Phenomenological approaches based on an integral formulation for forward and inverse problems in eddy current testing

Linear and nonlinear numerical formulations for an efficient solution of forward and inverse problems are summarized. The simulation tool is based on an integral formulation in terms of a two-component current density vector potential expanded over edge-elements. The methods are applied to the numerical simulation of a magnetic field sensor as well as to the crack simulation and detection via eddy current testing (ECT), comparing the results to the experimental measurements. The class of problems treated includes both thin and thick cracks in metallic plates, taking into account the possible presence of leakage in the crack as well as magnetic materials. The inversion of ECT data is carried out by means of genetic algorithms or methods, based on algorithms developed for digital communications, that allow to reduce the computational cost for the solution of the inverse problem.