Microwave detection of surface cracks under dialectric coatings using open-ended coaxial sensors

摘要

Open-ended ractangular waveguked sensors have been proven a poweful approach in metal surface crack/slot detection. With these sensors remote and in-contact measuremtns are possible. However, the physical dimensions of such sensors are relatively arge, and inspection of hard to reach places becomes difficult or even impossible. An alternative approach has been developed at the Applied Microwave Nondestructive Testing Laboratory, Colorado State University. Hence, in order to overcome some of these difficulties, open-ended coaxial sensors are utilized. This sensor can be readily shaped to accommodate various environments of inspection, such as around rivets, within tubes or cavities with a small opening. These sensors are highly sensitive to cracks in the micrometer range, evan at relatively low microwave frequencies. This paper presents some preliminary experimental results of measurements on coated metal surfaces with open-ended coaxial sensors.