Carbon Fiber Epoxy Research Articles

Predicting the thermal conductivity of polymer composites with one-dimensional oriented fillers using the combination of deep learning and ensemble learning

Polymer composites with one-dimensional (1D) oriented fillers, recognized for their high thermal conductivity (TC), are extensively utilized in cooling electronic components. However, the prediction of the TC of composites with 1D oriented fillers poses a challenge due to the significant impact of filler orientation on composite TC. In this paper, we use a strategy that combines deep learning and ensemble learning to efficiently and quickly predict the TC of composites with 1D oriented fillers. First, as a control, we used convolutional neural network (CNN) model to predict the TC of 1D carbon fiber-epoxy composite, and the R-squared (R2) on the test set reached 0.924. However, for composites consist of different matrices and fillers, the CNN model needs to be retrained, which greatly wastes computing resources. Therefore, we define a descriptor ‘Orientation degree (Od)’ to quantitatively describe the spatial distribution of the 1D fillers. CNN model was used to predict this structural parameter, the accuracy R2 can reach 0.950. Using Od as a feature, random forest regression (RFR) was used to predict the TC, and the accuracy R2 reached 0.954, which was higher than that of CNN control group. We further successfully extended this strategy to composites consist of different 1D fillers and matrices, and only one CNN model and one RFR model needed to be trained to achieve fast and accurate TC prediction. This strategy provides valuable insights and guidance for machine learning-based material property prediction.

Post-Buckling Response of Carbon/Epoxy Laminates with Delamination under Quasi-Static Compression: Experiments and Numerical Simulations.

Delamination is a common type of damage in composite laminates that can significantly affect the integrity and stability of structural components. This study investigates the post-buckling behavior of carbon fiber-reinforced epoxy composite laminates with embedded delamination under quasi-static compression. Experimental tests were conducted using an electronic universal material testing machine to measure deformation and load-bearing capacity in the post-buckling stage. The specimens, prepared from T300 carbon fiber and TDE-85 epoxy resin prepreg, were subjected to axial compressive loads with delamination simulated by embedding Teflon films. Finite element analysis (FEA) was performed using ABAQUS software, incorporating a four-part model to simulate delaminated structures, with results validated against experimental data through comprehensive convergence analysis. The findings reveal that increasing delamination depth and length decrease overall stiffness, leading to an earlier onset of buckling. Structural instability was observed to vary with the size of delamination, while the post-buckling deformation mode consistently exhibited a half-wave pattern. This research underscores the critical impact of delamination on the structural integrity and load-bearing performance of composite laminates, providing essential insights for developing more effective design strategies and reliability assessments in engineering applications.

A systematic framework for the design and material selection of composite for tennis racket upon impact

The present study explores the comprehensive composite material selection methodology of a tennis racket involving coupled Multi-Criteria Decision-Making (MCDM) and numerical analysis. Initially all the possible material alternatives from the composite family were shortlisted using CES Selector 2016. A design space was developed incorporating MCDM technique naming VICKOR (VIseKriterijumska Optimizacija I Kompromisno Resenje), PROMETHEE (Preference Ranking Organisation Method for Enrichment Evaluation) and TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) to rank the most suitable composite material based on critical mechanical properties to identify the most suitable composite materials for applications requiring optimal combinations of rigidity, strength, and structural performance. Using finite element analysis, the structural integrity of each of the materials was evaluated on static and dynamic stress analysis modules of ANSYS. Out of all material alternatives, T300 carbon fiber epoxy was considered as the most suitable for tennis rackets. Further, a comparison between the selected material was also made with conventional materials and were found in good agreement with selected material.

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

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.

Constructing Mechanochromic Fluorescent Interphase via Core-Shell Microcapsules: A Route for Interface Reinforcing and Damage Self-Reporting of CFRP Composites.

Perylenediimide-chitosan/γ-poly (glutamic acid) microcapsules sizing (PDI-CS/γ-PGA) core-shell microcapsule is designed and used to establish a novel interphase in carbon fiber/epoxy (CF/EP) composite, and the interfacial property, as well as the damage self-reporting of the composite, is compared with desized carbon fiber (CF-desized)/EP and commercial carbon fiber (CF-COM)/EP composite. The ruptured PDI-CS/γ-PGA microcapsule exhibits strong "turn-on" green fluorescence from the released PDI upon mechanical stimuli. The anchoring of PDI-CS/γ-PGA microcapsule on carbon fiber with PDI-CS/γ-PGA microcapsules sizing (CF@PDI-CS/γ-PGA) surface results in increased chemical activity and roughness, exhibiting a weak green fluorescence signal instead of non-fluorescence on CF-desized and CF-COM surface. The transverse fiber bundle tensile (TFBT) strength of CF@PDI-CS/γ-PGA composite is 80.97% and 31.09% higher than those of CF-desized/EP and CF-COM/EP composite, which is attributed to the mechanical interlocking and chemical bonding interaction between carbon fiber and epoxy matrix by introducing PDI-CS/γ-PGA microcapsule with spherular structure and active groups. After microdroplet testing, the strong "turn-on" green fluorescence signal of the released PDI from the microcapsules is detected in the interfacial debonding regions, realizing the microscopic damage self-reporting of CF@PDI-CS/γ-PGA composite.

Empirical model for the effect of air humidity during manufacturing on the glass transition temperature of carbon fiber reinforced hot curing epoxy – a case study

Carbon fiber-epoxy laminates are used in aerospace manufacturing, e.g. as substrates for solar cells of satellites. Commonly, fibers or fibermats are impregnated with epoxy resin and placed in the required orientation. During subsequent curing, the resin molecules are crosslinked. Cured parts are characterized by their glass transition temperature (Tg). It has been observed that Tg of epoxy matrix resin vary with recorded absolute air humidity during wet fiber placement manufacturing. Based on the production data of a series production of 203 carbon fiber laminates for space application, an empirical linear relationship between the absolute air humidity at the beginning of each production day and the observed glass transition temperature of the fully cured laminate is formulated and validated. The empirical equation describes a linear decrease of achievable glass transition temperature with increasing absolute air humidity. The quantitative nature of the results encourages straightforward practical application to determine the maximum achievable Tg for given production conditions.

Development and mechanical properties evaluation of environmentally sustainable composite material using various reinforcements with epoxy

In this study, the mechanical properties of advanced composites fabricated by the hand lay-up process were investigated. The mechanical properties evaluated in this study included tensile strength, flexural strength, and impact strength. Tensile tests were performed to measure the resistance of the composites to pulling forces, while flexural tests assessed their resistance to bending. Impact tests, on the other hand, determine the material's ability to absorb sudden forces or shocks. Results showed that all the composite materials exhibited high tensile strength, with the Carbon fiber epoxy composite displaying the highest value due to the exceptional strength of carbon fibers. In terms of flexural strength, the Glass-Fiber Polymer Matrix composite demonstrated the highest resistance to bending, while the Kevlar-Epoxy composite exhibited the highest impact strength, owing to the unique properties of Kevlar fibers, which offer excellent energy absorption capabilities. In the hardness test, the Kevlar composite to epoxy matrix showed hardness from HRB 105 to HRB 125 an increase of 19.04 %, while fiberglass increased hardness by 14.2 % and carbon fiber by 16.3 %. The Impact test shows that the Kevlar composite to epoxy matrix showed hardness from HRB 105 to HRB 125 an increase of 19.04 %, while fiberglass increased hardness by 14.2 % and carbon fiber by 16.3 %. Kevlar reinforcing composite produced the highest flexural strength, compared to neat epoxy by 91.7 %. Carbon fibre composites were 52.5 % higher, whereas glass fibre composites were 15.6 % higher. SEM imaging results from the cross-sections show that the best bonding between the base material and the fibers was observed for Kevlar reinforced with epoxy. All mechanical test showed that Kevlar (Aramid fiber) provides excellent mechanical properties when compared to carbon fibre and glass fibre. Hence, Kevlar (aramid fiber) can be an option for preparing light weight helmets, automobiles, aeronautics, safety equipments etc.

Study on Low-Velocity Impact and Residual Compressive Mechanical Properties of Carbon Fiber-Epoxy Resin Composites.

Room temperature drop hammer impact and compression after impact (CAI) experiments were conducted on carbon fiber-epoxy resin (CF/EP) composites to investigate the variation in impact load and absorbed energy, as well as to determine the residual compressive strength of CF/EP composites following impact damage. Industrial CT scanning was employed to observe the damage morphology after both impact and compression, aiding in the study of impact-damage and compression-failure mechanisms. The results indicate that, under the impact load, the surface of a CF/EP composite exhibits evident cratering as the impact energy increases, while cracks form along the length direction on the back surface. The residual compressive strength exhibits an inverse relationship with the impact energy. Impact damage occurring at an energy lower than 45 J results in end crushing during the compression of CF/EP composites, whereas energy exceeding 45 J leads to the formation of long cracks spanning the entire width of the specimen, primarily distributed symmetrically along the center of the specimen.

Interlaminar toughening of carbon fiber/epoxy composites via interleaving co‐polyamide (Co‐PA) veils

AbstractThermoplastic veil interlayers offer a promising approach to improve interlaminar reinforcement in composite materials. This study investigates co‐polyamide (Co‐PA) interleaved veils, fabricated through the hot melt adhesive (HMA) technique. These veils are then applied with varying areal weight densities as interleaves to simultaneously toughen and strengthen carbon fiber/epoxy (CF/EP) composites, utilizing the vacuum‐assisted resin infusion (VARI) method. Integrating Co‐PA veils with a low melting point in the interlaminar of CF/EP composites improves compatibility and promotes strong adhesion between thermoplastics and epoxy resins. As result, The Co‐PA laminates exhibited significant improvements compared with the untoughened composites, with a maximum enhancement of 148.1% and 67.8% for Mode‐I (GIC) and Mode‐II (GIIC), respectively. Moreover, ILSS, tensile strength, and flexural strength improvements were also 20.9%, 34.9%, and 14.5%, respectively. The fracture surface analysis via scanning electron microscopy directly revealed the crack propagation on the fracture surfaces of Mode‐I and Mode‐II specimens. This analysis revealed that Co‐PA demonstrated excellent compatibility with epoxy resin, melts during the stage of epoxy curing, and undergoes phase separation in the later stage, resulting in the formation of “bead‐like” structures within the fibrous network. Remarkably, this structure significantly enhanced the toughness of the CF/EP composites. The Co‐PA veils can improve the interlaminar toughness of CF/EP composites due to their compatibility with the epoxy matrix and high inherent toughness and strength. This method is straightforward to manage and can be utilized for manufacturing large‐scale composite materials incorporating CF fabrics, demonstrating promise for industrial applications.Highlights With its low melting point, co‐polyamide helps prevent structural failure or excessive damage and is proposed to be utilized in composites to enhance the interlaminar fracture toughness properties. The effects of Co‐PA veils of different areal densities on the mechanical characteristics of interlaminar composites were examined. Co‐polyamide particles with fiber‐carbon laminates offer superior fatigue properties and an optimum carbon fiber‐bridging mechanism. Co‐polyamide veils with CF/EP laminates are feasible for structural use in high‐tech automotive applications.

Influence of fatigue damage on the impact performance of toughened-interleave carbon fibre epoxy composite laminates

The impact performance of mechanically fatigued carbon fibre-reinforced polymer (CFRP) composite laminates with and without thermoplastic toughening particles has been investigated through a joint experimental and numerical campaign. Prismatic carbon fibre/epoxy specimens with added toughening particles at the ply interfaces were mechanically fatigued with different load amplitudes leading to a loss in apparent stiffness of 10% to 15%. Following the fatigue loading, high resolution computed tomography (CT) has been performed, revealing varying degrees of delamination starting from the free edges along the length of the specimens. In addition, transverse matrix cracks are observed in all fatigued specimens regardless of the amount of delamination. The residual ballistic impact performance of the damaged specimens has been investigated in a dynamic three-point bending configuration at three different velocities, showing a significant detrimental effect of even barely visible initial delamination. In addition, post-mortem CT scans and detailed finite element simulations are used to gain further insight into the mechanisms by which the two types of initial damage affected the impact resistance of the laminates. Finally, repeating the same experiments on a similar CFRP system without discrete toughening particles showed that their inclusion significantly increased the impact resistance both with and without prior fatigue damage.

Effect of immediate curing at elevated temperatures on the tensile and interfacial properties of carbon fiber-epoxy composites

Elevated temperature conditions known to improve curing from the onset and during the process of immediate curing are not available in the field, which can hinder the mechanical performance of these strengthening systems. In this study, mechanical testing and material characterization were conducted to identify the effects of subjecting nanomodified epoxy and fiber-reinforced nanomodified epoxy composites to room temperature (RT) (30 °C) and elevated temperature (110 °C) from the onset of curing. Static tensile testing and interfacial adhesion tests were conducted to evaluate the mechanical performance. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were performed to determine curing characteristics to inform on the immediate curing of nanomodified resins cured under the two temperature conditions. Scanning electron microscopy was performed to identify Carbon nanotube (CNT) dispersion characteristics. Overall, due to the incorporation of CNTs in epoxy, RT curing results in upto 62% increase in strain at failure. By supplying additional energy during immediate curing with elevated temperatures, a 51% increase in strength and 42% increase in Youngs Modulus can be observed in the nanomodified epoxy. In CFRP-epoxy composites, due to the incorporation of CNTs in the epoxy, RT curing results in upto 27% increase in strain at failure. By supplying additional energy during immediate curing with elevated temperatures, upto 133% increase in strain at failure is observed and upto 17% increase in strength is observed. CNTs incorporated in CFRP-epoxy composites demonstrated upto 50% increase in interfacial adhesion whereas supplying additional energy for their immediate curing with elevated temperatures, upto 130% increase in interfacial adhesion was observed. TGA and DSC results supported the mechanical observations and show a need for immediate curing when CNTs are used in epoxy matrices.

Investigating low velocity impact and compression after impact behaviors of carbon fiber/epoxy composites reinforced with helical multiwalled carbon nanotubes

Pre-damage and undetected micro-defects in fiber-reinforced polymer (FRP) composites are significant challenges compromising the integrity and mechanical performance of composite structures in aerospace applications. To address this challenge, this experimental study investigated the low velocity impact (LVI) and compression after impact (CAI) behaviors of carbon fiber/epoxy (CF/E) reinforced with 0.0 (control sample), 0.2, and 0.4 wt% helical multiwalled carbon nanotubes (HMWCNTs). The LVI test results showed that the control samples, with epoxy as the predominant phase, registered the lowest peak force compared to the 0.2 wt and 0.4 wt% HMWCNT/epoxy composite laminates. The CAI test results showed a decrease in strength with increased impact energy and an increase in the weight percent of HMWCNTs. Consequently, the 0.4 wt% HMWCNT ladened composites could withstand higher load without undergoing significant deformations, exhibiting the highest impact resistances due to the presence of CNTs, which function as load-bearing material. The HMWCNT interleaved CF/E composite laminate samples subjected to 25 J of impact energy achieved a higher maximum force of 9870.25 N compared to 8527.26 N for the damaged samples at the same level of impact energies. This fact indicates that the damaged samples could not withstand sufficiently high impact forces due to local instability arising from existing damages. The results strongly suggest a high potential for HMWCNTs CF/epoxy laminate composites in making structural and substructural components in aircraft and automobiles due to their proven superior properties.

Manufacture of a Nanocomposite of Carbon Fibre and Nanotubes and Epoxy Resin

Nanocomposite material have been manufactured by the manual contact method, using nanotubes and carbon fibres as the basis for manufacturing the nanocomposite and epoxy resin as the matrix. The CVD method was used to manufacture the carbon nanotubes on the carbon fibre with twill and plain weaves. Additionally, the mechanical properties of the nanocomposite with twill and plain weave were obtained from the tensile tests, and the density was obtained experimentally. The carbon nanotubes, CNTs, grew perpendicular to the surface of the carbon fibres, CF. The average diameter was 117 μm and the average length was 23.87 μm. The nanocomposite made of carbon nanotubes, carbon fibre and epoxy resin, CNT/CF/Epoxy with single layer twill weave had a thickness of 0.57 mm, while the plain weave nanocomposite had 0.56 mm. The densities obtained of the CNT/CF/Epoxy material were 1.03 g/cm3 with the plain weave and 1.08 g/cm3 with the twill weave. While the densities of the composite material, CF/Epoxy, where 1.21 g/cm3 and 1.19 g/cm3 with plain and twill weave. The densities of the CNT/CF/Epoxy were 14.28% and 9.14% lower than the densities of the CF/Epoxy, both with the plain and twill weave. From the tensile tests the mechanical properties obtained of the CNT/CF/Epoxy with twill weave were a modulus of elasticity of 31 GPa and a maximum stress of 153.47 MPa and with the plain weave the modulus of elasticity was 25.10 GPa and the maximum stress was 121.71 MPa. Both composite and nanocomposite materials were investigated with twill weave, and it was found that the best results of the mechanical properties were obtained with the nanocomposite, the increase of the modulus of elasticity and the maximum stress were 23.82% and 2.16% respectively.

Flame retardant, toughened, reinforced, transparent and long shelf-life one-component epoxy resins via a P/N/Si-containing hyperbranched polymer

One-component epoxy resins (OCEPs) cured from latent imidazole-based curing agents that exhibit high toughness, high strength, high fire safety, long shelf life, low dielectric properties and transparency are eagerly awaited in advanced manufacturing. However, existing research on latent imidazole-based curing agents/OCEPs mainly focuses on simultaneously improving their flame retardancy and shelf life, but neglects their poor toughness, strength and dielectric properties, and often compromises their transparency. Herein, a hyperbranched polymer (Si-DP) containing P/N/Si was fabricated to further improve the flame retardancy, toughness, strength and dielectric properties of EP10 (the transparent OCEPs comprising the latent imidazole-based curing agent PHI-HPP). EP10 containing Si-DP (EP10/Si-DP) boasted a shelf life longer than 81 days. The synergistic flame-retardant effect of P, N and Si elements enabled EP10/Si-DP3 to achieve a UL-94 V-0 rating with a limiting oxygen index of 33.9 %, the peak heat release rate and total smoke production of EP10/Si-DP5 were reduced by 44.4 % and 25.5 %, respectively, compared with EP10. The increased free volume and Si-O flexible bonds resulted in a 261.1 % higher impact strength of EP10/Si-DP5 than EP10. The excellent interfacial bonding of Si-DP with epoxy resins and the increased rigidity groups led to 74.0 % and 60.7 % higher tensile and flexural strengths of EP10/Si-DP5 than EP10, respectively. The intramolecular cavities and the low-polar Si-C bonds of Si-DP reduced the dielectric constant and dielectric loss of EP10/Si-DP. Meanwhile, EP10/Si-DP maintained inherent excellent transparency and high glass transition temperature (Tg). Carbon fiber epoxy composites prepared from EP10/Si-DP5 exhibited remarkable improvement in flame retardancy, smoke suppression as well as mechanical and interfacial performances. Overall, this research proposes an effective approach for preparing long shelf-life OCEPs with excellent overall performance.

Discontinuous interleaving strategies for toughening, damage sensing and repair in multifunctional carbon fibre/epoxy composites

Thermoplastic interleaving is a well-established approach to toughen carbon fibre thermoset laminates, studied over the past five decades. Recently, it has been revisited to create functional smart composites with damage sensing and repair capabilities with a renewed focus on the sustainability and longevity of components. However, the introduction of thermoplastic films within the interlaminar region often lowers fibre volume fraction and performance at elevated temperature, while the addition of impermeable continuous films during manufacture may also limit compatible fabrication methods. Moreover, the incorporation of dielectric thermoplastic films inevitably reduces through-thickness electrical conductivity and prevents accurate damage sensing of delamination in carbon fibre laminates. In this study, strategies of using discontinuous interleaving to improve both fracture toughness and thermomechanical properties of carbon fibre epoxy laminates, with the ability to monitor delamination damage and restore mechanical properties after a short healing step have been explored. Both the interleaving design and the physical properties of the thermoplastic were assessed, which has not been addressed previously. Interleaving high molecular weight thermoplastic with decreasing interleaf width and distance between interleaf zones results in increased fracture toughness (+347 %), by creating a superior toughened interlaminar zone, forcing a migration of delamination into the intralaminar region. A repair efficiency of 77 % was achieved when using a lower molecular weight of thermoplastic; however, the lack of thermoplastic over the entire fracture surface area affects the repairing performance universally. Damage sensing and thermomechanical properties were significantly improved compared to continuous interleaving, demonstrating that discontinuous thermoplastic interleaving strategies offer a favourable combination of toughening, thermal performance and accurate damage sensing for multifunctional high-performance composites.

Enhancement of electromagnetic interference shielding properties of hemp fiber sandwiched carbon fiber composites using electroless NiP coating

The present study aimed to improve the electromagnetic interference (EMI) shielding effectiveness (SE) of woven hemp fiber (HF) sandwiched carbon fiber (CF) epoxy composites using electroless Nickel-phosphorus coating. Furthermore, the phase composition, functional groups, microstructure, elemental composition, mapping and electrical conductivity of the raw fiber and coated fiber were analyzed in detail. Three different composite samples were prepared and their EMI SE was studied using a key sight 9374A vector network analyzer with 8–12 GHz frequency band (X-band frequency). The EMI SET of the raw HF sandwiched CF composite (S1) was observed as 61.17 dB. But, the addition of 1-layer coated HF between CF (S2) has increased the EMI SET from 61.17 to 83.16 dB. The 2 layer coated HF between CF (S3) had exhibited 92.77 dB which is 51.66 % higher than the S1 composite.

Developing A Temporary External Fixator (TEF) for Mandibular Reconstruction using Two-Phase QFD and TRIZ Approach

A temporary external fixator (TEF) is a device used to bridge resection defects after sequestrectomy and before secondary mandibular reconstruction surgery. A well-designed TEF should be customizable and adjustable to accommodate individual patient needs. This study developed a TEF for mandibular reconstruction using the quality function deployment (QFD) and the theory of inventive problem-solving (TRIZ). Customer needs (CNs) were investigated from literature reviews and a survey. Subsequently, a questionnaire was developed, refined, and delivered to 22 experts to identify the essential principles of TEF. Afterwards, the QFD priorities were analyzed based on the acquired CNs and technical requirements (TRs), and the top priorities were found to be safety and adequate operational space. The guidelines for developing a TEF with TRIZ were established as follows: First, using carbon fiber epoxy composite and Ti-6Al-4V as the material for TEFs is recommended Second, permanent magnet should be inserted into the clamp lock bolts to prevent them from falling off during surgery. Last, replacing one Schanz screw with three Bicortical screws is recommended for the fixator pins. Additionally, it was also found that changing the screw size from 2.5–4.0 mm to 2.0–2.4 mm could reduce hole defects in the mandible.

Mechanical, Tribological, and Biological Properties of Short Carbon Fiber/ Nano Hydroxyapatite Reinforced Hybrid Epoxy Composites

This investigation intends to examine the mechanical, tribological, and biological properties of hybrid epoxy composites reinforced with nanohydroxyapatite (nHA) and short carbon fiber (SCF). Due to its advantageous mechanical, tribological, and biocompatibility features, the proposed E/SCFs-nHA hybrid composites are meant to be recommended for composite structures that can be used to develop fixation plates used in orthopedic applications. In this study, single-layer hybrid composites reinforced with SCFs and nHA in varying ratios, as well as pure epoxy (E) and epoxy-carbon fiber composites, were all fabricated by hand lay-up method. Tensile tests, 3-point bending tests, and Izod impact tests were performed to investigate their mechanical characteristics. Moreover, the hybrid composite samples were tested for their biological properties in simulation body fluid (SBF). Mechanical and biological properties were found to be enhanced according to the results. Consequently, the hybrid composite (E-10CF-3nHA) of 10% carbon fiber (CF) and 3% nanohydroxyapatite (nHA) performed the best in all tests.

Static and fatigue performance of graphene nanoplatelets coated bi‐directional carbon fiber‐epoxy composites under bending loads

AbstractThe addition of graphene nanoplatelets as a nanofiller on the surface of pristine and oxidized carbon fiber for making reinforced polymer composites has shown improvement in monotonic flexural properties. However, the fatigue response of these laminates under bending loads has not been investigated so far. The current study aims to examine the monotonic and fatigue behavior of the graphene nanoplatelets (GNPs) coated bi‐directional pristine and oxidized carbon fiber epoxy composites under bending loads. Eight layers of fabrics were used to manufacture the laminates through vacuum‐assisted resin transfer molding technique (VARTM). An optimum amount of GNP addition on oxidized fiber leads to ~830‐fold enhanced fatigue life at higher stresses as compared to pristine laminates. However, excessive GNP addition on pristine as well as oxidized fiber leads to a deterioration in fatigue life. In‐situ optical microscopic examination was done to observe the crack initiation and propagation of all the specimens with respect to the number of cycles coupled with post‐mortem SEM images of the fracture surfaces.