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1.
Woven Kenaf/Kevlar Hybrid Yarn is the combination of natural and synthetic fibers in the form of thread or yarn. The yarn is weaved to form a fabric type of fiber reinforced material. Then, the fabric is fabricated with epoxy as the resin to form a hybrid composite. For composite fabrication, woven fabric Kenaf/Kevlar hybrid yarn composite was prepared with vacuum bagging hand lay-up method. Woven fabric Kenaf/Kevlar hybrid yarn composite was fabricated with total fiber content of 40 % and 60 % of Epoxy as the matrix. The fiber ratios of Kenaf/Kevlar hybrid yarn were varied in weight fraction of 30/70, 50/50 and 70/30 respectively. The composites of woven fabric Kenaf/Epoxy and woven fabric Kevlar/Epoxy were also fabricated for comparison. The mechanical properties of five (5) samples composites were tested accordingly. Result has shown that of value of strength and modulus woven fabric Kenaf/Kevlar Hybrid Yarn composite was increased when the Kevlar fiber content increased. Therefore, among the hybrid composite samples result showed the woven fabric Kenaf/Kevlar Hybrid Yarn composites with the composition of 30/70 ratio has exhibited the highest energy absorption with 148.8 J which 28 % lower than Kevlar 100 % sample. The finding indicated there is a potential combination of natural fiber with synthetic fiber that can be fabricated as the composite material for the application of high performance product.  相似文献   

2.
Intra-layer and inter-layer hybrid composite laminates were made with epoxy resin and compositions were varied in six different proportions. In-plane compressive mechanical properties were studied using finite element analysis and experiments, and the results found were in good agreement. Properties of intra-layer and inter-layer hybrids were compared with plain carbon/epoxy and plain glass/epoxy composites, and a comparison among themselves was also made. It was found that intra-layer hybrids to some extent exhibit better compressive properties compared to inter-layer hybrids. Percentage enhancement in compressive failure strain was noticed. Negative hybrid effects on compressive strength was noticed for both intra-layer and inter-layer hybrid configurations. It was found that proportion of carbon fiber content plays a key role in determining the compressive properties. According to macro-scale observation all composite laminates failed catastrophically under compressive loading. SEM observation depicted that under compressive loading carbon fibers break first followed by glass fiber.  相似文献   

3.
The present paper is concerned with the effect of cork and rice husk ash micro particles fillers on the mechanical properties (flexural resistance, fracture toughness, impact absorbed energy, elastic and viscous moduli) of polyester based composite. Composite sheets were hand molded using weight filler fractions of 1, 2.5, and 5 %. Flexural strength of filled materials was much lower than the polyester matrix, with more pronounced effect for cork powder, decreasing significantly with filler content increases. Fracture toughness decreases also on the filled composites. Using cork powder fracture toughness decreases significantly when filler content increases, while for rice husk ash filler a slight increase was observed. Both fillers improve absorbed impact energy, peaking at about 2.5 % of filler content. Best improvements were obtained using rice husk ash powder, reaching about 30 %. Both fillers increase glass transition temperature and the maximum use temperature and also the elastic modulus compared with polyester. It can be concluded from this study that the used agro-waste materials are attractive reinforcements from the standpoint of their mechanical properties.  相似文献   

4.
The aim of the presented research was to study the influence of surface layer material on improvement of impact, dielectric, EMI shielding and sound absorption properties of sandwich composites. The sandwich composite structure consisted of Kevlar or Carbon woven fabric at the surface layer, recycled high loft nonwoven in the center and a mixture of carbon particles/epoxy matrix as a binder to hold the surface layer and core together. The carbon particles were incorporated in epoxy in order to improve failure mechanism and enhance dielectric properties or electromagnetic shielding of sandwich composites. The biggest improvements on impact properties of sandwich composites were obtained when Kevlar fabric was used as surface layer. However, surface layer of carbon fabric was found to provide better dielectric properties and improve EMI shielding of sandwich composites against Kevlar fabric surface layer.  相似文献   

5.
In this study, we report the fabrication and evaluation of a hybrid multi-scale basalt fiber/epoxy composite laminate reinforced with layers of electrospun carbon nanotube/polyurethane (CNT/PU) nanofibers. Electrospun polyurethane mats containing 1, 3 and 5 wt% carbon nanotubes (CNTs) were interleaved between layers of basalt fibers laminated with epoxy through vacuum-assisted resin transfer molding (VARTM) process. The strength and stiffness of composites for each configuration were tested by tensile and flexural tests, and SEM analysis was conducted to observe the morphology of the composites. The results showed increase in tensile strength (4–13 %) and tensile modulus (6–20 %), and also increase in flexural strength (6.5–17.3 %) and stiffness of the hybrid composites with the increase of CNT content in PU nanofibers. The use of surfactant to disperse CNTs in the electrospun PU reinforcement resulted to the highest increase in both tensile and flexural properties, which is attributed to the homogeneous dispersion of CNTs in the PU nanofibers and the high surface area of the nanofibers themselves. Here, the use of multi-scale reinforcement fillers with good and homogeneous dispersion for epoxy-based laminates showed increased mechanical performance of the hybrid composite laminates.  相似文献   

6.
The aim of this work is the experimental evaluation of the residual strength of composite laminates under compression after low velocity impact. Different kinds of delaminations, partial, embedded and through-the-width, were studied. Carbon-fibre reinforced epoxy composite was used and the experimental tests were performed on [0]16, [0, 90, 0, 90]2S and [0i, 90i]s with i=2, 3, 4, 5, using a drop-weight-testing machine. The impacted plates were inspected by the ultrasonic C-Scan to evaluate the size and the shape of the delamination. Results show that the presence of delamination decreases the compressive strength. The stacking sequence and laminate thickness were verified to have a remarkable influence on the value of the residual compressive strength, and play an important role on the observed buckling failure modes.  相似文献   

7.
Kevlar fibers were treated in three kinds of coupling agents’ solutions by Co60 γ-ray co-irradiation. After the treatment, the interlaminar shear strength (ILSS) values of Kevlar fibers/epoxy composites were all improved. Surface elements of the fibers were determined by energy dispersive X-ray microanalysis (EDX). X-ray photoelectron spectroscopy (XPS) indicated that the oxygen/carbon ratio of the treated fibers was increased and Fourier transform infrared (FT-IR) spectrum confirmed the increase in the polar groups at the fiber surface. The tensile strength of the fibers was evaluated by statistical analysis using the Weibull distribution. The wettability of the fiber surface was also enhanced by the treatment. The possible mechanisms of γ-ray co-irradiation treatment are proposed by the radical reactions. The results indicated that γ-ray co-irradiation technique modified the physicochemical properties of Kevlar fibers and improved the interfacial adhesion of its composites.  相似文献   

8.
Recently, carbon fiber composites have been widely used as structural reinforcement materials of buildings, replacing reinforcing bars or concrete. And the increase in use of super fibers such as aramid and high strength PE, which is aimed at improving the reinforcement properties, has resulted in a demand for a resin system with excellent mechanical and thermal properties. In this research, a fiber-reinforced composite has been produced by using the super fibers such as carbon fiber or aramid fiber, reinforcement resin and the silica hybrid compound containing epoxy group. This study was carried out to confirm the effect of the silica hybrid on mechanical properties, heat resistance and adhesion strength of a fiber-reinforced epoxy composite, which was produced by blending silica or introducing silica hybrid through covalent bonds. And the silica hybrid containing epoxy group, which may be introduced to the structure of fiber-reinforced epoxy composite through covalent bonds caused by reaction with a hardener, has been used, so that the heat resistance and adhesion strength could be improved.  相似文献   

9.
Glass woven fabric interlayered nonwovens composed of Nylon 6 staple fibers, recycled Kevlar fibers, and low-Tm polyester fibers are prepared into the glass-interlayer plank. Afterwards, their tensile strength, bursting strength, quasistatic and dynamic puncture resistances are evaluated by changing low-Tm polyester and Kevlar fibers mass fractions. The results show that when comprising 30 wt% of low-Tm polyester fibers and 20 wt% of Kevlar fibers, the composite plank yields the maximum tensile strength, bursting strength, quasi-static and dynamic puncture resistances. The double planks arranged in cross direction have higher quasi-static and dynamic puncture resistances than those oriented in parallel direction. According to stereoscope observations, the quasi-static and dynamic puncture resistances of glass-interlayer plank have different fracture mechanism for resisting against spike penetration. In addition, the bursting strength is proportional to quasistatic puncture resistance.  相似文献   

10.
The objective of this study is to develop an advanced stab proof material composed of shear thickening fluid (STF) and Kevlar fabric. In this study, silica/ethylene glycol suspension was prepared for the use as the STF, and it was analyzed by a rheometer, TEM and dynamic light scattering spectrophotometer. From the results, it was observed that the STF significantly showed the reversible liquid-solid transition at a certain shear rate. Also, we treated Kevlar plain fabric with the STF by 1 dip-1nip finishing method and investigated the mechanical and stab resistant properties. Through the investigation of the fumed silica/Kevlar composite fabric, we found that the STF impregnation significantly improved the stab resistance of Kevlar fabric against spike threats and so enhance the protection performance of Kevlar fabric as a stab proof material.  相似文献   

11.
In this study, a new approach consisting of chemical treatment steps followed by electrospinning process was applied to produce cellulose nanofibers from wheat straws. Wheat straws were initially pretreated by NaOH solution to open the complex structure of raw materials and remove non-cellulosic materials. Then, acid and alkali hydrolysis was separately performed to eliminate hemicellulose and soluble lignin. Also, bleaching processes were implemented to remove the insoluble lignin. Cellulose nanofibers were produced by electrospinning of various concentrations of cellulose in different solvents including sodium hydroxide/urea/thiourea, pure trifluoroacetic acid (TFA), and TFA/methylene chloride. Images obtained by Scanning Electron Microscope (SEM) showed long and uniform nanofibers produced from electrospinning of cellulose/TFA/methylene chloride solution. An epoxy based laminated composite was prepared by a lamina of cellulose microfiber and electrospun nanofiber mat using hand lay-up composite manufacturing method. The fracture surface of the epoxy nanocomposite was analyzed by SEM images. In addition, the mechanical properties of laminated epoxy composites were compared with pure epoxy by conducting tensile and impact tests. Tensile test results showed that the ultimate tensile strength, elongation, and modulus of laminated epoxy nanocomposites were significantly increased. Moreover, it was found that by adding a nanofiber lamina in the epoxy composite, the impact resistance was significantly improved as a result of crack growth prevention.  相似文献   

12.
In this paper, the bending properties of woven carbon/glass and carbon/aramid fabric-reinforced polymer laminates is studied using a combination of experimental analysis and fracture observation. Six types of each hybrid composite were manufactured by lamination of the carbon/aramid fabric and carbon/glass fabric using VARTM. Bending behaviors were fundamentally evaluated for the six types of monolithic composites laminated by the same fabric. The objective was to achieve a good bending strength by effective combination of composite structures using limited amounts of a raw material. It was shown that the bending property was different, depending on the type of fiber, lamination structure, and the number of layers.  相似文献   

13.
In the first stage, polyethylene terephthalate (PET) fibers and Kevlar fibers are combined at a blending ratio of 80/ 20 wt% in order to form PET/Kevlar nonwoven fabrics. Two pieces of PET/Kevlar nonwoven fabrics that enclose a carbonfiber (CF) interlayer are then needle punched in order to form PET/Kevlar/CF (PKC) composites. In the second stage, the sandwiches compose PKC composites as the top and the bottom layers, as well as an interlayer that is composed of a spacer fabric and polyurethane (PU) foam. PU foams have different densities of 200, 210, 220, 230, and 240 kg/m3. These resulting nonwoven fabric/spacer fabric/PU foam sandwiches are then tested using a drop-weight impact test, a compression test, a bursting strength test, a sound absorption test, and a horizontal burning test. The test results indicate that the optimal properties of sandwiches occur with their corresponding PU foam density as follows: an optimal residual stress (240 kg/m3), an optimal compressive strength (240 kg/m3), and an optimal bursting strength (220 kg/m3). In addition, the sandwiches reach the HF1 level according to the horizontal burning test results. They also have an average electromagnetic interference shielding effectiveness of -48 dB, as well as a sound absorption coefficient of 0.5 in a frequency between 1500-2500 Hz, which indicates a satisfactory sound absorption effect. The nonwoven fabric/spacer fabric/PU foam sandwiches proposed in this study are mechanically strong, sound absorbent, and fire retardant, and can be used in construction material and electromagnetic shielding composites.  相似文献   

14.
To improve interfacial adhesion between carbon fiber and epoxy resin, the epoxy matrix is modified with N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane (YDH602) and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (YDH792), respectively. And the effect of matrix modification on the mechanical performance of carbon/epoxy composites is investigated in terms of tensile, flexural and interlaminar properties. The flexural properties indicate that the optimum concentration of silane coupling agents YDH602 and YDH792 for the matrix modification is approximately 0.5 wt% of the epoxy resin system, and the mechanical properties of the YDH792-modified epoxy composites is better than that of the YDH602-modified epoxy composites at the same concentration. Compared to unmodified epoxy composite, the incorporation of 0.5 wt% YDH792 results in an increase of 4, 44 and 42 % in tensile, flexural and interlaminar shear strength (ILSS) values of the carbon/epoxy composite, respectively, while the corresponding enhancement of tensile and flexural modulus is 3 and 15 %. These improvements in mechanical properties can be considered to be an indication of better fiber/matrix interfacial adhesion as confirmed by SEM micrographs of the fracture surface after interlaminar shear testing. The viscosity of the modified epoxy resin system can be reduced by incorporation of silane coupling agent YDH792, which is beneficial for fiber impregnation or wetting during liquid composite molding process.  相似文献   

15.
Glass fiber, GF, which was first hydroxylated and silanized, was incorporated into epoxy resin modified with amino-terminated hyperbranched polymer (ATHBP) to obtain high performance composite. The effects of GFs content on the mechanical properties of composites were investigated, discussing the results from flexural, tensile, and impact tests. The composites revealed noticeable improvement in flexural strength, tensile strength as well as impact strength but slow decrease in elongation at break, compared to the epoxy/ATHBP thermoset. FESEM morphology results indicated the good compatibility between epoxy matrix and GF in the appearance of ATHBP and showed that the toughening mechanism was mainly attributed to the stress transfer mechanism.  相似文献   

16.
A study on the tensile and flexural properties of jute-glass-carbon fibers reinforced epoxy hybrid composites in inter-ply configuration is presented in this paper. Test specimens were manufactured by hand lay-up process and their tensile and flexural properties were obtained. The effects of the hybridization, different fibers content and plies stacking sequence on the mechanical properties of the tested hybrid composites were investigated. Two-parameter Weibull distribution function was used to statistically analyze the experimental results. The failure probability graphs for the tested composites were drawn. These graphs are important tools for helping the designers to understand and choose the suitable material for the required design and development. Results showed that the hybridization process can potentially improve the tensile and flexural properties of jute reinforced composite. The flexural strength decreases when partial laminas from a carbon/epoxy laminate are replaced by glass/epoxy or jute/epoxy laminas. Also, it is realized that incorporating high strength fibers to the outer layers of the composite leads to higher flexural resistance, whilst the order of the layers doesn’t affect the tensile properties.  相似文献   

17.
This paper presents an investigation of the influences causing failure in the materials comprising polymer matrix composites. Structures with differences in stacking sequences and design configuration are analysed. The objective of this study is to investigate and evaluate the reasons for the failure of composite lamination structures in terms of stress, strength, strain, and Young modulus within a morphology observation of composite materials. The materials selected for the study were a chopped strand mat (CSM) and a woven roving (WR) fabric. These materials are used as reinforcement and are produced by the hand lay-up technique using epoxy and polyester matrix resin. The experiment was performed using specimens made of notched (open-hole; OH) tension and un-notched (UN) shapes. The characteristics of different shapes, materials, and lamination structures are studied in this research. The results showed the failure phenomenon in the structure of the polymer matrix composite is dependent on the characteristics of the material used and the design configuration of both structures.  相似文献   

18.
This study proposes a combination for reciprocal reinforcement between warp knitting spacer fabrics and PU foams. PET/Kevlar nonwoven fabrics are made with an 80:20 ratio and an incorporation of various needle-punching speed of 100, 150, 200, 250, and 300 needles/min. Ascribing to having an optimal bursting strength, sound absorption coefficient, and limited oxygen index (LOI), the PET/Kevlar nonwoven fabric that is made by 200 needles/min are selected to be combined with a glass-fiber fabric by applying needle punch in order to form a surface layer. Next, warp knitting spacer fabrics and the nonwoven fabrics are laminated, followed by being combined with polyurethane (PU) foam that are featured with different densities of 200, 210, 220, 230, and 240 kg/m3 in order to form spacer fabric/PU foam composites with multiple functions. The composites are then tested with a drop-weight test, a compression test, a bursting strength test, a sound absorption test, and a horizontal burning test. The test results indicate that all spacer fabric/PU foam composites reach a horizontal burning level of HF1, and their sound absorption coefficients at 2500-4000 Hz also suggest a satisfactory sound absorption. In particular, the optimal residual stress and compressive strength are present when the composites contain 210 kg/m3 PU foam. Similarly, the optimal bursting strength of the composites occurs when they are composed of 230 kg/m3 PU foam. The spacer fabric/PU foam composites are proven to have high strengths, sound absorption, and fire retardant, and thus have promising potentials for use as construction materials and light weight composite planks.  相似文献   

19.
Single walled carbon nanotubes (SWNTs) are considered as a highly potential reinforcement material for the epoxy composites. Dispersion of SWNTs in epoxy and poor interfacial strain transfer are two major challenges. Surface functionalization is one efficient way to change the dispersion and interfacial properties of SWNTs. In this study, five different modification methods of SWNTs were used, and the functional groups on the SWNTs were tested by X-ray photoelectron spectroscopy and Raman spectroscopy. The SWNTs/epoxy composite were prepared using dimethylformamide (DMF) as the solvent. SWNTs at two concentration levels of 0.05 wt% and 0.5 wt% and with five different surface modifications were filled in to epoxy resins. The dispersion of the nanotubes in epoxy resin was evaluated by light optical microscope (LOM), with high content of SWNTs more aggregates appear. The interfacial strain transfer was tested by Raman shift of the 2D band when applying a strain on the epoxy composite sample. With equal strain levels in the composite more strain was transferred from epoxy matrix to SWNTs with 0.05 wt% of SWNTs than the 0.5 wt% of SWNTs filled epoxy resin. Mechanical properties were influenced by the strain transfer efficiency and the curing degree of the samples.  相似文献   

20.
Exfoliated graphite nanoplatelets (EGN) were successfully coated with a liquid rubber amine-terminated poly(butadiene-co-acrylonitrile) (ATBN) at various concentrations. The rubber-coated EGN was incorporated into epoxy resin at different contents. The result revealed that the impact toughness of EGN/epoxy composite was increased by about 18 % with increasing the ATBN coating concentration. The impact strength, the flexural and dynamic mechanical properties, and the thermo-dimensional stability of EGN/epoxy composites were simultaneously enhanced by the incorporation of 1 wt% EGN coated with 10 wt% ATBN rubber into epoxy, which turns out a very small amount of 0.1 wt% ATBN compared to the epoxy resin.  相似文献   

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