fibres), given in Table 2.12, were produced and tested in accordance with ASTM D638-76. They reported that a non-symmetrical stacking configuration, i.e., GF on one side and OPF in the other, resulted in un-symmetrical deformation because of large differences of elastic modulus between the two fibres. A negative hybrid effect for tensile properties may be attributed to the fact that the coefficient of thermal expansion of GF is much higher than that of OPF leading to tensile residual stresses in the OPF upon curing. In addition, the hybrid ratio was presented based on weight while the composite strength is given per unit area − the density of GF (2.56 g·cm -3 ) is much higher that that of the OPF (0.7 – 1.55 g·cm -3 ) leading to a decrease in hybrid ratio if it was presented in terms of volume. Another combination of natural fibre, i.e., flax fibre, and glass fibre to produce hybrid FRP composites was studied by Arbelaiz et al. . Various hybrid ratios were employed, see Table 2.13. It was reported that there was no hybrid effect observed with the substitution of glass fibre for flax fibre in the untreated hybrid FRP composites resulting in improved properties obeying the rule of mixtures. Poor wetting of the fibre by the matrix leading to weak fibre-matrix interfacial bonding, as was obvious from the SEM micrographs, may be responsible for the absence of a hybrid effect as has been reported by Li et al. .
Fibrereinforcedpolymercomposites are widely used in many applications because of their relatively good mechanical properties. When compared with a metallic material, FRPs have several advantages such as high strength, higher stiffness, better fatigue resistance, lightweight and remarkable designability. The functionality of FRP composites increase dramatically, specifically in weight and environmental crucial structures such as aircrafts, vehicles and wind blades (Xu et al., 2017). Moreover, in automobile field, the weight of the vehicle is one of the huge factors that impede the achievement of sustainable development which is energy saving and environmental care purpose. Also, the rate of carbon dioxide emission from the vehicles has been restricted by emission-reduction standards. Hence, to achieve lighter-weight automobiles, the most predominant method is by replacing the main parts with lighter weight materials. FRP composites are an alternative material as they have high specific modulus and strength especially relatively lightweight compared to the metallic material. Therefore, the automobile industry has introduced the use of FRP composite in for a long time to manufacture vehicles which are environmental- friendly, energy saving and lightweight (Wang et al., 2017). FRP composite have many applications because of the ease of processing, price is low and better mechanical properties. In electronic packaging application, FRP composites can be a substitute for metal materials particularlly the combination of metallic fibre with polymeric matrix is an attractive material (Sakthivel, 2013).
If two fibre types are completely hybridised at filament level, then the two fibre types should be randomly distributed within polymeric matrix. When such intermingled UD hybridcomposites are subjected to longitudinal tension, the initial failure is most likely to occur in the fibre type with the lower failure strain while the nearest neighbouring fibres of the other fibre type with a larger strain to failure should still carry load and stop the failure from propagating. Such a hybrid composite therefore should have a higher strain to failure with a gradual tensile failure behaviour as compared to single fibre type composites. Some investigators attempted to use simultaneous filament winding [80, 83, 84], co-weaving [72, 73] and an air-texturing commingling process  to produce the fibrehybridcomposites hybridised at the finer level than the conventional fibrehybridcomposites that are produced by making a laminate from two prepregs of different fibre types [60-68]. There are few experimental studies in the literature which establish a relationship between the composites hybridised at different levels and the corresponding tensile behaviour [79, 81]. In addition, only few literatures were found to provide the definition and quantification of the degree of hybridisation at filament level. For instance, Summerscales  proposed that the contiguity index can be used to define the intimately-mixed hybrid composite. The contiguity index is the ratio of the number of changes of fibre type (along a transect of the micrograph) to the number of fibre-fibre space. However, this method is only able to quantify the degree of hybridisation in the one dimension.
Mechanical Engineering Department N.I.T. Rourkela Page 3 nature. There are two major classes of polymers used as matrix materials such as thermoplastic and thermosetting. Thermoplastic (e.g. nylons, acrylic, polyethylene, polystyrene etc.) are reversible and can be resized by application of heat and pressure. However, thermosetting (e.g. epoxies, phenolic, polyimides, polyesters etc.) are materials that undergo a curing process through part fabrication, after which they are fixed and cannot be transformed or resized. Epoxy resin is the most commonly used polymermatrix with reinforcing fibres for advanced composites applications. Epoxy resin possesses so many advantages such as very good mechanical properties, and electrical characteristics, chemical resistance and environmental resistance etc.
ABSTRACT:Composite materials placed a predominant role in many of the conventional materials. Fibrereinforced plastics have gained recognition as structural material. Reinforcement with natural fibre in composites has recently gained attention due to low cost, easy availability, low density, easy of separation, biodegradability, and recyclable in nature. Fibrereinforced plastics can replace steel in chemical, marine and transport industries. The present work describes the development and characterization of mechanical properties of natural fibre based polymercomposites consists of Cordia Dichotoma as reinforcement and Epoxy resin as matrix. Experiments carried out to develop the composites and different weight fraction natural fibre. The fabrication is done by Hand lay-up technique with the extracts of the natural fibre and the matrix material. The laminates was done by using different Fibre-Epoxy weight ratio.
Abstract: Last few decades have seen fibrereinforced composite materials being used predominantly in various applications. This review paper discusses about the flexural properties of banana fibre with bio-fibres, which are reinforcedhybridpolymercomposites. Banana fiber is a lingo-cellulosic fiber, which is obtained from the pseudo-stem of banana plant. Banana fibre is the best fibre with relatively good mechanical properties. Banana fiber has good specific strength properties comparable to those of conventional material, like glass fiber. This material has a lower density than glass fibers. Flexural strength of reinforced composite materials is an important factor in the manufacturing of aircraft structures and woven or braided composites. These are used for a wide variety of cross-sectional forms such as stiffeners, truss members, rotor blade, automobile body parts, spares, etc. and they reduce the fabrication cost and weight. A composite material is made by combining two or more materials of banana fibre or bio-fibres with suitable binders or resin. Reinforcement with natural fibre in composites has recently gained attention due to low cost, low density, eco-friendliness, acceptable specific properties, ease of separation, enhanced energy recovery, Co 2 neutrality, biodegradability and recyclable nature.
Abstract: Kevlar is a revolutionary material that utilized for making automobile, marine, aerospace, body and vehicle armors for past few decades. It has better mechanical properties like higher strength to mass ratio, resistance to wear, tear, penetrations and high strength, modulus, toughness and thermal stability. Whereas E-glass fiber is well known for its commercial applications and properties like dimensional stability, outstanding electrical resistance, and durability. This proposed work focuses and studies flexural and impact response of Kevlar and E-glass fiber reinforced epoxy matrixhybridcomposites made by vacuum assisted resin transfer molding (VARTM).
was added to 200 g of polyester resin (mixed ratio 200:1:1). They are mixed thoroughly to form gel. For tensile specimen, half portion of the tensile mould was filled with the polyester gel and pre-determined proportion of chopped pineapple leaf fibres were arranged continuously on the gel, then, the remaining gel was poured to fill up the mould; for flexural specimen, predetermined proportion of the chopped fibres were mixed thoroughly with the gel and poured into the mould. The casts were allowed to cure for 20 mins at room temperature before being stripped from the mould and further curing for 14 days before testing. Several samples with varying fibre content (0, 10 wt%, 20 wt%, 30 wt%, and 40 wt%) were prepared as shown in Table 1.
The development in carbon based fillers since the discovery of graphene has demonstrated significant improvement over the past decade. This has triggered interest and increasing implementation within commercial applications for both textile and engineering hybridcomposites [1-4]. Use of reduced graphene and graphene oxide (GO) in epoxy-carbon fibrereinforcedcomposites is still at infancy stages has been limited however due to the challenges in processing and dispersion of the fillers along with the high price associated therewith . Homogeneous dispersion of the filler within the polymer and the strong interfacial interactions required between the filler and the matrix are the two biggest concerns when fabricating polymer nanocomposites .
The present project work deals with the deformation studies of polymermatrixcompositesreinforced with jute fibres, utilizing continuum modelling approach. Jute Fibrereinforcedpolymermatrix composite consists of better mechanical properties such as high stiffness and high strength due to low density, corrosion resistance, electrical insulation, these advanced composites replaced the metals. The composite strength mainly depends upon volume/weight of reinforcement, Length/ diameter ratio of fibres, orientation angles and other aspects. In the current analysis using ANSYS simulation software designed a composite model with respective Jute fibre reinforcement polymermatrix, subjected it to longitudinal, transverse loading (Depends on Fibre orientation). From that investigated the mechanical properties and stress strain behaviour of composite material. Designed a Six ply composite (Jute 60 wt % + polymer 40 wt %) with and without crack, subjected it to three point bending test, from that analysed the deformed shape of the body, stress-strain distribution at each layer, and calculated flexural stress and strain, von misses yield criterion, maximum shear stress theory, simulation results are giving more accurate after comparing with literature values. And also calculated stress intensity factor (Mode I) for six ply jute fibrereinforcedpolymer composite with introducing a crack, analysed that stress intensity factor by variation of crack length and applied stress.
stress-strain response. The reasons for this non-linearity are plastic and viscoelastic behaviour of the matrix and, probably above all, micro-damage . Typically a micro crack in the matrix propagate until it is stopped by a crossing fibre. At the location of the micro-damage, the stiﬀness of the matrix is reduced to zero, while the rest of the matrix material holds the initial stiﬀness. As more and more of these micro cracks develops, the overall global stiﬀness will be degraded in a progressive manner. The development of these micro-cracks will a ﬀ ect the global transverse stiﬀnesses E 22 and E 33 , the in- and out-of-plane
on the measured strength value as well as the apparent failure mechanism. In terms of the overall sample dimensions, a decrease of the strength value can be expected with increasing sample size for a constant s/d ratio. However, the overall sample size does not seem to have a major effect on the apparent failure mode observed for the composite for the same s/d ratio. These results clearly demonstrate how easily a simple change of testing parameters can lead to significantly different conclusions on the properties and failure behaviour of the same composite material. Therefore, the need for standardised testing methods for geopolymer matrixcomposites shall be emphasised again. That is not to say that the parameters applied here are necessarily the ideal parameters and the influence of other variables such as fabrication method, fibre content and fibre architecture (e.g. unidirectional or fabrics) may have to be taken into consideration, too. However, based on the present results, a minimum s/d ratio of 32:1 is recommended for the flexural testing of geopolymer matrixcomposites in order to reduce shear stresses and achieve tensile failure. Although smaller s/d ratios have been applied in previous studies as described in chapter 2.3.1 with different outcomes, the present results clearly indicate that smaller s/d ratios tend to induce predominantly shear failure. In case of the use of high-modulus fibres such as carbon and alumina, even higher s/d ratios seem to be required to ensure the validity of the flexural test. However, the application of s/d ratios > 32:1 may be limited by practical and economic reasons. Due to the apparent issues related to the flexural testing of geopolymer matrixcomposites, other testing methods such as a direct tensile strength test may be better suited for the characterisation of these materials.
From the last few years, Jute fibers are being looked at as an alternative reinforcement material in the development of composites in a variety of engineering fields. Jute fiber has some exceptional properties such as bio-degradability, low cost, moderate mechanical properties. These properties along with its easy availability have made it suitable to use as a reinforcement material in the ongoing development of composite containing polymermatrix. Hence, Jute fibers can replace commonly used synthetic fiber along the lines of Kevlar, glass fiber etc., in composite material. Also, matrix used here is hybridpolymermatrix which is a mixture of Cashew Nut Shell Liquid and General Purpose Resin instead of pure synthetic matrix. This combination of reinforced composite can be utilized in diverse engineering applications. In this work, Jute fiber reinforcedHybrid resin (CNSL and GP) composites are fabricated by using hand lay up technique. Volume percentage of jute fiber in reinforcement (3%, 6%, 9%), specimen thickness (2mm, 3mm, 4mm) and fiber length (30mm, 100mm, 350mm) are the parameters varied in the respective mold dimensions. The experimental plan was developed according to TAGUCHI’s Design of Experiments. The testing is performed using cantilever fixture. By applying impact, the response of the system is analyzed by utilizing “DEWEsoft” software. Using the ANNOVA technique, influence of different vibration frequencies was investigated.
thickness, reduced tool wear, good thermal and mechanical characters, low price, infinite availability, and eco-friendly disposal instead of conventional synthetic fibers like glass and aramid fibers . Coir is multipurpose, renewable, low-priced, abundant and decomposable lignocellulosic fiber which is used for producing an extensive variety of engineering products (Satyanarayana et al., 1982). Coir fiber has also been tested as reinforcement in various composite materials . When compared with synthetic fibers, the natural lignocellulosic materials are used all over the world. These fibers are renewable and propose better quality. . Recently, the natural fibers have been getting significant concentration as a standby for chemically derived fiber. The benefits of the plant fibers are low thickness, low-priced, tolerable specific strength, reduced tool wear, decent thermal insulation behaviors, recycling, renewable resources without affecting the environment . At the present time, the growing consideration is being paid to coir fiber. Nowadays the coir fibers are commercially used in natural rubber latex industries for manufacturing automobile interior parts . In this literature the various uses and applications of coir fiber based polymercomposites are labeled. The products like helmets post-boxes made by coir fiber reinforcedpolymercomposites having 38MPa flexural strength up to 9 to 15 weight % of coir fiber loading . The mechanical characters of coir reinforcedpolymercomposites are increased when it is used along with some other fiber particles. Shiv Kumar, Dr.B.Kumar et al. have explored the mechanical behaviors of coir fiber and coconut shell particle reinforced epoxy composite. They have stated that ultimate strength and modulus of elasticity increase with addition of coir . Addition of red mud up to a certain limit with coir strengthened polyester composites increases the flexural strength of the composites . The composite treated woven coir- polyester exhibits superior mechanical properties . The coir fiber based composite’s flexural, tensile strength and the hardness value upgraded by increasing the fiber up to 60% of weight. . The coir is a suitable fiber for manufacturing the thermoplastic composites, especially for partial replacement of expensive and heavier glass fibers . Naturally wood is three-dimensional polymeric composite which is primarily consists of cellulose, lignin and hemicelluloses. In addition,
Coir fiber–polyester composites were tested as helmets, as roofing and post- boxes. These composites, with coir loading ranging from 9 to 15 wt%, have a flexural strength of about 38 MPa. Coir–poly ester composites with untreated and treated coir fibers, and with fiber loading of 17 wt%, were tested in tension, flexure and notched Izod impact. The results obtained with the untreated fibers show clear signs of the presence of a weak interface long pulled-out fibers without any resin adhered to the fibers—and low mechanical properties were obtained. Although showing better mechanical performance, the composites with treated fibers present, however, only a moderate increase on the values of the mechanical properties analyzed. Alkali treatment is also reported for coir fibers. Treated fiber–polyester composites, with volume fraction ranging from 10% to 30%, show better properties than composites with untreated fibers, but the flexural strength of these composites was consistently lower than that of the bare matrix. A maximum value of 42.3MPa is reported against a value of 48.5MPa for the neat polyester. Acetylation of coir fibers increases the hydrophobic behaviour, increases the resistance to fungi attack and also increases the tensile strength of coir– polyester composites. However, the fiber loading has to be fairly high, 45 wt% or even higher, to attain a significant reinforcing effect when the composite is tested in tension. Moreover, even with high coir fiber loading fractions, there is no improvement in the flexural strength. From these results, it is apparent that the usual fiber treatments reported so far did not significantly change the mechanical performance of coir–polyester composites.
, particularly surface performances of the composites supported natural fibres because of the poor surface bonding between the hydrophilic natural fibres and also the hydrophobic compound matrices. 2 varieties of fibre surface treatment strategies, particularly chemical bonding and chemical reaction were wont to improve the surface bonding properties of fibre bolstered compound composites. Surface properties were evaluated and analyzed by single fibre pull-out check and also the theoretical model. The surface shear strength (IFSS) was obtained by the applied math parameters. The results were compared with those obtained by ancient ways that. supported this study, Associate in Nursing improved technique that may a lot of accurately judge the surface properties between fibre and compound matrices was planned.  Joshi et al . compared life cycle environmental performance of natural fibrecomposites with glass fibrereinforcedcomposites and found that natural fibrecomposites are environmentally superior in the specific applications studied.  BC Ray et al . used three point flexural take a look at to qualitatively assess such effects for fifty five, sixty and sixty five weight percentages of the glass fibres strengthened epoxy composites throughout refrigerant and once thawing conditions. The specimens were tested at a spread of 0.5 mm/min to 5.00 mm/min crosshead speed to judge the sensitivity of mechanical response throughout loading at
numerous micro-cracks. On application of the load, the micro- cracks begin to propagate in the concrete matrix. The addition of randomly spaced discontinuous fibres help in restricting the propagation of the micro-cracks and macro-cracks. Fibres also improve the mechanical properties of plain concrete such as, resistance to impact, resistance to fracture and resistance to dynamic loads . In the modern era, hybridization technology has also been an area of interest to researchers. Hybridization is the process of combining fibers with different characteristics, such as, length, diameter, and aspect ratio, modulus of elasticity, material type and tensile strength, to produce a unique composite that derives benefits from each of the individual fibers . In this study, hybridfibrereinforced concrete is prepared by combining basalt and steel fibers together according to different volume fraction and aspect ratio. Different experiments were carried out to determine the flexural strength, toughness index and load deflection behaviour of hybridfibrereinforced beams. For comparison steel fibrereinforced concrete beams and basalt fibrereinforced concrete beams were also casted. All these beams were compared with control beam consisting of no fibres. Key Words: Hybridfibrereinforced concrete beam, Steel fibre, Basalt fibre.
Composite materials are produced by combining two dissimilar materials into a new material that may be better suited for a particular application than either of the original material alone. Many of our modern technologies require materials with unusual combination of properties that cannot be met by the conventional materials . This is very true for materials that are needed for the aerospace, underwater and automotive application. Many composite materials are composed of just two phases one is termed the matrix, which is continuously surrounded by the other phase, often called the dispersed phase . Fibrereinforcedcomposites are extensively used in present day technology because of its extensive benefits, Technologically the most important composites are those in which the dispersed phase is in the form of a fibre. Design goal of fibrereinforcedpolymer often include high strength and /or stiffness on a weight basis. Fibrereinforcedcomposites with exceptionally high specific strengths and moduli have been produced that utilize low density fibre and matrix materials. Composite laminates offer alternative material design solutions in terms of specific strength and stiffness allowing important weight savings. Polymercomposites also offer significant freedom to the designer by allowing, optimizing the strength and stiffness of a component or structure for a particular application. Furthermore, thermoplastic resins present increased interest due to their economic and mechanical advantages, such as easy fabrication, unlimited shelf life, intrinsic recyclability, high toughness and increased moisture resistance. Recently an increasing use of compositesreinforced with different types of fibres has occurred, owing the following advantages: they are strong enough, light in weight, abundant, non-abrasive and cheap . It is well known that the mechanical properties
The coarse aggregate is the strongest and the least porous component of concrete. It is also a chemically stable material. Presence of coarse aggregate reduces the drying shrinkage and other dimensional changes occurring on account of movement of moisture. Coarse aggregate contributes to impermeability in concrete provided that it is properly and the mix is suitably designed. Coarse aggregate in cement and there is a weak interface between cement matrix and aggregate surface in cement concrete. These two factors result in lower strength of cement concrete. But in high strength concrete, by restricting the maximum size of aggregate and also by making the transition zone stronger by usage of mineral admixtures, the cement concrete becomes more homogenous and there is a marked enhancement in the strength properties as well as durability characteristics of concrete.
Fibrereinforcedpolymer(FRP) composites are one of the most commonly used materials due to their adaptability to diverse environmental conditions and the comparative ease of combination with different materials to perform definite purposes and reveal advantageous properties. These materials exhibit exceptionally good characteristics such as low density, high specific strength, good anticorrosion properties, fatigue resistance and low manufacturing costs. The components made up of fibrereinforced polymeric composites are exposed to temperature variations (thermal shock, thermal spike, low temperature environment, high temperature environment, freeze thaw), humidity variations, UV radiation and often the combined exposure of these environments leads to more detrimental effect on the performance of the composites during fabrication, in-service time and storage. Further, the rate of loading has significant effects on the mechanical performance of FRP’s. Rate of loading can significantly change the mode of failure. The combined effect of harsh environmental conditionings and loading rates leads to very complex situations and more than one damage micro-mechanisms act simultaneously and result in composite failure. Therefore the performance of FRP composites should be well assessed under these complex situations to improve the reliability of FRP composite systems under various critical applications. The present experimental investigation deals with the mechanical behavior of FRP composites exposed at low temperature and thermal spiking conditioning with different loading rate and holding time. The glass/epoxy samples are exposed to ambient temperature, -20 °C, -40 °C and -60 °C temperatures and tested in 3-point bending test at 1, 10, 100, 300, 600, 1000 mm/min loading rates. Also, the thermal spike conditioning of glass/epoxy and carbon/epoxy samples were carried out at 50 °C, 100 °C, 150 °C, and 200 °C temperatures for a holding time of 5, 10, 15 and 20 minutes respectively and then tested for the interlaminar shear strength (ILSS) assessment in short beam shear (SBS) test at 1,100, 200, 700 and 1000 mm/min loading rates. Scanning electron microscopy (SEM) analysis was performed to identify various degradation mechanisms in fractured samples. Also, DSC measurement have been done to evaluate the glass transition temperature (T g ) is very important because it calculates the critical service temperature of the polymercomposites. From FTIR analysis it is further confirmed that these environmental conditionings affects the bonding characteristics of the polymeric composites.