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Journal of Sensors
Volume 2012, Article ID 954867, 14 pages
Research Article

Terahertz and Thermal Testing of Glass-Fiber Reinforced Composites with Impact Damages

Department of Electrical and Computer Engineering, Faculty of Electrical Engineering, West Pomeranian University of Technology, Al. Piastów 17, 70-310 Szczecin, Poland

Received 4 December 2011; Revised 3 February 2012; Accepted 6 February 2012

Academic Editor: Raimond Grimberg

Copyright © 2012 T. Chady et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The studies on glass-fiber reinforced composites, due to their growing popularity and high diversity of industrial applications, are becoming an increasingly popular branch of the nondestructive testing. Mentioned composites are used, among other applications, in wind turbine blades and are exposed to various kinds of damages. The equipment reliability requirements force the development of accurate methods of their health monitoring. In this paper we present the study of composite samples with impact damages, using three methods: terahertz time domain inspection, active thermography with convective excitation, and active thermography with microwave excitation. The results of discrete Fourier transform of obtained time sequences of signals will be presented as well as some image processing of resulting amplitude and phase images. Proposed experimental methods combined with harmonic analysis are efficient tool of defects detection and allowed to detect flaws in examined specimens. Reader may find it interesting that in spite of differences in nature of applied experimental methods, one technique of signal processing (harmonic analysis) gave adequate and comparable results in each case.