Eddy-Current Inspection Modelling of Symmetrical Work-Pieces Using Three-Dimensional Probes Based on a Mixed Numerical/Modal Formulation

A mixed numerical/modal approach is presented for the modelling of eddy-current inspection of work-pieces with translational or rotational symmetry. Introducing a modal expansion along the direction of invariance, the original threedimensional problem is decomposed into a number of planar ones, which are obtained by the projection of the original problem onto the modes eigenspace. The projected planar problems are then treated numerically using the finite integration technique. The main interest in proceeding to such decomposition relies on the simpler and conformal discretisation of the work-piece, the reduction of the numerical noise, as well as the smaller size of the linear system, which allows the simultaneous treatment of different probe positions.