A two-step algorithm for finite-element solution of electromagnetic-testing problems: Eddy-current testing

An algorithm for finite-element simulation of eddy-current testing problems is described. This algorithm allows calculation of transducer signals from any 3D flaw in a metallic item. In practice, the studied flaws are often characterized by small dimensions. Therefore, the measured increment of the voltage induced in the transducer’s output winding owing to the presence of such a flaw is only several percent of the voltage’s average value. If a standard calculation scheme based on the finite-element method is applied, significant computational resources are needed to solve this problem. The two-step algorithm allows a significant reduction in the required resources. The essence of the algorithm is that the source of the field of a flaw’s effect is determined from the distribution of eddy currents in metal free of flaws. Such an approach allows the calculations of the “unperturbed field” to be simplified significantly through consideration of the geometric symmetry of the problem solved and thus, through reduction of its dimensionality. The efficiency of the two-step algorithm is demonstrated during the solution of a typical problem: the use of a through differential transducer for eddy-current testing of a segment of a heat-exchange pipe in the steam generator of a nuclear power plant.