AN EXPLORATION OF THE UTILITIES OF TERAHERTZ WAVES FOR THE NDE OF COMPOSITES
AIP Conf. Proc. -- June 23, 2011 -- Volume 1335, pp. 533-540
REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Volume 30A; Volume 30B; doi:10.1063/1.3591897
ABSTRACT
Issue Date: 23 June 2011David K. Hsu, Kwang-Hee Im, Chien-Ping Chiou, and Daniel J. Barnard
Center for Nondestructive Evaluation, Iowa State University, Ames, Iowa 50011
We report an investigation of terahertz waves for the nondestructive evaluation of composite materials and structures. The modalities of the terahertz radiation used were time domain spectroscopy (TDS) and continuous wave (CW). The composite materials and structures investigated include both non-conducting polymeric composites and carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse can detect a crack hidden behind a larger crack. This was demonstrated in thick GFRP laminates containing double saw slots. In carbon composites the penetration of terahertz waves is quite limited and the detection of flaws is strongly affected by the angle between the electric field vector of the terahertz waves and the intervening fiber directions. The structures tested in this study include both solid laminates and honeycomb sandwiches. The defects and anomalies investigated by terahertz waves were foreign material inclusions, simulated disbond and delamination, mechanical impact damage, heat damage, and water or hydraulic fluid ingression. The effectiveness and limitations of terahertz radiation for the NDE of composites are discussed. ©2011 American Institute of Physics
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