Numerical Analysis of a Dahle-Probe Response to a Hidden Point Flaw

We propose a method to analyze the response of a Dahle-probe to a hidden point flaw. Eddy-current density distribution due to the probe is calculated numerically by using the superposition principle. We modeled the flaw-eddy current interaction by using a pair of circular currents. An analytical expression for the magnetic vector potential produced by a circular current was also developed and the induced voltage measured by the probe pickup coils was numerically calculated. The method has been extended to a pair of point flaws and a long flaw. Finally, we compared the results of numerical calculation with the experimental results which showed a very good agreement. The validity of the method to predict the produced pattern was confirmed by the experiments