Fiber Reinforced Epoxy Composites Research Articles

Effect of hollow glass microspheres on transverse properties of carbon fiber reinforced epoxy composites

AbstractHollow glass microsphere (HGM)—based composites are gaining popularity in materials research due to their ability in altering material characteristics drastically. The current study investigates HGMs filled carbon fiber reinforced epoxy (CE) composites on transverse properties, aiming for aerospace and defense applications mainly in composite pressure vessels. Unidirectional laminates of Carbon/Epoxy with varying HGM percentages (0.2, 0.4, 0.6, 0.8, 1.0 wt. %) were wounded onto a flat‐plate mandrel using a 4‐axis filament winder, along with a baseline sample without HGM for comparison. The glass transition temperature (Tg) and thermal stability were analyzed by carrying out dynamic mechanical analysis and thermogravimetric analysis. The fracture mechanism of the samples loaded under tension was investigated using FESEM. Experimental results indicate reduction in density with increase in HGM content, up to 0.4% HGM there is increase in transverse tensile strength of 25% compared to baseline and further increase in HGM content, decrease trend is observed. 30% decrease in transverse compressive strength is observed compared from baseline to 1.0 wt. % of HGM. No significant change was noticed in the thermal stability and Tg on introduction of HGM. Microscopy images of fractured samples revealed effective physical interaction and dispersion of the HGM within the matrix.Highlights Transverse mechanical properties are tested to know the influence of HGM filler on filament wound composites. Density of the composite decreases with increase in HGM content. Thermal stability and Tg shows less change on introduction of HGM in composites.

Improving tensile properties of glass fiber-reinforced epoxy resin composites based on enhanced multiphase structure: The modification of resin systems and glass fibers

Glass fiber-reinforced polymer (GFRP) composites have been widely used as reinforced materials in marine engineering due to their good corrosion resistance and economic benefits. However, the mechanical properties of GFRP are lower than that of composites reinforced by carbon and aramid fibers etc. Methods to improve the mechanical properties of GFRP received ongoing attention. GFRP have various mechanical properties due to the characteristics of its multiple phases. This study developed an optimized processing method based on multiphase structures for GFRP composites, significantly enhancing the tensile properties of GFRP laminates. The modified GFRP can be produced efficiently by this method to meet more utilization situations in marine engineering. The influence of curing agents, silane coupling agents (SCA)-treated glass fibers (GFs), and nanomaterials on GFRP's tensile properties was investigated. The findings reveal a 10.64 % increase in the characteristic load of GF bundles due to the improved bonding between fibers by SCA. Besides, the contact angle between SCA-treated GFs and epoxy resin shows a significant reduction (26.69 %). Variations in ply thickness and resin system distinctly influence the tensile properties and failure modes of GFRP laminates. Laminates with 4-ply GF fabrics facilitate more effective load transfer across the matrix-fiber boundary, yielding optimal tensile properties for GFRP. Epoxy/phenolic amine resin system with more reactive functional groups (-OH) enhances the fiber-resin bonding, further improving the tensile properties of GFRP. The enhancement mechanism of the multiphase structure in GFRP was elucidated by microscale characterization, indicating that the multiphase structures in GFRP, enhanced by SCA, nanomaterials, and functional curing agents, significantly improve its tensile properties.

Impact of plasma-modified pretreatment on the tensile properties of carbon fiber-reinforced epoxy composites

Abstract Low-temperature jet plasma modification technology is a surface treatment method designed to enhance the surface properties of materials without causing severe thermal damage. This technique modifies surface characteristics by creating plasma and utilizing ions and reactive groups within the plasma to chemically interact with the material’s surface. In this study, surface modification of carbon fibers was carried out by using low-temperature jet mixed oxygen plasma technology at treatment speeds of 25 mm/s, 50 mm/s, 100 mm/s, and 200 mm/s. Following the modification process, carbon fiber-reinforced epoxy composites were fabricated by using a hand-lay-up technique. Subsequently, the tensile properties of the carbon fiber composites were tested to evaluate the impact of the plasma treatment on their mechanical performance. The experimental results demonstrated a significant enhancement in the tensile properties of the composites when the carbon fibers were pretreated at a rate of 50 mm/s. This enhancement was evidenced by an impressive increase of 82.38% in tensile strength and 30.96% in tensile modulus compared to untreated samples. This signifies that low-temperature plasma treatment has a beneficial effect on enhancing the surface properties of carbon fibers and improving the performance of composites. This finding provides substantial support for the extensive application of carbon fiber composites.

Improvement of interfacial properties and hygrothermal resistance of CF reinforced epoxy composites by fluorine-containing sizing agent

To enhance the interfacial bonding performance between carbon fibers (CFs) and epoxy resin, the fluorine-containing sizing agent was prepared by the unique characteristics of fluorine. The incorporation of C-F bonds endows the interfacial layer with a higher degree of homogeneity, effectively mitigating stress concentrations that arise from surface imperfections. This mitigation is attributed to the repulsive interactions among fluorine atoms. The test results showed that the interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composites (CFREs) can be increased to a maximum of 66.01 MPa, representing a notable enhancement of 15.79 % in comparison to unsized CFREs. The enhancement of interfacial bonding ability is primarily ascribed to the synergistic effects of mechanical interlocking and chemical bonding interactions at the interface between CFs and resin. Concurrently, the hygrothermal resistance of CFREs was subjected to rigorous testing. The electron cloud of fluorine atoms exerts a pronounced shielding effect on the carbon chains, thereby significantly bolstering the hygrothermal resistance of CFREs. This enhancement is critical for the CFREs ' application in environments with high humidity and temperature. Moreover, the sizing agent developed in this study boasts a streamlined production process, which is expected to be applied in the commercial large-scale production of CFs.

Experimental and numerical investigation of damage in multilayer sandwich panels with square and trapezoidal corrugated cores under quasi-static three-point bending

Multilayer composite sandwich panels with corrugated cores have the potential for structural applications requiring high stiffness and strength-to-weight ratios. This study aims to experimentally and numerically investigate the bending response of sandwich panels with novel square and trapezoidal corrugated core configurations fabricated from E-glass fiber-reinforced epoxy composites, both with and without polyurethane foam filling. Quasi-static three-point bending tests were conducted to evaluate and compare the flexural stiffness and maximum load capacity of the panel designs. The cores were manufactured using vacuum-assisted resin transfer molding. Key results showed that changing the core geometry from square to trapezoidal improved the bending stiffness by up to 26 %. Incorporating polyurethane foam further increased the bending stiffness by up to 41 % and maximum load by up to 47 % compared to solid cores. Failure initiation and progression were governed by matrix cracking in the face sheets and cores, followed by core cell wall buckling and delamination. Finite element modeling using ABAQUS captured the progressive damage behavior, exhibiting good agreement with experimental force-displacement responses. Failure modes included matrix cracks, fiber fractures, core buckling and delamination. This study provides valuable insights into the mechanical performance of innovative corrugated core sandwich panel designs under quasi-static bending loads. The validated FE approach also enables virtual testing and optimization of composite sandwich structures.

Investigation of Drilling Performances, Tribological and Mechanical Behaviors of GFRC Filled with B4C and Gr

AbstractIn this study, the effects of Gr and B4C filler materials on drilling performance, mechanical, and tribological behaviors of glass fiber-reinforced epoxy composites were experimentally investigated. Glass fiber-reinforced composite materials filled with B4C and Gr at different weight ratios (5%, 10%, and 15%) were manufactured using hand lay-up method. The produced composite materials underwent various tests, including mechanical tests (tensile and flexural tests), tribological tests (wear behavior), and drilling tests under different parameters. Additionally, SEM images of the worn and fractured surfaces were examined. The addition of both B4C and Gr fillers adversely affected the mechanical properties of glass fiber-reinforced composites. It was observed that tensile and flexural strengths decreased with increasing filler ratios. However, the addition of B4C and Gr fillers enhanced the wear resistance of glass fiber-reinforced composites. It was revealed that in drilling operations, as the feed rate increased, the thrust forces increased, while the cutting speed increased, the thrust forces decreased. It was determined that delamination values in glass fiber reinforced composites decreased as the feed rate increase, while delamination values increased as the cutting speed increased. Generally, the thrust forces, vibration, delamination, and moment values obtained during the drilling of B4C-filled glass fiber composites were found to be higher compared to Gr-filled glass fiber composites.

Correlative Investigation on Dielectric-Mechanical-Morphological Characteristic for Kenaf-Glass-Hybrid Fibers Reinforced Epoxy Composite

In recent years, there are many applications where synthetic fibers and natural fibers are used as reinforcing materials in composites, such as the automotive and aerospace industries, the medical industry, and the construction industry. While these hybrid fibers effectively enhance mechanical and electrical properties, research into electrical characteristics remains inadequate and is an ongoing endeavor. In this work, synthetic woven glass fibers and natural woven kenaf fibers were used to fabricate composite materials by vacuum infusion technique. The dielectric properties of three different substrates, glass fibers, kenaf fibers and glass/kenaf fibers reinforced epoxy composites were investigated at 0° orientation. The ENA Network Analyzer was used to measure dielectric properties in a wide microwave frequency range. The substrates were single-joint overlapped with an adhesive and then mechanically tested. The shear strength of the joint as a function of strain, was tested using a Shimadzu universal testing machine. Visual inspections were performed to determine the failure modes of the composites. The dielectric constant and loss factor of the glass fiber composite were the highest, while the kenaf fiber composite had the lowest value. When a small amount of glass fibers is incorporated into kenaf fibers, which is called a hybrid composite, the polarization increases and the mechanical strength also increases compared to the kenaf fiber composite. Scanning electron microscopy (SEM) of the fractured tensile tests was performed to understand the nature of the interfaces between glass, kenaf and matrix. The kenaf/matrix interface was heterogeneous but exhibited voids, resulting in low dielectric properties and mechanical strength. By inserting a small amount of glass fibers, the hybrid with kenaf fibers improve the dielectric constant by 20.7% and the dielectric loss factor by 27% compared with the kenaf fiber composite. The results also show that the composites exhibit a correlation between the dielectric properties, tensile strength, and the morphological nature of the interfaces.

Effects of carbon nanomaterials on the interfacial properties of carbon fiber reinforced epoxy resin composite

Effects of carbon nanomaterials on the interfacial properties of carbon fiber reinforced epoxy resin composite

Effects of Boric Acid on Laminated Composites: An Experimental Study.

In this study, the effect of boric acid (H3BO3) on fiber-reinforced layered composites was investigated. Glass fiber-reinforced epoxy composites were used, and the effects of boric acid on thermal and mechanical properties were investigated. For this purpose, composite plates were manufactured by adding boric acid (BA) to the epoxy in different ratios (0, 0.5, 1, and 1.5% by weight). Tensile tests, compression tests, and shear tests were performed to determine the mechanical properties of these plates, and DSC, TGA, and DMA analyses were performed to determine their thermal properties. SEM and EDS analyses were performed on the specimens to examine their morphologies. Furthermore, examinations were conducted on how BA affected the specimens' failure behavior. In the study, it was found that, except for the compressive strength, the mechanical properties were improved by the added BA. The highest tensile strength, shear strength, modulus of elasticity, shear modulus, and Poisson's ratio were obtained from 0.5% BA-added specimens and were 24.78%, 8.75%, 25.13%, 11.24%, and 12.5% higher than the values obtained from 0% BA-added specimens, respectively. The highest loss and storage modulus were obtained from 0% and 0.5% BA-added specimens, respectively. The specimens' glass transition temperatures were decreased by the addition of BA; the specimen with a 1% addition of BA had the lowest value. Furthermore, interlayer delamination and fiber/matrix failure were observed in all BA-added specimens.

Concurrent predictions of tension, compression, and shear characteristics of epoxy using three-network viscoplastic model

Epoxy resin controls the mechanical behavior of fiber-reinforced epoxy composites, which are extensively deployed in the aerospace and automotive industries. For numerical simulations to accurately predict the mechanical deformations of these components under multi-axial loading, matrix characteristics must account for tension, compression, and shear loads at varying strain rates. The existing literature lacks a comprehensive approach to predicting the experimental outcomes across all three loading conditions in a polymer matrix simultaneously using a unified set of viscoelastic or viscoplastic model parameters. In this study, the Three-Network (TN) viscoplastic model was successfully applied to concurrently predict the tension, compression, and shear experimental data of an epoxy resin, published by Littel et al. ( Journal of Aerospace Engg., 2008). The elastic modulus, strain softening-hardening response after yield for tension-compression deformation, and post-yield stress saturation under shear deformation are all accurately predicted by the model at different rates of loading conditions. The predicted and simulated results matched well when the TN viscoplastic model predicted parameters were employed as material property in Abaqus (a commercial finite element software) to simulate the deformation modes. This integrated approach highlights the potential of the TN model in enabling precise predictions for epoxy-based composites, which is crucial for optimizing their performance and reliability in aerospace engineering.

An in-depth investigation into the utilization of nettle fiber-reinforced epoxy composites with embedded MgO nanoparticles

An in-depth investigation into the utilization of nettle fiber-reinforced epoxy composites with embedded MgO nanoparticles

Towards greener wind power: Nanodiamond-treated flax fiber composites outperform standard glass fiber composites in impact fatigue tests

Wind energy is facing two major problems, recyclability of wind turbine blades, primarily made from fiberglass, and rain erosion on the blade’s leading edges. Here, we show that flax fiber reinforced epoxy composites have less impact fatigue damage than glass fiber (GF) composites made with the same resin. The novel treatment of flax with non-toxic nanodiamonds even boosts its outstanding performance. Nanodiamond-treated flax fiber (FFND) composites exhibit a damage incubation period up to 17 times as long as GF composites and have at least 74% less mass loss. This is connected to lower initial impact pressure, less shock wave reflections and better impact absorption of flax composites. The nanodiamonds act as fiber sizing, strengthening the fibers and their matrix interface. This delays fracturing and results in less erosion, making the biodegradable FFND a promising replacement for GF towards a fabrication of more sustainable and longer lasting wind turbine blades.

Investigation of the properties and weathering behaviour of arecanut sheath fibre reinforced epoxy composites

ABSTRACT Engineered materials having unique elements such as reinforcing phases and matrix materials, such as composites, provide improved stiffness, strength, lightweight characteristics, and corrosion resistance. The utilisation of natural fibre composites, which are derived from sustainable resources such as areca nut sheath, is on the rise because of their affordability, favourable strength-to-weight ratio, and lightweight characteristics. These composites offer a more environmentally friendly option to traditional synthetic fibre composites while also reducing the negative effects of production processes on the environment. The development of these composites has been greatly aided by areca nut sheath fibre epoxy composites, which have applications in construction materials, biodegradable packaging, and other areas. In this research, areca nut sheath reinforced epoxy composites were tested for their mechanical and thermal characteristics along with their durability (weathering). It was observed that areca nut sheath fibre reinforcement improved both the tensile, flexural and impact properties of the composites due to their effective reinforcement, fibre–matrix interaction and load bearing capability. However, this study demonstrates that composites containing 20% areca nut sheath fibres have the best tensile and flexural strengths. Weathering studies revealed that the durability slightly decreased upon exposure to moisture and vermicompost due to moisture intake by the fibres.

Evaluation of surface response of SiC and fly ash-filled Prosopis juliflora fibre-reinforced epoxy composites under dry sliding wear conditions using Taguchi method

Prosopis juliflora (PJ) fibre-reinforced polymer composites are fabricated with fly ash and SiC as fillers with different weight percentages. Jute layers are also sandwiched for added strength in the structure. The wear behaviour is found for the prepared composition of samples. Pin-on-disc wear testing apparatus is used for the wear performance along with the design of experiments approach using orthogonal arrays of Taguchi’s. The effect of the input parameters (load, sliding velocity, speed) is studied on wear resistance. The experimental design creates sliding wear evaluations based on Taguchi’s L9 orthogonal array to identify the most dominating factors influencing the wear rate. This study demonstrates that the most important component affecting the sliding wear rate of the composite materials is followed by the sliding velocity, speed, and load. The result of the wear rate decreases with an increase in filler content and also increases with sliding velocity. The samples with fly ash and SiC fillers reportedly seemed to have the best wear rates.

The noteworthy tensile plasticity and strength of CoFeSiB metallic glass fiber reinforced epoxy composites

AbstractMetallic glass fibers have high strength, poor plasticity and low Young's modulus. In this study, it was used as a reinforcement to prepare metallic glass fiber reinforced epoxy composites with different fiber volume contents (20%, 30%, 40%, and 50%). The effect of fiber volume contents on the tensile properties of the metallic glass fiber reinforced epoxy composites was studied by experiment and the finite element analysis method. The experiment and simulation results are in good agreement. The tensile strength and plasticity of the metallic glass fiber reinforced epoxy composites increase with the increase of fiber volume contents. When the fiber volume content is 40% or 50%, a sharply necking feature appeared on the fibers and exhibited improved plasticity, due to the formation of interacting and arresting events of shear bands occurring at the interface between the metallic glass fibers and the epoxy. In addition, the strain hardening due to plastic deformation of the metallic glass fibers further enhanced the tensile strength of the metallic glass fiber reinforced epoxy composites. This is a first step toward toughening the inherently brittle metallic glass fibers under tensile conditions.Highlights A novel CoFeSiB metallic glass fiber reinforced epoxy resin composite The increase of fiber volume fraction improves the tensile strength and plasticity of fiber reinforced composites. The strain hardening due to plastic deformation of the metallic glass fibers further enhanced the tensile strength of the metallic glass fiber reinforced epoxy composites.

Performance evaluation of kevlar fiber reinforced epoxy composite by depositing graphene/SiC/Al2O3 nanoparticles

The synergistic effect of adding Silicon Carbide (SiC), Aluminum Oxide (Al2O3), and Graphene (GR) nanoparticles into Kevlar fiber-reinforced epoxy composites is investigated in this study. Within the epoxy matrix and Kevlar fibre reinforcement, these nanoparticles come in a variety of compositions. The mechanical and flammability features of the composite are revealed by experimental evaluation. Of the nanoparticles, graphene performs the best; the composite reinforced with graphene shows 324 MPa of tensile strength, 8 J/mm of impact strength, and 75.2 HRC of hardness. The composite layers' interior structure is investigated using scanning electron microscopy examination. To evaluate thermal stability of the composition the thermogravimetric (TG) and the differential thermal analysis (DTA) investigations were performed. Thermal stability is achieved by the graphene-reinforced composite at 775 °C. Additionally, corrosion tests and water absorption tests were conducted to assess the material's moisture sensitivity. The overall goal of the research is to ascertain whether adding various nanoparticles to Kevlar produces the best outcomes; graphene has demonstrated promising results in terms of improving mechanical and thermal stability.

High-performance carbon fiber-reinforced epoxy resin composites based on novel, environmentally friendly, stability, and heat-moisture resistant nano emulsion encapsulated POSS sizing agent interface modification

Considering the development of CFRPs, addressing the challenge through the simplistic industrial operational methods to achieve high strength and toughness in carbon fiber-reinforced epoxy resin (EP) composites (CFRPs) is imperative. In this work, an innovative approach introduced to improve the strength and toughness of CFRPs by application of a nano emulsion encapsulated polyhedral oligomeric silsesquioxane (POSS) sizing agent (POE sizing agent). The employment of a POE sizing agent markedly enhanced the surface energy and roughness of carbon fibers (CF) as well as the interface properties of CFRPs. Furthermore, the 10-PCF (10 wt% POE sizing CF) reinforced EP unidirectional CFRPs demonstrated superior strength and toughness. Relative to the DCF (Desizing CF) reinforced EP unidirectional CFRPs, their interlaminar shear strength, flexural strength, and unnotched impact strength increased by 24.9 %, 37.8 %, and 45.6 %, respectively, reaching 99.8 ± 2.3 MPa, 1376.8 ± 21.6 MPa, and 94.9 ± 4.6 kJ/m2. Concurrently, the 10-PCF reinforced EP composite laminates exhibited outstanding impact resistance, minimal damage area, and enhanced compressive strength after impact. Additionally, the strength, bundling, and flexibility of the sized CF were maintained, ensuring the processability of CF. The utilization of POE sizing agent for strength and toughness improvement in CFRPs offers a straightforward and industrially feasible approach. This research opens up a novel strategy for high-performance CF and CFRPs preparation.

Fabrication of a high-temperature resistant and water-soluble sizing agent to significantly improve the interfacial properties of carbon fiber reinforced epoxy composites

Applying suitable sizing agents is effective in improving the interfacial performance of carbon fiber reinforced composites (CFRPs). However, the poor thermal stability of conventional epoxy-based sizing agent limits their application at elevated temperatures for preparing advanced CFRPs. The question could lead to interfacial damage of composites at high temperatures, thus deteriorating their mechanical properties. In this work, diethanolamine (DEA) was selected to modify E51 resin to obtain a high-temperature resistant sizing agent (E51@DEA). The decomposition temperature of E51@DEA was 320 °C, which was 140 °C higher than that of E51. Furthermore, the resultant composites treated by E51@DEA 2 % showed robust interfacial performance (ILSS = 74.32 MPa, IFSS = 100.70 MPa), which was both increased by about 25 % compared to unmodified samples. In addition, the modified fiber could completely retain their interfacial reinforcement after treatment at 300 °C for 4 h. The prepared composites combined excellent thermal and interfacial properties, further expanding the application range of CFRPs.

Effect of seawater corrosion on the mechanical properties of basalt fiber reinforced polymer composites modified by silane coupling agent KH560 and carboxylated carbon nanotubes

Basalt fiber reinforced composite (BFRP) has been widely used in various engineering fields, while the corrosion resistance of BFRP in harsh environments needs to be improved. In this work, the effects of seawater corrosion on mechanical properties of silane coupling agent (KH560) and carboxylated carbon nanotubes (CNTs) modified basalt fiber reinforced epoxy resin composites (BF/EP) were studied by simulating seawater corrosion under different conditions. The results showed that with the increase in corrosion time and temperature, the flexural performance and interlaminar shear strength (ILSS) of the composite material significantly decreased. Under the same corrosion conditions, the modified basalt fiber composite has better corrosion resistance to seawater than the untreated one due to an enhanced "soft-rigid" multi-scale stress transfer region between the BF and resin matrix. The flexural strength, flexural modulus and ILSS of modified basalt fiber composites decreased by 17.7 %, 12.2 % and 11.3 %, respectively, after 7 weeks of seawater corrosion at 60 °C, while that of untreated basalt fiber composites decreased by 28.2 %, 20.4 % and 19.7 %, respectively. In addition, the corrosion of distilled water on basalt fiber composites was also studied. Similarly, the modified basalt fiber composites showed better corrosion resistance to distilled water compared to the untreated basalt fiber composites. The research shows that the synergistic modification of KH560 and CNTs can effectively improve the corrosion resistance of BF/EP. This work is significant for promoting the development of BFRP and its application in marine environment.

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.