Heat‐damage assessment of carbon‐fiber‐reinforced polymer composites by diffuse reflectance infrared spectroscopy

Dara, I. H.; Ankara, Alpay; Akovali, G.; Süzer, Şefik

doi:10.1002/app.21500

Cited by 21 publications

(15 citation statements)

References 9 publications

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“…Figure 6 shows a plot of the ILSS loss as a percentage against temperature exposure from 10 min, 1 h and 6 h exposures, and for 10 min exposures, the temperature range where ILSS decreases slowly is extended to higher temperatures, while for 6 h exposures rapid ILSS loss begins earlier. A comparison with Figure 4 suggests the interpretation that the increase in ILSS loss rate corresponds to the onset of physical damage rather than chemical damage; this conclusion has been drawn by other researchers as well [ 10 , 14 ].…”

Section: Resultssupporting

confidence: 77%

“…Moderate and severe thermal damage to CFRE can be detected visually or with standard in-service NDE/NDI techniques such as ultrasonic C-scan. However, the initial stages of thermal damage are often difficult to detect with these methods, and can cause reduction in the part’s mechanical properties, changes in glass transition temperature, matrix embrittlement, and matrix cracking [ 10 ]; these difficult-to-detect changes have been called Incipient Thermal Damage (ITD). Laboratory analysis techniques such as Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) have had success at quantifying ITD by monitoring associated chemical changes in the epoxy matrix [ 11 , 12 ]; their applicability to in-service inspection is limited, however.…”

Section: Introductionmentioning

confidence: 99%

“…Laboratory analysis techniques such as Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) have had success at quantifying ITD by monitoring associated chemical changes in the epoxy matrix [ 11 , 12 ]; their applicability to in-service inspection is limited, however. Potential field-level inspection techniques based on diffuse reflectance FTIR and laser-induced fluorescence are in development, but have limitations in inspection area [ 10 , 13 , 14 , 15 , 16 , 17 ]. An adequate in-service NDE/NDI technique to detect ITD quickly and over a large area would be of great utility to the aerospace industry.…”

Section: Introductionmentioning

confidence: 99%

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Thermochromic Polymer Film Sensors for Detection of Incipient Thermal Damage in Carbon Fiber–Epoxy Composites

Toivola

Jang

Baker

et al. 2018

Sensors

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Carbon fiber–epoxy composites have become prevalent in the aerospace industry where mechanical properties and light weight are at a premium. The significant non-destructive evaluation challenges of composites require new solutions, especially in detecting early-stage, or incipient, thermal damage. The initial stages of thermal damage are chemical rather than physical, and can cause significant reduction in mechanical properties well before physical damage becomes detectable in ultrasonic testing. Thermochromic fluorescent probe molecules have the potential to sense incipient thermal damage more accurately than traditional inspection methods. We have designed a molecule which transitions from a colorless, non-fluorescent state to a colorful, highly fluorescent state when exposed to temperature–time combinations that can cause damage in composites. Moreover, this molecule can be dispersed in a polymer film and attached to composite parts as a removable sensor. This work presents an evaluation of the sensor performance of this thermochromic film in comparison to ultrasonic C-scan as a method to detect incipient thermal damage in one of the most widely used carbon fiber–epoxy composite systems. Composite samples exposed to varying thermal exposures were used to evaluate the fluorescent thermal sensor films, and the results are compared to the results of ultrasonic imaging and short-beam shear tests for interlaminar shear strength.

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Section: Resultssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermochromic Polymer Film Sensors for Detection of Incipient Thermal Damage in Carbon Fiber–Epoxy Composites

Toivola

Jang

Baker

et al. 2018

Sensors

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“…without the presence of delaminations, correlates only with the intensity ratio of the IR-bands 1510 cm À1 to 1486 cm À1 measured with ATR-FTIR-spectroscopy. 33 mCT has the limitation that delaminations smaller than 7.1 mm and the weakening of the fiber-matrix adhesion cannot be detected. Insofar, matrix degradation analyzed with ATR-FTIR-spectroscopy, which is assumed to accompany with the weakening of fiber-matrix-adhesion and the development of micro-delaminations, is a possibility to observe moderate thermal loading.…”

Section: Influence Of the Damage Phenomena On The Mechanical Performancementioning

confidence: 99%

Characterization of one-sided thermal damage of carbon fiber reinforced polymers by means of depth profiles

Vetter

Bibinger

Zimmer³

et al. 2020

Journal of Composite Materials

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This study investigates one-sided thermal damage of carbon fiber reinforced polymers (CFRP) by means of depth resolved infrared spectroscopy, tomography and mechanical testing. All CFRP samples are thermally irradiated at one side with a heat flux of 50 kW/m2 over various time intervals. ATR-FTIR spectroscopy along a ground incline plane through the sample allows a chemical characterization of the thermal degradation of the polymer matrix into depth. Developing delaminations are observed with a depth-resolved gray-value-analysis of microfocused computed X-ray tomographic (µCT) data. Mechanical behavior is determined by tensile, compressive, and interlaminar shear strength (ILSS) testing of specimens taken from different depths of the irradiated samples. The depth profiles show how pronounced damage phenomena like matrix degradation and the development of delaminations are after one-sided thermal loading and how they influence strength in different ways. Compressive strength and ILSS is found to be more sensitive towards thermal damage than tensile strength, as they are most influenced by formed delaminations at higher thermal loads.

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“…Colour change and degradation of the binder can be used to estimate thermal damage . Infrared spectroscopy is capable of characterizing degradation of the binder and is widely used to pursue polymer decomposition . New developments in spectrometer construction allow a mobile and in‐service application of the technique .…”

Section: Introductionmentioning

confidence: 99%

Quantification of a thermal pre‐load on polymer matrix composites by the degradation and colour change of polyurethane top coats

Eibl

2016

Materialwissenschaft Werkst

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This work provides techniques to separately determine temperature (90-340°C) and duration (1 minute to 240 days) of a thermal pre-load as well as residual strength of polymer matrix composites on basis of the degradation of the top-coat. Infrared spectroscopy and colorimetry characterizing binder degradation and colour changes of polyurethane top-coats were used to provide a non-destructive in-service method to quantify incipient heat damage. A multivariate (chemometric) analysis of infrared and colorimetric data was performed. The precision of the calculated values for duration and temperature of the thermal pre-load as well as residual strength for specimen with unknown thermal history is slightly better for the infraredspectroscopic analysis. Deviation of the calculated temperature is less than 10°C. However, the sole analysis of colorimetric data allows a separate evaluation of these parameters. Limitations of the techniques are identified.

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Heat‐damage assessment of carbon‐fiber‐reinforced polymer composites by diffuse reflectance infrared spectroscopy

Cited by 21 publications

References 9 publications

Thermochromic Polymer Film Sensors for Detection of Incipient Thermal Damage in Carbon Fiber–Epoxy Composites

Thermochromic Polymer Film Sensors for Detection of Incipient Thermal Damage in Carbon Fiber–Epoxy Composites

Characterization of one-sided thermal damage of carbon fiber reinforced polymers by means of depth profiles

Quantification of a thermal pre‐load on polymer matrix composites by the degradation and colour change of polyurethane top coats

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