Carbon Fiber Composite Research Articles

High-throughput in-situ mechanical evaluation and parameter optimization for 3D printing of continuous carbon fiber composites

High-throughput in-situ mechanical evaluation and parameter optimization for 3D printing of continuous carbon fiber composites

Manufacturing of Thermoset Polyimide Composites by Laser Sintering

Selective Laser Sintering (SLS) is an additive manufacturing technique that builds 3D models layer by layer using a laser to selectively melt cross sections in powdered polymeric materials, following sequential slices of the computer-aided design (CAD) model. SLS generally uses thermoplastic polymeric powders such as polyamides. The resultant 3D-printed objects are often weaker in their strength compared to traditionally processed materials, due to their higher porosity. This paper described the process development of using melt-processable imide oligomers terminated with reactive 4-phenylethynylphthalic anhydride (4-PEPA) to conduct laser sintering (LS). The first successful 3D-printing of high temperature RTM370 thermoset polyimide carbon fiber composite was further post-cured to promote additional crosslinking for achieving higher temperature (Tg = 370°C) capability. Another novel imide oligomer, RTM385-SLS, formulated with a complex melt viscosity [h*] of ~104-105 poise is also suitable for LS. RTM385-SLS resin powder was mixed with 20-25% of hexagonal boron nitride (h-BN) and subjected to LS to print out “Green” specimens which could be further post-cured to afford a thermally conductive but electrically insulating composites with high Tg of 385°C. The cured composite specimens were then subjected to mechanical testing, thermal conductivity and porosity evaluation as well as SEM characterization.

Ultrasonic detection, characterization, and simulation of delamination defects in composite laminates

Composite materials are of great importance in many industries due to their unique properties, strength and durability, but they also include disadvantages that can affect their use and must be studied. In this article, we simulate the acoustic interference field received by a delay line following an interaction between an acoustic field and a multilayer carbon fibre composite material using the ray approach. In this case, the simulation is performed using carbon fiber composite plates, where some plates have lamination defects such as delamination, while others are free of these defects. Experimental measurements are performed on carbon fiber composite plates with and without delamination defects introduced beforehand, without knowing their thickness. The thickness of each ply is 0.125 mm. The transducer used is a focusing immersion transducer type parametric (V 312) that operates at a frequency of 10 MHz The simulation results almost exactly corroborate those of the experiment. The simulation model was employed to determine the thickness of the induced delamination, which is 0.2 mm, found in the second and third layers.

Coordination Regulation Strategy in Fabricating Bi2S3@CNFs Composites with Uniform Dispersion for Robust Sodium Storage.

To solve large volume change and low conductivity of Bi2S3-based anodes, a coordination regulation strategy is proposed to prepare Bi2S3 nanoparticles dispersed in carbon fiber (Bi2S3@CNF) composites. It has been discovered that introducing trimesic acid as a ligand can significantly improve the loading and dispersion of Bi3+ in polyacrylonitrile fibers. The results exhibit that Bi2S3 nanoparticles of 200-300 nm are uniformly anchored on the superficial surface layer of CNFs, and Bi2S3 nanoparticles of about 20 nm are evenly dispersed in the interior of CNFs. Assessed as sodium-ion batteries' anode material, the discharge capacity of the Bi2S3@CNF anode in the second cycle is 669.3 mAh g-1 at 0.1 A g-1 and still retains 620.2 mAh g-1 after 100 cycles, with the capacity retention rate of 92.7%. Even at 0.5 A g-1, the specific capacity of the second cycle is 432.99 mAh g-1, which still keeps 400.9 mAh g-1 after 800 cycles, with a retention rate of 92.5%. The excellent cycle stability is mainly attributed to the uniform distribution of small Bi2S3 nanoparticles in CNFs providing abundant active sites, preventing side reactions, relieving volume expansion, improving the electrical conductivity, and accelerating the electrochemical reaction kinetics.

Synergetic Hybridization Strategy to Enhance the Dynamicity of Poorly Dynamic CO2‐derived Vitrimers achieved by a Simple Copolymerization Approach

AbstractCopolymerization allows tuning polymer's properties and a synergetic effect may be achieved for the resulting hybrid, i.e., outperforming the properties of its parents as often observed in natural materials. This synergetic concept is herein applied to enhance both dynamicity and properties of vitrimeric materials using poorly dynamic hydroxyurethane and non‐dynamic epoxy thermosets. The latter generates activated hydroxyl, promoting exchange reactions 15 times faster than pure polyhydroxyurethanes. This strategy allows obtaining catalyst‐free high‐performance vitrimers from conventional epoxy‐amine formulations and an easily scalable (bio‐)CO2‐based yet poorly efficient dynamic network. The resulting hybrid network exhibits modulus retention superior to 95% with fast relaxation (<10 min). The hydroxyurethane moieties actively participate in the network to enhance the properties of the hybrid. The material can be manufactured as any conventional epoxy formulation. This new strategy to design dynamic networks opens the door to large‐scale circular high‐performance structural carbon fiber composites (CFRP). The CFRP can be easily reshaped and welded from flat plates to complex geometries. The network is degradable under mild conditions, facilitating the recovery and re‐use of high‐added‐value fibers. This accessible and cost‐effective approach provides a versatile range of tunable dynamic epoxides, applicable across various industries with minimal adjustments to existing marketed products.

Multi-scale correlation of impact-induced defects in carbon fiber composites using X-ray scattering and machine learning

Impact-induced defects in carbon fiber-reinforced polymers (CFRPs)-spanning from nanometer to macroscopic length scales-can be monitored using an aggregate of X-ray-based methods, but this is impractical in typical field conditions. We report on a low-velocity impacted CFRP, which is mapped using small- and wide-angle X-ray scattering and X-ray computed tomography, and employ machine learning for correlating material parameterizations derived from these techniques. The observed 1 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}m to 1 mm-sized defects are parameterized in terms of relative density and fiber orientation indicative of fiber failures (kink bands), and the nanometer sized defects in terms of crystal size and unit cell frustration. The 30 to 300 nm defects are parameterized by a power-law scattering decay, differentiating fractal-like behaviors. We find three spatial domains experimentally and by K-means Clustering: Domains of severe damage (with a visual dent), intact domains (without visual or measurable defects) and a transition domain (defects measurable by X-rays). How the parameters are correlated and how they overlap between the domains are discussed. All parameters are able to point to the detrimental fiber breakage in the severe damage domain, and scattering decay also in the transition domain, for example. How individual parameters determined from one experimental technique can be predicted from that of another is also described.

A hierarchical multistage holistic model for acoustic emission source monitoring in composites

Abstract This paper introduces a multistage smart structural health monitoring (SHM) model for carbon-fiber composites, with a focus on multiple types of acoustic emission (AE) source localization and classification. The SHM model uses time-frequency data from various AE events (such as tool drops, impact, and artificial debonding) across different zones of a composite structure. The SHM strategy demonstrates a robust smart monitoring of composites with high accuracy. Further, a hypothesis testing has been carried out that supports the superiority of a 2-stage identification process, revealing statistically significant higher accuracy and confidence intervals across all zones and AE source types. This research establishes a novel framework for solving a hierarchical multistage holistic damage source identification problem, offering robustness in identifying various damage scenarios and quantifying associated prediction uncertainties.

Imaging and reconstruction of asymmetric wrinkles in carbon fibre composites using high-frequency eddy current and full matrix capture-based ultrasound

Ply wrinkles are a common defect found in Carbon Fiber Reinforced Polymer (CFRP) laminates that can lead to failure in composite structures if not correctly evaluated during manufacture stages. The mechanical performance of a structure depends on multiple parameters of a wrinkle, such as amplitude, wavelength, and asymmetry, which ideally need to all be measured to characterise the wrinkle properly. To address this issue, the authors designed and manufactured a set of complex wrinkles with various asymmetry offsets and amplitude and obtained raw data by testing them with a high-frequency eddy-current system. A unique trajectory in the complex Nyquist plot was found on asymmetric wrinkles, demonstrating the dominant influence of wrinkle asymmetry on electrical resistance. The authors also used full matrix capture ultrasound to characterise the wrinkles and measured the profiles by extracting texture phase randomness. The study revealed the superior capability of FMC UT for characterising and retrieving the profile in wrinkle coupons, while HF ECT was more adaptable for identifying the region of interest effectively. This work also implements a state-of-the-art deep fusion strategy to demonstrate a lightweight architecture can be easily used to combine multiple sources of wrinkle profiles and generate a more accurate prediction than traditional methods. Overall, the demonstrated work can be further applied to CFRPs with increasing geometric complexity and defects to facilitate the design efficiency and testing of CFRP components.

Upcycling end-of-life carbon fiber in high-performance CFRP composites by the material extrusion additive manufacturing process

Each year, a significant amount of waste is produced from carbon fiber polymer composites at the end of its lifecycle due to extensive use across various applications. Utilizing regenerative carbon fiber as a feedstock material offers a promising and sustainable approach to additive manufacturing based on materials. This study proposes the additive manufacturing of recycled carbon fiber with a polyamide-12 polymer composite. Filaments of recycled carbon fiber-reinforced polyamide-12 (rCF-PA12) with different recycled carbon fiber contents (0%, 10%, and 15% by weight) in the polyamide-12 matrix are developed. These filaments are utilized for 3D printing of specimens by using various infill density parameters (80% and 100%) on a fused deposition modeling 3D printer. The study examined how the fiber content and infill densities influenced the flexural performance of the printed specimens. Notably, the part containing 15 wt% recycled carbon fiber (rCF) composites showed a significant improvement in flexural performance due to enhanced interface bonding and effective fiber alignment. The results indicated that reinforcing the printed part with 10% and 15 wt% recycled carbon fiber (rCF) improved the flexural properties by 49.86% and 91.75%, respectively, compared to the unreinforced printed part under the same infill density and printing parameters. The investigation demonstrates that the additive manufacturing-based technique presents a potential approach to use carbon fiber-reinforced polymers waste and manufacture high-performance engineering, economic, and environmentally friendly industrial applications with the complicated design using different polymer matrices.

Design optimization of automotive carbon fiber composite material floor laminate based on PSO-BFO algorithm

In response to the current challenges of low precision and efficiency in the optimization of composite material layups, the insufficient lightweight of automotive body floors, and the high cost of carbon fiber composites, this study introduces an optimized design method for carbon fiber composite flooring layups. Based on implicit parametric technology, a hybrid PSO-BFO (Particle Swarm Optimization-Bacterial Foraging Optimization) algorithm is employed. This approach achieves an integrated optimization of materials, processes, and structures, thereby balancing and reducing costs. The SFE-CONCEPT is utilized to establish an implicit parameterization model for the body floor, which is validated through experiments and finite element simulation analysis. Concept design and modeling of the carbon fiber composite material floor laminate are performed. Continuous variable optimization is employed to determine the thickness, tile shape, and number of layers for the front, middle, and rear floors. A continuous variable discretization rounding strategy is used to obtain the discrete layer numbers for each laminate orientation of the composite material floor. The continuous fiber lamination strategy is applied to create different shared lamination regions. The PSO-BFO hybrid optimization method is proposed to optimize the lamination sequence as a multi-objective optimization, addressing the challenges of discrete lamination sequence, explosive combinations, and multiple variables in the optimization design of carbon fiber composite material floor laminates. The optimization results demonstrate improvements of 34.4% in floor quality M, 6.0% in static bending stiffness BS, and 5.3% in lightweight coefficient QLX using the proposed PSO-BFO method. PSO-BFO and PSO-GA (Particle Swarm Optimization-Genetic Algorithm) methods are more capable of obtaining global optimal solutions for complex optimization problems than single optimization algorithms. Still, the results obtained by the PSO-BFO method are more balanced.

Three-Dimensional Printing Limitations of Polymers Reinforced with Continuous Stainless Steel Fibres and Curvature Stiffness

This study investigates the printability limitations of 3D-printed continuous 316L stainless steel fibre-reinforced polymer composites obtained using the Materials Extrusion (MEX) technique. The objective was to better understand the geometric printing limitations of composites fabricated using continuous steel fibres, based on a combination of bending stiffness testing and piezoresistive property studies. The 0.5 mm composite filaments used in this study were obtained by co-extruding polylactic acid (PLA), with a 316 L stainless steel fibre (SSF) bundle. The composite printability limitations were evaluated by the printing of a series of ’teardrop’ shaped geometries with angles in the range from 5° to 90° and radii between 2 and 20 mm. The morphology and dimensional measurements of the resulting PLA-SSF prints were evaluated using μCT scanning, optical microscopy, and calliper measurements. Sample sets were compared and statistically examined to evaluate the repeatability, turning ability, and geometrical print limitations, along with dimensional fluctuations between designed and as-printed structures. Comparisons of the curvature bending stiffness were made with the PLA-only polymer and with 3D-printed nylon-reinforced short and long carbon fibre composites. It was demonstrated that the stainless steel composites exhibited an increase in bending stiffness at smaller radii. The change in piezoresistance response of the PLA-SSF with load applied during the curvature bending stiffness testing demonstrated that the 3D-printed composites may have the potential for use as structural health monitoring sensors.

Free Vibrations of Three-Dimensional Woven Composite Made of Aramid Glass, Epoxy Graphite and Epoxy Carbon Fibers

Free Vibrations of Three-Dimensional Woven Composite Made of Aramid Glass, Epoxy Graphite and Epoxy Carbon Fibers

Prediction of composite pressure vessels’ burst strength through machine learning

In Hydrogen Fuel Cell Electric Vehicles, hydrogen is stored as compressed gas in tanks made from carbon fiber composite. Tanks are designed to withstand 2.25 times the nominal working pressure. If low variability in tank strength can be demonstrated, this margin of safety could be reduced. This requires accurate prediction of the strength of the vessel and quantification of its uncertainty. In this work, several composite pressure vessels are manufactured using filament winding, and the parameters that control the winding and curing recorded as time signals. Process parameters include fiber tension, winding speed, liner pressure, fiber volume fraction, winding time and curing pressure. The vessels are tested for burst pressure. Several configurations are defined, where each manufacturing parameter is changed. The recorded manufacturing data are fed to machine learning(ML) algorithms and trained to predict the vessel’s burst pressure. These ML algorithms include neural networks, Gaussian process regression GPR, Kernel Principal Component Analysis-Lasso (kPCA-Lasso), and an Ensemble regressor. The KPCA-Lasso and GPR models show good correlation. The Ensemble regressor yields better results by combining the KPCA-Lasso and GPR models. The study demonstrates the potential of ML algorithms in predicting the burst pressure of carbon fiber vessels from the monitored manufacturing data.

Rate-dependent mechanical and self-monitoring behaviors of 3D printed continuous carbon fiber composites

3D printed continuous carbon fiber reinforced polymer (CFRP) composites offer great advantages in structural health monitoring (SHM) owing to their flexibility in complex structure fabrication. Considering the many prospective aerospace applications, tensile experiments were designed to study their mechanical and self-sensing behaviors under a wide range of strain rates. The turning points in the resistance vs strain curves reveal the damage evolution of the specimens and divide the deformations into linear straining and damage evolution regions. Fiber elongation and fiber contact reduction dominate the resistance increase in the linear straining region and the resistance curve behaves linearly. But fiber breakage is the predominant factor in the damage evolution region, yielding a concave resistance curve. Strength, fracture strain, and resistance variation are found to display significant strain rate dependencies that increase with increasing strain rate. Numerous microcracks are formed and evolved into secondary cracks under dynamic loading. This process absorbs more strain energy and produces more carbon fiber breaks, sustaining a higher fracture strain and resistance variations. A model is developed to describe the strain- and strain rate- dependent resistance behaviors, and the predicted results agree well with experimental data. The outcomes of this work contribute to the application of 3D printed continuous CFRP composites in SHM.

Carbon fiber and carbon fiber composites—creating defects for superior material properties

AbstractRecent years have seen a rise in the use of carbon fiber (CF) and its composite applications in several high-tech industries, such as the design of biomedical sensor components, 3D virtual process networks in automotive and aerospace parts, and artificial materials or electrodes for energy storage batteries. Since pristine CF have limited properties, their properties are often modified through a range of technologies, such as laser surface treatment, electron-beam irradiation grafting, plasma or chemical treatments, electrophoretic deposition, carbonization, spinning-solution or melt, electrospinning, and sol–gel, to greatly improve their properties and performance. These procedures cause faulty structures to emerge in CF. The characteristics and performances of CF (thermo-electric conductivity, resistivity, stress tolerance, stiffness and elasticity, chemical resistivity, functionality, electrochemical properties, etc.) vary greatly depending on the modification technique used. Thus, the purpose of this review is to demonstrate how the insertion of faults can result in the production of superior CF. The characteristics of CF defects were examined using a variety of analytical techniques, such as defect-forming chemistry, molecular organization, and ground-level chemistries like their crystallinities. Finally, some future work is also included. Graphical abstract

Dynamic covalent epoxy network of hyperbranched-synergistic-supramolecular: catalyst-free reprocessing, and application in carbon fiber composites recycling

Dynamic covalent epoxy network of hyperbranched-synergistic-supramolecular: catalyst-free reprocessing, and application in carbon fiber composites recycling

Mode I crack propagation in polydimethylsiloxane-short carbon fiber composites

Mode I crack propagation in polydimethylsiloxane-short carbon fiber composites

Impact of graphene oxide lateral sizes on the mechanical and thermal properties of carbon fiber composites

AbstractThe impact of carbon fiber (CF) composites sizing with graphene oxide (GO) to form brick‐and‐mortar structures on their mechanical properties and thermal conductivity has not been closely examined. This study systematically investigates the effect of GO sheet size on the interfacial properties and thermal conductivity of CF composites. Three sizes of GO—small (0.11 μm), medium (0.33 μm), and large (0.97 μm)—were used to modify CF surfaces via layer‐by‐layer self‐assembly, forming the brick‐and‐mortar structures. The mechanical properties were assessed through flexural tests, interlaminar shear strength (ILSS) tests and tensile tests, while thermal conductivity was measured using a thermal constant analyzer. The results revealed that medium‐sized GO (GO‐M) significantly enhanced the interfacial strength and toughness of the composites. This improvement is attributed to the orderly arrangement of GO‐M on the CF surface, which enhances stress transfer between the fiber and the matrix. In contrast, small‐sized GO (GO‐S) tended to scatter, resulting in less effective reinforcement, while large‐sized GO (GO‐L) exhibited stacking and agglomeration, limiting its reinforcement effectiveness. However, GO‐L provided the highest thermal conductivity due to the formation of continuous heat conduction pathways. These findings suggest that GO‐M offers a balanced improvement in mechanical properties, whereas GO‐L is more suitable for applications requiring high thermal conductivity. This work underscores the importance of selecting the appropriate GO sheet size to optimize the interfacial properties and thermal conductivity of CF composites, which is crucial for enhancing their performance in high‐end engineering applications, such as aerospace, automotive, and marine industries.Highlights Modification of CF composites by GO‐M sheets significantly improved toughness and strength. GO‐L sheets formed an effective heat transfer channel with the highest thermal conductivity. The study emphasized the critical role of selecting the appropriate GO sheet size to optimize the mechanical and thermal properties of CF composites.

Application of Computer-Aided Design Software to the Simulation and Analysis of Composite Material Properties in Housing Engineering Structures

Reinforced polymer composites are widely used in engineering applications due to their excellent mechanical properties, and this paper combines experiments and numerical simulations to fully examine the properties of the composites. The article takes the reinforced concrete structure of civil engineering as the basis for experimental testing on the basic properties of carbon fiber composites in its application. Subsequently, the intrinsic model of reinforced concrete and carbon fiber composites was constructed, and each finite element unit of the member was selected to simulate and finite element analysis the performance of the composites through ABAQUS computer-aided design software. The results show that increasing the diameter of carbon fibers will reduce the number of carbon fibers at the same time, which will reduce the toughness of the composite material, random and chaotic distribution of carbon fibers for the improvement of the compressive properties of concrete can achieve a relatively balanced effect, and the high elastic modulus carbon fibers for the improvement of uniaxial and cyclic compressive properties of concrete play a dominant role. In addition, the oriented elliptical fibers in the long-axis direction have a significant increase in the modulus of elasticity and strength of the material, and this phenomenon will become more and more obvious with the increase of the length-to-diameter ratio. The reasonable structural design may help to improve the performance of composites and enhance their adaptability for engineering applications.

Aspect ratio-dependent volume resistivity in unidirectional composites: Insights from electrical conduction behavior

The electrical properties of carbon fibers serve as the foundation for the multifunctional applications of carbon fiber-reinforced composite structures. In scenarios that exploit the electrical characteristics of materials, accurate estimation of electrical resistivity stands as a critical factor. This study endeavors to elucidate the electrical conduction behaviors in unidirectional composites with different fiber orientation angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) and aspect ratios, thereby deriving the volume resistivity within an arbitrary Cartesian coordinate system. Employing thermal infrared imaging technology and finite element analysis, we identified distinctive electrical conduction behaviors associated with aspect ratios in carbon fiber composite plates. Notably, a critical aspect ratio exists wherein the diagonal yarn is the only conductive path between two electrodes. Below this critical threshold, no direct conductive path exists, and current flows through the shortest distance between parallel yarns. Conversely, beyond the critical aspect ratio value, multiple yarns form conductive paths between the two electrodes. Based on the electrical conduction behavior of unidirectional composites under different angles and aspect ratios, the volume resistivity with finite boundaries was derived and examined under an arbitrary Cartesian coordinate basis.