Carbon Fiber Length Research Articles

A Resistance Model of Carbon Fiber Composite Materials Based on Interfacial Effect

Based on the single fiber pull-out testing, the resistance of carbon fiber cement increases during the tensile test in elastic stage. Through the experiment, The fiber embedded length shorter, sample pullout strength is greater. But the resistance change rate is smaller, the lower the sensitivity of the sample. So, considering the fiber length and interface set interface effect of carbon fiber reinforced cement based composite resistance model. A simple model was proposed to explain the mechanism of compression sensitivity of carbon fiber reinforced cement-based composites based on interface effect. The results showed that the content of carbon fiber and interface strain can change the sensitivity of CFRC.

Evaluation of multi-brush anode systems in microbial fuel cells

The packing density of anodes in microbial fuel cells (MFCs) was examined here using four different graphite fiber brush anode configurations. The impact of anodes on performance was studied in terms of carbon fiber length (brush diameter), the number of brushes connected in parallel, and the wire current collector gage. MFCs with different numbers of brushes (one, three or six) set perpendicular to the cathode all produced similar power densities (1200 ± 40 mW/m(2)) and coulombic efficiencies (60% ± 5%). Reducing the number of brushes by either disconnecting or removing them reduced power, demonstrating the importance of anode projected area covering the cathode, and therefore the need to match electrode projected areas to maintain high performance. Multi-brush reactors had the same COD removal as single-brush systems (>90%). The use of smaller Ti wire gages did not affect power generation, which will enable the use of less metal, reducing material costs.

Tensile and thermomechanical properties of short carbon fiber reinforced polyamide 6 composites

In this study, carbon fiber (CF) reinforced polyamide 6 (PA6) composites were prepared by using melt mixing method. Effects of fiber length and content, on the mechanical, thermal and morphological properties of CF reinforced PA6 composites were investigated. Fiber length distributions of composites were also determined by using an image analyzing program. It was seen that the maximum number of fibers were observed in the range of 0–50μm. Mechanical test results showed that, increasing CF content increased the tensile strength, modulus and hardness values but decreased strain at break values of composites. DSC results showed that Tg and Tm values of composites were not changed significantly with increasing CF content and length. However, heat of fusion and the relative degree of crystallinity values of composites decreased with ascending CF content. DMA results revealed that storage modulus and loss modulus values of composites increased with increasing CF content.

Nanoindentation and nanoscratching responses of PEEK based hybrid composites reinforced with short carbon fibers and nano-silica

The micromechanical properties of PEEK based hybrid composites reinforced with short carbon fibers (SCF) and nano-SiO2 particles were examined using nanoindentation and nanoscratching methods. The composites were fabricated by the melt-mixing process at 400 °C. The neat polymer was in granulated form, the size of the nanoparticles was 13 nm and the original length of short carbon fibers was 6 mm. More than 30 nanoindentation and 3 nanoscratching tests were performed on each specimen. Surface topography of the indented and scratched regions was evaluated using AFM. The effects of reinforcing particulates on the typical nanoindentation load-displacement curves of the composites were investigated. Also, the overall reinforcing effects of the carbon fibers and nanoparticles were investigated. Nanoscratching tests were effectively performed to evaluate the frictional properties in the matrix, fiber and interphase regions and also to estimate the thickness of the interphase. There were notable differences between the nanoindentation responses and the microfrictional properties of the composites in matrix and fiber phases. Results showed a significant increase in hardness and elastic modulus due to the presence of reinforcing agents.

Experimental Research on Mechanical Behavior of Carbon Fiber Reinforced Concrete under Different Length of Carbon Fiber

To further study the mechanical properties of carbon fiber reinforced concrete (CFRC) about carbon fiber length, and determine the optimum length of the fiber. In this paper, based on the test, the enhancement effect of four different length of carbon fiber reinforced concrete is studied. Compressive strength curves and load-deformation curves of the test blocks mixing the different lengths carbon fiber are obtained. In the loading process, the change curve of the ratio of transverse strain and longitudinal strain are obtained. The results showed that the compressive strength increase and after decrease with the increase of fiber length. When the length of carbon fiber is 10 mm, the improved effect is best, and it can effectively improve the brittle failure of concrete. When the length of carbon fiber is more 30 mm, the improved effect of deformation of carbon fiber reinforced concrete is not obvious.

Experimental Research on Flexural Mechanical Behavior of Fiber Reinforced Concrete Flexural Members

Based on the cross-section bending of 5 carbon fiber concrete beams, the mechanism of deflection and strain of carbon fiber concrete beam were studied considering the variation of the length of carbon fiber and stirrup ratio. The experimental results show that the deflection of destruction increased with the increase of the length of the carbon fiber, and the effect of stirrup ratio on deflection and strain of beams is not obvious. The carbon fiber can effectively improve the brittle failure of concrete beam, and the stain of concrete accorded with that steel bar at the same height. According to the existing test model, the theoretical calculating formula of CFRC was proposed and applied for the cracking load calculation expression of CRFC beams, and theoretical calculated results agree well with experimental results.

Experimental Research on Mechanical Behavior of Carbon Fiber Reinforced Concrete Beam

Based on the cross-section bending of 5 carbon fiber concrete beams, the mechanism of deflection and strain of carbon fiber concrete beam were studied considering the variation of the length of carbon fiber. The experimental results show that the deflection of destruction increased with the increase of the length of the carbon fiber. The carbon fiber can effectively improve the brittle failure of concrete beam, and the stain of concrete accorded with that steel bar at the same height. According to the existing test model, the theoretical calculating formula of CFRC was proposed.

Experimental Research on Mechanical Behavior of Carbon Fiber Reinforced Concrete

This text introduced the research results of carbon fiber reinforced concrete beams and columns, and a brief description was presented about the influence of freeze-thaw cycles of carbon fiber reinforced concrete. Based on the experiment and related documents, studies the effects of the different dosage and different lengths of short carbon fiber on the compressive strength of concrete cube test. The results of experiment show the optimum dosage of carbon fiber is 0.24%.The improved compressive strength of carbon fiber reinforced concrete was particularly remarkable. The compressive strength could have a downward trend with the dosage increase. When the lengths of short carbon fiber is 10mm, compared to plain concrete, compressive strength increased 17.7%, and then the compressive strength could have a downward trend with the length increase. When the length of short carbon fiber is 50mm, compressive strength decreased 3%.

Anisotropic Dielectric Properties of Short Carbon Fiber Composites

Dielectric materials based on short carbon fiber (Csf) dispersed inside epoxy resin (EP) matrix composites were prepared. Here we report the complex permittivity of two types of distributions over the frequency range from 2.6 to 8.2 GHz. The effects of orientation with different content and length of carbon fibers on dielectric properties were investigated. It is found that axial permittivity of carbon fibers is several times larger than their radial permittivity. The real and imaginary parts of complex permittivity increased gradually with increasing the Csf contents in the composites, and the fiber length also affects the anisotropic property greatly. The two layered transmission line model is used to explain the phenomena.

Oxidation Kinetics and Its Impact on the Strength of Carbon Short Fiber Reinforced C/SiC Ceramics

AbstractBecause of the excellent fracture toughness and oxidation resistance, carbon short fiber reinforced ceramics have a sound potential for a variety of high‐temperature applications. For the composite's reliable use in long‐term applications, however, the oxidation effects on the mechanical strength are of crucial interest and have hitherto not been investigated in detail yet. In this study, the weight change of carbon short fiber reinforced C/SiC composites with carbon fiber lengths of 9 mm (long cut fiber composite – LCFC) and 2 mm (short milled fiber composite – SMFC), respectively, are evaluated in the temperature range from 500 to 1200 °C for two different fiber orientations. Both types of composites were additionally tested in bending mode after 25 and 50 min of exposure to air at 700 °C depending on fiber orientation. After 3 h of exposure at 1000 °C, a total weight loss of up to 37% for LCFC and 47% for SMFC could be determined. The bending test carried out after 50 min exposure at 700 °C showed a dramatic decrease down to 50% of the initial flexural strength for LCFC samples with fibers orientated in parallel to the beam axis. The smallest strength decrease of around 13% was found for SMFC samples with fibers orientated perpendicularly to the beam axis. Microstructural investigations suggest strongly that oxidation along the fibers is the most dominating weakening mechanism and is therefore directly affected by the fiber orientation and length.

Effects of initial fiber length and fiber length distribution on the properties of carbon-fiber-reinforced-polypropylene composites

In this study, short carbon fiber-reinforced polypropylene composites with three different initial carbon fiber lengths were prepared by using extrusion compounding and injection molding techniques. The physical and morphological properties of the prepared short carbon fiber-reinforced composites were investigated by means of tensile test, differential scanning calorimetry and scanning electron microscopy. Final fiber length distributions of composites were also determined by using an image analyzing program. It was found that the maximum number of fibers was observed in the range from 51 to 100 µm. Number average final fiber lengths were calculated between 230 and 280 µm. Regardless of the used initial carbon fiber length, tensile strength and modulus values of the composites increased with the increasing carbon fiber content. It has been concluded that the initial fiber length at the studied range did not have any significant effect on the properties of composites.

CFRP Chip 표면처리에 따른 페놀복합재료의 강화, 내열성 및 난연성 향상

CFRP chip is the byproduct from carbon fiber reinforced plastic (CFRP) processing. CFRP chip is not simply a waste mainly composed of fine carbon fiber and epoxy resin. CFRP chip keeps matrix to maximize their reinforcing effect. To obtain a uniform length of carbon fiber in CFRP chip, chip was chopped ina mortar. CFRP chip should be purified to get better interface adhesion. Epoxy resin on the carbon fiber was removed by H2O2 surface etching treatment. Optimal dispersion and fabrication conditions of CFRP chip embedded in phenolic resin were determined by thermal stability for fire retardant applications. CFRP chip-phenolic composite exhibits better mechanical and thermal properties than neat phenolic resin. Surface condition of CFRP chip-phenolic composite was evaluated by static contact angle measurement. Contact angle of CFRP chip-phenolic composite was greater than neat phenolic due to heterogeneous condition of fine carbon fibers. From the evaluation for fire retardant (ASTM D635-06) test, thermal stability of CFRP chip-phenolic composite was found to be improved with higher concentration of CFRP chip.

Study on Short Carbon Fiber Asphalt Concrete Marshall

The addition of chopped carbon fiber will effect on the pavement performance of asphalt concrete and reinforce and crack-resistance the concrete. The type, length and mixture of pitch carbon fiber have a significant impact on chopped carbon fiber asphalt concrete. This article discusses the effect of carbon fiber on the Marshall of concrete short asphalt, visits the change of Marshall Index, chooses the best short-cut ratio of concrete with carbon fiber asphalt and asphalt and gives guidance to the design of chopped carbon fiber asphalt concrete and construction.

Artificial neural network for structural behavior prediction of RC one-way slab strengthened by CFRP

In this project, 6 Reinforced Concrete (RC) slabs with various length and thickness of carbon fiber reinforced polymer (CFRP) in comparison with the plain RC slab have been used to generate Artificial Neural Networks (ANNs) for structural behavior prediction. The slab dimension was 1800 × 400 × 120 mm and the length of the CFRP was 700, 1100 and 1500 mm in two different cross section area of 60 and 96 mm2. The results of this experimental work are noted in each testing process. The general regression neural network (GRNN) was the first practical approach that has applied for structural analysis prediction. The feed forward back-propagation (FFB) was the second method with a per regression method for data collection to increase the number of data for training, verifying and testing. The two used method had minimal error and maximum correlation coefficient. The amounts of MSE and RMSE in GRNN and FFB system were in the acceptable ranges. The correlation coefficient is closed to 1 for output data. Key words: Artificial neural networks, carbon fiber reinforced polymer, general regression neural network, feed forward back propagation, mean squared error, root mean squared error.

Experimental Research for Scour Resistance of Basalt and Carbon Fiber Hydraulic Concrete

According to a series scour resistance experiment of basalt fiber and carbon fiber hydraulic concrete, in which different length and different volume ratio of basalt fiber and carbon fiber to compare to cement volume are mixed in the concrete, the scour resistance characteristics of hydraulic fiber concrete are analyzed in this paper. Experimental results show that basalt fiber and carbon fiber may enhance scour resistance of hydraulic concrete, and the volume ratio of fiber to compare to cement volume in concrete is the main reinforcement factor, but the influence of fiber length in concrete on the scour resistance of concrete is not obvious.

Nonlinear analysis of load-deflection testing of reinforced one-way slab strengthened by carbon fiber reinforced polymer (CFRP) and using artificial neural network (ANN) for prediction

Load-deflection curve is the most important part of the structural analysis of RC beam and slab. The load-deflection analysis of the RC one-way slab strengthened by CFRP using experimental work, finite element analysis (FEA), artificial neural network (ANN), and a comparison of them together are the important objective of this study. The dimension of the one-way slab was 1800A�400A�120 mm which was strengthened by different length and width of carbon fiber reinforced polymer (CFRP). The experimental results sufficiently adapted with FEA and ANNs output. The feed forward back-propagation (FFB) was the best ANN for prediction of load-deflection curve with minimum error below 1, and maximum correlation coefficient close to 1.

Damage self-diagnoses feasibility of fiber-reinforced concrete structure

The seepage theory was used to explain the variation between the specific resistance of the carbon fiber reinforced cement concrete and the carbon fiber volume ratio. The electro-dynamic seepage was observed in the cement. The longer the carbon fiber is, the smaller the critical volume to produce the electro-dynamic seepage phenomenon will be. However, the forming and stirring process is harder. In general, the average length of carbon fiber is 5 mm. Under the condition of three-point bending load, the specific resistance changes with the loading process, and a good correlation could be obtained according to the load-deflection relationship. The experimental results reveal that the carbon fiber reinforced cement based composites can be used as sensors to self-diagnoses of the damage.

Electromagnetic Design and Realization of Innovative Fiber-Reinforced Broad-Band Absorbing Screens

This paper presents the design and the realization process for radar absorbing panels made of composite materials. It is demonstrated that the proper selection of the carbon fiber length and volume fraction allows reducing sensibly the overall thickness of the screen compared to a standard absorber, and obtaining at the same time broad-band absorption response in the X- and Ku-bands. To this end, the carbon fiber composite material realizing the lossy sheet of the absorbing screen is designed by simulation in order to have tailored complex effective permittivity. Two prototypes of absorbing screens are realized and tested experimentally. The first one is a three-layer panel, characterized by reflection coefficient lower than -10 dB in the frequency range from 8 to 14 GHz, and total thickness of 4.5 mm. The second one is a five-layer panel with reflection coefficient less than -20 dB in the range 9-18 GHz, and total thickness of 5.5 mm.

繊維強化プラスチックの破壊モード特性に関するマイクロメカニクス

Discontinuous fiber reinforced plastics have superior productivity and formability in comparison with continuous fiber reinforced plastics. However, their strengths are remarkably low. Thus there is an urgent need to establish a fundamental model in order to improve the strength of discontinuous fiber reinforced plastics. In the present work, we utilized numerical simulations that consider the microscopic damage in the composite and incorporate an individual constitutive law of thermosetting resin or thermoplastic resin. The fundamental mechanism that affected the strength and failure of the composite was investigated when the fiber length and/or matrix properties were varied from continuous glass fiber reinforced plastics to discontinuous glass fiber reinforced plastics. Our results clarified two factors that cause the strength degradation of discontinuous fiber reinforced plastics. One is the low yield stress of thermoplastic resin, which is frequently used for the matrix of discontinuous fiber reinforced plastics. As the other factor, the final failure mode is changed from fiber breaking mode to matrix cracking mode in the case of the low fiber volume fraction of discontinuous glass fiber reinforced plastics. Moreover, we investigated the relationship between fiber length and strength of carbon fiber reinforced polypropylene and the effect of thermoplastic matrix properties depending on the loading rate as well.

Tensile strength and its variation of PAN‐based carbon fibers. I. Statistical distribution and volume dependence

AbstractThe effects of the diameter, gauge length, and volume of carbon fibers on the tensile properties and their variation are discussed on the basis of the weak‐link theory and Weibull distribution in a single‐filament test. As far as variation is concerned, the stress of carbon fibers should be obtained by the division of the force not by the mean cross section of all the fibers but by the cross section of individual fibers because of the diameter variation. The volume effect of carbon fibers influences not only the mean of the tensile properties but also their variation. The experimental results indicate that the volume dependence in the radial direction is much bigger than that in the axial direction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3175–3182, 2006