THE EFFECTS OF DEBULKING ON THE MICROSTRUCTURE OF CARBON FIBER REINFORCED COMPOSITES

2021 ◽  
Author(s):  
MATHEW SCHEY ◽  
SCOTT STAPLETON ◽  
TIBOR BEKE

Carbon fiber reinforced plastics (CFRPs) are widely used due to their high strength to weight ratios. A common process manufacturers use to increase the strength to weight ratio is debulking. Debulking is the process of transversely compacting a dry fibrous reinforcement prior to wet out with the matrix resin, in order to induce fiber nesting, effectively increasing the volume fraction of the sample. While this process is widely understood macroscopically its effects on fibrous microstructures have not yet been well characterized. The aim of this work is to compare the microstructures of three CFRPs, varying only the debulking step in the manufacturing process. The microstructural effects of debulking on three unidirectional CFRPs made from three different levels of debulking were studied. High resolution serial sections of all three samples were taken using the UES ROBO-MET at the NASA Glenn Research Center in Cleveland, Ohio. Using these scans, the fiber positions were measured and connected to make fiber paths. Statistical descriptors such as local fiber and void volume fractions, and void distribution and morphology were then generated for each sample and compared. Using these descriptors, the effects of debulking on the composite microstructure can be measured.

2019 ◽  
Vol 54 (14) ◽  
pp. 1797-1806 ◽  
Author(s):  
Masayuki Nakada ◽  
Yasushi Miyano

The formulation for time- and temperature-dependent statistical static and fatigue strengths for carbon fiber reinforced plastics laminates is newly proposed based on the physically serious role of resin viscoelasticity as the matrix of carbon fiber reinforced plastics. In this study, this formulation is applied to the tensile strength along the longitudinal direction of unidirectional carbon fiber reinforced plastics constituting the most important data for the reliable design of carbon fiber reinforced plastics structures which are exposed to elevated temperatures for a significant period of their operative life. The statistical distribution of the static and fatigue strengths under tension loading along the longitudinal direction of unidirectional carbon fiber reinforced plastics were measured at various temperatures by using resin-impregnated carbon fiber reinforced plastics strands as specimens. The master curves for the fatigue strength as well as the static strength of carbon fiber reinforced plastics strand were constructed based on the time–temperature superposition principle for the matrix resin viscoelasticity. The long-term fatigue strength of carbon fiber reinforced plastics strand can be predicted by using the master curve of fatigue strength.


Polimery ◽  
2021 ◽  
Vol 66 (1) ◽  
pp. 36-43 ◽  
Author(s):  
N. M. Z. Nik Baihaqi ◽  
A. Khalina ◽  
N. Mohd Nurazzi ◽  
H. A. Aisyah ◽  
S. M. Sapuan ◽  
...  

This study aims to investigate the effect of fiber hybridization of sugar palm yarn fiber with carbon fiber reinforced epoxy composites. In this work, sugar palm yarn composites were reinforced with epoxy at varying fiber loads of 5, 10, 15, and 20 wt % using the hand lay-up process. The hybrid composites were fabricated from two types of fabric: sugar palm yarn of 250 tex and carbon fiber as the reinforcements, and epoxy resin as the matrix. The ratios of 85 : 15 and 80 : 20 were selected for the ratio between the matrix and reinforcement in the hybrid composite. The ratios of 50 : 50 and 60 : 40 were selected for the ratio between sugar palm yarn and carbon fiber. The mechanical properties of the composites were characterized according to the flexural test (ASTM D790) and torsion test (ASTM D5279). It was found that the increasing flexural and torsion properties of the non-hybrid composite at fiber loading of 15 wt % were 7.40% and 75.61%, respectively, compared to other fiber loading composites. For hybrid composites, the experimental results reveal that the highest flexural and torsion properties were achieved at the ratio of 85/15 reinforcement and 60/40 for the fiber ratio of hybrid sugar palm yarn/carbon fiber-reinforced composites. The results from this study suggest that the hybrid composite has a better performance regarding both flexural and torsion properties. The different ratio between matrix and reinforcement has a significant effect on the performance of sugar palm composites. It can be concluded that this type of composite can be utilized for beam, construction applications, and automotive components that demand high flexural strength and high torsional forces.


2015 ◽  
Vol 649 ◽  
pp. 38-45 ◽  
Author(s):  
Chung Shin Chang

Nine kinds of chamfered main cutting edge nose radius tools were used in turning of high-strength carbon-fiber-reinforced-plastics (CFRP) materials to study the cutting temperature of tip's surface. A new cutting temperature model using the variations of shear and friction plane areas occurring in tool nose situations are presented in this paper. The frictional forces and heat generated in the cutting process are calculated by using the measured cutting forces and the theoretical cutting analysis. The heat partition factor between the tip and chip is solved by using the inverse heat transfer analysis, which utilizes temperature on the K type carbide tip’s surface measured by infrared as the input. The tip’s carbide surface temperature is determined by finite element analysis (FEA) and compared with temperatures obtained from experimental measurements. Good agreement demonstrates the proposed model.


Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 205
Author(s):  
Insung Choi ◽  
Su-Jin Lee ◽  
Dongsig Shin ◽  
Jeong Suh

There has been an increase in demand for the development of lightweight and high-strength materials for applications in the transportation industry. Carbon fiber reinforced polymer (CFRP) is known as one of the most promising materials owing to its high strength-to-weight ratio. To apply CFRP in the automotive industry, various machining technologies have been reported because it is difficult to machine. Among these technologies, picosecond laser beam-induced machining has attracted great interest because it provides negligible heat transfer and can avoid tool wear. In this work, we conducted and compared machining of 2.15 mm-thick thermoset and 1.85 mm-thick thermoplastic CFRPs by using a green picosecond laser. The optimized experimental conditions for drilling with a diameter of 7 mm led to a small taper angle (average ~ 3.5°). The tensile strength of the laser-drilled specimens was evaluated, and the average value was 570 MPa. Our study indicates that green picosecond laser processing should be considered as a promising option for the machining of CFRP with a small taper angle.


2018 ◽  
Vol 26 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Chung-Shin Chang

Nine kinds of carbide nose radius worn tools were used in turning of high-strength carbon-fiber-reinforced-plastics (CFRP) materials to study the cutting temperature of tip's surface. A new cutting temperature model using the variations of shear and friction plane areas occurring in tool nose wear situations are presented in this paper. The frictional forces and heat generated in the cutting process are calculated by using the measured cutting forces and the theoretical cutting analysis. The heat partition factor between the tip and chip is solved by using the inverse heat transfer analysis, which utilizes temperature on the K type carbide tip's surface measured by infrared as the input. The tip's surface temperature is determined by finite element analysis (FEA) and compared with temperatures obtained from experimental measurements. Good agreement demonstrates the proposed model.


Author(s):  
Mehran Tehrani ◽  
Ayoub Y. Boroujeni ◽  
Timothy B. Hartman ◽  
Thomas P. Haugh ◽  
Scott W. Case ◽  
...  

Carbon fiber reinforced plastics (CFRPs) possess superior in-plane mechanical properties and are widely used in structural applications. Altering the interphase of CFRPs could alleviate the shortcomings of their out-of-plane performance. In this work, the effects of adding multi-walled carbon nanotubes (MWCNTs) to the epoxy matrix of a CFRP are investigated. Two sets of CFRPs with matrices comprising MWCNTs/epoxy and neat epoxy, respectively, were fabricated. The tensile properties of the two systems, namely the stiffness, the ultimate strength, and the strain to failure were evaluated. The results of the tension tests showed slight changes on the on-axis (along the fiber) tensile modulus and strength of the carbon fiber reinforced epoxy/MWCNT compared to composites with no MWCNTs. The addition of MWCNTs to the matrix moderately increased the strain to failure of the composite. Energy absorption capabilities for the two sets of composites under an intermediate impact velocity (100 m.s−1) test were measured. The energy dissipation capacity of the CFRPs incorporating MWCNTs was higher by 17% compared to the reference CFRPs.


2010 ◽  
Vol 654-656 ◽  
pp. 2620-2623 ◽  
Author(s):  
Kimiyoshi Naito ◽  
Jenn Ming Yang ◽  
Yutaka Kagawa

The polyacrylonitrile (PAN)-based and pitch-based carbon fiber-reinforced nanoparticle filled polyimide based multiscale hybrid composites have been fabricated using vacuum assisted resin transfer molding (VaRTM) and autoclave curing. The carbon fibers used in this study were high tensile strength PAN-based (T1000GB) and high modulus pitch-based (K13D) carbon fibers. Fiber orientations of the T1000GB/K13D hybrid composites were set to [0(T1000GB)/0(K13D)]2S (T1000GB and K13D unidirectional layers were alternately and symmetrically laminated). The fiber volume fraction was 50 vol% (T1000GB: 24.9 vol%, K13D: 25.1 vol%). Polyimide used in this study was a commercially available polyimide precursor solution (Skybond 703). Four different types of nanoparticle (25nm-C, 20-30nm-β-SiC, 130nm-β-SiC and 80nm-SiO2) and particle volume fraction was 5.0 vol% used for the inclusion. The tensile properties and fracture behavior of T1000GB/K13D nanoparticle filled and unfilled hybrid composites have been investigated. For 25nm-C, 20-30nm-β-SiC and 80nm-SiO2 nanoparticle filled and unfilled hybrid composites, the tensile stress-strain curves show a complicated shape. By the high modulus pitch-based carbon fiber, the hybrid composites show the high modulus in the initial stage of loading. Subsequently, when the high modulus carbon fiber begin to fail, the high strength fiber would hold the load (strength) and the material continues to endure high load without instantaneous failure.


2007 ◽  
Vol 334-335 ◽  
pp. 509-512 ◽  
Author(s):  
Kenichi Takemura

Fracture toughness and the possibility of recycling for Carbon Fiber Reinforced Plastics (CFRP) under mode one and mode two loadings are examined. Epoxy matrix is modified by CNBR rubber particle which diameter is smaller than 100 nano meter. Three kinds of rubber content (5,10,15%) are used. Two types of test methods whose modes are different are conducted. After the specimen fracture, recycled specimens are made by adhesion. Fracture toughness is measured at the tests. Fracture surface is also observed by SEM. As a result, following conclusions are obtained. When the interlaminar fracture test using recycled CFRP specimen is conducted under Mode one loading, fracture toughness is improved using rubber modified matrix. For recycled CFRP specimen under mode two loading, fracture toughness of CFRP using unmodified epoxy is improved. In this case, fracture toughness for modified CFRP is improved but it is not as high as than CFRP with unmodified recycle CFRP. From SEM ovservation on fracture sufface under mode two loading, there is a difference on fracture surfaces. Specimen whose fracture toughness is high has a ductile properties.


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