Electromagnetic Inspection of Carbon-Fiber- Reinforced Polymer Composites With Coupled Spiral Inductors

This paper presents a new type of an electromagnetic sensor for nondestructive testing of carbon-fiber-reinforced polymer composites. The sensor utilizes coupled planar spiral inductors operating typically in the range of 10-500 MHz. The method proposed here shows some similarity to the eddy current technique, but as will be shown, the principles of operation are different as the sensitivity to defects is mostly due to the magnetic field components tangential to the surface of a material. It is shown that the method is applicable to 3-D inspection of carbon-fiber-reinforced composites widely employed in the aerospace industry.