results.…”

“…The coil is scanned across the surface of the test specimen to detect the presence of any flaws. In the case of a point flaw, the coil picks up the flaw signal over a range larger than the coil size[12]. In other words, even for a tiny flaw, the support of the flaw signature is at least equal to the coil diameter.…”