Preliminary results of detecting and locating defects under triangular thick composite structural members

Jacob K. Easter; Nasser Qaddoumi; Reza Zoughi; Lawrence M. Brown; Johnnie J. DeLoach Jr.

doi:10.1117/12.301511

31 March 1998 Preliminary results of detecting and locating defects under triangular thick composite structural members

Jacob K. Easter, Nasser Qaddoumi, Reza Zoughi, Lawrence M. Brown, Johnnie J. DeLoach Jr.

Proceedings Volume 3396, Nondestructive Evaluation of Materials and Composites II; (1998) https://doi.org/10.1117/12.301511
Event: Non-Destructive Evaluation Techniques for Aging Infrastructure and Manufacturing, 1998, San Antonio, TX, United States

Abstract

Thick triangularly shaped structural sections used in a variety of applications are inspected using open-ended microwave rectangular waveguide probes. Previous work has shown the ability of microwave techniques to detect and locate planar defects in thick composite structures. In all of those applications, the microwave sensor aperture has been parallel to the surface under inspection. However, in certain cases involving triangular joints, the geometry may require that the microwave sensor be positioned at an angle to the joint surface. Therefore, the inspection is conducted with the waveguide maintaining a certain angle with the surface of the sample. This angle causes the incident fields to bend at an angle which can be determined using Snell's law and the dielectric properties of the sample under inspection. The bending of the fields causes defects and internal structural features to appear at positions at which they are not actually located. The proper location of defects can be found by using Snell's law along with the geometrical and dielectric properties of the material under inspection. The preliminary results of this investigation, including the results of a simple mathematical model and several experimental results, are presented.

Citation Download Citation

Jacob K. Easter, Nasser Qaddoumi, Reza Zoughi, Lawrence M. Brown, and Johnnie J. DeLoach Jr. "Preliminary results of detecting and locating defects under triangular thick composite structural members", Proc. SPIE 3396, Nondestructive Evaluation of Materials and Composites II, (31 March 1998); https://doi.org/10.1117/12.301511

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