Epoxy Composite Materials Research Articles

The effects of cutout size and fibre orientation to the failure behaviour of glass epoxy and boron epoxy composite laminates

The composite laminate was widely used in aerospace, marine and automobile structure. The application of glass epoxy composite widely uses because of the lightweight demand from aerospace industry. The implementation of boron epoxy on the helicopter blade structure is one of the examples the of boron epoxy composite material. This research is to study the effect of square cut-out to failure behaviour of Glass Epoxy and Boron Epoxy composite laminates with various fibre orientations. The research is being conducted in two stages, which is numerical validation of the software used and failure analysis. The method of determining the failure analysis is accomplish by using the finite element method (FEM) with Maximum stress theory as the failure criteria. As the results, a significant variance of strength character between without cut-out and cut-out. The results for all three types of cut-out are somehow different with no cut-out results. The gap in between no cut-out and A1 cut-out is around 96.8% of percentage difference at 0° fibre orientation but at 90° fibre orientation, the different is reduce to 38.3% of percentage difference. By varying the result, the main finding for the research is that material removal effect due to cutting has an impact on the strength of composite laminates. The cut-out size and the direction of fibre orientation also does affect the failure behaviour of the composite laminates research result. Results gaps for all three cut-out sizes on 0-degree also different by around 5% in between A1 and A2 and decrease to 25.32% in between A2 and A3. Consistency is found on the results at 90-degree with different by 38.3% and 20.45%. Although it is not much, all the failure curves for cut-out shows gradually decrease by the increase of degree in fiber orientation after 50°. As the conclusion, it is proven that the current study is important in understanding the failure behaviour of the composite plate in which can be useful in contributing the knowledge for further study.

Hybrids of glass fibers coated with carbon nanotubes and nickel for high‐performance electromagnetic wave absorption composites

AbstractTo expand the application of insulating glass fiber (GF) in the field of microwave absorption, one type of GF hybrids with carbon nanotubes (CNTs) and nickel (Ni) was successfully synthesized by chemical vapor deposition and electroless plating methods. By changing the reaction conditions, the morphology of GF hybrids including CNT's length, CNT's growth density, and Ni′s thickness could be adjusted. The as‐produced hybrids were used as multifunctional reinforcement to fabricate epoxy composites. The dielectric properties of composites were particularly measured from 1 to 18 GHz. It was found that the variation of GF hybrids structure significantly changed the dielectric properties of the composites in the tested frequency range. Furthermore, the analytical simulation work based on the experimental results was conducted for optimizing the structural parameters of multilayered composites. The results showed that the best reflection loss of −60 dB with a −10 dB range of 5.6 GHz could be obtained in an absorber with a triple‐layered structure composed by GF‐CNTs/epoxy with different CNT contents and GF‐CNTs@Ni/epoxy. Thus, the proposed hybrid method might be quite efficient for developing composites that can achieve high‐performance electromagnetic absorbing.

Evaluation of fiber volume fraction of kenaf-coir-epoxy based green composite by finite element analysis

Scientists and specialists have moved their attention from conventional synthetic composites to green fiber composites. These fiber strands are light in weight as well as high in strength and more reasonable and economical in comparison to the regular fibers. Additionally, the green fibers are biodegradable, sustainable, and environmentally friendly. Among various other natural fibers, the kenaf fibers show higher and better properties as composite reinforcement compared to other fibres, in presence of varying loading conditions. Whereas coir fibers have been found to possess excellent strength and durability. Epoxy resin possesses magnificent binding characteristics and is treated as a good matrix for the development of composites. In previous researches, it has been seen that fiber stacking or fiber part volume, influences the mechanical strength, qualities, and properties of green fiber- composite. Therefore, this study has been focused on evaluating the fiber volume fraction and strength of kenaf coir fiber-based epoxy composite material by analytical as well as finite element analysis techniques. This paper likewise proposes an analytical model based on the rule of hybrid mixtures, and solutions of flexural and tensile tests conducted on ANSYS 15.0. Based on this research, it can be stated that kenaf-coir composite may be utilized for a varying loading modern application.

Strength of carbon fiber/epoxy in sea water

Abstract Composite materials are widely used in the marine industry. The marine environment, on the other hand, has a significant impact on the strength of composite materials. The tensile strength is adversely affected because the matrix material absorbs water. In this study, the effect of orientation, number of layers and different mediums over time on the tensile strength of the woven carbon fiber reinforced epoxy composite material was investigated experimentally from a comprehensive perspective. The findings of the experiments were subjected to variance analysis. The repeated tests and cross-results of the experimental parameters were found to be compatible with each other. Seawater reduces the tensile strength of composite materials in any case. The tensile strength increased with increasing the number of layers. However, it has been observed that the seawater medium reduces strength when the number of layers increases. At the same time, as orientation angle rises, the seawater medium’s negative effect on strength rises.

Synergistical Performance Modification of Epoxy Resin by Nanofillers and Carboxyl-Terminated Liquid Nitrile–Butadiene Rubber

Epoxy composite materials are widely used in power equipment. As the voltage level increases, the requirement of material properties, including electrical, thermal, and mechanical, has also increased. Introducing thermally conductive nanofiller to the epoxy/liquid rubber composites system is an effective approach to improve heat performance, but the effects of thermally conductive nanofillers on relaxation characteristics remain unclarified. In this paper, nano-alumina (nano-Al2O3) and nano-boron nitride (nano-BN) have been employed to modify the epoxy/carboxyl-terminated liquid nitrile–butadiene rubber (epoxy/CTBN) composites system. The thermal conductivity and glass transition temperature of different formula systems have been measured. The effect of the nanofillers on the relaxation behaviors of the resin matrix has been investigated. Results show that the different kinds of nanofillers will introduce different relaxation processes into the matrix and increase the conductivity at the same time. This study can provide a theoretical basis for the synergistic improvement of multiple properties of epoxy resin composites.

Experimental and analytical study of bio-based epoxy composite materials for strengthening reinforced concrete structures

Abstract This paper presents a new approach to strengthen reinforced concrete structures using natural fiber composites. Natural fibers are often used in civil engineering for thermal or acoustic insulation, but rarely are they employed to strengthen structures. Natural fiber composites are constituted of a matrix based on epoxy adhesive and aligned continuous fiber reinforcements. In this study, we investigate several fibers (carbon, hemp, fiberglass, and linen) in tensile and bending tests. The bending results show twice the magnification of the ultimate bending load in a strengthened specimen. The study also evaluates the stress distribution in the structure. In the case of a beam strengthened by a bonded carbon plate, the functioning of an assembly single lap and the optimal anchor length was determined by analogy. The analytical study describes the shear and peel stresses in the adhesive, composite, and concrete joints, revealing the optimum values of shear stress near the ends of the adhesive joint. The same was observed in concrete. The tests showed the influence of strengthening on the ultimate load and stiffness as well as the concentration of shear stresses at the ends of the adhesive joint.

Effect of TiC nanoparticles on accelerated weathering of coir fiber filler and basalt fabric reinforced bio/synthetic epoxy hybrid composites: Physicomechanical and thermal characteristics

AbstractIn the present research, the physical, mechanical, and thermal characteristics of bio and synthetic basalt fabric epoxy composites reinforced with coir microparticles and TiC nanofillers under before and after exposure of accelerated weathering were investigated. All the bio and synthetic epoxy hybrid composites were exposed to humidity, elevated temperature, and ultraviolet radiation. It has been examined that both bio and synthetic epoxy composites exhibited reduced mechanical characteristics after the exposure of accelerated weathering when compared with before exposure. The wettability experiment was performed from the contact angle evaluation method and found that all the fabricated samples before and after the exposure of accelerated weathering have contact angle value lower than 90° that is assigned with the hydrophilic surface characteristics of the laminate. The water absorption capacity showed that all the bio and synthetic epoxy composites reacted for water absorption up to 45 days and then endured constant in both conditions. After the exposure of accelerated weathering, epoxy hybrid composites absorbed more water than before exposure. The chemical modifications possessed on the surface were evaluated from Fourier transform infrared spectra. The intensity of hydroxyl and carbonyl functional groups of bio and synthetic epoxy hybrid composites decreased compared with the original samples, which tends to decrement in tensile, flexural, and impact characteristics of the laminate. The production of more fracture lines on the cross‐sectional surface of epoxy hybrid composites has been observed from scanning electron microscope micrographs after the exposure of accelerated weathering. The onset, end set, and glass transition temperature of bio and synthetic epoxy composites in the thermal examination were reduced after the disclosure of accelerated weathering for all fabricated specimens. The reason may be assigned to the weaker bonding between the coir microparticles and TiC nanofillers. The undesirable impact emerged from ultraviolet radiation, elevating the temperature and humidity. The test results showed that the accelerated weathering has negative impact on physicomechanical characteristics of bio/synthetic epoxy hybrid polymer composites. The overall thermal characteristics were not considerably affected with 570 h of the weathering exposure.

An investigation and comparison of tensile strength in Fiber Sandwiched Wood Composite (FSWC) materials subjected to axial loading

The demand of composite materials like Fiber Reinforce Polymer (FRP), Carbon Fiber Reinforce Polymer (CFRP) and Glass Fiber Reinforce Polymer (GFRP) are increasing rapidly in industrial use because the characteristics of these materials involving higher strength to weight ratio and least cost incorporates the researchers to make interest. Composite materials are helping the industries in combination with different materials to achieve the desired material properties. Now a days, these materials had taken a part of sheet metal in many aerospace industries. Carbon fabric or epoxy composite materials are used in various industries for manufacturing special purpose applications. To evaluate the material performance, it is necessary to understand their mechanical properties like tensile strength. The tensile strength is usually used to determine the tensile testing data for the quality assurance of materials. Fiber Sandwiched Wood Composite (FSWC) materials are prepared by sandwiching the layers of wood and fibers. The composite materials with wood lead to variation in tensile strength. In that event, some specimen was prepared using teak wood and fibers involving Carbon, Aramid, Jute, and Banana. The specimens were evaluated for tensile strength using Universal Testing Machine (UTM) as per the ASTM 3039 standards. The comparison had been made with plain teak wood having known properties. The hybrid layers of Carbon and Aramid Fibers with teak wood presented the higher value. A comparison had made of FSCM and plain Materials like teak wood and aluminium. The results shows that the Carbon Aramid hybrid composites have 2.65% more strength as compare to Teak Wood and 1.79% more than the Aluminium.

Investigation of Mechanical Properties of Silk and Epoxy Composite Materials

This research Investigates the new composite materials are fabricated of two or more materials raised. The fibers material from the sources of natural recycled materials provides certain benefits above synthetic strengthening material given that very less cost, equivalent strength, less density, and the slightest discarded difficulties. In the current experiments, silk and fiber-reinforced epoxy composite material is fabricated and the mechanical properties for the composite materials are assessed. New composite materials samples with the dissimilar fiber weight ratio were made utilizing the compression Molding processes with the pressure of 150 pa at a temperature of 80 °C. All samples were exposed to the mechanical test like a tensile test, impact loading, flexural hardness, and microscopy. The performing results are the maximum stress is 33.4MPa, elastic modulus for the new composite material is 1380 MPa, and hardness value is 20.64 Hv for the material resistance to scratch, SEM analysis of the microstructure of new composite materials with different angles of layers that are more strength use in industrial applications.

A comparative study of mechanical and machining performance of polymer hybrid and carbon fiber epoxy composite materials

Fiber-reinforced plastics are known as advanced composite materials thanks to their high strength and lightweight features. Carbon fiber reinforced polymers (CFRPs) are one of the high-performance and high-cost fiber-reinforced polymer (FRPs) materials. They are used in several high-performance engineering applications such as motorsports, marine, aviation, energy and defense industry. The cost of carbon fiber is higher compared to many other materials, more competitive and cost-effective productions will spur the demand for composite parts exponentially. Thus, hybrid laminate composite containing carbon and glass fiber materials were manufactured as an alternative for CFRP materials. Because using glass fiber prepreg instead of carbon fiber prepreg will lead the material to become cheaper. However, machining of the FRP materials is still an important issue. For this reason, the present study is focused on the mechanical and machining performance of the polymer hybrid and carbon fiber epoxy composites.

Network structure and properties of crosslinked bio-based epoxy resin composite: An in-silico multiscale strategy with dynamic curing reaction process

A multiscale simulation strategy was proposed to study the curing reaction on the network formation and corresponding mechanical properties of a bio-based epoxy resin composite. The crosslinking process of the system to form an epoxy network structure was reproduced on the mesoscopic scale by the dissipative particle dynamics simulation coupled with a curing reaction model. The density functional theory (DFT)-based method, IRC and relaxed potential energy surface scanning calculations were combined with the reverse mapping operations in order to improve the overall quality the reverse mapped structures. Finally, molecular dynamics simulations were performed on the atomistic level to analyze the mechanical properties, the volume shrinkage and the glass transition of the bio-based epoxy resin system, etc. This multiscale simulation strategy can provide as a possible investigation scheme for the subsequent improvement and design of bio-based epoxy resin composite materials.

All-optical tunable fiber filter based on a few-mode optical fiber mode interferometer coated with graphene epoxy resin composite material

A compact all-optical tunable fiber filter based on a few-mode optical fiber modal interferometer coated with graphene epoxy resin composite material is proposed and experimentally demonstrated. The interferometer is constructed with a 2-cm FMF connected to two single mode fibers. After coating the graphene epoxy resin composite material on the outside of the interferometer, it shows the all-optical wavelength tunability, and experimental results show that the wavelength shift changes quasilinearly with the pump power changing. The wavelength tunable range reaches 5.062 nm with a step of 0.016 nm/mw. It is expected to have practical application in optical communication, fiber sensing, fiber laser and optical spectrum analysis.

Development of dynamic constitutive model of epoxy resin considering temperature and strain rate effects using experimental methods

Epoxy resin composite materials are increasingly used in the aerospace field. The dynamic mechanical behavior of the resin matrix is of great significance in studying the impact response of composites. In the current study, the quasi-static and dynamic compression properties of TDE86 epoxy are studied at different temperatures, and the influence of the temperature and strain rate on the mechanical properties of epoxy are analyzed. The quasi-static and dynamic compression stress–strain curves are used to fit the parameters of the Zhu–Wang–Tang (ZWT) constitutive equation at different temperatures. A subroutine for the ZWT constitutive model is developed in ABAQUS, and numerical simulations of split Hopkinson pressure bar tests are performed. The results show that, at low strain rates, the elastic modulus, yield stress, and yield strain of the epoxy increase as the strain rate increases and decrease as the temperature increases. The dynamic stress–strain curve of the epoxy can be divided into four stages, namely the initial elastic, yield, strain softening, and unloading stages. There is no distinct relationship between the yield strain and the logarithmic strain rate under high strain rates, although the yield strain is generally smaller than that under low strain rates. The yield stress increases linearly with the logarithmic strain rate. Under the same strain rate, the yield stress decreases as the temperature increases, whereas the yield strain does not change monotonically. By comparing the stress–strain curves obtained by simulations with the test results, the developed subroutine is validated and the applicability of the ZWT constitutive model at different temperatures is verified.

Experimental Investigation of Open-Hole Compression Strength of Carbon Epoxy Composite Material and Determination of Localized Strains Using Digital Image Correlation Technique

The biggest application of the fiber-reinforced composites are in the field of military and commercial aircrafts. Carbon fibers either alone or with the Kevlar 49 fibers, are widely used as main material in many aero plane wing, fuselage and empennage components. Composites materials have wide applications in different industries because of it has very different properties from the metals and polymers. In the drilling of Carbon/Epoxy Composites the cut surface quality is very much dependent on the drilling parameters set during drilling which further effect the strength of the hole during extension/compression loading. In this research, Carbon Fiber Epoxy Composite material is drilled with the standard carbide drill bit and Open Hole Compression (OHC) tests are performed on the Universal Testing Machine. The Digital Image Correlation (DIC) technique is used to find out the strain distribution around the hole during compression loading. From the experimental method and DIC, maximum strength of carbon epoxy composite is achieved by drilling at 1600-2400 mm/min in presence of notch. It was also observed that failure of the structure is dependent on the drilling feed rate and 1600-2400 mm/min was the optimized drilling range.

Development of advanced composite materials: Defining the fabrication process for hybridization of graphene and natural silk reinforced epoxy composites

In structural applications, Epoxy resin finds extensive application for its low cost, high strength to low weight ratio, higher amenability with superior dimensional stability in elevated temperatures, and chemical inertness. Furthermore, graphene has been extensively used as reinforcement materials to enhance strength and tensile/flexural stiffness. In contrast, natural silk within the other natural fibres showed higher impact strength and ductility, good biodegradability, and excellent biocompatibility for a reinforcement filler material. Several ongoing field research on graphene and natural silk as an individual reinforcement in the epoxy composites have shown significant positive results. This paper concentrates on the research gap of hybridization of graphene and natural silk fibres (SF) as a combined reinforcement material to develop lightweight and high-performance epoxy composite material for structural applications. This paper discusses the suitable material selection and fabrication process for hybrid GO/SF epoxy composite. Graphene Oxide (GO) choice for the reinforcement on epoxy resin by (0,0.5,1,1.5,2,3 and 5) % volume fractions via wet transfer ultrasonication process and plain-woven Bombyx mori silk for 60% SF reinforcement discussed in the paper. The optimum volume fraction of GO and SF promoting significant improvements of the epoxy resin composites’ mechanical properties needs further evaluation during material characterization.

Optimisation of Water Absorption Parameters of Bagasse, Cocoa Pod Husk and Guinea Fowl Feather Reinforced Hybrid Epoxy Composites using Taguchi Method

Particulate waste of bagasse, cocoa pod husk and guinea fowl feathers may be adopted to fabricate epoxy composites due to their properties of biodegradability, lightweight and cheapness. However, most research has excluded the combination of these reinforcements while the optimisation behaviour of the reinforced composites at room temperature water absorption process is not known. To fill this knowledge gap, this paper aims to analyse issues related to optimisation of the mentioned reinforced composites considering Taguchi’s L25 orthogonal array, the smaller the better signal-to-noise criterion and remodelling of signal-to-noise ratio after the exponential smoothening structure for optimisation. The experiment considered 25% reinforcement blends to 75% epoxy resin. But the 25% reinforcement had five formulations among the component reinforcements. The experiment, using tap water, was conducted for 216 days with measurement intervals random. The response table yielded A5B5C4, indicating 158 experimental days, 12.29g of weight gained by the drained composites, and 7.32g of weight gained by composites damped in 190ml of water. The revised response table that has been influenced by the exponential smoothening method yielded A5B5C5, interpreted as 158 days of experiments, 12.29g of weight gained by the drained composites, and 7.44g of weight gained by composites dumped in 190ml of water. Using the damping factors from 0.05 to 1, different combinations as optimal parameters were obtained, assuring the investigator that the method is feasible. Thus, the optimisation assessment could provide a new method of combining the reinforcement to enhance the composite development process using waste.

Highly thermally conductive epoxy composites with anti-friction performance achieved by carbon nanofibers assisted graphene nanoplatelets assembly

Thermally conductive epoxy composites have a broad range of applications in many fields relating to microelectronic devices and encapsulating materials of high-power electrical appliance. However, it is still a challenge to effectively fabricate thermally conductive epoxy composite materials that have various excellent comprehensive properties. In this work, a simple suction filtration method is developed to construct the self-supported framework of graphene nanoplatelets (GNPs) and carbon nanofibers (CNFs), and then epoxy is impregnated into the framework to prepare the composites. The morphological characterizations show that one dimensional CNFs exhibit the “supporting” effect between the parallelly arranged GNP layers in axial direction and the “bridging” effect between adjacent GNP aggregates in radial direction, and the self-supported framework is maintained in the epoxy composites. The highest thermal conductivities are 3.74 W/m·K in radial direction and 3.28 W/m·K in axial direction, at filler contents of 13.09 and 14.49 wt%, respectively, which are 1770% and 1540% higher than that of the pure epoxy. Further results show that the composite samples have high storage modulus, enhanced thermal resistance, and improved anti-friction performance, all of them ensure that the epoxy composites can be used as the materials of the components and parts of the electrical appliance toward continuous loading, vibration, and large heat dissipation.

DETERMINATION OF MECHANICAL PROPERTIES OF COMPOSITE MATERIALS WITH DIFFERENT FILLERS POLYMER MATRIX

In this study, the preparation and characterization of carbon fiber reinforced epoxy composites are aimed at today's increasing use of composite materials. In this study, composite materials consisting of unidirectional carbon fiber-epoxy resin were prepared and the effects of fiber inclination angle on layered epoxy composite materials were investigated using various characterization techniques. Composite materials were prepared by autoclave method. At the stage of characterization of prepared composite materials Scanning electron microscopy (SEM) has been applied for tensile, compression tests and characterization of fracture surfaces to determine the mechanical properties. Keywords: Carbon fiber,epoxy resin,polymer composite,mechanical properties.

Assessment of Replacement of Metal Parts by BFRP Composites into a Highly Efficient Electrical Prototype

This work intends to evaluate the use of epoxy composite materials reinforced with basalt fibers as replacement to metallic mechanical parts of a highly efficient electrical prototype. The analysis of the behavior of the original metallic bracket was made and an optimization process was carried out in order to achieve the most suitable geometry and stacking sequence if produced in composite material. Finite element analysis using Siemens NX12 and experimental tests to the produced composite part were performed in order to access it. It was verified that the total weight of the composite part shows a 45% reduction. The composite part shows a higher deformation than the metallic one due to basalt fiber’s higher flexibility. However, the advantages added by the new component largely compensate for the disadvantages that may have been added without compromising its performance. Obtained results show that the use of basalt fiber reinforced composites as the material of mechanical parts of a highly efficient electrical prototype that is a good alternative.

Development of an Analytical and Graphic Method for Determining the Compositions of Epoxy Compounds with Increased Chemical and Biological Resistance

The task of developing durable and effective building materials for protection against aggressive environments is urgent. One of the ways to increase the durability of buildings and structures is the use of polymer composite materials during their construction. In addition, the urgent task of recycling waste from construction and chemical industries also has to be considered. Determination of rational compositions of composite materials manufactured by compression and vibrocompression methods is of considerable interest. The problems of obtaining compositions of polymer composites based on the use of a modifying additive - a plasticizer (organosilicon varnish KO-922) and asbestos-containing fillers based on waste from construction and chemical industries are addressed. An analytical and graphical method for calculating the compositions of epoxy composite materials based on production wastes has been developed. Rational formulations based on modified epoxy binder have been obtained. The nomograms make it possible to make a practical choice of one or another filler composition for given conditions.