Tensile Properties Of Carbon Fibers Research Articles

Preparation of carbon fiber conductive concrete and study on its mechanical and heating properties

Carbon fiber conductive concrete demonstrates great potential for effectively removing ice and snow from road surfaces. This study investigates the electrical conductivity and electromagnetic heating effects of carbon fiber conductive concrete, considering different carbon fiber dosages and temperatures. Experimental and numerical simulation methods were employed to assess the material's performance. The results show that as the carbon fiber content increases to 0.38 % and 1.5 %, the compressive strength decreases by 19 % and 55 %, respectively, which is related to the introduction of more bubbles and the agglomeration of carbon fiber when the carbon fiber is added, making it easier to produce stress concentration when the concrete is compressed. However, when the content of carbon fiber is small, the tensile properties of carbon fiber itself can improve the overall splitting tensile strength of concrete. With the increase of carbon fiber content, carbon fiber gradually forms a conductive network in the concrete, and the overall resistivity of the concrete decreases, but there is a certain threshold. Overall, 0.75 % fiber is the best solution. In addition, the heating process is accurately simulated by numerical simulation method. The simulation results are in good agreement with the experimental results, showing that the heating rate decreases with the increase of energizing time until reaching the heat equilibrium state. And the precise temperature distribution and change process that can be obtained through simulation provides valuable insights for engineering design.

Study on the influence of fiber layering on the tensile properties of carbon fiber composites

In order to study how the tensile properties of carbon fiber composites change under different layering angles and layering sequences, this paper analyzed the tensile process of CFRP laminates under six different layering modes by using numerical simulation method based on ABAQUS finite element software, and compared the major tensile mechanical properties parameters of CFRP laminates under different layering modes. For example, tensile strength, tensile stiffness, and other physical quantities can measure the mechanical properties of the laminates, and finally obtain a reasonable laminate way that can effectively improve the tensile properties of CFRP laminates. The simulation results show that, under the premise that the number of CFRP laminates is certain, the 0° laminates should be placed on the outside of the laminates as far as possible, and the proportion of 0° laminates should be increased appropriately, which can effectively improve the longitudinal tensile strength of the laminates. The tensile stiffness of laminates can be increased by the existence of positive symmetric or antisymmetric laminates.

Design of Experiment to Determine the Effect of the Geometric Variables on Tensile Properties of Carbon Fiber Reinforced Polymer Composites

Carbon fiber reinforced polymers (CFRPs) are increasingly used in the aerospace industry because of their robust mechanical properties and strength to weight ratio. A significant drawback of CFRPs is their resistance to formability when drawing continuous CFRPs into complex shapes as it tends to bridge, resulting in various defects in the final product. However, CFRP made from Stretch Broken Carbon Fiber (SBCF) aims to solve this issue by demonstrating superior formability compared to conventional continuous CFRPs. To study and validate the performance of SBCF, a statistical design of the experiment was conducted using three different types of CFRPs in tow/tape form. Hexcel (Stamford, CT, USA) IM7-G continuous carbon fiber impregnated with Huntsman (The Woodlands, TX, USA) RDM 2019-053 resin system, Hexcel SBCF impregnated with RDM2019-053 resin, and Montana State University manufactured SBCF impregnated with Huntsman RDM 2019-053 resin were tested in a multitude of forming trials and the data were analyzed using a statistical model to evaluate the forming behavior of each fiber type. The results show that for continuous fiber CFRP tows forming, Fmax and Δmax do not show statistical significance based on temperature fluctuations; however, in SBCF CFRP tows forming, Fmax and Δmax is dominated by the temperature and geometry has a low statistical influence on the Fmax. The lower dependence on tool geometry at higher temperatures indicates possibly superior formability of MSU SBCF. Overall findings from this research help define practical testing methods to compare different CFRPs and provide a repeatable approach to creating a statistical model for measuring results from the formability trials.

Simulation of Tetrahedral Profiled Carbon Rovings for Concrete Reinforcements.

Textile reinforcements are increasingly establishing their position in the construction industry due to their high tensile properties and corrosion resistance for concrete applications. In contrast to ribbed monolithic steel bars with a defined form-fit effect, the conventional carbon rovings' bond force is transmitted primarily by an adhesive bond (material fit) between the textile surface and the surrounding concrete matrix. As a result, relatively large bonding lengths are required to transmit bond forces, resulting in inefficient material utilization. Novel solutions such as tetrahedral profiled rovings promise significant improvements in the bonding behavior of textile reinforcements by creating an additional mechanical interlock with the concrete matrix while maintaining the high tensile properties of carbon fibers. Therefore, simulative investigations of tensile and bond behavior have been conducted to increase the transmittable bond force and bond stiffness of profiled rovings through a defined roving geometry. Geometric and material models were thus hereby developed, and tensile and pullout tests were simulated. The results of the simulations and characterizations could enable the optimization of the geometric parameters of tetrahedral profiled rovings to achieve better bond and tensile properties and provide basic principles for the simulative modeling of profiled textile reinforcements.

Effect of surface modification of carbon fiber based on magnetron sputtering technology on tensile properties

In this study, carbon films were constructed on the surface of carbon fibers using magnetron sputtering to improve the surface defects and mechanical properties of carbon fibers. The tensile properties of the single carbon fiber and multifilament carbon fiber before and after modification were tested, and the influence of the modification method on the tensile properties of the carbon fiber was analyzed. Moreover, the effect of the modification process on the dispersion of the tensile breaking strength of the carbon fiber was analyzed using the Weibull distribution. The magnetron sputtering process based on a carbon target successfully repaired the surface and improved the dispersion of the tensile breaking strength of the carbon fiber. After surface modification, the CV value of the breaking strength of the single carbon fiber and multifilament carbon fiber decreased by up to 57.5% and 31%, respectively. The Weibull modulus m of the modified single carbon fiber increased. Furthermore, the surface modification of the carbon fibers by magnetron sputtering was conducive to improving the tensile properties of the carbon fibers. The tensile breaking strength of the modified single carbon fiber and multifilament carbon fiber slightly increased. As the magnetron sputtering time was increased, the tensile breaking strength of the carbon fiber further increased. The influence of the carbon film on the surface of the carbon fiber greatly enhanced the tensile fracture toughness using the crack effect mechanism.

The Role of Al4C3 Morphology in Tensile Properties of Carbon Fiber Reinforced 2024 Aluminum Alloy during Thermal Exposure.

The aluminum alloy drill pipe suffers long-term high-temperature conditions during ultra-deep well drilling. In this paper, the samples were prepared by vacuum hot pressing, followed by hot extrusion and T6 heat treatment. The mechanical properties of short carbon fiber reinforced 2024 aluminum alloy composites (SCFs/2024 Al) and the microstructure evolution at the interface region thermal exposure at 160 °C for 500 h are discussed. The experimental results showed that the effect of short carbon fiber on 2024 aluminum alloy remained steady throughout the whole process of the heat exposure experiment. The distribution and volume of interface products (Al4C3) changed with the prolonging of heat exposure time, and connected after coarsening. The evolution of the morphology of Al4C3 relieved the stress of the interface between carbon fiber and aluminum alloy matrix and enhanced the mechanical properties of the composite.

Comparison of Tensile Properties of Carbon Fiber, Basalt Fiber and Hybrid Fiber Reinforced Composites Under Various Strain Rates

Comparison of Tensile Properties of Carbon Fiber, Basalt Fiber and Hybrid Fiber Reinforced Composites Under Various Strain Rates

Evaluation of tensile properties of carbon fiber reinforced polymers produced from commercial prepregs

This paper presents the tensile properties of real products produced from prepregs based on the carbon fiber-reinforced polymer (CFRP) composite. In this study, we compared tensile properties of the two types of CFRP laminates with a different number of layers, different type of used carbon fiber woven fabrics, and epoxy resins. Both types are used for production of some interior and exterior parts of the luxury automobiles. This research showed that material No. 1 with DT121HT epoxy resin matrix, which has a higher number of reinforcing layers, is characterized by a higher value of tensile strength. Material No. 2 with DT121R epoxy resin matrix with higher reactivity and higher viscosity, which has a lower number of reinforcing layers, is characterized by a lower value of tensile strength. Reproducibility verification of tensile properties of both chosen materials showed that the CFRP laminates produced from commercial prepregs provide a guarantee of safety of the entire production of the CFRP parts.

The Role of Al4c3 Morphology in Tensile Properties of Carbon Fiber Reinforced 2024 Aluminum Alloy During Thermal Exposure

The Role of Al4c3 Morphology in Tensile Properties of Carbon Fiber Reinforced 2024 Aluminum Alloy During Thermal Exposure

Finite element analysis and validation of tensile properties of carbon fiber reinforced polymer matrix composites

In present day scenario, moving towards an environment friendly material may be a key issue for manufacturing industries so as to produce suitable alternatives for the prevailing conventional materials. Composite materials are being popular alternative materials within the last three decades because of their low cost and unmatched properties. Composite materials have grown in volume and number of applications over time, steadily entering and conquering new markets. Composite materials now account for a major portion of the development materials industry, starting from everyday products to classy niche applications. In the present work, carbon fiber reinforced composite specimen are fabricated by hand layup and vacuum bag method and experimental evaluation of mechanical properties like tensile test as per ASTM standard has been successfully completed. The tensile properties are studied and therefore the breaking load has been measured. The inclusion of carbon fiber material to composite significantly enhanced the ultimate tensile strength of the composite. The specimen is modelled using FEA and also the peak load and displacement results are analysed and compared. It is found that in comparision with FEA results there was a deviation of 7.65% in displacement and 8.52% in peak load.

Tensile properties of carbon fiber reinforced polymer matrix composites: Application for the strengthening of reinforced concrete structure

The paper presents the determination of material properties of carbon fiber-reinforced composite materials (carbon/epoxy) by numerical homogenization and experimental investigation. A periodic square array model of microstructure with and without pores is utilized for the homogenization. In the FEM software ANSYS, the numerical homogenization, as well as simulation of the experiment are performed. At first, to investigate the material characteristics of the carbon/epoxy composite laminate, a unidirectional quasi-static tensile test was conducted. The comparison of the results gathered from the numerical and experimental investigation followed. Secondly, we dealt with the application of FRP composite lamella for strengthening of the reinforced concrete structure. The high-strength glue epoxy used at the beam bottom in the milled slot, the composite lamella was fixed to the beam. In this application, firstly the reinforced concrete flexural four-point beam with steel bracing was evaluated and then the bonded lamella effect was considered. MSC MARC and Mechanical APDL ANSYS software were used for the analysis. The Von Mises stress and deflection of the concrete reinforced beam without and with lamella bracing was examined numerically, as well as experimentally. The results revealed that using of the lamella influenced the reduction of maximum tensile stress in concrete and concrete reinforcement.

Tensile properties of Z-pinned composite laminates with low damage insertion technique

In this paper, the effects of Z-pin diameter and Z-pin length on the tensile properties of carbon fiber reinforced laminates were studied. A new Z-pin insertion technique which causes less microdamage damage than the original method was developed. Experimental testing reveals that the in-plane tensile strength of Z-pin specimens is 96.98%-105.32% of the control group. The best performance of in-plane tensile properties is TF18 group which pinned by full-depth Φ0.18mm diameter. The tensile strength increases by 5.32%, and the Young’s modulus increases by 4.71% relative to the control group. Compared with the group of large diameter Z-pin, the in-plane performance of the ultra-fine diameter group is better due to the less in-plane damage. In the half-depth group, delamination occurred between the middle Z-pin sublayer and the upper and lower layers, thus reducing the in-plane tensile property. The Poisson’s ratio increases in both full depth and half depth after Z-pinned and it is only related to insertion depth.

Effect of carbon nanotubes grown temperature on the fracture behavior of carbon fiber reinforced magnesium matrix composites: Interlaminar shear strength and tensile strength

The design of an interfacial structure is particularly important for load transfer in composites. In this paper, different amounts of carbon nanotubes (CNTs) were grafted onto the carbon fiber (CF) surface by adjusting grown temperature using injection chemical vapor deposition (ICVD). The prepared CF preform grafted with CNTs (CNTs-CF) were used to reinforce magnesium alloy by squeeze casting process. The microstructures were analyzed by means of optical microscope (OM) and scanning electron microscope (SEM), and the interlaminar shear strength (ILSS) and tensile strength of the composites were determined by double-notch shear test and tensile test. The results indicated that moderate ILSS was more conducive to improving the tensile properties of carbon fiber reinforced magnesium matrix (Cf/Mg) composites. Compared with Cf/Mg, the tensile strength of composite with CNTs increased by about 80%. For Cf/Mg composites grafted with CNTs, CNTs had the effects of delaying crack propagation and increasing energy consumption by the pull-out and bridging mechanism, which were the main reasons for improving the strength. The analysis of shear fracture surface showed that the crack propagation path can be optimized by adjusting the amounts of grafted CNTs. The presence of CNTs affects the stress distribution and consequently the crack initiation as well as the crack propagation.

Structure and tensile properties of carbon fibers based on electron-beam irradiated polyacrylonitrile fibers

Electron-beam irradiation has demonstrated the promising results for tuning the exothermic behavior of polyacrylonitrile (PAN) fibers, and the stabilization time can be shortened accordingly. However, the mechanical properties, especially the tensile strength, of carbon fibers based on irradiated PAN fibers are usually lower than those of standard carbon fibers. In this study, PAN fibers irradiated with an electron beam to 1200 kGy are continuously stabilized and carbonized to produce carbon fibers (i-CFs). The mechanical properties of the i-CFs are optimized by controlling the density of the stabilized fibers, and the best performing i-CF achieves a tensile strength of 2.27 GPa and a modulus of 174 GPa. The structure and properties of the carbon fibers and the precursor fibers are investigated to determine the origin of the low tensile properties of the i-CFs. The results show that the graphite crystalline structures are comparable between the CFs and the i-CFs. However, two distinct peaks at 2020 and 1668 cm−1 emerge in the FT-IR spectra of PAN fibers after irradiation that correspond to the C=C=N (ketenimine) and C=N–N=C conjugation groups. These cross-linking structures may disrupt the cyclization reaction and hinder the formation of the aromatic structure of PAN during stabilization, which bring about defects in the resultant carbon fibers.

Three-dimensional finite element models and tensile properties of carbon fiber needled felt reinforced composites

In this study, the three-dimensional finite element models of carbon fiber needled felt reinforced composites were built by using the embedded element technique and the virtual yarn method. Three sizes of samples for carbon fiber needled felt reinforced composites were designed and prepared. The tensile properties were investigated by experiments and theoretical methods, and the influences of sample size on tensile modulus were discussed. The results showed that, the longitudinal tensile moduli of carbon fiber needled felt reinforced composites decreased with the increase of sample size. Compared with the rule of mixtures and the inclusion theory, the longitudinal tensile moduli obtained by finite element method were closer to the experimental values. In addition, the transverse tensile moduli obtained by finite element method were greater than that obtained by the rule of mixtures and the inclusion theory. That was due to the orientation of some fibers had a proportion along the thickness. It was concluded that, these three-dimensional finite element models can be used to investigate the elastic properties of carbon fiber needled felt reinforced composites with different sizes.

The effects of fiber orientation and adhesives on tensile properties of carbon fiber reinforced polymer matrix composite with embedded nickel-titanium shape memory alloys

Tensile tests of Nickel-titanium (NiTi) shape memory alloys (SMA) embedded within carbon fiber reinforced polymer matrix composite (CFRP/PMC) laminates were evaluated with simultaneous monitoring of modal acoustic emissions (MAE). Three different layup configurations utilizing two different thin film adhesives were applied to bond the materials. Ultimate tensile strengths, strains, and moduli were obtained along with cumulative AE energy of events and specimen failure location. Scanning electron microscopy was used to examine the break areas of the specimens post-test. Microscopy was used to validate failure locations revealed from MAE analysis. A unique finding within this research showed that 90° plies in the outer ply gave the strongest acoustic signals as well as the cleanest fracture of the specimens tested. Overlapping 0° ply layers surrounding the SMA was found to be the best scenario to prevent failure of the specimen itself.

Investigation into the Gelation of Polyacrylonitrile Solution Induced by Dry-jet in Spinning Process and Its Effects on Diffusional Process in Coagulation and Structural Properties of Carbon Fibers

The jet effect in dry-jet wet spinning of a polyacrylonitrile (PAN) solution was investigated. The two parameters, jet-stretch ratio and air gap length, of the jet were controlled to elucidate each effect on PAN precursors and resulting carbon fibers. Excessively high jet-stretch ratio (>4) or air-gap (>1 cm) resulted in the development of the internal pore structure in PAN precursors. The pores remained even after the densification by thermal treatment acting as defects for poor tensile properties of carbon fibers (CFs). It was revealed that two parameters critically controlled the bidirectional diffusion of both solvent and non-solvent by determining the degree of the surface gelation at the jet. Excessively high jet-stretch ratio or high air-gap length created a thick solid skin on extruded dope limiting solvent/non-solvent diffusion. As a method to limit the development of the pores under the condition of high jet stretch ratio (>4), raising the dope temperature for limiting the degree of gelation at the jet was attempted and successfully manufactured mechanically improved fiber with a dense structure without pores under high jet-stretch condition. The study suggests that the high quality PAN precursors for high performance CFs can be manufactured under high jet-stretch ratio condition with proper management on gelation at the jet.

Influence of treatment with superheated steam on tensile properties of carbon fiber

The influence of treatment with superheated steam (SHS) during the recycling of carbon fiber reinforced plastics was assessed by exposing unidirectional carbon fiber reinforced (UD) sheets to SHS under various conditions. The thermal behavior of UD sheets was identified through thermal analysis. The polymer decomposition was clarified microscopically and based on the weight reduction. Carbon fiber recovery was optimal after treatment at temperatures higher 650 °C as well as at relatively lower temperatures when 4 vol% O2 was used. The effects of SHS on the fibers were evaluated by comparing the tensile properties of the recycled carbon fibers (r-CFs) with those of corresponding virgin ones. The strength of r-CFs exhibited appreciable scatter, despite the average strength being lower. The cross-sectional area and tensile modulus of the individual r-CFs were approximately equal to those of the virgin fibers. Statistical and fracture surface analyses were performed to elucidate the experimental results.

Evaluating the stabilization of isotropic pitch fibers for optimal tensile properties of carbon fibers

The stabilization effects of isotropic pitch fibers on the tensile properties of the resulting carbon fibers were systematically studied to develop a simple method for finding a suitable degree of stabilization. As the stabilization temperature (250–290 °C) and duration (30–180 min) increased, the densities of the stabilized fibers increased from 1.31 to 1.47 g/cm3, indicating that oxygen up-take and chemical reactions led to changes in their chemical compositions. Stabilized fibers with higher densities resulted in lower density carbon fibers due to the removal of oxygen-related gases during carbonization. Each stabilization temperature had an optimal duration for obtaining high tensile strengths, which was correlated with the oxygen content after stabilization. Interestingly, when the stabilized fibers had densities of 1.35–1.36 g/cm3, the resulting carbon fibers showed the highest tensile strength regardless of the stabilization conditions. Therefore, it is suggested that the density of the stabilized isotropic pitch fibers is a reasonable index for the evaluation of the degree of stabilization for producing high-performance carbon fibers.

Interfacial microstructure and tensile properties of carbon fiber reinforced Mg–Al-RE matrix composites

2D carbon fiber reinforced Mg–Al-RE matrix composites (2D-Cf/AE44 composites) were fabricated by liquid–solid extrusion following vacuum pressure infiltration technique (LSEVI). Pyrolytic carbon (PyC) coating was deposited on surface of T700 carbon fiber by chemically vapour deposited (CVD) to modify the interface. TEM observation of the composites revealed that particle shaped Al2RE and lamellar shaped Al11RE3 precipitated at the interface. The precipitation of Al-RE phase inhibited the formation of Mg–Al phase and the PyC coating protected the fiber effectively. SEM observation of fracture surface, as well as TEM analysis of the interface, were employed to explain the inherent relation between interface behavior and mechanical properties of 2D-Cf/AE44 composites.