Defect detection in CFRP by infrared thermography with CO2 Laser excitation compared to conventional lock-in infrared thermography

Keo, Sam Ang; Brachelet, Franck; Breabăn, Florin; Defer, Didier

doi:10.1016/j.compositesb.2014.09.018

Cited by 29 publications

(9 citation statements)

References 9 publications

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“…In terms of modulated thermography, the Four Point Correlation Method (FPCM) [9] as well as Lock-In Thermography (LIT) [10] are the existing signal processing techniques used. Comparisons were also drawn between different techniques from previous studies [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…It is interesting to note that variations in conventional thermography techniques exist, such as the use of induction loops for real time detection of cracks in steel [13] with Lock-In Thermography, as well as the development of real time Lock-In Thermography [14] to obtain processed images while capturing data. It can also be observed that extensive work on thermography has been conducted in the past on different materials such as ceramics [15,2], metals [16,17,15,13], aluminium foam [18], as well as composite structures [11,8,3,19,20]. From the existing literature, it can be concluded that many infrared techniques exist, for a wide variety of materials.…”

Section: Introductionmentioning

confidence: 99%

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Asynchronous Lock In Thermography of 3D Printed PLA and ABS samples

Goh¹,

Lim²,

Pallathadka³

2018

Preprint

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Lock-In thermography is a useful Non Destructive Technique (NDT) for enhanced detection of defects in components, as it amplifies the phase contrast where defects exist. This amplification was found to be around 2-3 times compared to constant heating. The current used a Fuse Deposition Modelling (FDM) 3D printer to print samples with known defects, in order to characterise the relative effects of different variables on the Lock-In phase data. Samples were printed using ABS (Acrylonitrile Butadiene Styrene) and PLA (Polylactic Acid) for comparisons, and variables such as print direction, cameras, heating power, Lock-In frequency, as well as thickness, width and depth of defects were explored. It was found that different materials resulted in different baselines, but had similar phase contrast. A novel asynchronous technique was derived to enable Lock-In measurements with 5 different infrared cameras, and similar results were found. Even cheap cameras like the Seek Thermal CompactXR were proven capable of detecting the same defects as other cameras such as the FLIR SC7500. Heating power did not affect phase contrast, except for shallower defects up to 1.0 mm deep, where higher power resulted in better contrast. As expected, deeper defects could only be detected using lower Lock-In frequencies, and there was better phase contrast with wider, thicker and shallower defects. It was shown that defects 4 mm in width could be detected automatically up to a depth of around 1.5 mm, based on the phase signal trends. Sub-sampling of frame data showed that at least 10 frames were required per Lock-In period for minimal deviations in Lock-In phase contrast. Also, it was shown that phase contrast was similar for shallower defects up to 1.5 mm deep, with data from 1 Lock-In period, as long as the first frame was synchronised with the heating cycle.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Asynchronous Lock In Thermography of 3D Printed PLA and ABS samples

Goh¹,

Lim²,

Pallathadka³

2018

Preprint

View full text Add to dashboard Cite

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“…The signal to noise ratio (SNR) has been calculated for a sample by following a sequence of steps [6].…”

Section: F Snrmentioning

confidence: 99%

“…The use of water bath has been reported to reduce the infra-red content of halogen lamp excitation source [6], [11]. The use of infra-red filter coatings have also been described [12], [13].…”

Section: Introductionmentioning

confidence: 99%

Characterization and Energy Absorption Efficiency Determination of LED as an Effective Photothermal Excitation Source in Lock-In Thermography

2015

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This paper studies the use of light-emitting diode (LED) as an excitation source for photothermal lock-in experiments, and investigates the energy absorption efficiency and signal-to-noise ratio of the established setup. Existing lock-in excitation sources usually use high power (in the range of kilowatt) halogen lamps. The present LED excitation source has an advantage of low power consumption making the setup much more energy efficient. Another advantage of LED in this paper is their low infrared (IR) content, in contrast to halogen lamps, the IR content gets reflected into the IR camera, and leads to an unpredicted change in phase image in lock-in thermography.Index Terms-Infrared imaging, photothermal effects, lock-in thermography NDT, LED lamp photothermal characterization.

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“…for various applications, such as spot weld inspection [18] and the detection of a metal element behind a wooden plate [19]. Other applications for defect detection include defects of roll-to-roll printed conductors [20], defects in reinforcement with a carbon fiber-reinforced polymer (CFRP) [21][22][23][24], as well as defects in biomedical materials [25]. The latest development with a new microwave excitation system has enabled the detection of reinforcement in a reinforced concrete wall, which has highlighted the contributions of microwave excitation [26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Detection of Concrete Cover of Reinforcements in Reinforced Concrete Wall by Microwave Thermography with Transmission Approach

et al. 2022

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Concrete cover has an important role in reinforced concrete (RC) structures because it protects reinforcement bars from the bad effects of weather, fire, and bad environmental conditions that cause the corrosion of the reinforcements. Although it is an essential parameter to be considered for structural health monitoring (SHM), its detection by infrared thermography, especially in the heating phase, has not been accessed yet. The detailed analysis and discussions of physical phenomena, known as diffraction and interference, affecting the thermograms during the detection of the steel bars by microwave thermography have given an essential key for resolving this issue. The present paper proposes an innovative methodology with microwave thermography for determining the concrete cover thickness of one-layer reinforcements (12 mm in diameter and regularly placed at 10 cm) in an RC wall (1 m × 1m × 6.5 cm). By using the transmission approach with five angles of microwave antenna direction (0°, 15°, 30°, 45°, and 60°) and the Snell–Descartes law and linear law, the proposed methodology leads us to deduce the approximate value of the concrete cover thickness (37.74 mm), which is close to the real value (38 mm), as well as the spacing of the steel bars and dielectric constant of the concrete. The detection of the concrete cover thickness is another new remarkable achievement of infrared thermography methods.

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Defect detection in CFRP by infrared thermography with CO2 Laser excitation compared to conventional lock-in infrared thermography

Cited by 29 publications

References 9 publications

Asynchronous Lock In Thermography of 3D Printed PLA and ABS samples

Asynchronous Lock In Thermography of 3D Printed PLA and ABS samples

Characterization and Energy Absorption Efficiency Determination of LED as an Effective Photothermal Excitation Source in Lock-In Thermography

Detection of Concrete Cover of Reinforcements in Reinforced Concrete Wall by Microwave Thermography with Transmission Approach

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