Preliminary Results of Detecting and Locating Defects under Triangular Thick Composite Structural Members


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.

Meeting Name

Nondestructive Evaluation of Materials and Composites II (1998: Mar. 31-Apr. 1, San Antonio, TX)


Electrical and Computer Engineering

Keywords and Phrases

Bending (Deformation); Composite Structures; Defects; Dielectric Properties; Geometry; Joints (Structural Components); Mathematical Models; Microwave Devices; Microwave Measurement; Microwave Sensors; Nondestructive Examination; Defect Characterization; Microwave NDT&E; Thick Composites; Wave Bending

International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version


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© 1998 SPIE--The International Society for Optical Engineering, All rights reserved.

Publication Date

01 Apr 1998