Finite Element Modeling of Eddy Current Probes for Edge Effect Reduction

Abstract

Eddy current methods are a widely used technique in the nondestructive inspection of aircraft structures and parts. The method consists of inducing eddy-currents in the material being tested using a probe coil. The magnetic field produced by these eddy-currents opposes that of the probe coils (Lenz’s law) and the net effect is a reduced magnetic flux linking the coil. The presence of defects in the material under test disturbs the distribution of eddy-currents which in turn disturbs the net field. This change in the field is detected as a change in the impedance of the coil. The changes in coil impedance measured as the probe scans the specimen contitutes an eddy current defect signal.