Optimizing thermographic testing of thick GFRP plates by assessing the real energy absorbed within the material

Müller, J.; Krankenhagen, Rainer

doi:10.1016/j.compstruct.2019.02.027

Cited by 16 publications

(11 citation statements)

References 37 publications

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“…The same kind of studies have been performed by Ibarra et al [12] with a technique based on pulsed phase transformation (PPT) and thermographic signal reconstruction similar to [13]. As depicted in [14] one alternative to these qualitative methods is the use of parametrized 1D simulations with the quadrupole method as presented in the book of Maillet et al [15]. Some works were performed by coupling infrared thermography (IRT) and the quadrupole approach, such as the one of Bendada et al [16][17][18].…”

Section: Introductionmentioning

confidence: 92%

“…In fact, with these analytical methods, it becomes easy to calculate a multilayer sample with several thermal properties as well as thermal resistance. Then, by using nonlinear regression methods as proposed by Muller et al [14], the parameters of the model can be adjusted by least square minimization between the model output and the experimental data. This approach is difficult when the initial values are poorly known and could be time consuming when addressing a large amount of data, such as temperature fields, with IRT.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Thermal Resistance Field in Layered Materials by Analytical Asymptotic Method

et al. 2020

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In this paper, the problem of the quantitative characterization of thermal resistance fields in a multilayer sample is addressed by using the classical front face flash method as the thermal excitation and infrared thermography (IRT) as the monitoring sensor. In this challenging problem, the complete inverse processing of a multilayer analytical model is difficult due to the lack of sensitivity of some parameters (layer thickness, depth of thermal resistance, etc.) and the expansive computational iterative processing. For these reasons, the proposed strategy is to use a simple multilayer problem where only one resistive layer is estimated. Moreover, to simplify the inverse processing often based on iterative methods, an asymptotic development method is proposed here. Regarding the thermal signal reconstruction (TSR) methods, the drawback of these methods is the inability to be quantitative. To overcome this problem, the method incorporates a calibration process originating from the complete analytical quadrupole solution to the thermal problem. This analytical knowledge allows self-calibration of the asymptotic method. From this calibration, the quantitative thermal resistance field of a sample can be retrieved with a reasonable accuracy lower than 5%.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Estimation of Thermal Resistance Field in Layered Materials by Analytical Asymptotic Method

et al. 2020

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“…Fiber-reinforced polymers are gaining a great deal of attention over common structural metals. More specifically, glass fiber reinforced polymers (GFRPs) offer an attractive potential for many applications, such as marine infrastructures [ 1 ] or wind turbine blades [ 2 , 3 ], due to their efficient mechanical performance and corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Carbon Nanotube Reinforced Poly(ε-caprolactone)/Epoxy Blends for Superior Mechanical and Self-Sensing Performance in Multiscale Glass Fiber Composites

2021

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In this paper, a novel carbon nanotube (CNT) polycaprolactone (PCL), epoxy, and glass fiber (GF) composite is reported. Here, the nanoreinforced composites show a flexural strength increase of around 30%, whereas the interlaminar shear strength increases by 10–15% in comparison to unenhanced samples. This occurs because the addition of the CNTs induces a better PCL/epoxy/GF interaction. Furthermore, the nanoparticles also give novel functionalities to the multiscale composite, such as strain and damage monitoring. Here, the electrical response of the tensile- and compressive-subjected faces was simultaneously measured during flexural tests as well as the transverse conductivity in interlaminar tests, showing an exceptional capability for damage detection. Moreover, it was observed that the electrical sensitivity increases with PCL content due to a higher efficiency of the dispersion process that promotes the creation of a more uniform electrical network.

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“…The development of adequate excitation and post-processing techniques to overcome the aforementioned detectability limits of optical infrared thermography has been widely researched [3][4][5][6][7][8][9][10][11][12]. Principally, temporal and spectral shaping of the excitation waveform can control its effective diffusion length and corresponding thermal response in order to achieve improved defectinduced contrast and deeper detection range.…”

Section: Introductionmentioning

confidence: 99%

Performance of frequency and/or phase modulated excitation waveforms for optical infrared thermography of CFRPs through thermal wave radar: A simulation study

Hedayatrasa

Poelman

Segers

et al. 2019

Composite Structures

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Following the developments in pulse compression techniques for increased range resolution and higher signal to noise ratio of radio wave radar systems, the concept of thermal wave radar (TWR) was introduced for enhanced depth resolvability in optical infrared thermography. However, considering the highly dispersive and overly damped behavior of heat wave, it is essential to systematically address both the opportunities and the limitations of the approach. In this regard, this paper is dedicated to a detailed analysis of the performance of TWR in inspection of carbon fiber reinforced polymers (CFRPs) through frequency and/or phase modulation of the excitation waveform. In addition to analogue frequency modulated (sweep) and discrete phase modulated (Barker binary coded) waveforms, a new discrete frequency-phase modulated (FPM) excitation waveform is introduced. All waveforms are formulated based on a central frequency so that their performance can be fairly compared to each other and to lock-in thermography at the same frequency. Depth resolvability of the waveforms, in terms of phase and lag of TWR, is firstly analyzed by an analytical solution to the 1D heat wave problem, and further by 3D finite element analysis which takes into account the anisotropic heat diffusivity of CFRPs, the non-uniform heating induced by the optical source and the measurement noise. The spectrum of the defectinduced phase contrast is calculated and, in view of that, the critical influence of the chosen central frequency and the laminate's thickness on the performance of TWR is discussed. Various central frequencies are examined and the outstanding performance of TWR at relatively high excitation frequencies is highlighted, particularly when approaching the so-called blind frequency of a defect.

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Optimizing thermographic testing of thick GFRP plates by assessing the real energy absorbed within the material

Cited by 16 publications

References 37 publications

Estimation of Thermal Resistance Field in Layered Materials by Analytical Asymptotic Method

Estimation of Thermal Resistance Field in Layered Materials by Analytical Asymptotic Method

Carbon Nanotube Reinforced Poly(ε-caprolactone)/Epoxy Blends for Superior Mechanical and Self-Sensing Performance in Multiscale Glass Fiber Composites

Performance of frequency and/or phase modulated excitation waveforms for optical infrared thermography of CFRPs through thermal wave radar: A simulation study

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