Application of Open-Ended Rectangular Waveguides for Detecting Surface Cracks

Surface crack detection in metallic structures is an important issue in many environments (such as steel bridge members) and industries. A relatively new microwave method of detection using an open-ended rectangular waveguide has shown great practical promise. This method is quite versatile and may be applied to long, finite, filled, and covered cracks. Furthermore, crack dimensional analysis is also possible with this method. The measured and theoretical results of several exposed, filled, and covered cracks/slots are shown in this paper. Furthermore, a new theoretical approach to model the interaction of the waves incident at the waveguide aperture and a metal surface with a crack are very briefly mentioned as well. The results show the utility of this method for detecting filled and covered cracks as well as cracks separated from the waveguide aperture by a slight amount of airgap (i.e. noncontact approach)