Studies in Applied Electromagnetics and Mechanics vol:27
Electromagnetic Fields in Mechatronics, Electrical and Electronic Engineering pages:247-253
This paper deals with a new 3D finite element scheme for nondestructive eddy-current testing (ECT) problems. It concerns a perturbation technique applied to the magnetodynamic h − φ formulation. The unperturbed field (in the absence of the flaw) is computed conventionally in the complete domain. The source of the perturbation problem is determined by the projection of the unperturbed field in a relatively small region around the defect that depends on the work frequency. The discretisation of this reduced domain is adapted to the size of the defect and independent of the discretisation of the complete domain. The impedance change is computed by integrating only over the defect and a layer of elements in the reduced domain that touch its boundary. As test case, we consider the second eddy current benchmark problem proposed by the WFNDEC. It involves a pancake coil scanning the inner surface of a metal tube for the detection of flaws on the outer surface.