Visualization of subsurface damage in woven carbon fiber-reinforced composites using polarization-sensitive terahertz imaging

Dong, Junliang; Pomarède, Pascal; Chehami, Lynda; Locquet, Alexandre; Meraghni, Fodil; Declercq, Nico F.; Citrin, D. S.

doi:10.1016/j.ndteint.2018.07.001

Cited by 42 publications

(28 citation statements)

References 24 publications

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“…11,12,16,21 Other researchers have used advanced techniques to assess sub surface damage including terahertz imaging and epiflourescent microscopy. 22,23 Wang et al 24 have used a new image subtraction method to quantify the extent of delaminated fibres on an edge trimmed edge using an image subtraction method. SEM imaging, scanning acoustic microscopy and surface roughness measurements have also been applied to assess novel processes for cutting fibre composites such as laser cutting.…”

Section: Review Of State-of-the-art Measurement Methods and Statisticmentioning

confidence: 99%

Towards intelligent CFRP composite machining: Surface analysis methods and statistical data analysis of machined fibre laminate surfaces

Duboust

Watson

Marshall

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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Many carbon fibre reinforced polymer composite parts need to be edged trimmed before use to ensure both geometry and mechanical performance of the part edge matches the design intent. Measurement and control of machining induced surface damage of composite material is key to ensuring the part retains its strength and fatigue properties. Typically, the overall surface roughness of the machined face is taken to be an indicator of the amount of damage to the surface, and it is important that the measurement and prediction of surface roughness is completed reliably. It is known that the surface damage is heavily dependent on the fibre orientation of the composite and cutting tool edge condition. This research has developed a new ply-by-ply surface roughness measurement methods using optical focus variation surface analysis and image segmentation for calculating areal surface roughness parameters of a machined carbon fibre composite laminate. Machining experiments have been completed using a polycrystalline diamond edge trimming tool at increasing levels of cutting edge radius. Optical surface measurement and µ-CT scanning have been used to assess machining induced surface and sub-surface defects on individual fibre orientations. Statistical analysis has been used to assess the significance of machining parameters on Sa (arithmetic mean height of area) and Sv (areal magnitude of maximum valley depth) areal roughness parameters, on both overall roughness and ply-by-ply fibre orientations. Empirical models have been developed to predict surface roughness parameters using statistical methods. It has been shown that cutting edge degradation, fibre orientation and feed rate will significantly affect the cutting mechanism, machining induced surface defects and surface roughness parameters.

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Section: Review Of State-of-the-art Measurement Methods and Statisticmentioning

confidence: 99%

Towards intelligent CFRP composite machining: Surface analysis methods and statistical data analysis of machined fibre laminate surfaces

Duboust

Watson

Marshall

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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show abstract

“…In addition, we point out that our technique can be easily employed even in the reflection geometry. Reflection spectroscopy is more convenient for industrial applications when compared to the transmission spectroscopy, because the reflection geometry is easier to handle for operators [38,40,41,44,71,72,73,74]. Very recently, we demonstrated the inspection of the internal filler orientation of black rubbers by PS THz-TDS in reflection mode [75].…”

Section: Discussionmentioning

confidence: 99%

“…Thus, many terahertz applications involving polymers have been developed; the fingerprint spectroscopy [29], the differentiation between the enantiomer and stereo-complex [30], the determination of the glass transition temperature [31] and the monitoring of the phase transition [26,32,33]. Very recently, the polarization-sensitive (PS) THz-TDS has attracted interest from the viewpoints of both fundamental research [34,35,36,37,38,39,40] and potential terahertz applications [41,42,43,44]. For instance, the PS THz-TDS enables the inspection of the birefringent properties [15,25,26,38,42] and the filler orientation in glass-fiber reinforced polymers [38].…”

Section: Introductionmentioning

confidence: 99%

Internal Status of Visibly Opaque Black Rubbers Investigated by Terahertz Polarization Spectroscopy: Fundamentals and Applications

Okano

Watanabe

2018

Polymers

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We discuss the internal status of rubber composites consisting of an insulating rubber matrix and conductive carbon black (CB) fillers (“black rubber”) using polarization-sensitive terahertz time-domain spectroscopy (THz-TDS). The black rubber composites under stretched conditions exhibit a large optical anisotropy or birefringence in the terahertz regime. From systematic studies, it is revealed that the large birefringence of black rubbers is due to the orientation distribution of anisotropically shaped CB aggregates in the rubber matrix and the orientation distribution is strongly linked to the mechanical deformation of the black rubber. A model simulation based on this relation between deformation and reorientation allows conversion of the birefringence (optical) information into strain (mechanical) information. In addition, the spectroscopic information obtained using the THz-TDS technique is useful to evaluate the changes in the internal conductive filler network caused by the mechanical deformation. Our findings demonstrate that the terahertz polarization spectroscopy is a promising nondestructive inspection method for contactless investigation of the internal condition of black rubber composites.

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“…They were able to highlight the efficiency of such approaches in providing valuable information relative to damage detection and its severity prediction. Dong et al (2018) employed terahertz imaging on woven carbon fibre-reinforced composite subjected to four-point bending load. This method is shown to be efficient and sensitive to damage.…”

Section: Introductionmentioning

confidence: 99%

Detection and evaluation of barely visible impact damage in woven glass fabric reinforced polyamide 6.6/6 composite using ultrasonic imaging, X-ray tomography and optical profilometry

Miqoi

Pomarède

Meraghni

et al. 2020

International Journal of Damage Mechanics

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The present experimental work investigates the response of woven glass fabric reinforced polyamide 6.6/6 subjected to drop weight impact loading. The main objective is the development and the introduction of a new experimental procedure/approach, based on different complementary detection techniques, that aims at investigating the damage induced by impact loading in thermoplastic woven fabric composites. The developed approach is intended to be generalized to other types of composite materials. The main idea is to assess all the experimental results obtained through the developed procedure with a direct investigation method. The latter consists in the Permanent Indentation (PI) measurement providing an indicator of the damage criticality in the composite sample. To this end, several non-destructive testing methods are carried-out and their experimental findings are analyzed and cross-linked. The identification of the different damage mechanisms, caused by the drop weight impact, is performed using X-Ray micro-computed tomography (µCT). C-scan ultrasonic investigation is conducted according to two types: transmission and reflection for the detection of the impact damage and the identification of the induced degradation area. B-scan imaging are then obtained through specific post-processing of the impacted surface to extract the permanent indentation (PI). The latter is validated through surface flatness measurement using the highly resolved 3D optical profilometry. The correlation between the X-Ray tomography results and the permanent indentation measurement is then established. It correlates the PI level with the damage mechanisms of a barely visible impact damage (BVID) in woven glass reinforced polyamide 6.6/6 composite.

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Visualization of subsurface damage in woven carbon fiber-reinforced composites using polarization-sensitive terahertz imaging

Cited by 42 publications

References 24 publications

Towards intelligent CFRP composite machining: Surface analysis methods and statistical data analysis of machined fibre laminate surfaces

Towards intelligent CFRP composite machining: Surface analysis methods and statistical data analysis of machined fibre laminate surfaces

Internal Status of Visibly Opaque Black Rubbers Investigated by Terahertz Polarization Spectroscopy: Fundamentals and Applications

Detection and evaluation of barely visible impact damage in woven glass fabric reinforced polyamide 6.6/6 composite using ultrasonic imaging, X-ray tomography and optical profilometry

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