Microwave Measurement-Parameter Optimization for Detection of Surface Breaking Hairline Cracks in Metals

Fatigue and stress induced hairline surface crack detection in metals is an important practical issue. A newly developed microwave inspection approach, using an open-ended rectangular waveguide, has proved to be an effective tool for detecting such cracks. This novel microwave approach overcomes some of the limitations associated with the standard detection methods for surface crack detection. In addition, this approach is applicable to exposed and filled cracks (with a dielectric such as dirt, rust, etc.), and cracks under dielectric coatings such as paint and composite dielectric laminates. This paper briefly presents the basic foundation of this surface crack detection methodology. More importantly, this paper focuses on the ways by which measurement parameters may be optimized for increased crack detection sensitivity. Theoretical as well as experimental results are provided.