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This study is dedicated to conducting a comprehensive examination, both experimentally and numerically, to characterize the mechanical properties of a composite material composed of Alfa fibres and unsaturated polyester resin. In pursuit of this objective, we diligently prepared composite specimens in accordance with the ASTM D3379-75 standardization. The Alfa fibres used were prepares using a purely natural-based extraction technique, which retains approximately 78% of the composite's performance achieved through chemical treatment. The resulting composite consists of polyester resin reinforced with varying weight fractions of fibres, ranging from 0 to 18%.The test results of the manufactured bio-composite show that specimens with an 18% weight fraction offer a tensile strength of 49.749 MPa, whereas specimens with a 10% weight fraction exhibit a strength of 44.312 MPa. Additionally, the specimens with 18% fibre reinforcement exhibit a net increase in Young's modulus by 46% compared to the fibre-free composite, with Young's modulus ranging from 1469.66 MPa to 2726 MPa. When compared with composites based on fibre glass, the introduced bio-composite with 18% Alfa fibres exhibits similar stiffness to that of glass fibres. Additionally, the outcomes from the Finite Element Model (FEM) reveal a remarkable agreement with the experimental data, underscoring the practical applicability of the proposed methodology and tools for accurately simulating tensile tests in composite structures. [ABSTRACT FROM AUTHOR]

The purpose of this research is to make a nanocomposite with combined fibers in order to achieve two integrated mechanical characters including strength and plastic deformation in an optimal way. Novalac type phenolic resin (PF), short fibers carbon (CF) and glass (GF) and silica (SiO2) nanoparticles were used for making. The results showed that with the hybrid of carbon and glass fibers (CGF) in the composite, the ultimate strength and Plastic deformation increased compared to the samples without a combination, and it was modified as an optimal sample. Also, the results showed that the composite sample with hybrid fibers with 2 wt% SiO2 nanoparticles increased the tensile strength by 25%, the bending strength by 48% and the buckling strength by 37%. From the X-ray diffraction and EDX tests, the dispersion of nanoparticles in the composite was determined, and the SEM images showed that with the presence of SiO2 nanoparticles, The amount of adhesion and penetration between resin and fibers has increased. One of the main applications of hybrid nanocomposite can be mentioned portable light structures on land, sea and air, sports goods and orthopedic equipment. [ABSTRACT FROM AUTHOR]

In this experimental study, hybrid composite properties for hydrokinetic turbine blades were determined, and its performance was examined. The reinforcements included glass fiber, treated and untreated highland bamboo fiber, reinforced polyester-based composites and their hybrid composites, as well as row bamboo (bamboo culm). The row bamboo was prepared on the bamboo culm's outer surface to get rid of any leftovers, before cutting in accordance with the specimen test standards. In order to make hybrid composite materials, polyester resin was mixed with fibers in the proportions of bamboo fiber/glass fiber (50%/50%), and fiber/matrix (30%/70%). The composite containing glass fiber has a flexural strength that is 12% and 21% higher than materials reinforced with alkali-treated and untreated highland bamboo fiber reinforced composites respectively. The alkali treatment of highland bamboo fiber improved its physical-mechanical properties, making it suitable for use different application. Alkaline treatment boosts the composite's tensile and compressive strength by 37% and 3.4% for composite reinforced with untreated bamboo fiber, and 10.2% and 23.8% for composite reinforced with glass fiber, respectively. The fiber density of highland bamboo was increased by removing less dense non-cellulosic components (hemicellulose and lignin). However, the fiber's moisture absorption is the main issue in using it in a composite that works submerged in water. This study investigated whether incorporating glass fiber in highland bamboo-glass fiber polyester hybrid composite reduces the composite material's water uptake. A reduction was found, however, the density was increased. It is challenging to employ row bamboo for the construction of hydrokinetic turbine blades as water ingress of the compositemust be avoided even in the presence of erosion caused by cavitation and impact with foreign bodies in the water. [ABSTRACT FROM AUTHOR]

In this study, cold atmospheric pressure plasma jet was adopted to glass fibers surface modification with tetraethyl orthosilicate as a precursor. To enhance the interfacial bonding forces of glass fiber reinforced polypropylene (GFRP) composites, SiOx nanoparticles were polymerized on the fiber surfaces. The effect of two factors (the distance between nozzle and fiber (D) and the treatment time (T)) on the interfacial bonding behavior of GFRP composites was studied. The modified fibers and composites properties, including surface topography, chemical composition, wettability and interfacial mechanical properties, were studied comprehensively. The optimal parameters were obtained at D = 17 mm and T = 12 s. Our results indicated that the interlaminar shear strength of GFRP composites was increased by 30.79% compared to control group. Further studies found that plasma treatment introduced larger surface roughness, surface energy and more oxygen-containing functional groups, which was responsible for the interlaminar shear strength improvement. [ABSTRACT FROM AUTHOR]

Mechanical properties considerably reduce in wood-plastic composites (WPCs) due to the use of wood particles, so the structural applications of these composites are scarce. Thus, embedding continuous fibers is considered the most reliable method for increasing mechanical properties, although there are still challenges in employing this method on a large scale. In this study, an elaborated, special modular die with the capability of adjusting 14 rovings of continuous fibers was designed, manufactured, and implemented to simultaneously embed continuous glass fibers into the extruded WPC profile. More precisely, it was aimed to investigate the arrangement of fiber rovings into the desired positions in a WPC profile of 70 wt% wood content. Also, the effect of the glass bundle tex (at three level, 1200,2400 and 4800) and the fiber position (at four levels, 0, 2, 4, and 6 mm of relative movement of the guides) on the mechanical properties of WPCs was evaluated. According to the results, the flexural strength of reinforced specimens for 1200, 2400, and 4800 texes increased by 85.8, 107, and 159.7%, respectively, compared with the non-reinforced composite. Theoretical values were calculated and compared with experimental outcomes. Based on the results, The failure mode was non-catastrophic, which means the specimens were able to carry partial loading; a desirable characteristic for the structural applications. [ABSTRACT FROM AUTHOR]

In this work, we investigate toughening mechanisms in soft polymers reinforced with stiff fibers, particularly focusing on the effect of the strength of the fiber-matrix bond on the toughness. We print polydimethylsiloxane with short milled glass fibers using direct ink writing, an extrusion-based 3D printing method. This process produces composites with aligned fibers. Fibers can be treated with acid prior to printing, which improves the strength of the fiber-matrix bond. This results in higher yield stress and toughness. The higher toughness of the composites can be attributed to intrinsic mechanisms such as matrix deformation and fiber pullout, as well as to extrinsic mechanisms like mechanical dissipation. The intrinsic toughness of the composites is analytically estimated using a micro-mechanical model and experimentally measured by stretching the composites in the direction of fiber alignment. Finally, we demonstrate partial healing of the fiber-matrix bond after initial pre-stretch. Thermal treatment of the damaged composites results in partial recovery of stiffness and toughness. [ABSTRACT FROM AUTHOR]

Glass fiber reinforced polypropylene (GF-PP) composites have proven a great potential in the designation and manufacturing of control arms, leaf springs, barriers, beams and bridge decks. Two-pass injection molding of GF-PP was investigated in this study. Polypropylene (PP) was injected with different weight fractions (w%) of chopped glass fibers (GFs) with different fiber feedstock lengths (FFSLs). The composites were then crushed and re-injected once again. Some specimens were burned out to check the actual weight fractions and fiber lengths after the injection processes. The fiber lengths dramatically decreased due to damages during two-pass injection processes and crushing. The manufactured specimens were tested in tension, and the results indicated that the tensile strength increased slightly at w = 10% of GF. Further increase of GF weight fraction leads to a drop in the tensile strength below neat PP. The results of SEM micrographs showed an increase in air voids concentrations at high GF percentages which clarifies the reason behind the drop in the tensile strength. Also, in-plane shear tests were carried out using the Iosipescu fixture where a slight increase in the in-plane shear strength was noticed by increasing fiber weight fractions. In-plane shear moduli of all specimens were measured experimentally by strain gauges and calculated theoretically. The shear modulus was enhanced by glass fiber addition and a further increase was noticed by increasing the fiber weight fractions. [ABSTRACT FROM AUTHOR]

Single lap shear specimens were manufactured using resistance welding of carbon fibre reinforced substrates by means of CNT web-based heating elements. Heating elements were manufactured by embedding the CNT web layers between layers of PEKK/glass fibre and connecting them to copper electrodes. An experimental campaign explored their electrothermal behaviour influencing the welding process. Single lap shear specimens were then welded at a pressure of 0.05 MPa and different levels of power and duration. An optimum bond was obtained with a specific power of 80–90 kW/m2 and a time of 150 s, achieving a shear strength of 30 MPa. Post-mortem analysis revealed that fracture propagated within the substrates. This work represents a further step in the integration of CNT web-based heating elements in an industrial welding process. [ABSTRACT FROM AUTHOR]

Applying specific amount of fiber pretension during the manufacturing process of the composite rebars would potentially enhance their performance and durability. In this study, five sets of lab-scale prestressed glass fiber/vinyl-ester composite rebars were fabricated. Each set was manufactured using unique amount of fiber pretension. A set of unprestressed composite rebar was prepared as well. The effect of fiber pretension on the microstructure, tensile properties and long-term durability of rebars was investigated. In addition, the performance of the prestressed composite rebars was compared to composite rebars currently available in the market. An improvement in fiber alignment and a reduction in void content were observed within the pretensioned rebars. The composite rebars fabricated with pretension of 30 MPa showed the maximum increase in tensile properties. The guaranteed tensile strength and average tensile modulus were improved by 7.5% and 2.6%, respectively, compared to the unprestressed counterpart. The prestressed rebars showed relatively less surface degradation and lower moisture absorption after conditioning in alkaline solution at 60°C for 90 days. After conditioning, the tensile properties of the prestressed composite rebars showed superiority over the unprestressed rebar. Comparing to composite rebars available in the market, the prestressed composite rebars prepared in this study showed high performance in both short-term and long-term use. [ABSTRACT FROM AUTHOR]

Hybrid carbon fiber and glass fiber reinforced thermoset composites are commonly used in structural applications throughout the energy, aerospace, automotive, and marine industries. The differing fiber types can be combined into a hybrid composite with the intent to efficiently utilize the beneficial properties of each type of reinforcement. The fiber fraction of each individual fiber type influences the mechanical properties of the overall composite. Measurement of the fiber fraction of each individual fiber type allows understanding and prediction of the mechanical properties as well as a method of quality control in manufacturing. A combination of a carbonization in nitrogen method for the measurement of fiber content in carbon fiber reinforced composites and an oxidation method to measure the glass fiber content are used for the first time. It has been demonstrated that the approach is effective at measuring the carbon fiber and glass fiber contents in hybrid glass and carbon fiber thermoset composites in both epoxy and vinyl ester resin systems. [ABSTRACT FROM AUTHOR]

Fibre architecture of glass fibre (GF) reinforced polymer composites has a major impact on the mechanical properties for structural applications. In this study, a novel continuous glass fibre non-woven GF mat based on Spirograph art pattern is laid using a customized mechanical system. Spirograph-based continuous glass fibre non-woven (SNW) mat of different patterns was prepared and GF laminate epoxy composites were fabricated with the aim of achieving quasi-isotropic mechanical properties. The samples were cut to dimensions of test specimens from various identical locations symmetrically from a circular-shaped SNW composite laminates which were subjected to flexural, impact, shear and modified compression with anti-buckling tests. One particular SNW pattern composite laminate exhibited 40.82% better impact and 49.01% better shear resistance than commercial 0°/90° woven roving mat composite. The developed SNW laminate composite had quasi-isotropic fibre orientation and better mechanical properties without any stitching and interlacing as in case of woven fibre laminate composite. [ABSTRACT FROM AUTHOR]

The demand for durable and sustainable eco-friendly materials in recent times has caused many researchers to consider the use of plant fibers in composite development. In this research, the suitability of treated pawpaw fiber as a substitute for glass fiber was considered. The pawpaw fiber was extracted from the plant stem by dew retting and treated before been incorporated into the epoxy matrix. Two distinct fiber structures in linear and network forms were identified, separated, and used for the development of the composites. The composites were produced by incorporating a fixed amount of pawpaw fiber with a varied amount of glass fiber within 3–15 wt% in epoxy-based polymer matrix after which mechanical and biodegradation tests were carried out on the developed samples. Fractured surface morphology was also observed using a scanning electron microscope. The results revealed that the fiber structures influence the properties of the material. While mechanical properties were mostly enhanced by treated linear structure pawpaw fiber, biodegradation was highly promoted by treated network structure pawpaw fiber. Tensile (except for strain), hardness, and flexural properties were enhanced by the linear-structured treated pawpaw fiber, while biodegradability, impact, and tensile strain were improved by the network-structured treated pawpaw fiber compared to the control sample. [ABSTRACT FROM AUTHOR]

In this study, a total of 105 shear specimens of fiber reinforced polymer bars with different reinforced phases, including the glass fiber, the hybrid of carbon fiber with glass fiber, and the hybrid of steel wire with glass fiber, were prepared to systematically investigate their transverse shear properties. The surface configuration of specimens, the performance characteristics and distribution pattern of reinforced phase were mainly regarded as variables. The results showed the shear strengths of glass fiber reinforced polymer bar specimens increased from 247.9 MPa to 263.5 MPa as the rib depth changed from shallow ribs to deep ribs, and their ultimate strain decreased from 0.374 to 0.328 with the increase in rib spacing from 8 mm to 16 mm. The shear strengths of carbon/glass hybrid fiber reinforced polymer (C/G HFRP) bar specimens declined from 247.4 MPa to 226.3 MPa as the distribution pattern of carbon fiber changed from centralized distribution to dispersed distribution. The shear strength of C/G HFRP bars decreased from 256.5 MPa to 247.4 MPa as the ratio of glass fiber to carbon fiber ranged from 0:1 to 1:4, and increased from 138.7 MPa to 214.8 MPa for steel wire/glass HFRP bars as the volumetric fraction of steel wire replacing glass fiber increased from 0 to 33.3%. This indicated that the surface configuration of specimen, the distribution pattern of fiber, and the performance characteristics of reinforced phase have great effects on the ultimate strain and shear strength of FRP bars, respectively. [ABSTRACT FROM AUTHOR]

Distribution of stresses in fiber/matrix interface in UD flax fiber reinforced composites is investigated under transverse loading and compared with conventional synthetic fibers. Micro-scale finite element models with representative volume elements are generated with various fiber packing types and fiber volume ratios. The study is performed for various strain values, which take into account the material nonlinearity of matrix. The results show that significantly lower stress concentrations exist in the case of flax fibers compared to glass fiber composites, explaining the absence of transverse cracks until failure in previously conducted transverse tension tests. Increase in the applied transverse strain causes a further decrease in the stress concentrations due to the nonlinear behavior of the matrix. [ABSTRACT FROM AUTHOR]

The mechanical properties of fiber-reinforced polymer composites depend on several aspects such as the characteristics of constituents, fiber volume fraction, and manufacturing techniques. Fiber prestressing is considered a very attractive manufacturing technique that can be used to produce fiber-reinforced polymer composites with high mechanical properties. This technique has the potential to eliminate or reduce some manufacturing problems like fiber waviness. In the present study, a new approach was used to prepare prestressed fiber-reinforced polymer composites. Unidirectional E-glass fiber-stitched mats were impregnated with epoxy matrix through vacuum-assisted resin transfer molding process. Once the infusion was done, a pre-calculated tensile force was applied to the fiber mats through a hydraulic tensile machine. The impregnated fiber mats were left under tension and vacuum during curing of the epoxy matrix (24 h). Five prestressed samples were prepared by using five different prestressing levels 20, 40, 60, 80, and 100 MPa. In addition, non-prestressed (control) sample was prepared for the purpose of comparison. The influence of fiber prestressing on fiber waviness, fiber volume fraction, and void content was investigated. Flexural, tensile, and compression tests were performed to observe the effect of fiber prestressing on the mechanical properties. The results have shown the success of this new approach in producing prestressed fiber-reinforced polymer composites with high mechanical properties comparing to non-prestressed composites. The microstructure analysis has shown dramatical reduction in fiber waviness for the prestressed samples over control sample. All prestressed samples have shown higher fiber volume fraction and lower void content comparing to the control sample. Also the results have shown as the prestressing level increases, fiber volume fraction increase and void content decreases. Prestressing levels of 40 and 60 MPa were found to be the best candidates, they have led to an increase in tensile strength, compressive strength, and flexural strength by 24.2%, 72.5%, 28% and 28.6%, 100.4%, 26.1%, respectively, comparing to the non-prestressed sample. Ease of implementation and promising results of this new approach would attract the attention toward it. Automotive industry is one potential nominee to apply this approach during manufacturing of fiber-reinforced polymer leaf spring. [ABSTRACT FROM AUTHOR]

One of the most important fields of research dealing with the use of carbon-, basalt-, and glass-fiber composites in the civil construction industry is their behavior under various chemical exposure conditions. Fiber-reinforced-polymer composites used as internal and external reinforcement in various structural applications can be subjected to widely differing pH situations. This study investigated the chemical durability of various carbon, basalt and glass fibers. The fibers were immersed in four types of solutions with acid, saline, alkaline, and deionized-water conditioning schemes. The fiber mass loss and surface damage along with changes due to chemical reactions were observed through weight-loss measurements and scanning electron microscopy. A criterion was developed to characterize the performance of fibers as very good, good, fair, and poor. This methodology can also be used by manufacturers as a quick quality-control tool for evaluating the chemical resistance of different fibers prior to large-volume production. The results reveal that the carbon fibers exhibited higher chemical resistance than the basalt and glass fibers based on weight loss and evidence of chemical reactions. Moreover, the determination of the fiber chemical composition before and after conditioning in acid and alkaline solutions clearly shows that the E-glass fibers, which are known to contain boron, were very sensitive to chemical corrosion. The ECR-glass fibers showed excellent chemical durability, even better than the basalt fibers. [ABSTRACT FROM AUTHOR]

This study was focused on the comparative effect of tube- and sheet-like nanocarbons on the structure–property relationships of fiber-reinforced composites. Graphene nanosheets and multi-walled carbon nanotubes (MWCNTs) were dispersed into commercial glass fiber fabric (Gf) to obtain multiscale graphene-Gf- and MWCNT-Gf-reinforcing materials, respectively, followed by a vacuum-assisted resin infusion process. The influence of MWCNTs and graphene on the mechanical and thermal performance of multiscale composites were investigated. The experimental results indicated that oxidized MWCNTs or graphene could ensure excellent dispersibility on the fiber surface, and ultimately enhance the mechanical properties and thermal stability of the resultant composites. Graphene oxide (GO), with a wrinkled and roughened texture, was shown to be superior to MWCNTs in terms of toughening the fiber/matrix interface and delaying the deformation or failure of the epoxy matrix. Under the same dosage of nanocarbons, the interlaminar shear strength of GO-Gf-reinforced composites (GO-GfCs) was raised by approximately 12%, and the relevant onset thermal-decomposition temperature was increased by > 11℃, compared with carboxyl MWCNT-Gf-reinforced composites (Mc-GfCs). Meanwhile, the GO-GfCs exhibited superior static and dynamic mechanical properties compared to those of Mc-GfCs. [ABSTRACT FROM AUTHOR]

Single high-performance fibers (Kevlar® K129, Twaron® 2040, Technora® T200, Dyneema® SK76, Zylon® AS, Vectran® HT, and S-glass) are subject to lateral cutting action by an industrial blade. Due to the inherent variability of such testing, 40–60 replicate experiments were performed for each fiber type, at each of three different loading orientations, and the data were fit with a generalized extreme value distribution to summarize likelihood of failure under each condition. The results show that when organic fibers are cut at an angle that introduces shear loads, cut resistance drops by 60–90% compared to normal-incidence cut loading. This trend is driven by the highly oriented and fibrillar nature of organic fibers, in contrast to the isotropic S-glass fibers which show comparatively little change in cut resistance with blade orientation. Overall, the Vectran fibers provide the best resistance to normal loading, while the S-glass fibers are most resistant to non-normal loading. Micrographs show that, for organic fibers, shear loads lead to more localized failure compared to normally loaded fibers. [ABSTRACT FROM AUTHOR]

Surface defects cause the measured tensile strength of alkali glass fibers to be significantly lower than their theoretical values. Coatings can be used to “heal” surface flaws and to modify surface properties. In the present work, the nanocoating on alkali-resistant glass (ARG) fiber rovings was carried out by self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS). The ARG roving was dipped into OTS nanosol, which deposited the organic–inorganic SAMs of OTS on the ARG surface. The assessment of changes in the fiber surfaces was characterized by scanning electron microscopy (SEM) and fluorescence microscopy, while the chemical changes were characterized by X-ray photoelectron spectroscopy (XPS). Furthermore, the influence of nanocoating on the tensile properties of ARG and OTS-treated ARG with and without an epoxy matrix was also studied. The SEM analysis revealed the formation of nanoscale layers on the ARG surfaces and the XPS confirmed the deposition of organic–inorganic monolayers. The tensile strength of ARG rovings with and without the epoxy matrix was improved significantly. The OTS treatment almost created a superhydrophobic nanocoating on ARG, which was confirmed by the sessile drop water contact angle, and the water absorption by the ARG/epoxy composites reduced. [ABSTRACT FROM AUTHOR]

In the present work, the effects of fiber structure and fluid absorption on the compaction behavior of jute woven fabrics and sisal mats were analyzed and compared with the response of glass fiber mats. It was found that the fiber content that can be achieved with a certain compaction pressure is lower in the case of natural fiber preforms. In addition, due to the hollow structure of these natural fibers, jute and sisal preforms suffered larger permanent deformation than glass fiber preforms after the compressive loading cycle. In addition, it was found that fluid absorption reduced the compaction pressure in natural reinforcements due to fiber softening. These phenomena were not observed in glass fiber mats. [ABSTRACT FROM PUBLISHER]

An experimental investigation into the adhesion of regenerated cellulose fiber lyocell, natural cellulose fiber ramie, and E-glass fiber to the polypropylene (PP) and epoxy matrices, by means of the microbond technique, was conducted. Force–displacement plots indicate a brittle failure of the interface, followed by high frictional forces in the PP matrix and low frictional forces in the epoxy matrix. The interfacial shear strength (IFSS) of lyocell–epoxy system was significantly higher than that measured in the lyocell–PP system. Chemical modification of lyocell fiber with maleic anhydride resulted in a two-fold increase in IFSS with PP. Ramie exhibits better adhesion characteristics, due mainly to the rough surface, than lyocell. [ABSTRACT FROM AUTHOR]

The use of natural fibers in polymer composites has given renewed interest to the development of green composites today. However, the moisture absorption of natural fibers gives serious concern, especially for their potential outdoor applications. This article reports the study results on the water absorption of pultruded jute/glass fiber-reinforced unsaturated polyester hybrid composites, which was subjected to various water conditions and their effects on its mechanical properties. Water absorption tests were performed by immersing composite specimens into three different water conditions, namely: distilled water, sea water, and acidic water, which were at room temperature, for a period of 3 weeks. The characteristic parameter of diffusion coefficient (D) and maximum moisture content (Mm) were determined from the obtained water absorption curves. The water absorption behavior of the glass/jute fiber-reinforced unsaturated polyester hybrid composite was found to follow a non-Fickian behavior. The effects of the various aqueous environments on the flexural and compression characteristics were investigated in this study. The flexural and compression properties were found to decrease with an increasing percentage of water uptakes. [ABSTRACT FROM AUTHOR]

This study investigates the influence of process conditions on the tensile properties of polyoxymethylene (POM) composites that contain three amounts of glass fiber-reinforcement (0 wt%, 15wt% and 25 wt%). Four processing parameters -- orientation of fiber, thickness of fiber layer, amount of fiber, and injection molding parameter were considered. The morphology of the fiber layer is observed by scanning electron microscopy (SEM), to elucidate the correlation between the orientation of the fibers and the mechanism of fracture of the bucking surface. The experimental results show that the maximum ultimate stress is obtained at a filling time of 1.5 s, a melt temperature of 215°C, a mold temperature of 75°C, and a packing pressure 75 MPa. SEM revealed that the composite contained two distinct layers. The fibers in the frozen layer were parallel to the melt flow, while the fiber was perpendicular to the melt flow in the core layer. The thickness of the frozen layer increased with the amount of fiber, increasing tensile strength. Additionally, fiber pullout and across-matrix cracking are the main fracture mechanisms of the frozen layer, whereas failure of the fiber-matrix interface is the major fracture mechanism in the core layer. [ABSTRACT FROM AUTHOR]

A continuous glass fiber (GF) roving reinforced polypropylene (PP) tape is prepared with a pin-assisted-melt impregnation set-up. This study originally applied the Taguchi method to statistically assess the effect of selected impregnation parameters on the impregnation process, and to optimize the parameters to realize a high quality impregnated tape. The quality of the impregnated tape is characterized by the degree of impregnation, ratio of the impregnated fiber number to the total fiber number. According to the Taguchi method, impregnation experiments are designed and the experimental results are analyzed. An optimal parameter combination is determined, which led to a degree of impregnation more than 94%. Analysis of variance (ANOVA) was performed on the measured data and S/N (signal to noise) ratios. The results indicated that palling speed, melt temperature, and the number of impregnation pins are the significant factors in a declining sequence affecting the impregnation process. [ABSTRACT FROM AUTHOR]

The present study develops a fatigue damage parameter to assess the fatigue damage of unidirectional glass fiber reinforced plastic (GRP) composites. The proposed parameter is based on the physics and the mechanism of fatigue cracking within three damage regions of matrix (1), fiber-matrix interface (II), and fiber (III) in these materials as the number of cycles progresses. In region I, damage was initiated in the form of microcracks within the matrix. For region II, damage progress took place along the matrix-fiber interface leading to fiber fracture in region III. The proposed fatigue damage model successfully correlated fatigue lives of unidirectional GRP composites at various off-axis angles θ and stress ratios R as compared with other earlier developed fatigue parameters. [ABSTRACT FROM AUTHOR]

The present study describes the processing and mechanical characterization of two different fibers (glass and carbon) and two different fabric architectures (woven roving and stitch bonded) made into composites with Dow Chemical's Derakane 510A-40, a brominated vinyl ester (VE) resin. Both E-glass and T700 carbon fibers are coated with VE compatible sizing. The composite panels are fabricated by the vacuum assisted resin transfer molding (VARTM), the specimens are machined, and the mechanical tests are conducted as per the accepted test standards. Tension, compression, in-plane shear, and interlaminar shear properties are measured and their associated failure modes are compared with each other. The specific properties of the composites are compared with that of the marine steel. The carbon composites have superior properties, higher specific strength, and specific modulus than the marine steel. The glass composites have higher specific strength but lower specific modulus than marine steel. The glass composites are well suited for constructing ship hulls which are only strength critical. The topside (upper) structures of the ship are stiffness critical. The carbon composites are applicable to both the topside and the hull structures of the ship to reduce the total weight. The straightness of the fiber and the FOE sizing are the possible reasons for the superior performance of the carbon composites. The predicted elastic constants based on the simple micromechanical equations of the composites agree very well with the experimental data. [ABSTRACT FROM AUTHOR]

Push pull-processing (PPP) is a live in-mold manipulation method of co-injection molding used for enhancing the orientation of the polymer molecules and reinforcing fillers. This technique implements an alternating shear field induced by a coordinated action of two injection units to create multiple oriented layers across the thickness of molding during the packing phase. In this investigation, the PPP is employed to enhance the weldline strength of short-glass-fiber reinforced polycarbonate (SFRPC) with respect to the fiber orientation in the weldline areas. The effects of glass-fiber concentration and processing parameters including the number of push-pull strokes and the holding pressure differences between both of the injection units have been studied. In addition the degradation of the fiber length caused by the oscillation is also investigated. [ABSTRACT FROM AUTHOR]

Mechanical fatigue response of fiber-reinforced polymeric (FRP) composites is essential to better understand the durability of composite materials systems and to develop design specifications. Currently, the fatigue response of multi-directional glass composite materials is not well-understood and much needs to be done to understand their behavior under fatigue loading. In this study, three glass fabric FRP composite material coupons and systems are tested at constant low-amplitude fatigue loading. Experimental results show that for a given FRP material and load configuration, the energy loss per cycle due to fatigue damage is linear from about 10-90% of the fatigue life of the FRP composite material. The energy loss per cycle is determined to be a characteristic value of the constituent materials, and is found to vary with the induced fatigue strain levels by a power law. Based on the experimental results, a fatigue life prediction model is proposed, with internal strain energy as damage metric, to predict the useful life of FRP composites. The experimental and predicted fatigue lives at various strain levels are compared (S-N curves) and the model is found to be conservative. [ABSTRACT FROM AUTHOR]

The static and dynamic mechanical properties of banana and glass woven fabric-reinforced polyester composites have been determined with special reference to the effect of fiber volume fraction, layering pattern, and the weaving architecture. Even though articles related to natural fiber composites are abundant in the literature, work on natural fiber textile composites is found to be rare. Composites with high tensile strength can be obtained using banana and glass in the fabric form, using two layers of the fabric. The impact strength of the composites increases with the number of layers and the fiber volume fraction. By incorporating the fabric, the G′ curve shows an improved rubbery plateau indicating that the incorporation of the fabric induces reinforcing effects in the polyester matrix. The storage modulus has been found to be the highest for composites with four layers of the fabric. In all the composite samples, the relaxation peak of polyester is visible as peak in G″ at about 98°C. In the case of composites with four layers of the fabric, two peaks and one shoulder are seen. Increase in the number of layers made a second relaxation peak visible. The damping peaks have been found to be lowered by the incorporation of more number of layers. [ABSTRACT FROM AUTHOR]

The mechanical properties of composites based on different natural fibers and glass fibers using unsaturated polyester and modified acrylic as matrix are evaluated. In spite of the several works done in natural fiber composites, there are very few results on acrylic as matrix. Fabrication of the composites is done by means of vacuum infusion. Flexural, tension, and impact test are conducted on the composites. Ignition, thermal degradation, and water absorption are determined. Jute composite with unsaturated polyester resin as matrix showed the best results on flexural and tensile strengths and the lowest in impact energy, because of the strong interphase developed. Flax composites show higher impact energy than the other natural fiber composites, due to the existence of the effective energy dissipation mechanisms, like pull-out and axial splitting of the fibers. Scanning electron micrograph confirmed this fact. None of the samples resisted the five-second exposition to the flame on the ignition test. All of them were completely consumed, and flax composites burned the longest. [ABSTRACT FROM AUTHOR]

Epoxy systems reinforced with E-glass fibers, exposed to 100 h in three separate media were subjected to compressive mode of deformation. The difference in weight, i.e., before and after exposure to 100 h, following immersion in media was noted. Compared to the data obtained at room temperature in plain water (i.e., PR), the absorption levels in plain water containing a small proportion of dilute HCl at room temperature (i.e., PAR) were lower while samples in plain water at elevated (50°C) temperature (i.e., PH) show higher absorption. The compression strength and fractographic features, noted on the compression failed samples, are reported in this work. The experiment reveals that the media exposed samples generally exhibit lower strengths compared to the dry (i.e., unexposed) samples. Among the media exposed samples, the PAR set shows a small rise in strength while the PR and PH sets display a lowering of values. These changes have been attributed to various factors like medium ingress into samples inducing an alteration in the response of the interface regions, presence of either lengthy or fragmented fibers and resin smear on the fibers. In PAR case, the lower diffusion helps first in lowering the extent of its recording a decrement in strength vis-a-vis the dry case and this trend may be countered by the size of the Cl- being different and in the end a small rise in strength is recorded. The fractographic features reveal interface separation, either scattered debris or a cleaner surface of fibers or adherence of resin on fibers region as well as appearance or otherwise of long or short fibers depending on whether the tests were done on unexposed samples or on the ones subjected to immersion in a specific aqueous medium. [ABSTRACT FROM AUTHOR]

The mechanical performance of injection-molded short glass-fiber-reinforced thermoplastic components is anisotropic and is highly dependent on the fiber-orientation and distribution. Similarly, the bulk and short and long-term mechanical performance at the weld is influenced by these fibers and the specific welding technology used as related to melt-pool formation. The purpose of this analysis is to show: 1. the short-fiber-orientation (analytical and simulation data) and distribution at the prewelded bead, ribs, and wall areas; 2. advantages of SigmaSoft injection-molding simulation software, which utilizes full three-dimensional fiber representation of any molded part; 3. the mechanical performance of welds with optimized geometry (US Patent 6,447,866). Findings on the mechanical performance of butt-joints with different designs and localized geometry will help designers and technicians with plastic part design optimization. In a previous ANTEC paper (Part I) (Kagan, V.A. and Roth, C. (2002). The Effects of Weld Geometry and Glass-Fiber Orientation on the Mechanical Performance of Joints -- Part I: Kinetics of Glass-fiber-orientation and Performance at Bulk and Weld Areas, Design Issues, In: ANTEC Proceedings), we related these findings to the kinetics of welds and part design issues for straight and T-type butt-joints. [ABSTRACT FROM AUTHOR]