Non-destructive testing of carbon-fiber-reinforced polymer composites with coupled spiral inductors

A new type of an electromagnetic sensor for nondestructive testing of carbon-fiber-reinforced polymer composites, based on coupled planar spiral inductors, is presented. The sensor operates in the range of 10 - 500 MHz, where the largest detectability of buried defects is expected. The new method shows some similarity to the eddy currents technique but the principles of operation are different as the sensitivity to possible defects is mostly due to a magnetic field horizontal to the surface of the material. One of advantages is the applicability of the method to a three-dimensional inspection of the carbon-fiber-reinforced composites.