Vibrothermographic spectroscopy with thermal latency compensation for effective identification of local defect resonance frequencies of a CFRP with BVID

Hedayatrasa, Saeid; Segers, Joost; Poelman, Gaétan; Verboven, Erik; Paepegem, Wim Van; Kersemans, Mathias

doi:10.1016/j.ndteint.2019.102179

Cited by 16 publications

(6 citation statements)

References 21 publications

(25 reference statements)

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“…However, the viscoelastic damping (or self-heating) is more significantly present at the areas with a higher strain energy density. This may be at a defected area due to local defect resonance [ 20 , 21 ], but also at a non-defected area due to global resonance of the test-piece [ 15 , 46 , 47 ]. In this section, a simplified 1D analytical model is used for simulating the surface thermal response in case of (vibration-induced) subsurface heating of a material with 5 mm thickness, using MATLAB (R2020a, MathWorks, Natick, MA, USA).…”

Section: Vibro-thermal Wave Radar (Vtwr)mentioning

confidence: 99%

“…However, the viscoelastic damping is present at the areas with a higher strain energy density, i.e. at a defected area due to local defect resonance [14,15] or at a non-defected area due to global resonance of the test-piece [40]. In this section, a simplified 1D analytical model is used for simulation of the surface thermal response to vibrationinduced heating as a subsurface heating source.…”

Section: Theory Of Vibro-thermal Wave Radar (Vtwr)mentioning

confidence: 99%

“…Although adequate vibrational activation of the defects normally requires very high excitation power of a few kilowatts [9], tuning the excitation frequency band at a local defect resonance (LDR) frequency, enables low-power vibrothermography using a piezoelectric wafer or an air-coupled transducer [10][11][12][13][14]. As LDR frequencies should be known a priori for the LDR based low-power vibrothermography, a more recent study by the current authors [15] has paved the ground for a stand-alone identification of LDR frequencies through an efficient vibrothermographic spectroscopy procedure.…”

Section: Introductionmentioning

confidence: 99%

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Vibro-Thermal Wave Radar: Application of Barker Coded Amplitude Modulation for Enhanced Low-Power Vibrothermographic Inspection of Composites

et al. 2021

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This paper proposes an efficient non-destructive testing technique for composite materials. The proposed vibro-thermal wave radar (VTWR) technique couples the thermal wave radar imaging approach to low-power vibrothermography. The VTWR is implemented by means of a binary phase modulation of the vibrational excitation, using a 5 bit Barker coded waveform, followed by matched filtering of the thermal response. A 1D analytical formulation framework demonstrates the high depth resolvability and increased sensitivity of the VTWR. The obtained results reveal that the proposed VTWR technique outperforms the widely used classical lock-in vibrothermography. Furthermore, the VTWR technique is experimentally demonstrated on a 5.5 mm thick carbon fiber reinforced polymer coupon with barely visible impact damage. A local defect resonance frequency of a backside delamination is selected as the vibrational carrier frequency. This allows for implementing VTWR in the low-power regime (input power < 1 W). It is experimentally shown that the Barker coded amplitude modulation and the resultant pulse compression efficiency lead to an increased probing depth, and can fully resolve the deep backside delamination.

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Section: Vibro-thermal Wave Radar (Vtwr)mentioning

confidence: 99%

Section: Theory Of Vibro-thermal Wave Radar (Vtwr)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vibro-Thermal Wave Radar: Application of Barker Coded Amplitude Modulation for Enhanced Low-Power Vibrothermographic Inspection of Composites

et al. 2021

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“…Fiber-reinforced polymers have great properties making them a suitable replacement for metallic components. Hedayatrasa et al, 27 in 2019, used viborthermographic spectroscopy to identify the LDR frequencies of a defected sample made of CFRP based on the second derivative of surface temperature. This technique localizes the vibrational energy at the defected area and increases its detectability even in the low excitations.…”

Section: Introductionmentioning

confidence: 99%

Defect detection by laser shear interferometry based on the thermal response of materials with vibratory loading

Nasrabad

Akbari

Karfi

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part B:

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Laser shear interferometry or shearography is one of the optical and non-contact methods for measuring surface displacements. Shearography can be used in non-destructive testing by applying a kind of excitation such as partial vacuum, mechanical and thermal loadings. Parameters of the excitation techniques significantly affect the test results. In many cases, these loading methods deform the whole surface reducing the detection capability of the technique. This paper considers the vibratory loading method as an alternative to the previously mentioned standard methods. In this method, local heat is generated at the defected area due to the internal and external damping of the piece. A simulation has been conducted using COMSOL software to estimate the generated local heat due to the vibratory loading. The local temperature at the defect area is measured, and the simulation results are validated with an experimental infrared thermography test. The experimental shearography setup is adjusted, and the defects are detected. By comparing the results with those of typical thermal loadings, it has been shown that the fringe patterns obtained by the presented method have higher quality.

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“…[4][5][6][7][8][9][10][11] The heat wave may be stimulated by various means, e.g., by delivering optical energy to the inspection surface (i.e., optical thermography), [12][13][14][15][16][17][18] applying an electromagnetic field to the sample (i.e., eddy current thermography), 19,20 or applying a vibrational excitation to the test piece (i.e., vibrothermography). [21][22][23][24][25][26][27][28] The defect detectability and quality of thermographic NDT is strongly dependent on the employed excitation signal. The diffusion length of the heat wave is inversely related to its frequency, 29 and it is of great importance to properly shape the excitation signal in order to tune the probing depth range of the inspection.…”

Section: Introductionmentioning

confidence: 99%

Phase inversion in (vibro‐)thermal wave imaging of materials: Extracting the AC component and filtering nonlinearity

Hedayatrasa

Poelman

Segers

et al. 2021

Structural Contr & Hlth

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In active infrared thermographic inspection of materials, heat wave is stimulated by activation of heat sources, e.g., through optical heat radiation or vibration-induced heat dissipation. Therefore, the monopolar (i.e., heating only) nature of excitation introduces an inevitable ascending trend in the measured thermal response. To obtain an improved thermal wave imaging quality, it is crucial to remove this ascending trend and to analyze the decoupled bipolar (i.e., AC) component of the thermal response. This study introduces the concept of phase inversion in thermographic inspection, as a deterministic method for (i) decoupling the AC component and (ii) filtering the prominent second-order nonlinearities from the thermal response. First, this "phase inversion thermography (PIT)" is theoretically substantiated by analysis of heat diffusion through the thickness of a solid material subjected to dissipative boundary conditions. Then, the performance of PIT in accurately decoupling the AC response from various excitation waveforms is verified by finite element simulation of optical infrared thermography on an anisotropic composite coupon. It is shown that by proper selection of the signal's initial phase and waveform duration, PIT yields the AC response with a zero-mean amplitude. At last, the experimental applicability of PIT is evaluated for two different test cases:(1) optical thermography on a backside-stiffened carbon fiber-reinforced polymer (CFRP) aircraft panel with a complex cluster of production defects and(2) low-power vibrothermography on an impacted CFRP coupon. It is shown that PIT, as a physics-based signal processing technique, robustly resolves the strongly transient onset of the excitation and systematically decouples an AC response which is equivalent to the thermal response to an ideally linear and bipolar excitation. The recorded thermal responses are post-processed through Fourier transform, and the enhanced thermal imaging quality and improved defect detectability of the decoupled AC component are demonstrated.

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Vibrothermographic spectroscopy with thermal latency compensation for effective identification of local defect resonance frequencies of a CFRP with BVID

Cited by 16 publications

References 21 publications

Vibro-Thermal Wave Radar: Application of Barker Coded Amplitude Modulation for Enhanced Low-Power Vibrothermographic Inspection of Composites

Vibro-Thermal Wave Radar: Application of Barker Coded Amplitude Modulation for Enhanced Low-Power Vibrothermographic Inspection of Composites

Defect detection by laser shear interferometry based on the thermal response of materials with vibratory loading

Phase inversion in (vibro‐)thermal wave imaging of materials: Extracting the AC component and filtering nonlinearity

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