Terahertz Non-destructive testing and imaging of corrosion in coated steel plates

Jiang, Xuelei; Xu, Ying; Zhao, Debin

doi:10.1016/j.conbuildmat.2023.131427

Cited by 12 publications

(3 citation statements)

References 23 publications

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“…The unique position of terahertz waves, which combines the excellent properties of electronics and photonics, has attracted a huge amount of attention [1,2]. Due to the remarkable advances in terahertz technology in recent years, its high penetration, low energy and high sensitivity have enabled it to have a wide range of applications in wireless communication [3][4][5], biomedicine [6][7][8], non-destructive testing and other fields [9][10][11]. To facilitate the growth of terahertz technology, a multitude of functional devices relevant to its applications have been proposed, such as polarization converters [12,13], detectors [14,15], absorbers [16,17], etc.…”

Section: Introductionmentioning

confidence: 99%

Design of ultra-thin multi-band sub-terahertz metamaterial absorber using three concentric ring resonators with same opening direction

Zhao,

Qin,

et al. 2024

Phys. Scr.

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In this paper, an ultra-thin sub-terahertz multi-band terahertz metamaterial absorber is proposed, its cell consists of three concentric ring resonators with the same opening direction, which can realize three discrete absorption peaks in the sub-terahertz frequency domain. The absorption peaks are mainly formed when the three open circular resonators interact with each other, and the superposition of the three discrete peaks creates a three-band absorption. The physical mechanisms of three-band absorption are illustrated by the electric fields and surface current distributions of three absorption peaks. Adjustment of the absorption effect could be obtained by altering the dimensions of the cleft circular resonator. By fixing the dimensions and changing the opening direction, these resonators will couple to each other and play an important role in regulating the frequency, intensity, and number of absorption peaks. Moreover, the multi-band metamaterial structure could be combined with vanadium dioxide, a phase change material, to actively modulate the absorption. In addition, the three-band metamaterial absorber has the characteristics of polarization-sensitive and wide-angle, which has extensive applications in the domains of security detection, biomedicine and communication.

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Section: Introductionmentioning

confidence: 99%

Design of ultra-thin multi-band sub-terahertz metamaterial absorber using three concentric ring resonators with same opening direction

Zhao,

Qin,

et al. 2024

Phys. Scr.

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“…Previous studies, such as those by H. Jiang et al, utilized three feature parameters, namely, the maximum absolute value, the signal power, and the envelope area, to image mid-gap defects of various shapes [9]. Alternatively, Jiang X et al extracted delay time differences in THz wave reflection signals to detect and image corrosion in coating steel plates [10]. While these studies employed the manual determination of defect features for image analysis, multi-layer lightweight composite structures exhibit a variety of defect types, leading to unclear patterns in the shape and position changes of THz time-domain signals.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Detection of Defects in Multi-Layer Lightweight Composite Structures Using THz-TDS Based on a U-Net-BiLSTM Network

Zhang,

Li,

Zhang

et al. 2024

Materials

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Multi-layer lightweight composite structures are widely used in the field of aviation and aerospace during the processes of manufacturing and use, and, as such, they inevitably produce defects, damage, and other quality problems, creating the need for timely non-destructive testing procedures and the convenient repair or replacement of quality problems related to the material. When using terahertz non-destructive testing technology to detect defects in multi-layer lightweight composite materials, due to the complexity of their structure and defect types, there are many signal characteristics of terahertz waves propagating in the structures, and there is no obvious rule behind them, resulting in a large gap between the recognition results and the actual ones. In this study, we introduced a U-Net-BiLSTM network that combines the strengths of the U-Net and BiLSTM networks. The U-Net network extracts the spatial features of THz signals, while the BiLSTM network captures their temporal features. By optimizing the network structure and various parameters, we obtained a model tailored to THz spectroscopy data. This model was subsequently employed for the identification and quantitative analysis of defects in multi-layer lightweight composite structures using THz non-destructive testing. The proposed U-Net-BiLSTM network achieved an accuracy of 99.45% in typical defect identification, with a comprehensive F1 score of 99.43%, outperforming the CNN, ResNet, U-Net, and BiLSTM networks. By leveraging defect classification and thickness recognition, this study successfully reconstructed three-dimensional THz defect images, thereby realizing quantitative defect detection.

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“…The FDTD algorithm analyzes continuous electromagnetic problems by using finite differences and obtains the electric field value at the sampling point, which offers several advantages, such as robustness and the ability to study dispersive, nonlinear, or anisotropic materials. Thus, the FDTD method has been successfully used to analyze complex mediums, including glass fiber-reinforced plastics [7,8], thermal barrier coatings [9][10][11], epoxy resin [12], etc. This work group carried out a theoretical analysis of the interaction of terahertz radiation with marine protective coatings using the FDTD method, in which the model was simplified and the coating was treated as a non-dispersive medium, that is a Nondispersive model.…”

Section: Introductionmentioning

confidence: 99%

Improved Numerical Modeling of Terahertz Wave Propagation in Epoxy Coating with the Finite-Difference Time-Domain Method

Tu,

Zhong,

Zhang

et al. 2023

Coatings

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Electromagnetic theoretical analysis was usually used to investigate the pulsed terahertz wave interaction with the medium. For epoxy coatings, the material dispersion of the coating was often simplified or ignored in the traditional propagation model. It is difficult to elaborate on the propagation mechanism and to differentiate the coating deterioration as serving time increases. An improved propagation model based on the finite-difference time domain was established to characterize the propagation in the epoxy protective coating under broad-band terahertz radiation. Either an intact or defective coating structure was investigated, and the simulated results were compared with the experimental test. The dissipation mechanism was considered in the proposed model. The results indicated that the terahertz reflections varied with the change in optical and dielectric properties caused by coating aging, which influences the intrinsic impedance of the medium. Moreover, it could well elucidate the propagation mechanism of pulsed terahertz waves in rusted, defective coating structures.

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Terahertz Non-destructive testing and imaging of corrosion in coated steel plates

Cited by 12 publications

References 23 publications

Design of ultra-thin multi-band sub-terahertz metamaterial absorber using three concentric ring resonators with same opening direction

Design of ultra-thin multi-band sub-terahertz metamaterial absorber using three concentric ring resonators with same opening direction

Quantitative Detection of Defects in Multi-Layer Lightweight Composite Structures Using THz-TDS Based on a U-Net-BiLSTM Network

Improved Numerical Modeling of Terahertz Wave Propagation in Epoxy Coating with the Finite-Difference Time-Domain Method

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