APPLICATION OF A DIFFUSION-TO-WAVE TRANSFORMATION FOR INVERTING EDDY-CURRENT NONDESTRUCTIVE EVALUATION DATA

A transformation from diffusion fields to wave fields is examined as a n approach to inverting eddy current nondestructive evaluation (NDE) d ata, An analytic inversion to the transformation is used as a means to gain insight into robustness issues associated with the method, A dis cretized version of the transformation is utilized to solve a 1-D inve rse problem with a direct ''wave-based'' approach, Because the transfo rmation lacks robustness, two regularization schemes are used to stabi lize the inversion, which ate themselves enhanced by an averaging algo rithm, The technique is shown to be unstable when applied to sources w hich are not ideal impulse functions; in which case the transformation can be stabilized via low-pass filtering, The transformation is not u seful with time-harmonic sources and is therefore limited to pulsed ed dy current inspections.