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Microwave Detection of Stress-Induced Fatigue Cracks in Steel and Potential for Crack Opening Determination



N Qaddoumi, E Ranu, Joseph D. McColskey, R Mirshahi, R Zoughi


Fatigue crack detection in metals is an important practical issure in many industries. In this paper the results of an investigation, using the dominat mode approach, employing flange-mounted open-ended rectangular waveguides at several microwave frequencies are presented. The goal of this investigation has been to demonstrate the capability of this approach for detecting stressinduced cracks under various static loads. In addition, a correlation between the features of the measured crack characteristic signals and crack opening has been sought. The results show that at all of the investigated frequencies, cracks from being nearly closed to having openings of up to 0.0508 mm are effectively detected. Futhermore, it is found that the interaction of the flange edge with a crack results in features that can be used to significantly enhance crack detection robustness (i.e. increased probability of detection). Several features associated with these measured crack characteristic signals are shown to lineraly correlate with crack opening. Such simple correlations may then be used to closely estimate a crack opening after it has been detected using this approach. A complete discussion of the results is also provided in this paper.
Research in Nondestructive Evaluation
No. 2


crack opening, fatigue cracks, microwave techniques, open-ended rectangular waveguides


Qaddoumi, N. , Ranu, E. , McColskey, J. , Mirshahi, R. and Zoughi, R. (2000), Microwave Detection of Stress-Induced Fatigue Cracks in Steel and Potential for Crack Opening Determination, Research in Nondestructive Evaluation (Accessed May 29, 2024)


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Created May 31, 2000, Updated October 12, 2021