Predicting probe impedance change in eddy current nondestructive testing using finite elements

In recent times, the desire to extend the service life of aerospace structures to offset the cost of replacement has led to an increase in the need to accurately predict the state of a structure by means of nondestructive evaluations. One such type of inspection is that of eddy current nondestructive inspection. The inspection is however difficult, and the data interpretation requires a great deal of expertise and experience with these types of systems. In order to solve some of these problems the use of numerical models has been extensive and in particular, the modeling of eddy current nondestructive evaluation problems has been the subject of much research over the past few decades. The advent of faster computers has made the process of simulating the full three-dimensional space and the eddy current nondestructive inspection of parts feasible. However, in order to achieve full automation of the eddy current nondestructive inspection the availability of accurate models to predict the expected change of probe impedance due to a flaw within a structure are required. The purpose of such models is to generate quality synthetic data which can, in some cases, be used to aid in the evaluation of data collected during the inspection process. The study presented in this dissertation probes the state of the art in eddy current modeling by making use of a commercially available finite element software package and examining the compromises which must be made in order to generate quality synthetic data in a reasonable amount of time