Investigation of heat generation sources in lock-in sonic thermography using laser Doppler vibrometry

Montanini, Roberto; Freni, F.

doi:10.21611/qirt.2012.177

Cited by 8 publications

(5 citation statements)

References 14 publications

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“…Different excitation frequencies are studied, but only the results for a frequency of 5 kHz are reported here. This frequency is close to a resonant frequency of the samples that can guarantee the best results in terms of temperature variation as reported in [22,23,24]. Thermal images are acquired by an infrared camera (FLIR X6540) during 180 seconds at a 50 Hz frequency with an integration time of 3000 µs (to obtain the necessary resolution of above some tenths of a degree) [25].…”

Section: Experimental Approachmentioning

confidence: 91%

Investigation of multiple cracking in glass/epoxy 2D woven composites by vibrothermography

Bai

Lamboul

Roche

et al. 2015

Quantitative InfraRed Thermography Journal

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An experimental study about the application of vibrothermography for the investigation of multiple microcracking in woven composites is here reported. The material is first damaged during tensile loading tests in order to have samples that present increasingly damaged states. The goal of the study is to apply vibrothermography to compare the sensitivity of their heating behaviour (global and local) with the crack density. A correlation between the heating and the loss of a mechanical property of the material (in this case the Young modulus) estimated with the tensile loading tests is also highlighted.

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Section: Experimental Approachmentioning

confidence: 91%

Investigation of multiple cracking in glass/epoxy 2D woven composites by vibrothermography

Bai

Lamboul

Roche

et al. 2015

Quantitative InfraRed Thermography Journal

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“…Many researchers simply labeled heat generation in vibrothermography as friction induced, but other researchers suggested that thermo-plastic heat generation or thermoelasticity, viscoelasticity and anelasticity, or a combination of these mechanisms are the sources of crack heating [67]. For instance, Montanini et al stated that for flat-bottomed hole defects, viscoelasticity is the primary heat source, on the other hand the combination of viscoelasticity and friction is the primary heat source for elamination and cracks [68].…”

Section: Principle Of Heat Generation In Vibrothermographymentioning

confidence: 99%

Recent developments in vibrothermography

Gülcan¹

2021

Res. Eng. Struct. Mater.

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Due to the sensitivity of fluorescent penetrant inspection to surface roughness of the inspected material, researchers have been investigating alternative inspection methods. Vibrothermography is one of the contactless nondestructive testing methods in which vibration pulses with high frequencies (typically 20-40 kHz) are used in a part for a short period of time to produce thermal gradient at the defect. In this technique, thermographic or infra-red cameras are used for radiation detection due to thermal gradient in the range of 0.9-14 µm electromagnetic spectrum. This paper focuses on the recent developments in vibrothermography. It covers basics, history, equipments used, types, materials, probability of detection, principle of heat generation mechanism and factors that affect detectability in vibrothermography.

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“…These heat generation mechanisms may act individually or in combination. In the case of a flat-bottomed hole (FBH) defect, the primary heat source is viscoelasticity, whereas in delamination and cracks, the combination of both viscoelasticity and friction plays the main role [8,9]. Furthermore, a direct relationship between the excitation frequency and the generated heat on the cracks has been reported by Holland et al [10,11].…”

Section: Introductionmentioning

confidence: 99%

Automated extraction of local defect resonance using the principal component analysis in lock-in ultrasonic vibrothermography

Ghorashi

Honarvar

Tabatabaeipour

2020

Infrared Physics & Technology

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Ultrasonic vibrothermography is an emerging and promising nondestructive evaluation technique used for detection of surface and sub-surface defects. The heat-generating sources such as friction of the surface asperities of the defect and viscoelastic behavior of the structure may cause variations in non-linear elastic energy leading to the rise of temperature of the damaged area. In this paper, a Flat-Bottomed Hole (FBH) defect is modeled by finite element method in a polymethylmethacrylate (PMMA) structure. The desired information from this defect is retrieved by its local defect resonance (LDR) frequency which is estimated through a Principal Component Analysis (PCA). It is shown that the PCA algorithm can extract the LDR frequency of the FBH with high accuracy. The sample is then excited by a sine wave at its LDR frequency modulated by a low frequency corresponding to the thermal penetration depth. The lock-in amplitude and phase images are also generated at different modulation frequencies in order to find the optimal frequency in terms of contrast enhancement. The results of the finite element model are then verified by comparison with published experimental results and are found to be in very good agreement.

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Investigation of heat generation sources in lock-in sonic thermography using laser Doppler vibrometry

Cited by 8 publications

References 14 publications

Investigation of multiple cracking in glass/epoxy 2D woven composites by vibrothermography

Investigation of multiple cracking in glass/epoxy 2D woven composites by vibrothermography

Recent developments in vibrothermography

Automated extraction of local defect resonance using the principal component analysis in lock-in ultrasonic vibrothermography

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