Lock-in thermography using miniature infra-red cameras and integrated actuators for defect identification in composite materials

Ólafsson, G.; Tighe, Rachael C.; Boyd, Stephen; Dulieu-Barton, J.M.

doi:10.1016/j.optlastec.2021.107629

Cited by 17 publications

(6 citation statements)

References 23 publications

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“…Overall TSA worked reasonably well in terms of identifying the subsurface structure of the cable, with potential improvements to be gained in future if greater loads were applied. One prospective idea is to run a low frequency, AC current through the cable and utilise the heat the cable generates naturally in use as a means of detecting damage in the wires and or armour; a method of external excitation is proposed by Ólafsson et al [83] PT indicated areas of damage to the cable surface, and also the different materials used to make up the outer plastic sheath of the cable but did not manage to penetrate the outer sheath to provide an indication of structural response in the internal layers. However, knowledge of damage to the outer sheath is also integral as a point of reference for possible internal damage.…”

Section: Discussionmentioning

confidence: 99%

Non-destructive examination (NDE) methods for dynamic subsea cables for offshore renewable energy

et al. 2022

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Offshore renewable energy installations are moving into more challenging environments where fixed foundations are not economically viable, forcing the development of floating platforms. Subsea cables are critical for transfer of the power generated back to shore. The electrical capabilities of subsea cables are well understood; however, the structural capabilities are not, subsea power cable failures accounting for a significant proportion of insurance claims. Cables are challenging to repair, with specific vessels and good weather windows required, therefore making operations very costly. A good understanding of the internal structure of a subsea cable, and interaction between the layers, is integral to the development of robust and reliable, high voltage, dynamic, subsea cables. A requirement therefore exists for non-destructive examination (NDE) of live subsea cables to determine locations, and identify the causes, of faults and classify their type. An NDE framework such as this would assist in planning operations and reduce the risk and cost inherent to delivering offshore power. Improved understanding of subsea cable failure modes and mechanisms could also be achieved through us of NDE during onshore, dry, experimental testing. Three currently available NDE methods are considered, developed for use in other disciplines, for the purpose of structural monitoring of subsea power cables during onshore evaluation testing. The NDE methods were: i) thermography, ii) eddy current testing (ECT), iii) spread spectrum time domain reflectometry (SSTDR). The methods are assessed with regards to the information that could be obtained from both a static and oscillating cable in pilot physical tests. The results of the testing were promising, with cable motions and interlayer movements being detected by all techniques to various degrees.

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Section: Discussionmentioning

confidence: 99%

Non-destructive examination (NDE) methods for dynamic subsea cables for offshore renewable energy

et al. 2022

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“…Heat waves propagate inside the material, partially dissipate, and reflect from encountered inhomogeneities. The resultant reflected waves interfere with the waves originating from the excitation source [19,36]. Consequently, an infrared camera can observe and register surface temperature variations correlating with internal abnormalities.…”

Section: Introductionmentioning

confidence: 99%

Lock-In Thermography with Cooling for the Inspection of Composite Materials

Łukaszuk,

Marques,

Chady

2023

Materials

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This paper presents the development of the lock-in thermography system with an additional cooling system. System feasibility is tested by investigating a square-shaped glass fiber-reinforced polymer (GFRP) with artificially made outer flaws. The influence of heating mode and sinusoidal excitation period on the defect detectability is considered. Thus, the experiment is split into two modes: the sample is solely heated in the first mode or simultaneously heated and cooled in the second. In each mode, the temperature measurement is performed first with a shorter excitation signal period and second with a longer one. The signal-to-noise ratio (SNR) is used to assess defect detection quantitatively. The comparative analysis shows that employing a mixed heating–cooling mode improves the SNR compared to the conventional heating mode. The further enhancement of the SNR is obtained by extending the excitation period. The combination of simultaneous heating and cooling with longer periods of the excitation signal allows for the best SNR values for the most detected defects.

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“…Composite materials are often used as major components of supporting structure owing to their high strength, high modulus, and good fatigue resistance, and they are widely applied in automotive manufacturing [1][2][3], aerospace [4][5][6], infrastructure [7][8][9][10] and other various fields. However, due to the complexity and instability of the manufacturing process of composite materials, as well as the influence of the environment during the service life, various types of defects may arise, such as delamination, porosity, and fiber wrinkles and so on [11][12][13][14][15]. These defects will affect the mechanical performance of the components involved, and may lead to serious safety accidents.…”

Section: Introductionmentioning

confidence: 99%

Detection of flat-bottom holes in composite materials using multi-dimensional complementary ensemble empirical mode decomposition algorithm

Zhang,

Li,

Wang

et al. 2023

J. Inst.

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Due to high-temperature resistance, high strength, and excellent fatigue resistance, composite materials are widely used in automotive manufacturing, aerospace, infrastructure and other fields. Consequently, the demand for defect detection of composite materials is also increasing. As a non-destructive testing technique, the active infrared thermography, which can achieve full-field defect detection, is suitable for defect detection of composite materials. However, this method is susceptible to noises caused by the environment and heating sources. In order to solve the problem of the defect signal being submerged by these noises, a multi-dimensional complementary ensemble empirical mode decomposition (MCEEMD) algorithm is introduced in this paper. This method can decompose the signal into the low-frequency background noise, the high-frequency heating noise, and useful defect signals, and these noises can be easily removed to improve the contrast to noise ratio (CNR) of defect images. Based on this proposed method, a defect detection experiment on the carbon fiber reinforced plastic (CFRP) is performed in this paper, and experimental results show that the method can effectively remove environmental noise and heating noise, and it can detect 11 out of 12 defects on the CFRP sample with an average CNR of 9.107. Compared with the traditional differential absolute contrast method, this method can detect one additional small defect with the aspect ratio of 1.67 and one deep defect with a depth of 2 mm.

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Lock-in thermography using miniature infra-red cameras and integrated actuators for defect identification in composite materials

Cited by 17 publications

References 23 publications

Non-destructive examination (NDE) methods for dynamic subsea cables for offshore renewable energy

Non-destructive examination (NDE) methods for dynamic subsea cables for offshore renewable energy

Lock-In Thermography with Cooling for the Inspection of Composite Materials

Detection of flat-bottom holes in composite materials using multi-dimensional complementary ensemble empirical mode decomposition algorithm

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