FEM time domain analysis for the detection of depth and thickness of cylindrical defects in metallic plates

In this work, we will present a strategy for the evaluation of depth and thickness of defects like holes and cracks in metallic plates via the analysis of the response in frequency of a suitable eddy-current detection system. In order to obtain the data for the inversion in real time, the analysis in frequency domain is deduced by the analysis of the response of the system to an exciting rectangular voltage pulse of suitable length, according to the size of defect to detect. By finite element method numerical simulations in time domain of the detection system applied to known defect configurations, we have found some interesting information for the inverse problem solution. In this paper, we present the theory of the detection technique above mentioned and results about numerical and experimental analysis.