Analysis of Some Nondestructive Evaluation Experiments Using Eddy Currents

Nondestructive evaluation (NDE) is often conducted by inducing eddy currents in the materials to be examined, and characterizing those currents by the magnetic fields that they produce. Most papers describe experimental results produced by such methods; very few theoretical approaches have been proposed. In the present article, we develop some particularly very simple but ad-hoc analytical studies, notably in the case of various calibrated flaws such as cracks. The validity of the models has been checked with a classical High Tc radio frequency SQUID, which is described. Theory and measurement have been found to be in good agreement.