A perturbation method for calculating coil impedance in eddy-current testing

Publisher Website
Google Scholar
Abstract
A perturbation expansion for the impedance of a coil carrying constant-amplitude alternating current in the vicinity of a conductor is presented. The expansion, which is valid in the limit of small skin depth ( delta ), is developed in terms of the solution to the more tractable problem involving perfect conductors where delta =0. It is shown that the impedance calculated in this way agrees to first order with the exact expressions in both the case of a current loop and line current above a conducting half-space. The method is applied to the cases of (i) a two-dimensional conducting wedge and (ii) a slot in a conducting half-space, which simulate an edge and surface-breaking crack respectively. The results for a right-angled edge were compared with experiment and found to be in good agreement.

This publication has 7 references indexed in Scilit: