Improvement of the frequency behavior of an EC-NDT inspection system

The non-destructive testing based on eddy currents (EC-NDT) is an infield inspection technique mainly used to detect and characterize defects in conductive materials. This technique is adopted in many industrial, manufacturing and aerospace applications. Today, in aeronautical and industrial applications, new thin carbon fiber materials often substitute metallic materials as aluminum, copper and so on. Therefore, the actual trend of EC-NDT is the in-field inspection of these very thin materials. Considering the skin depth of induced eddy current, the thinness of these materials imposes the use of higher frequencies than those typically adopted in traditional tests. Due to the inductive load of the excitation coil, the voltage required to obtain the desired current values could reach very high values. The use of resonant excitation circuits couldmitigate this problem. The article describes the effect of some real resonant circuits on the improvement of feeding high-frequency EC-NDT probes in terms of required voltage and power.