Effect Of Carbon Fiber Research Articles

Modeling and mechanism of the mechanical interlocking for the carbon fiber/epoxy interphase

The intricate details governing the carbon fiber/epoxy interfacial characteristics at the molecular level have yet to be comprehensively unraveled. One of the reasons is that the effects of carbon fiber (CF) surface structures are oversimplified, leading to misconceptions regarding adhesion mechanisms. To advance knowledge of structure-property relationships, we employed molecular dynamics simulations to provide insights into the complexity of the CF surface and CF/epoxy interphase. A series of turbostratic surface models with different protrusion heights were built via crosslinking basic structural units inside hexagonal prism virtual energy walls to better model the physical and chemical features of a CF surface. Epoxy precursor and curing agent molecules were added and crosslinked to generate the CF/epoxy interphase models before loading the systems in tension and shear. It was found that the spatial variation of composition determines the longitudinal and transversal moduli distribution in the interphase. Moreover, higher protrusion increases the tensile strength and toughness in the transverse direction by transferring part of the tensile loading into the shear component. The mechanical interlocking between the polymer and the CF surface with microvoids and protrusions enhances both the interfacial shear strength and the effectiveness of load transmission.

Effect of carbon fibers and graphite particles on mechanical properties and electrical conductivity of cement composite

The utilization of self-sensing concrete for structural monitoring is currently a significant research focus. This study involves fabricating self-sensing cement-based composites(SCC) with different carbon fiber contents; the graphite powder content remains fixed at 20 % by mass. The investigation focuses on assessing the influence of carbon fiber on the mechanical strength, electrical conductivity, and piezoresistive properties of cement-based composites incorporating graphite. Furthermore, the study examined the modification mechanisms of carbon fiber in SCC through Nuclear Magnetic Resonance (NMR) and Scanning Electron Microscopy (SEM). The compressive strength initially increases and then decreases with the addition of carbon fibers, reaching a peak of 43.01 MPa at a carbon fiber concentration of 0.6 vol%. SEM analysis revealed that the primary failure mode of carbon fibers is pull-out behavior, which enhances the damage pathway of SCC, thereby improving their mechanical properties. According to NMR results, the porosity of the SCC decreases to varying degrees with the inclusion of carbon fibers, showing an 11.36 % reduction at a carbon fiber concentration of 0.6 vol%. Under cyclic compressive loading within the elastic range, the change in resistivity can reach up to −76.8 %, with a strain sensitivity factor of 1300. Based on the results, it was determined that the addition of 0.6 vol% carbon fibers can significantly improve the mechanical, electrical conductivity, and piezoresistive properties of SCC with a graphite-modified cement matrix.

Effects of Carbon Fiber on Mechanical Properties of Reactive Powder Concrete

Effects of Carbon Fiber on Mechanical Properties of Reactive Powder Concrete

Effect of Carbon Fiber and Potassium Titanate Whisker on the Mechanical and Impact Tribological Properties of Fe-Based Impregnated Diamond Bit Matrix.

Various contents of carbon fibers (CFs) and potassium titanate whiskers (PTWs) were added to an Fe-based impregnated diamond bit (IDB) matrix to enhance its adaptability to percussive-rotary drilling. A series of mechanical tests were conducted successively to find the effects of the reinforcing materials on the properties of the Fe-based IDB samples. Then, the fracture surfaces of the samples were analyzed via scanning electron microscopy (SEM) and energy-dispersive spectroscopy, and the worn surfaces and abrasive debris of the samples were analyzed using a laser scanning confocal microscope and SEM. The results show that both the CF and PTW can effectively improve the hardness and bending strength of an Fe-based IDB matrix, and those parameters reached their maximum values at the additive amount of 1 wt%. However, the CF had a better enhancement effect than the PTW. Furthermore, the CF improved the impact wear resistance of the IDB matrix, with a minimum wear rate of 2.38 g/min at the additive amount of 2 wt%. However, the PTW continuously weakened the impact wear resistance of the IDB matrix with increases in its content. Moreover, the morphologies of the worn surfaces indicated that the minimum roughness of the CF-reinforced IDB matrix decreased significantly to as low as 4.91 μm, which was 46.16% lower than that without CF, whereas the minimum roughness of the PTW-reinforced samples decreased by 11.31%. Meanwhile, the abrasive debris of the CF-reinforced samples was more uniform and continuous compared to that of the PTW-reinforced samples. Overall, the appropriate addition of CF or PTWs can enhance the mechanical properties of Fe-based IDB matrices, which can be used on different formations based on their impact wear resistance.

Evaluation of industrial byproduct iron ore tailings and carbon fiber cement-based materials under sulfate freeze-thaw cycles: Durability, piezoresistivity, and microscopic mechanism

This study investigated the feasibility of utilizing industrial byproduct iron ore tailings and carbon fiber cement-based materials (ICCM) in sulfate freeze-thaw (F-T) environments. The effects of carbon fiber (CF) and iron ore tailing (IOT) on the sulfate F-T resistance, piezoresistivity, and pore distribution were tested. The results revealed that CF (0.6 vol%) and IOT (30%) significantly improved the compressive strength (51.6 MPa) and resistance to sulfate F-T of ICCM. The stress sensitivity was obviously enhanced to 1.389 %·MPa−1. Furthermore, the stress sensitivity is closely related to the sulfate F-T environment. After the sulfate F-T cycles, the fractional change in resistivity (FCR) and compressive stress agreed with a first-order exponential decay relationship. Replacement with IOT compensated for the degradation in piezoresistivity by formation of balanced pore distribution over 200 F-T cycles. The combination of IOT and CF in cement material yields excellent performance in terms of stress sensing, cost, and environmental impact (EI). This approach is expected to be developed for self-sensing in extreme environments with a recycled conductive filler.

Effect of Carbon Fibers on Tensile Properties of Onyx Specimens with Circular Hole Fabricated by 3D Printer

Effect of Carbon Fibers on Tensile Properties of Onyx Specimens with Circular Hole Fabricated by 3D Printer

Engineering and microstructural properties of carbon-fiber-reinforced fly-ash-based geopolymer composites

Alkali-activated fly ash and slag-based geopolymer composites offer sustainable cement alternatives to conventional cement materials. Incorporating fibers mitigates issues such as brittleness, insufficient toughness, and cracking in geopolymers. However, limited systematic research exists on the influence of carbon fiber characteristics on geopolymer performance. In this study, the effects of carbon fibers having varying lengths (6 mm and 12 mm) and volume fractions (0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1.0%) on multiple properties of geopolymers, including workability, water absorption, porosity, mechanical strength, drying shrinkage, uniaxial tensile properties, fracture toughness, and microstructure, are investigated. Results indicate that the incorporation of carbon fibers diminishes the flowability of the geopolymer mix and accelerates its setting time. Parameters such as water absorption, porosity, and compressive and flexural strengths initially decrease and then increase with increasing fiber content. Carbon fibers positively affect drying shrinkage, particularly during the early stages. The fiber bridging effect enhances uniaxial tensile properties, reducing brittleness. Carbon fiber addition improves the fracture toughness of the composite, achieving an optimal volume fraction at 0.6%. At this volume fraction, carbon fibers of 6 mm length exhibit better crack initiation toughness and resistance to instability cracking than fibers of 12 mm length. Moreover, the presence of carbon fibers promotes the formation of hydration products, minimises the occurrence of microcracks, and interacts synergistically with the slurry matrix to enhance overall crack resistance and material toughness. This study provides a valuable reference for the development and application of fiber-reinforced geopolymer materials.

Effect of carbon fibers (length, dosage) on the Marshall and volumetric properties of HMA mixtures

Effect of carbon fibers (length, dosage) on the Marshall and volumetric properties of HMA mixtures

Effect of carbon fiber and thermoplastic resin on laminates under lightning and dielectric strength tests

AbstractThe incorporation of carbon fiber (CF) and thermoplastic resin in wind turbine rotor‐blade represents a challenge for lightning events because CF conducts electricity and the behavior of thermoplastic resins is not well known. A comparative study with laminates with epoxy or thermoplastic resins was performed, using lightning and dielectric strength tests. Lightning tests revealed that resins behaved similarly; the current preferentially flowed in fiber direction and in zones with high contact between fibers (e.g., criss‐crossed fibers at panel edges); the level of through‐thickness damage was inversely related to panel thickness; current flow did not affect the tensile properties in fiber direction, but produced a drop in bending strength; the adequate integration of earth terminals in CF laminates was critical for a proper lightning discharge. In dielectric tests, it was concluded that panels with glass fiber covering CF laminates behaved as through‐thickness insulators; the thermoplastic reduced the laminate's dielectric strength, while the incorporation of CF, or laminate aging in a salt spray chamber showed no difference. Electrical resistance tests showed that the results were not dependent on the type of resin, but on the level of fiber‐to‐fiber and fiber‐to‐terminal contact. The lowest linear resistance was obtained in the longitudinal fiber direction, followed by the transverse and through‐thickness ones.

Effect of carbon fiber and graphite on the mechanical properties of conductive fine-grained concrete in textile reinforced concrete

In order to further explore the influence of single and double-doped carbon fiber and graphite on the mechanical properties of fine-grained concrete, compressive tests, flexural tests and uniaxial compressive tests were used. Researches show that the bending strength increases the most when 0.25% carbon fiber and 10% graphite are added in the fine-grained concrete. The ultimate failure modes of fine-grained concrete under uniaxial compression contains two types: split and shear. The double-doped conductive material can make up for the defects existing after the addition of single conductive material and improve concrete performance. Finally, based on the Kent and Park constitutive model and combined with the full-stress–strain curve image obtained by the test in this paper, a modified Kent and Park three-line function stress–strain constitutive model of fine-grained concrete was established.

Investigation of Carbon Fiber on the Tensile Property of FDM-Produced PLA Specimen.

Herein, the effect of carbon fibers (CFs) on the tensile property of a polylactic acid (PLA) specimen prepared by utilizing the fused deposition modeling (FDM) method, is investigated. The tensile property, crystal structure, and morphology of FDM-produced specimens were detected by universal testing machine, X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. Meanwhile, the reinforcement mechanism of CFs on the FDM-printed PLA specimens was also studied. The DSC curves indicated that the crystalline structure of the PLA-CF specimen was higher than the PLA specimen. After the introduction of CFs, the XRD results showed the crystal structure of PLA varied from non-crystalline to α crystalline, and the SEM results illustrated the terrible bonding interface between carbon fiber and PLA. Interestingly, after the introduction of carbon fiber, the tensile strength of the PLA specimen reduced from 54.51 to 49.41 MPa. However, compared with the PLA component, the Young's modulus and the elongation-at-break of the PLA-CF specimen increased from 1.04 GPa and 6.26%, to 1.26 GPa and 7.81%, respectively.

Effect of carbon fiber on the properties of polymer cement based building sealant

AbstractThe working property, bond property, and mechanical property of five kinds of polymer cement based building sealant (PCBS) with different carbon fiber content were tested. The effect of carbon fiber on the properties of PCBS was discussed by analyzing the variation of the leveling performance, consistency, low temperature flexibility, surface dry time, elastic recovery rate, tensile mechanical property, and shear mechanical property of PCBS with carbon fiber content. And the modification mechanism of carbon fiber on PCBS was interpreted using scanning electron microscopy and mercury intrusion porosimetry techniques. The results shows that PCBS still has good working property and bonding property with carbon fiber addition. As the carbon fiber content increases, the leveling performance and low temperature flexibility of PCBS are unaltered., the consistency increases, while the surface drying time and elastic recovery rate decrease. The tensile and shear mechanical properties of PCBS can be improved by adding carbon fiber. With the increase of carbon fiber content, the strength performance indexes of PCBS increase, while the energy consumption performance indexes first increased followed by a decrease. When the carbon fiber content is 0.1%, the properties of PCBS is the best. The pore structure of PCBS gradually deteriorates, and the total porosity and the percentage of macropores increase with carbon fiber addition. Carbon fiber primarily exerts cracking resistance and internal deterioration effects in PCBS.

Effect of crack width on electromagnetic interference shielding effectiveness of high-performance cementitious composites containing steel and carbon fibers

In this study, the effects of carbon fibers and crack widths on the electromagnetic interference (EMI) shielding effectiveness of high-performance fiber-reinforced cementitious composites (HPFRCCs) with 2 vol.% straight steel fibers were evaluated. To this end, 0.2 vol.% carbon fibers were added and four penetrated pre-crack widths ranging from 0.02 to 0.2 mm were applied under tension. The tensile strength and electrical resistance of the composites were also investigated. The test results indicated that adding 0.2% carbon fibers effectively enhanced the tensile strength, electrical conductivity, and shielding effectiveness of the HPFRCC. Furthermore, the electrical conductivity was improved by 224%, and a 27% higher shielding effectiveness was achieved. A shielding effectiveness of 48.5 dB at 1 GHz was achieved with a specimen thickness of 25 mm. Tiny cracks with a width of 20 μm significantly reduced the EMI shielding effectiveness of the HPFRCC by approximately 40%. For the plain HPFRCC, the shielding effectiveness was not significantly affected by the crack width, as it was thoroughly cracked. The benefits of adding carbon fibers for improving the shielding effectiveness disappeared at crack widths greater than 0.1 mm. Thus, the addition of carbon fibers was effective only for HPFRCCs without cracks or with very tiny cracks of less than 40 μm.

Effect of carbon fibers on the mechanical properties of steam-cured concrete

While the use of the steam-curing method in the precast concrete can result in an early high compressive strength and thus can increase the production rate of structural elements, it should be noted that the steam-curing method has some negative effects on the mechanical properties of concrete due to the fact that the high-temperature steam causes micro-cracks. On the other hand, the inclusion of carbon fibers enhanced the overall mechanical properties in terms of high tensile strength and modulus of elasticity. This paper aimed to investigate the effect of adding carbon fibers to steam-cured concrete. Twenty-seven cube specimens of 15 cm dimensions were used to investigate the unit weights, the ultrasonic pulse velocity, the compressive strength, and the split tensile strength of the concrete. Three different mixes were made by adding carbon fibers (0%, 0.12% and 0.24%) by weight to the concrete. Three of each were kept in a standard curing environment for 3, 7 and 28 days. Three specimens of each mix were steam-cured for 4 hours, and three specimens were steam-cured for 8 hours. The result showed a significant increase in the rate of gaining compressive strength under steam-curing with an enhancement in the tensile strength due to the presence of fibers, all without compromising the integrity of the concrete and without increasing the amount of voids.

Microcellular injection molding of polyether-ether-ketone

Polyether-ether-ketone (PEEK) has been widely used in aerospace field for its excellent performance. Microcellular injection molding (MIM) is a promising method to reduce product weight and save energy consumption. In this study, microcellular PEEK was prepared by injection molding. Firstly, the thermal properties of raw PEEK, injection molded PEEK, and foamed PEEK were investigated and results show that the thermal performance of the three types of PEEK were similar. Secondly, the effects of process parameters, including melt temperature, injection speed, injection volume and gas concentration, on microcellular PEEK were studied. The results show that injection volume had the most significant influence on the weight-reduction ratio and tensile strength, while the change of melt temperature, injection speed, injection volume and gas concentration could alter the internal cell structure. After optimization, two kinds of microcellular PEEK with the largest weight-reduction ratio of 17.29% and the greatest tensile strength of 74.13 MPa were obtained respectively. Thirdly, the effect of carbon fiber on microcellular PEEK was preliminarily studied. It was found that carbon fiber could promote the formation of dense cell structure. This work laid the foundation for further fabrication of high strength and light weight microcellular PEEK. • Effects of parameters on foamed PEEK are studied by single factor and orthogonal test. • Weight reduction and tensile properties are mainly dependent on injection volume. • Melt temperature, injection speed and injection volume greatly affect cell structure. • The weight-reduction ratio increases to 17.29% through optimization. • The tensile strength and tensile modulus reach 74 MPa and 2784 MPa after optimization.

The combined effect of carbon fiber and carbon nanotubes on the electrical and self-heating properties of cement composites

This work investigates the electrical and heating performance of conductive cement composites by using carbonaceous materials (carbon fibers (CF) and carbon nanotubes (CNT)) as conductive materials. Various volume fractions of carbonaceous materials were used to indicate the electrical heating performance of the cement composites. Experimental results showed that adding the carbonaceous materials in cement composites reduced the electrical resistance by more than 98% than that of the main cement paste. The percolation threshold of all carbonaceous cement composites was found to be between 0.1 and 0.75 vol%. By applying a potential voltage to the cement composites, different heating temperatures were investigated depending on the type of carbonaceous materials and their volume fractions. The conductive cement composites showed high heating performance exceeded 100°C within a record time when the input voltage is 60 V. At the end of the study, an analysis of electric power consumption was carried out to determine the feasibility of using carbonaceous materials as self-heating components in the suggested conductive cement composites.

Numerical investigation on flexural behavior of RC beams with large web opening externally strengthened with CFRP laminates under cyclic load: Three-point bending test

In the current paper, the effect of carbon fiber reinforced polymer (CFRP) laminates on the flexural strength of reinforced concrete beam (RCB) with the web opening in the flexural zone was investigated using a numerical method. The main aim of the current work is to model the reinforced concrete beam strengthen by two shape of CFRP laminates (2layer and U-shape), to observe the influences of CFRP on the flexural strength of the beam. To this end, cyclic loading was applied to investigate the flexural behaviour of the Twelve RC beams under the cyclic loading. All beams kept the same dimensions length, breadth, and depth (2400 × 300 × 200) mm were modeled in the finite elements adopted by ABAQUS software. Steel bars have been used for both flexural strengthening and stirrups. A Three-point bending tests were performed using cyclic loading. Furthermore, the effect of web openings with different sizes (Side length of 40, 60, 75% of the breadth) on the flexural behavior of RC beams was investigated in detail. The flexural strength, local analysis, and ductility of the base beam and CFRP reinforced beam were analyzed. The results of the simulations revealed that the CFRP laminates enhanced the strength of the base beam significantly.

The Effect of Carbon Fibers on the Tensile Behavior of Bitumen Beams

Fatigue cracking is one of the most important types of failures, which decrease the asphalt pavement service life. Carbon fibers are amongst of the additives that have high tensile strength. It is expected this fiber reduce pavement cracks which increases the fatigue life of pavement. This paper experimentally investigated the effect of the carbon fibers on bitumen specimens. Hence, the effects of fiber characteristics such as length and fiber percentage on the indirect tensile strength and Marshall stability of asphalt mixture were studied. Then, the effect of fibers on bitumen and mastic behavior, which is the main objective of the study, was evaluated. Beam specimens were subjected to three-point bending tests to determine the effect of carbon fibers. Carbon fibers had a positive effect on the tensile strength of bitumen beams at loading rates of 0.5, 2, and 5 mm/min up to 100%. Mastic exhibited a similar behavior to pure bitumen in combination with fibers. 
  

Effects of Carbon Fiber & Sika Fiber on Improving the Geotechnical Properties of Clayey Soil

The effects of carbon & sika fibers on the Undrained unconsolidated strength (UUS) of weak clay soil have been studied in this research. The soil sample obtained from Al Basra city south of that can be classified according to USCS as weak silty clay of low plasticity (CL). The additives are carbon & sika fibers. The soil samples were improved by mixing with four ratios of each additive 0.5, 1, 1.5 and 2% of the dry soil weight. Mixture samples prepared using the optimum water content. Bearing capacity of samples measured by the unconsolidation undrained tri-axial shear test. Based on the results of tests at failure, the undrained unconsolidated strength (UUS) increased with increasing the ratio of additives, except in the case of sika fiber, which gave negative effects. In addition, it is important to avoid using carbon fiber in a high ratio of upper than 1% of dry soil weight due to a decrease in the (UUS).

Effects of carbon fibers with different particle sizes on the physical properties of MoS2-filled PTFE composites

ABSTRACT A series of polytetrafluoroethylene (PTFE) composites filled with CF (carbon fiber) and MoS2 (molybdenum disulfide) were prepared by cold-pressing sintering. The tensile strength and elongation at the breakpoint of the samples were measured with a bench-top tensile machine, friction and wear performance were tested with an abrasion machine, and the morphology and microscopic structure were analysed by SEM. The results show that the tensile strength, the elongation at breakage, and the wear resistance were all improved after filling compared to the pure PTFE. The CF/MoS2/PTFE composites filled with CF (particle size 7.498 μm) had the optimal tensile strength and elongation at the breakpoint. Correspondingly, the wear rate was the smallest when the particle size was 23.733 μm.