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The materials 2,2-bis [4-(4-maleimidophenoxy phenyl)] propane (BMIX) and bisphenol-A based cyanate ester (BCY) were synthesized. The monomers BMIX and BCY were physically blended (BMCY) in 1:1 mol ratio. The materials BMIX, BCY and BMCY were thermally polymerized and the structural characterisation of the materials was done using Fourier transform infrared spectrophotometer (FTIR). The curing characteristics of BMIX, BCY and its blend (BMCY) were investigated using differential scanning calorimeter (DSC). The blend BMCY shows considerable differences in the thermal curing behaviour as evidenced by the DSC studies. Blending BCY with BMIX drastically reduces the melting temperature, curing onset temperature and the amount of heat liberated during thermal curing. The thermal stabilities of the crosslinked network polymers (PBMIX, PBCY and PBMCY) were investigated using thermogravimetric analyser (TGA). Detailed TGA studies indicated that the PBMCY shows better thermal stability than the PBMIX and PBCY. The DSC and TG curves indirectly hint about the possible reaction between BMIX and BCY during thermal curing. Woven glass fibre reinforced laminates were prepared using BMIX, BCY and BMCY by solution impregnation followed by drying and compression moulding. The glass laminate having BMCY as the matrix resin showed much better mechanical property (tensile strength) compared to the laminate made using BMIX as the matrix resin. [ABSTRACT FROM AUTHOR]

Nowadays, usages of laminated composites have been extended to various applications such as automotive, aircraft and aerospace due to its high strength-weight ratio. Generally, aluminium alloys are developed using various casting techniques to achieve the required properties. However, laminated aluminium composites have received great attention among the scientist due to the weight reduction, the damping capacity they offer etc. In this present investigation, carbon and glass fibre laminated aluminium (Al2024-T3) composites are prepared by hand lay-up technique. Different form of aluminium structure namely sheet and mesh are used to fabricate − the composites. Different composites are prepared namely carbon fibre aluminium sheet laminate (CFASL), carbon fibre aluminium mesh laminate (CFAML), glass fibre aluminium sheet laminate (GFASL) and carbon fibre aluminium mesh laminate (GFAML). Effects of reinforcement of fibre on tensile, bending and flexural strength are studied. The microstructure of the composites is captured using scanning electron microscope (SEM) to study the failure mechanism. It was revealed that the CFASL and CFAML offered superior mechanical properties compared to the GFASL and GFAML. Higher tensile, bending and flexural strengths were obtained with carbon fibre and aluminium sheet laminated composites. They withstand the higher stresses due to less debonding and matrix cracking. Debonding and fibre breaking mechanisms observed in the glass fibre laminated composites caused reduced strength. CFASL composites showed superior mechanical properties followed by CFAML, GFASL and GFAML. [ABSTRACT FROM AUTHOR]

This research deals with the effect of stacking sequence over, the mechanical behavior of laminates that includes tensile, flexural, fractography, area of impact damage, and residual tensile strength. The angle‐ply laminate specimens were analyzed theoretically and correlated with experimental results. The highest interlaminar shear strength 32.89 MPa was exhibited by (60/30/60/30)S with better transverse stiffness of 444 N/mm. Among the developed laminates, (60/30/60/30)S showed the highest rate of residual strength degradation of 0.271. It has been found that an increase in interlaminar shear strength decreases the impact damage resistance of the composites. The angle‐ply laminate composites exhibited superior residual tensile and impact resistant properties when compared with uniply laminate composites. [ABSTRACT FROM AUTHOR]

Every day, the need for composite materials grows. The physical and chemical characteristics of the constituent materials inside the hybrid composite impact the final structure. The rate at which these individual properties are sustained varies, but it has an impact on the final properties of hybrid composites. Sporting goods and lightweight orthopaedic components are made from hybrid composites. Glass fibre epoxy and sawdust are utilised to construct hybrid composites in this study, using glass fibre to epoxy resin ratios of (60:40, 60:39, 60:38, 60:37).The current research involves the creation of hybrid composites and their study for flexural and tensile strength under various load conditions. Applying resin and hardener, as well as inserting reinforcement, is repeated in the hand-layup manufacturing process to improve characteristics and create a laminate form. They improve fatigue and fracture resistance while providing dimensional stability and weight savings. [ABSTRACT FROM AUTHOR]

Glass fibre reinforced polymer composites are the most common materials employed for the manufacturing of small crafts, with the scantlings governed by ISO 12215-5:2019. However, no validation data is available to ascertain the relevance of the default ultimate strengths provided by the standard. This paper experimentally characterises the ultimate flexural, tensile and compressive strength of hand laminated and vacuumed bagged quasi-isotropic glass-epoxy laminate. The results show that ISO 12215-5:2019 default ultimate strengths for the quasi-isotropic composite laminate tested are (i) conservative for the ultimate flexural strength, (ii) appropriate for the ultimate tensile strength, and (iii) optimistic for the ultimate compressive strength, especially for vacuum bagged samples, with the main cause identified as the value of the ultimate compressive breaking strain for chopped strand mat. These findings provide validation data for ISO12215-5:2019 and it is anticipated the results may contribute to future improvements in small craft regulations. [ABSTRACT FROM AUTHOR]

In this paper, the influence of E-glass fiber volume fraction and laying angle on the damping and strength of composite laminates was comprehensively analyzed. By increasing the fiber laying angle and reducing the glass fiber volume fraction, the damping capacity of the composite laminate was increased, but the tensile strength of the laminate was reduced; By reducing the fiber laying angle and increasing the glass fiber volume fraction, the tensile strength of the composite laminate was increased, but the damping characteristics of the laminate was reduced. In addition, in the damping experiment of composite laminates, in order to avoid the influence of external damping sources, the vacuum non-contact damping test method was adopted in this paper, and the influence of air damping on the damping experiment results of composite laminates was comparatively analyzed. The results of comparative experiments showed that air damping had a very obvious influence on the damping of composite laminates, especially when the damping of composite laminates was small, the influence of air damping would be greater. [ABSTRACT FROM AUTHOR]

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This work focuses on the study of variation in behaviour of Glass Fiber Reinforced Epoxy Composite laminate in the presence of healing agent filled microcapsules. Healing capacity was tested for the newly developed laminate with capsules. Two types of microcapsules were made and included in the resin system. One type consists of healing agent and other type consists of curing agent. These capsules were blended in the ratio of 10:3 in the resin system and laminate was fabricated by hand lay-up technique. Initially, the effect of microcapsules on the tensile properties of glass fiber epoxy composites was studied. No conspicuous variation was discerned in the tensile nature. The healing ability of the laminate was checked by producing minor indentation damage on the surface of the laminate with a 0.5 mm ball indenter. It was noticed that 80% of the indentation was recovered within the time span of 48 hours and 93% of healing efficiency was attained. FE analysis was performed with MIDAS NFX software to confirm the results. Both experimental and FE analysis results were observed to be identical. [ABSTRACT FROM AUTHOR]

The tensile behavior of fiber metal laminates consisting of layers of aluminum 2024-T3 alloy and glass fiber reinforced composites under high strain rate loading is investigated. Fiber metal laminates having four different layups, but all having the same total metal layer thickness, were fabricated using a combined hand lay-up cum vacuum bagging method. The fiber metal laminate specimens were loaded in high strain rate tension using a split Hopkinson tensile bar. The rate-dependent behavior of the glass fiber composite was also obtained as baseline data. The strain on the gage area of the specimen was measured directly using high-speed digital image correlation. Another high-speed camera was used to capture the sequence of damage by viewing the specimen edgewise. The results indicated that the strength of the fiber metal laminates increased at high strain rates primarily due to the rate-dependent behavior of the composite used. The response was also influenced by the distribution of the metallic layers in the fiber metal laminates. The failure in the case where the individual composite layers were separated by metallic layers was more progressive in nature. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effect of homogenous and hybrid external patches based on plain weave woven glass and Kevlar fabric on low velocity impact and quasi-static tensile after impact response of adhesively bonded external patch repairs in damaged glass/epoxy composite laminates. In all hybrid patches, the proportion of Kevlar and glass fibers were equal (i.e. 50% of Kevlar and 50% of glass by volume fraction), while lay-up configuration was different. This further enables to study the associated effect of hybridization and lay-up configuration on impact response of the repaired laminates. The intent of using hybrid external patches is to combine the excellent high displacement-to-failure property of Kevlar fiber as a ductile reinforcement with the superior mechanical property of glass fiber as a brittle reinforcement. The effect of glass/Kevlar content on impact response and tensile after impact response was investigated for various incident impact energy levels, such as 2, 4, 6, and 8 J. Results showed that hybridization and lay-up configurations of the external patches played a significant role on low velocity impact and quasi-static tensile after impact response of the repaired glass/epoxy specimens. Specimens repaired using intra-ply hybrid patches showed better impact properties and damage tolerance capability than that of the virgin and other repaired specimens. In specific, the use of intra-ply hybrid patches reduced the impact energy absorption by 10.17% in comparison to the virgin specimens at impact energy of 8 J. [ABSTRACT FROM AUTHOR]

The objective of this study was to produce the hybrid carbon/fiberglass composite laminates, to characterize their mechanical properties under room temperature and to evaluate the effect of nanoclay addition into epoxy matrix on the mechanical properties of the hybrid composites. During fabrication of fiber reinforced polymer composites, the organo modified nanoclay (0%, 0.5%, 0.75%, and 1.25% of nanoclay reinforcement by weight) was mixed with epoxy system using an ultrasonic mixer. The produced matrix was then applied onto fibers by using hand layup method. Mechanical tests were performed to investigate the effect of nanoclay content on tensile and flexural properties of the fabricated hybrid carbon/fiberglass composites. The tensile and three point bending tests were performed according to ASTM D3039 and ASTM D7264, respectively, to measure the highest tensile strength, modulus of elasticity and bending modulus of the hybrid laminates. Experimental results show that the tensile and flexural performance of hybrid carbon/fiberglass composites was changed with the nanoclay content. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental investigation into the durability behaviour of textile-reinforced concrete (TRC) subjected to both tensile and bending loads to compare its macroscale characterization. Composites are produced as a laminate material using 2 and 6 layers of glass fibre mat as reinforcements. The instantaneous and long-term (durability) properties of composite TRC are identified by tensile and flexural testing with specimens made from the same fresh mortar. The long-term tests are conducted in two ageing environments: natural ageing, which was conducted under the laboratory atmosphere (20 °C and 50% RH), and accelerated ageing, which consisted of immersion of the specimens in hot water at 50 °C. The durability performance of TRC is evaluated by the reduced macroscale performance and damage mechanisms. The effects of the reinforcement ratio, testing conditions, and thermal conditions on the long-term response of TRC are investigated, and the microstructure of both matrix and fibre is observed and discussed after the tests with observations via scanning electron microscopy (SEM). The addition of layers of glass fibre (reinforcement ratio) increased the strength capacity and the first macro-crack strength of TRC in both tensile and bending tests. The ultimate strength value of the TRC composites obtained from the tensile test is lower than that from the bending test over the same tested days as a result of the different redistribution mechanisms; however, the difference between tensile and flexural stress remains approximately equal with similar deviations. An increase in the tensile and flexural strength capacity over the ageing time is observed before 90 days of ageing. However, after 90 days, the test results showed a loss of ductility of the accelerated aged specimens. [ABSTRACT FROM AUTHOR]

In this study, four plied jute, carbon, E-glass fabric-reinforced and their hybridized composites are manufactured. Nine composite laminates with different stacking sequences are manufactured by vacuum infusion technique. In order to understand the structure of the composites, fiber weight and fiber volume ratios in the laminate system are initially figured out. Furthermore, void fractions of samples are calculated by using theoretical and experimental densities of the composite samples to examine the impact of amount of fiber content on the void fraction. The effect of hybridizing jute fabric-reinforced polyester composite with E-glass fabric and carbon fabric and also the effect of stacking sequence of fabric layers on the mechanical properties (tensile strength, impact strength) of composite laminates are investigated. According to the outcomes of this investigation, it is realized that incorporating high impact resistant fibers to the outer layers of the composites leads to higher impact resistance, and placing high tensile strength fibers at the inner layers results in higher tensile strength at the hybrid composite laminates. [ABSTRACT FROM AUTHOR]

An experimental study was focused on investigation of the failure properties of plain woven glass/epoxy composites under off-axis and biaxial tension loading conditions. Four fibre orientations (0°, 15°, 30° and 45° with respect to the load direction) were considered for off-axis tests and two biaxial load ratios for biaxial tests to study failure characteristics and mechanism. Four classical polynomial failure criteria - Tsai-Hill, Hoffman, Tsai-Wu and Yeh-Stratton - were analysed comparatively to predict off-axis and biaxial failure strength of the composites. For failure prediction of the plain woven composites under multiaxial tension loads, the Tsai-Wu criterion was modified by introducing an interaction coefficient F 12 obtained from 45° off-axis or biaxial tension tests and the Yeh-Stratton criterion was modified with the interaction coefficient B 12 = 0 or obtained from the biaxial tension test. The former criterion was found to have higher accuracy. Finally, according to macroscopic and microscopic studies, the failed specimens showed mostly distinct failure with a specific fracture orientation, mainly exhibiting fibre or fabric tensile fracture mode and a combination of matrix cracking and delamination, both in off-axis and cruciform samples. [ABSTRACT FROM AUTHOR]

The objective of this study is to characterize the damage in glass fiber reinforced composite laminated reinforced with nanosilica particles subjected to tensile, flexural, and transverse loadings. Tensile, three-point bending, quasi-static indentation test, and ballistic impact tests were used in order to obtain the perforation response, flexural and tensile behavior of the composites and nanocomposites. Experimental test series was carried out to determine the tensile and flexural strength and stiffness, impact energy absorption, and failure mechanisms of composites in the presence of nanoparticle. Hand lay-up method has been used to manufacture nanocomposites constituted of 12 layers of 2D woven glass fibers with 40% fiber volume fraction. The composites were reinforced by adding organically modified nano-silica in a 0%, 0.5%, 1%, and 3% ratio in weight with respect to the matrix. Results revealed that in 0.5 wt.% nanoparticles, energy absorption and tensile strength are maximum, but flexural strength has the highest value in 3 wt.%. Furthermore, the highest energy absorption, elastic energy, and energy absorption at maximum force in quasi-static penetration occur in 0.5% nanosilica content. In the case of ballistic tests, effect of nanosilica is more tangible than in quasi-static indentation. Nanocomposite at 0.5% nanosilica recorded higher ballistic limit and energy absorption in comparison with other composites and nanocomposites. SEM images showed that fracture surfaces in 0.5 wt.% nanocomposites are rough and engender more crack tips in comparison with other specimens, which contributes to higher energy absorption in static and dynamic tests. [ABSTRACT FROM AUTHOR]

Bending and tensile performance of hand lay-up produced glass fabric/epoxy laminated composites were investigated after matrix reinforcement with pre-dried graphene nanoplatelets (GNPs) up to 30% wt content. Two different types of E-glass fabric, i.e. twill 2 × 2 and uni-directional, were used for the tested composite samples. The response of the produced nano-composites is being explained by the settling mode of the GNPs onto the surface of the fiberglass filaments, as it was observed by a scanning electron microscope. Due to the different settling modes while increasing GNPs content, different fracture modes of the filaments were detected. [ABSTRACT FROM AUTHOR]

In this research, glass fibre reinforced composite laminate samples were manufactured with filament winding technique using four different vinyl ester resin systems to study ageing. The manufactured laminate samples were conditioned in an environmental cabinet (70 °C, 95 RH%), water immersion (95 °C), and in sulphuric acid solution immersion under pressure (5% H 2 SO 4 , 95 °C, 15 bar). After 6 and 12 months of conditioning, the samples were tensile tested and the results were compared with the initial values. Regardless of the matrix type, conditioning in the environmental cabinet resulted in the lowest weight gain and least decrease in tensile properties: the decrease in the tensile strength values was 10–25% after 12 months’ conditioning depending on the vinyl ester used. The water immersion was more detrimental to the samples than the 5% H 2 SO 4 immersion causing the highest weight gain and the greatest decrease in tensile strength (up to 65%). However, when comparing the tensile performance, it was noted that the highest weight gain did not inevitably correlate with the strongest ageing effect. In water immersion, the ultimate strength deteriorates faster than the proof stress level leading to a decreasing damage tolerance of the vinyl-ester composite laminates. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to study the mechanical behavior in fatigue tensile mode of different cross-ply laminates constituted of unidirectional carbon fibers, hybrid fibers and glass fibers in an epoxy matrix; and to identify and characterize the local damage in the laminated materials with the use of the acoustic emission (AE) technique.Design/methodology/approach The tests in the fatigue mode permitted the determination of the effect of the stacking sequences, thickness of 90° oriented layers and reinforcement types on the fatigue mechanical behavior of the laminated materials. The damage investigation in those materials is reached with the analysis of AE signals collected from fatigue tensile tests.Findings The results show the effects of reinforcement type, stacking sequences and thicknesses ratio of 90° and 0° layers on the mechanical behavior. A cluster analysis of AE data is achieved and the resulting clusters are correlated with the damage mechanism of specimens under loading tests.Originality/value The analysis of AE signals collected from tensile tests of the fatigue failure load allows the damage investigation in different types of cross-ply laminates which are differentiated by the reinforcement type, stacking sequences and thicknesses ratio of 90° and 0° layers. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the effect of hybridizing Kevlar and glass fibers on the tensile and Charpy impact properties of their composites. Produced hybrid samples were designed as unbalanced and asymmetric structures in terms of different mixing ratios between woven Kevlar and S-glass fibers, and their tensile properties were determined using ASTM standards. A series of Charpy impact tests were performed to evaluate the amount of impact strength and absorbed energy by impacting each side of the hybrid composite samples. When the hybrid samples were impacted on the surface of the Kevlar side, they exhibited higher impact resistance compared with glass side impact. The resulting degree of hybridization effects showed that addition of Kevlar layers instead of glass layers contributed a significant increase in impact strength and absorbed energy of the overall composite laminate. [ABSTRACT FROM AUTHOR]

In this study, the tensile and flexural behavior of metal–nanocomposite​ laminates under tensile and flexural loading were experimentally investigated as well as their failure mechanisms. Flat laminates were made by hand lay-up of Aluminum face layers and a nanocomposite mid-layer including MWCNTs-reinforced polymeric matrix and glass fibers. Aluminum 1050 annealed sheets and 2D woven glass fibers with a surface density of 200 g/m2 were used. The nanocomposite layers contained 0, 0.5, 1, and 1.5 weight percentages of MWCNTs relative to the total weight of the polyvinyl chloride matrix. The effects of adding different amounts of MWCNTs on the mechanical properties of the laminates were evaluated. The results showed that both the tensile and flexural strengths of the reinforced specimens increase by adding up to 1 wt% of MWCNTs. The further addition of MWCNTs leads to aggregation and agglomeration of MWCNTs so that the tensile and flexural strengths are reduced to even less than those of the primary specimens. Moreover, a microscopic study of the fracture surfaces showed that the predominant failure mechanism in the tensile specimens is cohesive failure due to the fiber–matrix and Aluminum–composite debonding. The predominant failure mechanisms in bending tests are the destruction of the nanocomposite layer and metal–nanocomposite delamination. • Tensile and flexural behavior of metal–nanocomposite laminates were investigated. • Al1050-O was used as face layer and MWCNT-reinforced PVC matrix and glass fibers as core layer. • Tensile and flexural strengths increased by addition of 1 wt% of MWCNTs. • Predominant failure mechanism in the tensile test was fiber–matrix debonding and Al-composite. • Predominant failure mechanism in bending tests was metal–nanocomposite delamination. [ABSTRACT FROM AUTHOR]

This study proposes a mixed-mode fracture criterion for glass fiber reinforced composite laminates based on numerical and experimental biaxial loading. An optimal cruciform geometry is introduced first based on finite element (FE) simulation. Characterization testing is performed successively on uniaxial and cruciform specimens to determine equivalent loaded area, notch sensitivity behavior and critical fracture toughness properties of cross-ply GFRP laminates. In experimental biaxial testing, two types of crack orientations (0°, 45°) are studied with varying crack lengths. The experimental failure points show that cross-ply GFRP laminates attain higher load bearing capability under biaxial tensile–tensile loading compared to uniaxial testing. Appropriate non-dimensional geometry factor relevant to cruciform shape is determined based on experimental data points and FE simulation. Eventually, a mixed-mode fracture criterion is proposed for cross-ply composite laminate based on the findings from biaxial experimental loading. [ABSTRACT FROM AUTHOR]

The prediction of the tensile strength of multi-bolted joints uses characteristics that are obtained from the open-hole tension (OHT), bolt-filled hole tension (FHT), pin-loaded tension (PLT) and single-bolt single-lap joint (BJ) tests. However, the relative relevance of each of these tests to multi-bolted joints is not clear. This investigation aims to fill the gap by performing these tests on carbon/epoxy and glass/epoxy laminates with quasi-isotropic and cross-ply configurations and on an Al-6065 aluminum alloy. It is found that the highest strength achieved by a multi-bolted joint corresponds to the OHT strength. The number of bolts required to achieve this upper bound depends on the material characteristics. The Al-6065 alloy achieves the OHT strength with two bolts, whereas the composites require up to four bolts. Narrower specimens require fewer bolts to achieve the OHT strength. The stiffness and strength of the BJ and PLT are comparable for Al-6065. However, for the composites, BJ has a lower stiffness but a higher strength than PLT. The pin contact force triggers delamination initiation and propagation in the PLT, whereas the tightened bolt in the BJ suppresses the delamination. In addition, the rotation of the bolt explains the lower stiffness of the BJ. [ABSTRACT FROM AUTHOR]

This paper investigates the through-thickness tensile behavior of woven glass fiber reinforced polymer (GFRP) composite laminates at cryogenic temperatures. Tensile tests were carried out with cross specimens at room temperature and liquid nitrogen temperature (77 K), and the through-thickness elastic and strength properties of the woven GFRP laminates were evaluated. The failure characteristics of the woven GFRP laminates were also studied by optical and laser scanning microscopy observations. A three-dimensional finite element analysis was performed to calculate the stress distributions in the cross specimens, and the failure conditions of the specimens were examined. It is found that the cross specimen is suitable for the cryogenic through-thickness tensile characterization of laminated composite materials. In addition, the through-thickness Young's modulus of the woven GFRP composite laminates is dominated by the properties of the matrix polymer in the given temperature, while the tensile strength is characterized by both, the fiber to matrix interface energy and the cohesion energy of the matrix polymer. [ABSTRACT FROM AUTHOR]

This paper addresses the nonlinear stress-strain response in glass fibre non-crimp fabric reinforced vinylester composite laminates subjected to in-plane tensile loading. The nonlinearity is shown to be a combination of brittle and plastic failure. It is argued that the shift from plastic to brittle behaviour in the vinylester is caused by the state of stress triaxiality caused by the interaction between fibre and vinylester. A model combining damage and plasticity is calibrated and evaluated using data from extensive experimental testing. The onset of damage is predicted using the Puck failure criterion, and the evolution of damage is calibrated from the observed softening in plies loaded in transverse tension. Shear loading beyond linear elastic response is observed to result in irreversible strains. A yield criterion is implemented for shear deformation. A strain hardening law is fitted to the stress-strain response observed in shear loaded plies. Experimental results from a selection of laminates with different layups are used to verify the numerical models. A complete set of model parameters for predicting elastic behaviour, strength and post failure softening is presented for glass fibre non-crimped fabric reinforced vinylester. The predicted behaviour from using these model parameters are shown to be in good agreement with experimental results. [ABSTRACT FROM AUTHOR]

In this work, the influence of micro/nanoalumina (Al2O3) on the mechanical properties of epoxy/jute fiber (J)/glass fiber (G) laminates was studied. All the composites are fabricated by the hand layup technique. The flexural strength and tensile strength of the epoxy/hybrid laminates were increased profoundly in the presence of micro/nano-Al2O3. The epoxy + GJGJ + 4 wt% nano-Al2O3 composites showed better flexural results when compared with the epoxy/glass fiber composites, whereas epoxy + GJJG + 4 wt% nano-Al2O3 composites show better tensile results. It was also found that nanofiller-added composites show better results when compared with and without microfiller-added composites. The morphology of the surfaces was examined by scanning electron microscopy to have better insight into the flexural and tensile mechanism. [ABSTRACT FROM PUBLISHER]

The glass-fiber-reinforced aluminum laminates were obtained by anodizing aluminum alloy under anodizing voltage of 10, 20, and 30 V in the 200 g/L H3PO4electrolyte. Scanning electron microscopy (SEM), short beam, and tensile tests were employed to determine the surface morphology, interlaminar shear strength (ILSS) and tensile strength of laminates, respectively. The results also show that the epoxy penetrates into the pores of the anodic films, and this is the mechanism of adhesion. The ILSS and tensile strength of the anodized specimens (under 20 V) respectively increased by approximately 50 and 15% comparing with those of the non-anodized specimens. This increase of mechanical properties results from the porous surface of aluminum providing greater mechanical interlocking to epoxy. The ILSS and tensile strengths of the anodized specimens increased with the increase of anodizing voltage from 10 to 20 V; however, it decreased when the voltage further increased to 30 V. It is considered that the microstructure evolution of the porous films has a significant effect on the mechanical properties of the laminates. [ABSTRACT FROM PUBLISHER]

Abstract: Nanoparticle reinforcement of the matrix in laminates has been recently explored to improve mechanical properties, particularly the interlaminar strength. This study analyses the fatigue behaviour of nanoclay and multiwalled carbon nanotubes enhanced glass/epoxy laminates. The matrix used was the epoxy resin Biresin® CR120, combined with the hardener CH120-3. Multiwalled carbon nanotubes (MWCNTs) 98% and organo-montmorillonite Nanomer I30 E nanoclay were used. Composites plates were manufactured by moulding in vacuum. Fatigue tests were performed under constant amplitude, both under tension–tension and three points bending loadings. The fatigue results show that composites with small amounts of nanoparticles addition into the matrix have bending fatigue strength similar to the obtained for the neat glass fibre reinforced epoxy matrix composite. On the contrary, for higher percentages of nanoclays or carbon nanotubes addition the fatigue strength tend to decrease caused by poor nanoparticles dispersion and formation of agglomerates. Tensile fatigue strength is only marginally affected by the addition of small amount of particles. The fatigue ratio in tension–tension loading increases with the addition of nanoclays and multi-walled carbon nanotubes, suggesting that both nanoparticles can act as barriers to fatigue crack propagation. [Copyright &y& Elsevier]

Abstract: Drilling induced in fibre reinforced polymer resulted in high rate of parts rejection and thus affects the in-service performance of the composite product. Therefore, the tensile testing of hybrid composite with drilled holes is necessary to render them satisfaction in industrial application. The objective of the present research is to develop long kenaf composites and long kenaf/woven glass reinforced polyester resin composites. The tensile properties of those composites with drilled holes were investigated. The measurements were taken from the residual tensile strength of impacted specimens and the open hole specimens. From there, the damage area of the composites could be predicted. It is found that the long kenaf composite was more notch sensitive than long kenaf/woven glass hybrid composite. The hybrid composite was stronger than long kenaf composite. However, the damage progression mechanisms in the two materials were similar. Failure for both kenaf composite and long kenaf/woven glass hybrid composite started around the hole. The polymer matrix failed initially followed by fibre–matrix debonding. [Copyright &y& Elsevier]

• The residual tensile strength after impact of glass/polyester laminates is investigated. • Damage areas are detected by using visually inspection. • Residual tensile strength of samples impacted by hemispherical tip is estimated using two fracture mechanics models. • The residual tensile strength for the damaged laminates is predicted using new model. • The proposed model predicts the residual strength with much higher accuracy and much less error than the existing models. In this study, the residual strength of the post impacted glass/polyester laminates is investigated by the conduction of tension after impact (TAI) loading. The specimens are placed on a rigid plane and subjected to low velocity impact using a drop weight impact tower. Damage areas are detected by using visually inspection and measuring the size of the permanent impression on the surface of specimens. The relationships between the impact energy and degradation of mechanical properties have been stablished for the composites. The residual tensile strength for the impact-damaged laminates is predicted using new model. The correlation between the experimental and new model results is found to be good. Two models proposed by Caprino and Koo have been using to compare the results. [ABSTRACT FROM AUTHOR]

Abstract: A newly developed confining system for rectangular columns required a wrapping, which sustained a large amount of parasitic bending due to the curved shape of the laminates at the cross-section corners. To investigate the effect of parasitic bending on unidirectional carbon (CFRP) and glass fiber (GFRP) reinforced polymer laminates, 4 ply coupons were laminated with a semi-elastic hybrid resin and cured in a curved shape. During the tensile tests, the curved coupons stretched and failed after further loading. Due to the parasitic bending, occurring during stretching, the tensile resistance was reduced by 48% for the CFRP and by only 18% for the GFRP coupons. Tests with high-strength, high-modulus epoxy resin laminated GFRP coupons were drawn upon and compared with the semi-elastic hybrid resin laminated GFRP coupons. There is a beneficial effect on the tensile resistance with the use of semi-elastic hybrid resin. [Copyright &y& Elsevier]

Standard printed circuit board base material is composed of E-glass woven fabric and FR-4 epoxy resin. The article highlights recent development of a low dielectric fibre, INNOFIBER LD glass fibre, to meet the growing demand for new base materials in applications requiring high speed signal integrity, high thermal stability, and low weight. Electrical, mechanical, and other material characterisations of INNOFIBER LD glass fibres relevant to printed circuit board fabrication processes, both glass and laminate forms, were performed. Reliability testing of circuit boards incorporating INNOFIBER LD glass fibre shows high conductive anodic filament resistance. [ABSTRACT FROM AUTHOR]

Abstract: The effect of thermal-shock cycles on the mechanical properties of fiber–metal laminates (FMLs) has been evaluated. FML plates were composed by two AA2024 Al sheets (1.6mm thick) and one composite ply formed by two layers of unidirectional glass fiber epoxy prepreg and two layers of epoxy adhesive tape of glass fiber reinforced epoxy adhesive. The set was manufactured by hand layup and typical vacuum bag technique. The curing cycle was in autoclave at 125±5°C for 90min and an autoclave pressure of 400kPa. FML coupons taken from the manufactured plate were submitted to temperature variations between −50 and +80°C, with a fast transition between these temperatures. Tensile and interlaminar shear strength were evaluated on samples after 1000 and 2000 cycles, and compared to nonexposed samples. 2000 Cycles corresponds to typical C Check interval for commercial aircraft maintenance programs. It was observed that the thermal-shock cycles did not result in significant microstructural changes on the FML, particularly on the composite ply. Similarly, no appreciable effect on the mechanical properties of FML was observed by the thermal-shock cycles. [Copyright &y& Elsevier]

The use of thick fiber reinforced polymer (FRP) laminates in composite armor and naval structures requires thorough characterization of the through-thickness properties of said laminates, both quasi-statically and at high strain rates. Specimens cut from an E-Glass/vinyl ester FRP were tested in compression both quasi-statically and dynamically using a split Hopkinson pressure bar (SHPB). The SHPB tests utilized a conical striker for pulse shaping, to reduce the variation in strain rate during the test. The quasi-static through-thickness compressive strength was 417 MPa, while the SHPB tests produced a strength of 462 MPa at an average strain rate of 5.1 × 102 s−1. A single HPB configured for spalling tests was used to determine the dynamic through-thickness tensile strength (interlaminar tension). The interlaminar tensile strength was 125 MPa at an average strain rate of 1.8 × 103 s−1. [ABSTRACT FROM AUTHOR]

The objective of this research was to gain a better understanding of tensile properties of epoxy resin composites reinforced with glass fiber. The effect of fiber orientation & thickness of laminates has been investigated & experimentation was performed to determine property data for material specifications, the laminates were obtained by hand layup process. The laminates were cut to obtain ASTM standards. The test ready specimens were subjected to tensile loads on UTM machine. This research indicates that tensile strength is mainly dependent on the fiber orientation & thickness of laminated polymer composites. [ABSTRACT FROM AUTHOR]

The principal objective of this research work was to investigate the results of impregnating epoxy matrix-glass fibre composite laminates with nanosilica as secondary reinforcement. 0.5, 0.75, 1 and 3 wt% nanosilica was used and thereafter properties of composites were assessed through tensile, three point bending, quasi static indentation tests and dynamic mechanical analysis. Scanning electron microscope examinations were done on fracture surfaces and failure modes were analyzed. The internal failures of the composite due to quasi-static indentation were evaluated through C-Scan. Among samples of different weight fractions, 0.75 wt% nanosilica reinforced composite laminates exhibited substantial increase of 42% in tensile strength and 39.46% in flexural strength. The reduction in glass transition temperature (Tg), increase in storage modulus (E′), loss modulus (E″) and damping factor (tan δ) were also observed. Quasi-static indentation assessments revealed that energy absorption property was enhanced significantly by 53.97%. Hence nanosilica up to 0.75 wt% can be used as a potential candidate for secondary reinforcement in epoxy composite laminates. [ABSTRACT FROM AUTHOR]