A Comparison of Millimeter Wave and Eddy Current Detection of Surface Breaking Defects in Conducting Materials
The detection of surface breaking defects in conducting materials is an important aspect of nondestructive evaluation (NDE). Eddy current NDE methods have been used effectively for the detection of fatigue cracks and other surface breaking flaws in conducting materials , however, a detracting characteristic is that the eddy current transducer must be placed in close proximity to the test specimen. Since millimeter wave energy can propagate in air and does not require a couplant, millimeter wave NDE offers an alternative technique with the significant advantage of detection in a stand off mode of operation. Millimeter wave NDE has been shown to be effective at detecting small cracks [2–3], however, some methods under study require that the transducer be in close proximity with the specimen and thus suffer from the same disadvantages as eddy current techniques. This paper compares the detection capabilities of surface breaking flaws on conducting materials for millimeter wave NDE in the stand off mode and conventional eddy current NDE.
KeywordsSynthetic Aperture Radar Synthetic Aperture Radar Image Eddy Current Test Eddy Current Transducer Eddy Current Probe
Unable to display preview. Download preview PDF.
- 1.Hagamaier, D. J., “Application of Eddy Current Impedance Plane Testing,” Materials Evaluation, pp. 1035–1040, Vol. 42, July, 1984.Google Scholar
- 2.Bahr, A. J., “Microwave Eddy-Current Techniques for Quantitative Nondestructive Evaluation,”, Eddy Current Characterization of Materials, pp. 311–331, American Society For Testing And Materials, Philadelphia, PA, 1979.Google Scholar
- 3.Yeh, C. Y., Ranu, E., Zoughi, R., “A Novel Microwave Method for Surface Crack Detection Using Higher Order Waveguide Modes,” Materials Evaluation, pp. 676–681, Vol. 52, No. 6, June 1994.Google Scholar
- 4.Mensa, D. L., High Resolution Radar Cross-Section Imaging. Artech House, Boston, 1991.Google Scholar
- 5.Steinberg, B. D. and Harish, M. S., Microwave Imaging Techniques. Wiley Series In Remote Sensing, John Wiley and Sons Inc., New York, NY 1991.Google Scholar
- 6.Lusk, M. T. and Han, H. C., “Nondestructive Evaluation Using Swept-Frequency Synthetic Aperture Radar,” Review of Progress In Quantitative Nondestructive Evaluation, edited by D. O. Thompson and D. E. Chimenti, Plenum Press, New York, NY, pp. 607–614, Vol. 13A, 1994.Google Scholar