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Journal ArticleDOI

Nondestructive evaluation of hidden damages in glass fiber reinforced plastic by using the terahertz spectroscopy

11 Apr 2017-International Journal of Precision Engineering and Manufacturing-Green Technology (Korean Society for Precision Engineering)-Vol. 4, Iss: 2, pp 211-219
TL;DR: In this article, a terahertz (THz) spectroscopy system was used for the detection and evaluation of hidden damages in a glass fiber reinforced plastic (GFRP).
Abstract: In this work, the terahertz (THz) spectroscopy system was used for the detecting and evaluation of hidden damages in a glass fiber reinforced plastic (GFRP). The interaction between THz and the GFRP was analyzed including the effects of reflecting, scattering and absorption of THz radiations with respect to the type of hidden damage. Both the transmission and reflective configurations were used to investigate the hidden damages including the delamination, fiber fracture and moisture absorption. Finally, the hidden damages inside of the composite laminates were successfully imaged simultaneously based on the time-domain spectroscopy of THz radiation. Additionally, the moisture absorption damage in the GFRP could be detected by analyzing of the frequency domain spectrum. It is expected that the developed THz nondestructive evaluation (NDE) technique can be widely used to evaluate the health of the composite structures.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors review the recent advances in nondestructive testing and evaluation (NDT&E) as applied to the inspection of thick composite parts and sandwich structures and determine possible research prospects to address the limitations of current technologies.

126 citations

Journal ArticleDOI
TL;DR: A review of thermal barrier coatings (TBCs) for high-temperature and other types of harsh environments, such as those found in nuclear-related applications, can be found in this paper.
Abstract: Today’s competitive world economy is creating an indispensable demand for increased efficiency of engineering components that operate in harsh environments (i.e., very high-temperature, corrosive, or neutron irradiation environments), for applications in the energy, automotive, aerospace, electronics, and power industries. Increased research is being done on thermal barrier coatings (TBCs) for protecting such components, since the versatility of manufacturing techniques and the scale of deployment result in increased life, economics, performance, and durability. This review focuses on the advances that led to using TBCs for component life extension and, more recently, as an integral part of advanced component design for high-temperature and other types of harsh environments, such as those found in nuclear-related applications. Factors that led to state-of-the-art advanced coating-fabrication techniques [e.g., electron-beam physical vapor deposition (EB-PVD), plasma spray deposition, and electrophoretically deposited TBCs, as well as functionally graded material (FGM) manufacturing] have also been emphasized in current coating R&D. This review explores the current state of TBCs, i.e., the latest advances regarding their fabrication and performance, associated challenges, and recommendations for their future use in aerospace, nuclear, high-temperature, or otherwise harsh environments.

33 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the efficacy of terahertz (THz) time-domain spectroscopy (TDS) imaging technology in detecting hidden defects in aircraft glass fiber (GF) sandwich composites.

32 citations

Journal ArticleDOI
TL;DR: In this paper, the authors employed Terahertz time-domain spectroscopy (THz-TDS) to detect hidden inclusions with various shapes and materials in glass fiber reinforced polymer (GFRP) composite solid panels.

29 citations

Journal ArticleDOI
TL;DR: A novel, convenient, online, nondestructive, and noncontact porosity evaluation method that could be potentially utilized to evaluate the integrity of TBCs in gas turbine blades is proposed.
Abstract: Porosity is one of the most important indicators for the characterization of the comprehensive performance of thermal barrier coatings (TBCs). Herein, we explored a fast, nondestructive porosity evaluation method based on the terahertz time-domain broadening effect. Different preparation process parameters were used to deposit the ceramic coatings, and the porosity ranged from 9.09% to 21.68%. Monte Carlo simulations were conducted to reveal the transitive relation between porosity and the terahertz time-domain broadening at different extinction coefficients and transmission distances. A transmission mode with an incidence angle of 0° was used to estimate the terahertz dielectric properties of ceramic coatings and the relative broadening ratio of terahertz pulses at different porosities. As a result, the Monte Carlo simulations showed that the time-domain broadening effect was enhanced when the extinction coefficient and transmission distances increased. As the porosity increased, the refractive index decreased and the extinction coefficient increased. The latter was more sensitive to minor porosity changes as demonstrated by linear fitting comparisons. Meanwhile, the relative broadening ratio increased when the porosity increased, and reserved the sensitivity of the extinction coefficient to porosity changes. The effect was more obvious on the relative broadening ratio which experienced multiple transmissions and reflections. Moreover, the relative broadening ratio could be obtained faster and in an easier manner compared to the dielectric parameters in both the transmission and reflection modes, based on single-step tests with the use of actual terahertz wave inspection. Finally, this study proposed a novel, convenient, online, nondestructive, and noncontact porosity evaluation method that could be potentially utilized to evaluate the integrity of TBCs in gas turbine blades.

27 citations

References
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Journal ArticleDOI
TL;DR: Terahertz spectroscopy and imaging provide a powerful tool for the characterization of a broad range of materials, including semiconductors and biomolecules, as well as novel, higher-power terahertz sources.
Abstract: Terahertz spectroscopy systems use far-infrared radiation to extract molecular spectral information in an otherwise inaccessible portion of the electromagnetic spectrum. Materials research is an essential component of modern terahertz systems: novel, higher-power terahertz sources rely heavily on new materials such as quantum cascade structures. At the same time, terahertz spectroscopy and imaging provide a powerful tool for the characterization of a broad range of materials, including semiconductors and biomolecules.

2,673 citations

Journal ArticleDOI
TL;DR: A comprehensive review of the various techniques used for terahertz image formation can be found in this paper, as well as numerous examples which illustrate the many exciting potential uses for these emerging technologies.
Abstract: Within the last several years, the field of terahertz science and technology has changed dramatically. Many new advances in the technology for generation, manipulation, and detection of terahertz radiation have revolutionized the field. Much of this interest has been inspired by the promise of valuable new applications for terahertz imaging and sensing. Among a long list of proposed uses, one finds compelling needs such as security screening and quality control, as well as whimsical notions such as counting the almonds in a bar of chocolate. This list has grown in parallel with the development of new technologies and new paradigms for imaging and sensing. Many of these proposed applications exploit the unique capabilities of terahertz radiation to penetrate common packaging materials and provide spectroscopic information about the materials within. Several of the techniques used for terahertz imaging have been borrowed from other, more well established fields such as x-ray computed tomography and synthetic aperture radar. Others have been developed exclusively for the terahertz field, and have no analogies in other portions of the spectrum. This review provides a comprehensive description of the various techniques which have been employed for terahertz image formation, as well as discussing numerous examples which illustrate the many exciting potential uses for these emerging technologies.

962 citations

Journal ArticleDOI
TL;DR: The latest results in tomographic imaging, in which waveforms reflected from an object can be used to form a three-dimensional representation, are described and substantial improvements in the spatial resolution are demonstrated.
Abstract: We review recent progress in the field of terahertz “T-ray” imaging. This relatively new imaging technique, based on terahertz time-domain spectroscopy, has the potential to be the first portable far-infrared imaging spectrometer. We give several examples which illustrate the possible applications of this technology, using both the amplitude and phase information contained in the THz waveforms. We describe the latest results in tomographic imaging, in which waveforms reflected from an object can be used to form a three-dimensional representation. Advanced signal processing tools are exploited for the purposes of extracting tomographic results, including spectroscopic information about each reflecting layer of a sample. We also describe the application of optical near-field techniques to the THz imaging system. Substantial improvements in the spatial resolution are demonstrated.

731 citations

Book
08 May 2002
TL;DR: Introduction to NDE, P.J. Shull Liquid Penetrant, F.H. Tittmann Magnetic Particle, A.T. Bahr, R. Zoughi, and N.D. Qaddoumi Optical Methods.
Abstract: Introduction to NDE, P.J. Shull Liquid Penetrant, F.A. Iddings and P.J. Shull Ultrasound, P.J. Shull and B.R. Tittmann Magnetic Particle, A. Lindgren, P.J. Shull, K. Joseph, and D. Hagemaier Eddy Current, P.J. Shull Acoustic Emission, W.H. Prosser Radiology, H.E. Martz, Jr., C.M. Logan, and P. J. Shull Active Thermography, J.W. M. Spicer and R. Osiander Microwave, A.J. Bahr, R. Zoughi, and N. Qaddoumi Optical Methods, D.D. Duncan, J.L. Champion, K.C. Baldwin, and D.W. Blodgett Index

521 citations

Journal ArticleDOI
TL;DR: In this paper, a review of composites usage in the Indian aerospace sector is presented, where the focus of the review is on applications of composite materials as structural materials where they have seen a significant growth in usage.
Abstract: Fibre-reinforced polymer composite materials are fast gaining ground as preferred materials for construction of aircraft and spacecraft. In particular, their use as primary structural materials in recent years in several technology-demonstrator front-line aerospace projects world-wide has provided confidence leading to their acceptance as prime materials for aerospace vehicles. This paper gives a review of some of these developments with a discussion of the problems with the present generation composites and prospects for further developments. Although several applications in the aerospace sector are mentioned, the emphasis of the review is on applications of composites as structural materials where they have seen a significant growth in usage. The focus of the paper is especially on the developments on the Indian aerospace scene. A brief review of composites usage in aerospace sector is first given. The nature of composite materials behaviour and special problems in designing and working with them are then highlighted. The issues discussed relate to the impact damage and damage tolerance in general, environmental degradation and long-term durability. Current solutions are briefly described and the scope for new developments is outlined. In the end, some directions for future work are given.

325 citations