Carbon Fiber Composite Research Articles

Modeling Electrical Conductivity of Injection-Molded Polymer Composite Bipolar Plates

Bipolar plates can be responsible for up to 40% of the total stack cost and 80% of the weight of a polymer electrolyte membrane fuel cell. To reduce these cost and weight limitations, this work explores modeling and injection molding of polymer composites. A fiber contact model was developed to predict electrical conductivity based upon direction in the material, fiber length and diameter, fiber resistivity, fiber volume fraction, and fiber angle of alignment. Fiber alignment was measured experimentally by imaging cross sections of injection-molded nylon/nickel-coated carbon fiber (NiCF) composites. Composites were molded with NiCF loadings ranging from 5 to 40 wt%. Up to 15 wt%, modeling predictions show good correlation with experimental conductivity measurements. Samples with at least 15 wt% NiCF exceeded the United States Department of Energy technical target for bipolar plate conductivity (>100 S/cm), reaching 250 S/cm.

Modeling Electrical Conductivity of Injection-Molded Polymer Composite Bipolar Plates

Bipolar plates can be responsible for up to 40% of the total stack cost and 80% of the weight of a polymer electrolyte membrane fuel cell. To reduce these cost and weight limitations, this work explores modeling and injection molding of polymer composites. A fiber contact model was developed to predict electrical conductivity based upon direction in the material, fiber length and diameter, fiber resistivity, fiber volume fraction, and fiber angle of alignment. Fiber alignment was measured experimentally by imaging cross sections of injection-molded nylon/nickel-coated carbon fiber (NiCF) composites. Composites were molded with NiCF loadings ranging from 5 to 40 wt%. Up to 15 wt%, modeling predictions show good correlation with experimental conductivity measurements. Samples with at least 15 wt% NiCF exceeded the United States Department of Energy technical target for bipolar plate conductivity (>100 S/cm), reaching 250 S/cm.

Fatigue Characteristics Analysis of Carbon Fiber Laminates with Multiple Initial Cracks

In the entire wind turbine system, the blade acts as the central load-bearing element, with its stability and reliability being essential for the safe and effective operation of the wind power unit. Carbon fiber, known for its high strength-to-weight ratio, high modulus, and lightweight characteristics, is extensively utilized in blade manufacturing due to its superior attributes. Despite these advantages, carbon fiber composites are frequently subjected to cyclic loading, which often results in fatigue issues. The presence of internal manufacturing defects further intensifies these fatigue challenges. Considering this, the current study focuses on carbon fiber composites with multiple pre-existing cracks, conducting both static and fatigue experiments by varying the crack length, the angle between cracks, and the distance among them to understand their influence on the fatigue life under various conditions. Furthermore, this study leverages the advantages of Paris theory combined with the Extended Finite Element Method (XFEM) to simulate cracks of arbitrary shapes, introducing a fatigue simulation method for carbon fiber composite laminates with multiple cracks to analyze their fatigue characteristics. Concurrently, the Particle Swarm Optimization (PSO) algorithm is employed to determine the optimal weight configuration, and the Backpropagation neural network (BP) is used to train and adjust the weights and thresholds to minimize network errors. Building on this foundation, a surrogate model for predicting the fatigue life of carbon fiber composite laminates with multiple cracks under conditions of physical parameter uncertainty has been constructed, achieving modeling and assessment of fatigue reliability. This research offers theoretical insights and methodological guidance for the utilization of carbon fiber-reinforced composites in wind turbine blade applications.

Interfacial properties and mechanical performance of hybrid graphene/carbon fibre composites

The interaction zone between the matrix and the reinforcing component within carbon fibre (CF) composites plays a crucial role in influencing their performance characteristics, as extensively documented in scientific literature. Building on this fundamental knowledge, this research focuses to the investigation of the interface of fibrous composites and the effect of the incorporation of graphene nanoplatelets (GNPs) into the epoxy matrix. Through the utilization of laser Raman spectroscopy, a significant increase of over 60 % in interfacial strength with just a 2 % weight fraction of GNPs, as expressed by the enhanced shear-lag parameter observed in single fibre model composites, has been observed on model composites indicating a stronger interfacial interaction between the matrix and fibres. The effect of the incorporation of GNPs on CF-graphene interaction has been also investigated on a macroscopic level. Hybrid carbon fibre epoxy resin composite produced, by the introduction of GNPs into the polymer matrix. A series of mechanical tests were conducted, including extensive tensile testing of epoxy/graphene nanocomposite films, thorough examination of bending characteristics, and meticulous measurement of interlaminar shear strength for hybrid GNP/carbon fibre composites. These evaluations provided a clearer understanding of how the GNP integration affects the interface parameters that govern the mechanical behaviour of both the resin and carbon fibre composites.

Enhancement of mechanical and structural characteristics through the hybridization of carbon fiber with Cordia‐dichotoma/polyester composite

AbstractSingle fiber polymer composites containing either natural or artificial fibers may not deliver the desired characteristics. The current study used the hand‐layup technique to make a hybrid composite by incorporating the natural fiber, Cordia‐dichotoma (CD) and artificial fiber, carbon fibers (CF) in a polyester matrix and compressing the mixture for the desired size. The current study investigates the influence of carbon fiber loading (0, 5, 10, and 15 wt%) on the mechanical, structural, and crystalline properties of CD/polyester composites keeping the total fiber loading at 20 wt%. Mechanical properties are investigated with a universal testing machine, and impact strength using Izod impact apparatus. Better mechanical properties (tensile strength‐457.38 MPa; flexural strength‐290.09 MPa and impact strength‐346.46 J/m) were obtained for the pure carbon fiber composite arranged in four layers (CF/CF/CF/CF), followed by hybrid composite (CF/CD/CD/CF) (tensile strength‐319.24 MPa; flexural strength‐253.03 MPa and impact strength‐291.34 J/m) whereas pure CD fiber (CD/CD/CD/CD) composite yielded the lowest values (tensile strength‐117.96 MPa; flexural strength‐164.99 MPa and impact strength‐118.11 J/m). Composites undergo hybridization, which improves their mechanical properties, lowers their cost, and makes them more environmentally friendly. The characteristics of the specimens were examined using Fourier Transform Infrared Spectroscopy (FTIR), X‐ray Diffraction Analysis (XRD), Atomic Force Microscope (AFM), and Scanning Electron Microscopy (SEM). According to findings, crystallinity index is increased from 77.94% for CD/CD/CD/CD composite and increased to 78.21% for CF/CD/CD/CF composite. Highest crystallinity index of 82.46% was obtained for CF/CF/CF/CF composite. These hybrid composites may be used for applications involving medium loads.Highlights In this study, Cordia‐dichotoma natural fibers are extracted and treated with alkali (NaOH) to reduce the biodegradability. To lower the cost and enhance mechanical and biodegradable properties Carbon and cordia‐dichotoma fibers have been hybridized. Mechanical Properties such as tensile, flexural and impact properties are evaluated for the prepared hybrid composites. Hybrid composites were analyzed using FTIR, AFM, XRD, and SEM to assess their suitability to various applications.

Flexural and interlaminar shear response of novel methylmethacrylate composites reinforced with high-performance fibres

This experimental work presents a comparative study on the mechanical behaviour of novel infusible methylmethacrylate matrix (Elium®) composites reinforced with different types of high-performance fibres. A vacuum-assisted resin infusion process was employed to fabricate the laminates using carbon, basalt, Kevlar®, and high molecular weight polyethene (UHMWPE) fibres. Flexural and interlaminar shear properties of the composites were evaluated. Test results revealed that carbon fibre composites had superior flexural strength, stiffness and interlaminar shear stress as compared to the other composites tested. Further, composites containing Kevlar and UHMWPE fibres demonstrated significantly higher flexural strains to failure. Post-testing, specimens were examined using scanning electron microscopy (SEM). Microscopy revealed possible interfacial interaction differences based on the reinforcement fibre type, which was further confirmed by an analytical approach for analysing the flexural behaviour of various types of composites. The sequence of damage progression in specimens was also analysed.

Feasibility study of carbon-fiber reinforced polymer linerless pressure vessel tank

Composite pressure vessels are used in aerospace engineering for storing fluids such as propellants, nitrogen, and oxygen. They are also used in life-support systems, High-performance pressure suits for astronauts, Helium Tanks for Balloons and Airships. Among many types of composites, Carbon fiber composites uses have been increasing due to its high strength to weight ratio, high thermal expansion, corrosion, fatigue and impact resistance and design flexibility. In order to improve the volume of the pressure vessel, the liner-less concept is tried. This increased volume efficiency is crucial in aerospace applications where space is at a premium and maximizing storage capacity within limited dimensions is important. Not only the volume efficiency, but also the Reduced Permeability Concerns, Enhanced Durability and Longevity, better thermal continuity and simplified manufacturing process make this research significant in the area of pressure vessel. This research paper deals with the fabrication and development of a cylinder without a lining. The test sample was subjected to several tests: tensile test, impact, shear test (3P Bending), leak test and Pressure test. The test sample was capable of withstanding 20 Bars without failure. The numerical results were also performed and compared with the experimental results. The difference was only 3%. Unsymmetrical dimethyl hydrazine (UDMH) AND red-fuming nitric acid can both be stored in this cylinder (RFNA). Unlike traditional composite overwrapped pressure vessels, the liner-less composite tanks rely completely on the composite shell to act as a permeation barrier as well as handling all pressure and environmental loads. The absence of a liner eliminates the potential for delamination or failure at the interface between the liner and the composite material.

Integrated process for eco-friendly synthesis and coating of ZrB2 onto carbon fiber substrates

In aerospace engineering, the demand for lightweight materials with superior strength and endurance drives the search for advanced composites. Carbon fiber composites offer exceptional strength-to-weight ratios but are vulnerable to high-temperature oxidation. To address this, protective coatings are crucial. Zirconium diboride (ZrB2) shows promise due to its high melting point and stability but faces challenges in application. Here, we propose a sustainable solution-based method using gum arabic, a natural polysaccharide, as a precursor to coat carbon fibers followed by pyrolysis to form ZrB2. Our technique simplifies production while enhancing coating effectiveness and adhesion. X-ray diffraction and microscopy analyses confirm successful ZrB2 formation and uniform coating. Thermal analysis demonstrates improved oxidative stability compared to pristine carbon fibers. This eco-friendly approach presents a novel avenue for aerospace materials synthesis, offering enhanced performance and sustainability. The study underscores the potential of solution-based techniques and natural precursors in advancing composite materials for extreme environments.

Design, Construction and Finite Element Analysis of a Hexacopter for Precision Agriculture Applications

Agriculture drones face important challenges regarding autonomy and construction, as flying time below the 9-minute mark is the norm, and their manufacture requires several tests and research before reaching proper flight dynamics. Therefore, correct design, analysis, and manufacture of the structure are imperative to address the aforementioned problems and ensure a robust build that withstands the tough environments of this application. In this work, the analysis and implementation of a Nylamid motor bracket, aluminum sandwich-type skeleton, and carbon fiber tube arm in a 30 kg agriculture drone is presented. The mechanical response of these components is evaluated using the finite element method in ANSYS Workbench, and the material behavior assumptions are assessed using a universal testing machine before their implementations. The general description of these models and the numerical results are presented. This early prediction of the behavior of the structure allows for mass optimization and cost reductions. The fast dynamics of drone applications set important restrictions in ductile materials such as this, requiring extensive structural analysis before manufacture. Experimental and numerical results showed a maximum variation of 8.7% for the carbon fiber composite and 13% for the Nylamid material. The mechanical properties of polyamide nylon allowed for a 51% mass reduction compared to a 6061 aluminum alloy structure optimized for the same load case in the motor brackets design. The low mechanical complexity of sandwich-type skeletons translated into fast implementation. Finally, the overall performance of the agriculture drone is evaluated through the data gathered during the flight test, showing the adequate design process.

Experimental and theoretical studies on 3D printed short and continuous carbon fiber hybrid reinforced composites

3D-printed carbon fiber composites hold significant potential in aerospace applications because of their lightweight, high strength and complex structure fabrication capabilities. However, additive manufacturing characteristics such as high porosity, anisotropy and continuous fiber content significantly affect the mechanical properties of printed parts. The aim of this study is to investigate the influence of hybrid printing of short and continuous carbon fibers on the mechanical properties and failure mechanisms of composites and to develop a model to predict elastic properties considering porosity. First, mechanical testing and characterization of short and continuous fiber reinforced polyamide (nylon) print filaments are performed. The results indicate that the elastic modulus and ultimate strength of continuous carbon fiber filaments reach 60 GPa and 1500 MPa, respectively, while the strength and elastic modulus of short carbon fiber filaments reach 60 MPa and 1 GPa, respectively. Then tensile specimens with different continuous fiber orientations and different continuous fiber placement sequences are printed and tested using a multi-material 3D printing technique. The specimens are characterized before and after testing using scanning electron microscopy and microscopy to assess the porosity and failure mechanisms of specimens with different configurations. The results show that the mechanical properties of the printed parts are much lower than those of the print filaments, which proves the serious negative impact of the material extrusion process on the mechanical properties of the printed structural parts. Finally, an analytical method for predicting the elastic behavior of printed composites is developed by introducing the porosity factor in the volume-averaged stiffness model. For continuous and short fiber filled composites with different fiber contents and printing orientations, the predicted results are in agreement with the experiments, and the prediction error is greatly reduced from 30 % to <5 %.

Identification of mechanisms and experimental implementation for enhancing the interfacial force between oxygen functionalized waste carbon fibers and polyamide resin

To recycle waste carbon fibers (CFs) and utilize them as a composite material with polyamide–6 (PA–6), the oxidation of the carbon surface is crucial for enhancing its bonding with PA–6 without damaging the waste CFs. However, the most effective oxygen-containing functional group (O–group) was hitherto unknown. In this study, computational simulations demonstrated that incorporating O–groups enhanced the interfacial bonding force via hydrogen bonding between the oxygen of the O–groups and hydrogen (N–H) of PA–6. Among various O–groups, the bonding of lactone groups to PA–6 was energetically most favorable, corroborated by different oxidation treatments such as acid, heat, and plasma. As the reaction time or temperature increased, the amount of O–groups, such as lactones, increased. Regardless of the oxidation treatment type, an increase in the amount of O–groups increased the interfacial force, and this tendency was predominantly observed in lactone groups. However, excessive surface oxidation introduced defects on the surface of CFs, which reduced the interfacial force. The modification of waste CFs by identifying the proposed mechanisms lays the groundwork for synthesizing high-quality waste CF composites.

Research on defect identification of carbon fiber composite materials based on ultrasonic phased array

AbstractIt is more and more difficult to identify defects in carbon fiber composite materials due to the difficulty in making defect samples and the single signal analysis method. In order to better solve the problem of defect identification in carbon fiber composite materials, this study uses ultrasonic phased array equipment to quantitatively locate and detect carbon fiber composite laminates with embedded delamination defects, so as to more intuitively and effectively display the appearance of different delamination defects. The time domain analysis of the collected ultrasonic original signal and the time‐frequency domain analysis using wavelet packet are carried out. A total of 6 eigenvalues were extracted to reflect the ultrasonic signals of different delamination defects. By using genetic algorithm to optimize BP neural network, the recognition accuracy of delamination defects of different sizes is more than 95%, and the recognition accuracy of delamination defects of different depths is 100%, so as to realize the effective intelligent recognition of delamination defects of different sizes and depths of carbon fiber composites. This study is of great significance to improve the accuracy and reliability of defect identification of carbon fiber composite materials.Highlights The ultrasonic phased array equipment is used to quantitatively locate the carbon fiber composite laminates with embedded delamination defects, so that the appearance of different defects can be displayed more intuitively and effectively. Using time domain analysis and time‐frequency domain analysis based on wavelet packet, the combination of the two can more comprehensively extract the effective features of the defect signal. The BP neural network is optimized by genetic algorithm, and the results can effectively and automatically identify different layered defects, which lays a good foundation for the rapid and accurate identification of more defects in the future.

Cardo poly (ether sulfone) toughened E51/DETDA epoxy resin and its carbon fiber composites

Cardo poly (ether sulfone) toughened E51/DETDA epoxy resin and its carbon fiber composites

Non-planar additive manufacturing of pre-impregnated continuous fiber reinforced composites using a three-axis printer

Non-planar additive manufacturing (AM) demonstrates great potential in enhancing interlayer bonding force and surface smoothness of parts, offering a more flexible design and manufacturing approach for continuous fiber composites to fully exploit material capabilities. This study developed a three-axis printer utilizing an adjustable fiber printing head that can achieve non-planar slicing (NPS) AM of pre-impregnated continuous fibers. The research delves into the influence of deposition inclined angle on the surface roughness of printed samples, enabling the design and printing of NPS samples using continuous carbon fiber (CF), glass fiber (GF), and hybrid fiber composites. The investigation also assesses bending failure morphologies of the printed parts and validates the efficacy of the NPS method through the fabrication of the double-sinusoidal curved surface structure and spherical surface grid structure. The results indicated that maintaining a deposition inclined angle below 15° is crucial to ensure surface accuracy in continuous fiber printed parts. Curved surface bending samples printed with NPS method exhibit substantial enhancements in bending performance and surface accuracy compared to those produced using planar slicing (PS). The NPS-CF sample achieves a remarkable increase of over 170% in maximum bending force and a 63% reduction in surface roughness compared to the PS-CF sample.

Adhesive Bonding of Carbon Fiber Reinforced Polymer Composite

Abstract Carbon fiber reinforced polymer composites are important and widely used material in today’s manufacture and automotive. It produces a high demand to research the material, therefore industrial sectors can improve. Developing industry and strict requirements leads us to use this type of material in different applications where we need to use bonding technologies. The exploration of bonding technologies is necessary, and adhesive bonds offer a promising alternative. This paper examines the adhesive bonding of carbon fiber composites using a high strength two-component epoxy.

Enhancing interlaminar fracture toughness and shear strength of carbon fiber composite laminates via orientation of nickel-plated short carbon fibers in a magnetic field

This study aimed to enhance the interlaminar mechanical properties of carbon fiber composites by incorporating nickel-plated short carbon fibers (Ni@SCFs) between adjacent layers in a magnetic field. Herein, non-flocked composites, flocked composites with unoriented Ni@SCFs, and flocked composites with oriented Ni@SCFs using a magnetic field were fabricated to investigate the impact of fiber orientation on the mode I interlaminar fracture toughness (GIC) and interlaminar shear strength (ILSS) of the composite laminates. It was observed that Ni@SCFs were distributed at varying vertical angles between adjacent layers under the influence of the magnetic field. The areal density of oriented Ni@SCFs was systematically increased, resulting in notable enhancements in both initiation and propagation of GIC for flocked composites. At a flocking density of 6 g/m2, maximum values reached 533 J/m2 and 769 J/m2 respectively, representing a substantial increase of 52 % and 63 % compared to non-flocked composites. Additionally, the ILSS of flocked composites with oriented Ni@SCFs significantly improved to 55.83 MPa at a flocking density of 2 g/m2, indicating an increase of 27 % over non-flocked composites. The oriented Ni@SCFs played a crucial role in inhibiting crack propagation through the fiber bridging effect.

Effective photocatalytic degradation of sulfamethoxazole using PAN/SrTiO3 nanofibers

Freshwater scarcity driven by pollution and climate change necessitates the development of effective water purification methods. There is an urgent need for innovative solutions that can efficiently remove contaminants from water sources. A effective material for the photocatalytic degradation of organic sulfonamide antibiotics from water was developed in this study. A composite of electrospun strontium titanate (SrTiO3) and carbon fibers polyacrylonitrile/strontium titanate (PAN/SrTiO3) was employed for the photocatalytic degradation of sulfamethoxazole (SMX). Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM-EDS), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterise the composite. The fibers had a thickness of ~250 nm and uniformly dispersed PAN and SrTiO3 particles. A PAN/SrTiO3 composite with a 1:1 mass ratio (20 mg) demonstrated excellent performance, achieving over 90 % degradation at pH 7 and a contaminant concentration of 5 mg/L under ultraviolet (UV) light irradiation during 60 min. The composite was tested for the photodegradation of the major organic pollutant (SMX) in distilled and river water. In river water, the degradation efficiency exceeded 80 % at pH 7 because of the formation of secondary radicals involved in antibiotic degradation. SMX degradation was described using a pseudo-first order kinetic equation using the Langmuir-Hinshelwood model. These results underscore the novelty and significance of the PAN/SrTiO3 composite and demonstrate its high efficiency and potential for large-scale water purification applications.

Comparison study of Izod impact properties on 3D printed thermoplastic and thermoset carbon fiber composite at different infill density

PurposeThis study aims to evaluate the low energy impact characteristics of 3D printed carbon fiber thermoplastic and thermoset polymer composite using the Izod impact test. The effects of infill density are examined on the Izod impact properties of 3D printed thermoset polymer and thermoplastic composite specimens. Furthermore, a thorough investigation is conducted into the effect of heat treatment using a hot-air oven on both types of 3D printed composite specimens. To characterize the impact characteristics of each specimen, the fracture surfaces caused by impact load are inspected, and the fracture mechanism is studied using scanning electron micrographs.Design/methodology/approachIzod Impact specimens of thermoset (epoxy resin) and thermoplastic carbon fiber of different infill density (70, 75, 80, 85, 90 and 100%) are fabricated using the different fiber impregnation 3D printing process. To carry out the heat treatment process, printing of composites is done for each infill design from both thermoset and thermoplastic composites and the impact characteristics of specimens are evaluated on a pendulum test-rig using the ASTM D-256 standard. Using a scanning electron microscope, each fracture zone underwent four separate scanning processes, ranging in size from 2 µm to 100 µm.FindingsThe impact resistance of the 3D printed thermoset and thermoplastic composite material is significantly influenced by the type of fiber placement and infill density in the matrix substrate. Because of the weak interfacial strength between the layers of fiber and polyamide 6, the specimen printed with continuous fiber implanted at the part exhibited reduced impact resistance. At 75% infill density, the impact specimen printed with coextruded fiber showed the highest impact resistance with a 367.02% greater magnitude than the continuous fiber specimen with the same infill density.Originality/valueThis work presents a novel approach to analyze the low energy impact characteristics and three-dimensional printing of carbon fiber reinforced thermoplastic and carbon fiber reinforced thermoset and thermoplastic composite material.

Comparative Analysis of Materials for Chassis Design in a Three-Wheeled Electric Vehicle

With the growing interest in sustainable transportation, three-wheeled electric vehicles have gained popularity as an eco-friendly mode of transportation. The design of the chassis is a critical aspect of ensuring the structural integrity and performance of these vehicles. This research paper presents a comparative evaluation of different materials for chassis design in three-wheeled electric vehicles. The objective of this study is to assess the suitability of various materials, including steel, aluminum, and carbon fiber composites, for chassis construction. The evaluation criteria encompass factors such as strength, weight, stiffness, durability, and cost. A systematic methodology is employed, including theoretical analysis, computer simulations, and practical testing, to evaluate and compare the performance of each material. The findings of this research provide valuable insights into the advantages and limitations of each material in the context of three-wheeled electric vehicle chassis design. The results assist in the selection of the most suitable material based on performance requirements, cost considerations, and sustainability goals. Furthermore, the research identifies potential areas for further improvement and innovation in chassis materials for future electric vehicle designs. The outcomes of this study aim to guide manufacturers, designers, and engineers in making informed decisions when selecting materials for chassis design, ultimately enhancing the safety, efficiency, and overall performance of three-wheeled electric vehicles. By contributing to the development of sustainable transportation solutions, this research promotes the transition towards a greener and more environmentally friendly mobility landscape.

Towards Sustainable and Fire-Safe Thermosets Using Phosphorus-Containing Covalent Adaptable Networks.

Dynamic covalent chemistry is a promising strategy for developing recyclable thermosets and their carbon fiber reinforced composites, in line with the goal of green and sustainable development. However, a significant challenge lies in balancing the dynamic reversibility and the desired service performances, such as thermal, mechanical properties, and flame retardancy. It has hindered the broader application of dynamic materials beyond the initial proof of concept. This concept provides an overview of the current state of research on phosphorus-containing covalent adaptable networks (CANs), highlighting key designing and regulating principles for tailoring comprehensive properties including flame retardancy, mechanical and thermal properties, as well as dynamic behaviours such as malleability, reprocessability and degradability. Finally, new frontiers and opportunities in developing high-performance sustainable CANs-based thermosets and their carbon fiber composites for structural engineering applications are prospected.