Development of a Novel Electromagnetic Technique for Detection of Cracks by Use of Micro Antenna

Abstract

When alternating current is applied to paramagnetic materials, such as austenitic stainless steels or aluminum alloys, the existence of cracks on the material surface or subsurface causes changes in current flow around them and, as a result, electromagnetic wave generated with this change in current flow can be detected on or near surface of a material. In this case, there is a possibility for detection of these defects by detecting electromagnetic wave by antenna. Hence, the measurements can be done without contact or without removing paint. In this paper, first results on detection of electromagnetic wave around defects with shielded loop antenna is described with a principle of this novel NDI method.