Defect detection in CFRP structures using pulsed thermographic data enhanced by penalized least squares methods

Zheng, Kaiyi; Chang, Yu-Sung; Yao, Yuan

doi:10.1016/j.compositesb.2015.04.049

Cited by 56 publications

(16 citation statements)

References 30 publications

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“…The temperature change on the surface of a structure after heating at a time instant t can be shown as per Equation 7, which is based on Equation (1) [32,50]. A double logarithmic scale of Equation 7is considered and Equation 8is obtained.…”

Section: Post-processing Technique: Thermal Signal Reconstructionmentioning

confidence: 99%

Thermography-Based Deterioration Detection in Concrete Bridge Girders Strengthened with Carbon Fiber-Reinforced Polymer

Mac

Huh

Doan

et al. 2020

Sensors

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In bridge structures worldwide, carbon fiber-reinforced polymer (CFRP) sheets are applied to strengthen weak components, especially concrete girders that are at a high risk of rapid degradation during the bridge’s operation owing to impacts from the superstructure’s weight and traffic loads. Regarding the thermography-based method (TM), although deteriorations in the concrete core are some of the main defects in concrete structures strengthened with CFRP, these do not receive as much attention as damage in the CFRP. Therefore, the interpretation of the structural health in terms of these defects using TM is still unclear. The problem presented in this work addresses the quantification of delamination inside the concrete part of a specimen with a CFRP sheet installed on the surface (assumed to be the girder surface strengthened with CFRP) via step heating thermography. Additionally, the empirical thermal diffusivity of concrete girders strengthened with a CFRP sheet (CSC girder), has not been provided previously, is proposed in the present study to predict delamination depths used for field investigations. Moreover, the effect of the CFRP sheet installed on the structure’s surface on the absolute contrast of delamination is clarified. Finally, advanced post-processing algorithms, i.e., thermal signal reconstruction and pulsed phase thermography, are applied to images obtained with step heating thermography to enhance the visibility of delamination in CSC girders.

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Section: Post-processing Technique: Thermal Signal Reconstructionmentioning

confidence: 99%

Thermography-Based Deterioration Detection in Concrete Bridge Girders Strengthened with Carbon Fiber-Reinforced Polymer

Mac

Huh

Doan

et al. 2020

Sensors

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“…In the context of data smoothing, WS has been applied in very different fields, including business and economy, Fourier transform (FT) near infrared spectroscopy, chromatography, or image processing . However, it would not be an understatement to say that the use of WS in NMR is not widespread.…”

Section: Applicationsmentioning

confidence: 99%

Applications of the Whittaker smoother in NMR spectroscopy

Cobas¹

2018

Magnetic Reson in Chemistry

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The Whittaker smoother, a special case of penalized least square, is a multipurpose algorithm that has proven to be very useful in many scientific fields, including image processing, chromatography, and optical spectroscopy. It shares many similarities with the Savitzky-Golay algorithm, but it is significantly faster and easier to automate. Its use in nuclear magnetic resonance, however, is not widespread although several applications have recently been published. In this review, the mathematical background of the method and its main applications in nuclear magnetic resonance spectroscopy will be discussed.

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“…However, both TSR and DAC have processed the time domain data while they ignored the spatial information. Hence, penalized least square (PELS) [10] has been developed to utilize the time series thermal images and their spatial information simultaneously. Furthermore, Chang et al have decomposed the thermal images into high-frequency noises, low-frequency background, and signal information using the signal decomposition, which is called the multimaintenance ensemble empirical mode decomposition (MEEMD) method [11].…”

Section: Introductionmentioning

confidence: 99%

Defect Detection in Composite Products Based on Sparse Moving Window Principal Component Thermography

Jie

Dai

Hou

et al. 2020

Advances in Polymer Technology

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As a nondestructive testing (NDT) technology, pulsed thermography (PT) has been widely used in the defect detection of the composite products due to its efficiency and large detection range. To enhance the distinction between defective and defect-free region and eliminate the influence of the measurement noise and nonuniform background of the thermal image generated by PT, a number of thermographic data analysis approaches have been proposed. However, these traditional methods only consider the correlations among the pixel while leave the time series correlations unmodeled. In this paper, a sparse moving window principal component thermography (SMWPCT) method is proposed to incorporate several thermal images using the moving window strategy. Also, the sparse trick is used to provide clearer and more interpretable results because of the structure sparsity. The effectiveness of the method is verified by the defect detection experiment of carbon fiber-reinforced plastic specimens.

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Defect detection in CFRP structures using pulsed thermographic data enhanced by penalized least squares methods

Cited by 56 publications

References 30 publications

Thermography-Based Deterioration Detection in Concrete Bridge Girders Strengthened with Carbon Fiber-Reinforced Polymer

Thermography-Based Deterioration Detection in Concrete Bridge Girders Strengthened with Carbon Fiber-Reinforced Polymer

Applications of the Whittaker smoother in NMR spectroscopy

Defect Detection in Composite Products Based on Sparse Moving Window Principal Component Thermography

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