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Journal articles on the topic 'Epoxy-based laminates'

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Author: Grafiati
Published: 10 December 2022
Last updated: 29 January 2023

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1

Zulkifli, M. A. A., Z. I. A. Halim, N. A. S. Norbani, and J. Mahmud. "Failure Analysis of Boron/Epoxy Composite Laminates with Square Cutouts in Various Size under Uniaxial Tension." Journal of Physics: Conference Series 2051, no. 1 (October 1, 2021): 012062. http://dx.doi.org/10.1088/1742-6596/2051/1/012062.

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Abstract Composite laminates have received much interest in precise engineering fields such as aerospace and automotive industries. Understanding the failure behaviour of laminated composites is important when designing modern structures, but many studies only focus on laminates without cutouts. In practice, the structures are design with cutouts to accommodate the space for fasteners, such as rivets, screws and bolts. This study analyses the failure behaviour of Boron/Epoxy composite laminates with square cutout of various sizes under uniaxial tension. In this study, failure analysis was performed using a Finite Element Analysis (FEA) software, ANSYS, for laminated composite plates with square cutout. The laminas were arranged in the sequence of [θ4/04/-θ4]s where the fibre angle, θ ranges from 0˚ to 90˚. The failure load was predicted based Maximum stress theory. For better visualisation, failure curves are plotted and analysed. Prior to that, the numerical validation procedure has proved the accuracy of the simulation as the results obtained from analytical approach (Matlab) and simulation (ANSYS) are in close agreement. The failure curves show that the Boron/Epoxy composite laminate has weaken seven times due to the square cutout. Such information is vital when designing a structure. Even though more rigorous research should be conducted, it could not be denied that the current study has contributed significant fundamental knowledge. The novelty of this work is that a new set of failure envelopes for Boron/Epoxy laminates with various cutout sizes was developed.
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2

Manomaisantiphap, Siwat, Vipin Kumar, Takao Okada, and Tomohiro Yokozeki. "Electrically conductive carbon fiber layers as lightning strike protection for non-conductive epoxy-based CFRP substrate." Journal of Composite Materials 54, no. 29 (June 24, 2020): 4547–55. http://dx.doi.org/10.1177/0021998320935946.

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A large amount of electrically conductive fillers is needed to enhance a Carbon Fiber Reinforced Plastics (CFRP) electrical conductivity enough to withstand lightning strikes of peak currents. However, such large alien constituents hamper the inherent good mechanical properties of CFRP structures. In this work, a solution has been proposed to retain both desired properties in a CFRP laminate. Layer-wise hybrid laminate has been demonstrated as a solution for lightning strike protection of Carbon Fiber Reinforced Plastics (CFRP). Top few layers of a hybrid laminate are prepared using electrically conductive polymer-based resin (CF/C-POLY) to provide effective dissipation of lightning current while epoxy-based CFRP substrate (CF/Epoxy) provides the main structural strength. An insulating adhesive layer is used to bond CF/C-POLY and CF/Epoxy to prepare the laminate. The hybrid laminates were tested for their effectiveness against lightning strikes. Laminates were struck by modified lightning waveform of component A with peak current of -14 kA and -40 kA. The performance of the laminates against lightning strike were evaluated using high speed camera, high-speed and thermal camera. It is found that CF/C-POLY layer successfully defended the main structural component i.e. CF/Epoxy from lightning direct damage.
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3

Biswas, Dhiraj, and Chaitali Ray. "Comparative perspective of various shear deformation theories with experimental verification for modal analysis of hybrid laminates." Journal of Vibration and Control 23, no. 8 (July 21, 2015): 1321–33. http://dx.doi.org/10.1177/1077546315592766.

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The present paper deals with the free vibration modal analysis of hybrid laminates using a finite element model based on the third order shear deformation theory (TSDT) and the first order shear deformation theory (FSDT). A computer code has been developed using MATLAB, 2013. The experimental investigation on the free vibration of hybrid laminates made of carbon and glass fibres has been conducted. The hybrid laminate is prepared by placing carbon fibres in the outermost laminae and glass fibres in the rest of the laminate. The bi-directional glass and carbon fabrics and the epoxy resin are used for the preparation of laminates in the laboratory. The experimental models of laminates have been prepared by the resin infusion process using vacuum bagging technique. The natural frequencies of hybrid laminates for different modes are determined and the mode shapes are plotted for the corresponding frequencies by experiment and numerical procedure. The finite element formulations based on TSDT and FSDT for the composite laminates predict the natural frequencies and are validated by comparing with the experimental results.
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4

Parlapalli, Madusudhanan R., Kwok C. Soh, and Dong Wei Shu. "Delamination Buckling of Kevlar and Twaron Stitched Glass\Epoxy Composite Laminates by Experiments." Solid State Phenomena 136 (February 2008): 109–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.136.109.

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In the present paper, effects of through-the-thickness stitching of delaminated glass/epoxy composite laminates with two different types of aramid threads, Kevlar® and Twaron® threads, on the buckling loads are studied. The buckling loads are predicted based on the Southwell, Vertical displacement and Membrane strain plot methods from the experimental data. Flexural modulus of the stitched and unstitched glass/epoxy composite laminates, knot tensile strength of Kevlar® and Twaron® stitching threads are obtained experimentally. From the Southwell, Vertical displacement and Membrane strain plot methods it is observed that stitching either by Kevlar® or Twaron® threads is effective in improving the buckling strength of glass/epoxy composite laminates when the delamination length is greater than 0.5L, L is the length of the laminate.
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5

Ijaz, Hassan, L. Gornet, M. A. Khan, W. Saleem, K. Nisar, and S. R. Chaudry. "Prediction of Delamination Crack Growth in Carbon/Fiber Epoxy Composite Laminates Using a Non-Local Cohesive Zone Modeling." Advanced Materials Research 570 (September 2012): 25–36. http://dx.doi.org/10.4028/www.scientific.net/amr.570.25.

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The global behavior of composite materials is strongly influenced by the quality of adhesion between different components. A component can be single phase, like fibers or particles used as reinforcement in a homogenous matrix, or a multiphase material like a layer in long-fiber laminate. In the latter case the degradation of adhesion implies the separation of the layers, known as delamination. Among all different failure mechanisms, Delamination is considered to be the most prominent mode of failure in fiber-reinforced laminates as a result of their relatively weak inter-laminar strength. When laminated structures are subjected to static, dynamic or cyclic loadings, the inter-laminar adhesion strength between individual plies tends to deteriorate significantly and act as the origin of the final failure. Therefore, an efficient and reliable design tool capable of predicting delamination could improve the durability for composite laminates. There exist damage mechanics based formulations capable of simulating the delamination crack growth in carbon/glass fiber epoxy based composite laminates. The present study is focused on taking a step forward in this respect. At first, already existed local interface models effectiveness is tested and results are successfully compared with available experimental data for UD IMS/924 Carbon/fiber epoxy composite laminate. Next, a non-local integral-type regularization scheme is introduced to overcome the spurious localization problem associated to the existing local model. Basic concepts and mathematical modeling of Non-Local damage evolution law are comprehensively studied and presented in this study. Finite Element simulation results based on proposed model are discussed in detail and are compared with experimental results.
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6

Wang, Fu You, Guo Li Zhang, Li Chen, Guang Wei Chen, and Qiang Zhou. "Study on the Tensile Strength Loss Rate of Glass Fiber 2D Woven Fabric Reinforced Laminates with Ladder Splicing." Applied Mechanics and Materials 34-35 (October 2010): 1855–58. http://dx.doi.org/10.4028/www.scientific.net/amm.34-35.1855.

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This research paper presents an experimental investigation on the tensile strength loss rate of glass fiber reinforced 2D woven fabric with ladder splicing laminate composites. On the basis of three kinds of ply sequence, two series of laminates with different plies numbers were prepared through RTM molding technology, including ladder splicing(LS) laminates and continuous laminates (CL). And the RTM technological parameters of RTM processing were designed as follows: injection temperature was room temperature, injection duration time was 180min and injection pressure was 0.5MPa, the epoxy resin based 2D glass fiber woven fabric RTM laminated specimen were prepared. According to the GB/T 1447-2005 standard test method, the tensile tests of the 2D glass fiber woven fabric laminates were carried out. Results show that the tensile strength loss rate of ladder splicing laminates is 11.05%, 9.37%, 7.78% while the number of plies is 8, 10, 12 respectively. In other words, the tensile strength loss rate is reduced with the plies number increasing. In addition, because of the concentration of tensile stress, all fractures of ladder splicing laminates occur at the site of splicing line.
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7

Kashtalyan, M., and C. Soutis. "Modelling of stiffness degradation due to cracking in laminates subjected to multi-axial loading." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2071 (July 13, 2016): 20160017. http://dx.doi.org/10.1098/rsta.2016.0017.

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The paper presents an analytical approach to predicting the effect of intra- and interlaminar cracking on residual stiffness properties of the laminate, which can be used in the post-initial failure analysis, taking full account of damage mode interaction. The approach is based on a two-dimensional shear lag stress analysis and the equivalent constraint model of the laminate with multiple damaged plies. The application of the approach to predicting degraded stiffness properties of multidirectional laminates under multi-axial loading is demonstrated on cross-ply glass/epoxy and carbon/epoxy laminates with transverse and longitudinal matrix cracks and crack-induced transverse and longitudinal delaminations. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.
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8

Marchfelder, Cornelia, Robert Pugstaller, Gernot M. Wallner, Oliver Brüggemann, and Maëlenn Aufray. "Effect of Epoxy Structure on Properties of Waterborne Coatings and Electrical Steel Laminates." Polymers 14, no. 8 (April 11, 2022): 1556. http://dx.doi.org/10.3390/polym14081556.

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Epoxy varnishes are of high relevance to advanced steel laminates for the transformation of electric energy. Structure–property correlations of epoxy varnishes, coil coatings and electrical steel laminates are poorly described. Hence, the main objective of this paper was to develop, implement and evaluate well-defined waterborne model epoxy varnishes for electrical steel laminates, and to elucidate structure–property correlations. Adhesives with systematically varied equivalent epoxy weight (EEW) based on bisphenol-A-diglycidyl ether (DGEBA) were investigated and used to formulate waterborne varnishes. Crosslinking agent dicyandiamide (DICY) was added in an over-stoichiometric ratio. The waterborne model varnishes were prepared by shear emulsification at elevated temperatures. The model varnishes in the A-stage were applied to electrical steel using a doctoral blade. At a peak metal temperature of 210 °C, the coatings were cured to the partly crosslinked B-stage. Coated steel sheets were stacked, laminated and fully cured to C-stage at 180 °C for 2 h. For laminates with an epoxy adhesive layer in the C-stage, glass transition temperatures (TG) in the range of 81 to 102 °C were obtained by dynamic mechanical analysis in torsional mode. Within the investigated EEW range, a negative linear correlation of EEW and TG was ascertained. Presumably, higher EEW of the varnish is associated with a less densely crosslinked network in the fully cured state. Roll peel testing of laminates at ambient and elevated temperatures up to 140 °C confirmed the effect of EEW. However, no clear correlation of roll peel strength and glass transition temperature was discernible. In contrast, fatigue fracture mechanics investigations revealed that hydroxyl functionality and crosslinking density were affecting the crack growth resistance of laminates in a contrary manner. The energy-based fracture mechanics approach was much more sensitive than monotonic peel testing.
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9

Matsuda, Tetsuya, Jin Toyomura, Tsubasa Ogaki, and Masahiro Arai. "Two-Scale Analysis of Thermal Behavior of CFRP Laminates Based on a Thermoelastoviscoplastic Homogenization Theory." Key Engineering Materials 725 (December 2016): 433–38. http://dx.doi.org/10.4028/www.scientific.net/kem.725.433.

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In this study, a two-scale thermoelastoviscoplastic analysis method for carbon fiber-reinforced plastic (CFRP) laminates is proposed based on a homogenization theory for time-dependent composites. For this, macroscopic and microscopic boundary value problems for CFRP laminates are derived to discuss the relation between the two problems. Using the relation, a two-scale thermoelastoviscoplastic analysis method is constructed, and then applied to the analysis of thermal behavior of an unsymmetric cross-ply carbon fiber/epoxy laminate. The laminate is subjected to a macroscopic temperature change from 180°C to 20°C. It is shown that quite high residual stress and strain occur both macroscopically and microscopically in the laminate, resulting in large macroscopic warpage of the laminate.
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10

Zilberman, Joseph, David Yoffe, Andrew Piotrowski, Mayank Pratap Singh, Kali Suryadevara, and Sergei Levchik. "Comparative study of reactive flame retardants based on 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide." Journal of Fire Sciences 35, no. 3 (April 11, 2017): 235–56. http://dx.doi.org/10.1177/0734904117702157.

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Two new 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-containing compounds, (6,6′-(1-methylethylidene)-bis(9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide)) (bis-DOPO) and 2,4,6-tris-(9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide)-1,3-diacetoxybenzene (DOPO-RA), were synthesized and characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopy. These new flame retardants were incorporated into epoxy formulations to produce a copper-clad laminate. When fully cured, the DOPO-groups of bis-DOPO become a part of the epoxy chains, whereas the DOPO-groups of DOPO-RA remain pendant to the epoxy polymer network. Despite their higher phosphorus content, bis-DOPO-based laminates showed a poorer flame-retardant performance compared to the DOPO-RA laminates. It is believed that the pendant position of the DOPO group with respect to the polymer chains is essential for a gas-phase flame-retardant action.
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11

Thinh, Tran Ich, and Ngo Nhu Khoa. "Hygroscopically induced residual stresses in composite laminates." Vietnam Journal of Mechanics 23, no. 3 (October 1, 2001): 173–82. http://dx.doi.org/10.15625/0866-7136/9950.

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In this paper the exact moisture concentration function m(z, t) is used to compute the hygroscopic residual stresses in laminated composites. The governing equations were established by using a full higher-order displacement theory. Hygroscopically induced residual stresses in thick graphite-epoxy composite laminates: Cross-ply [0/90] 8 based on this approach were compared with those obtained by assumption: the moisture concentration m is a constant in all plies through the laminates thickness
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12

Zhang, Guo Li, Fu You Wang, Jia Lu Li, Guang Wei Chen, and Li Chen. "The Effect of Splicing Shape and Interval Length on the Failure Mode of Laminated Composites under Tensile Condition." Applied Mechanics and Materials 44-47 (December 2010): 2922–25. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.2922.

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This paper presents an experimental investigation on the failure modes of glass fiber reinforced 2D woven fabric with ladder splicing laminate composites. On the basis of [0/0/+45/90/-45/90]s ply sequence, six kinds of laminated performs with different splicing interval lengths which were 4mm, 8mm, 12mm respectively and two different splicing shape which were ladder splicing and double vertical line splicing, and a kind of laminated perform with continuous laminates of 2D glass fiber woven fabric were made. By means of RTM molding technology, the technological parameters of RTM processing were designed as follows: injection temperature was 25°C, injection duration time was 180min and injection pressure was 0.4MPa, the epoxy resin based 2D glass fiber woven fabric RTM laminated specimen were prepared. According to the GB/T 1447-2005 and GB/T 1449-2005standard test method, the failure modes of 2D glass fiber woven fabric laminated RTM specimen were tested. Results show that the failure modes of laminate composites manifest as rapid damage in the form of line inlay mode and wedge shape mode at 4mm interval length condition, and accumulating failure in the form of inlay layer slippage - fiber pulled out mode and fiber fracture - splicing layer deboning mode at 12mm interval length. Otherwise, all fracture position of splicing laminates occurs at the site of splicing line because of the concentration of tensile stress.
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13

Manoj Kumar Rath. "Condition Assessment of a Reinforced Concrete Residential Building using Non-destructive Testing Methods - A Case Study." Electronic Journal of Structural Engineering 21 (November 30, 2021): 18–33. http://dx.doi.org/10.56748/ejse.21288.

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The present study deals with both experimental and numerical investigation on buckling effects of laminated composite plates subjected to varying temperature and moisture. A simple laminated plate model is developed for the buckling of composite plates subjected to adverse hygrothermal loading. A computer program based on FEM in MATLAB environment is developed to perform all necessary computations. The woven fiber Glass/Epoxy specimens were hygrothermally conditioned in a humidity cabinet where theconditions were maintained at temperatures of 300K-425K and relative humidity (RH) ranging from 0-1% for moisture concentrations. All the investigations are made with a symmetric cross-ply laminates. The present study deals with both experimental and numerical investigation on buckling behavior of laminated composite plates subjected to varying temperature and moisture concentration. Quantitative results are presented to show the effects of geometry, material and lamination parameters of woven fiber laminate onbuckling of composite plates for different temperature and moisture concentrations with simply supported boundary conditions with different aspect and side-to-thickness ratios. Experimental results show that there is reduction in buckling loads in KN with the increase in temperature and moisture concentration for laminates with clamped-free-clamped-free boundary conditions
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14

Calabrese, Luigi, Vincenzo Fiore, Paolo Giovanni Bruzzaniti, Tommaso Scalici, and Antonino Valenza. "An Aging Evaluation of the Bearing Performances of Glass Fiber Composite Laminate in Salt Spray Fog Environment." Fibers 7, no. 11 (October 31, 2019): 96. http://dx.doi.org/10.3390/fib7110096.

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The aim of the present paper is to assess the bearing performance evolution of pinned, glass-composite laminates due to environmental aging in salt-spray fog tests. Glass fibers/epoxy pinned laminates were exposed for up to 60 days in salt-spraying, foggy environmental conditions (according to ASTM B117 standard). In order to evaluate the relationship between mechanical failure mode and joint stability over increasing aging time, different single lap joints, measured by the changing hole diameter (D), laminate width (W) and hole free edge distance (E), were characterized at varying aging steps. Based on this approach, the property-structure relationship of glass-fibers/epoxy laminates was assessed under these critical environmental conditions. Furthermore, an experimental 2D failure map, clustering main failure modes in the plane E/D versus W/D ratios, was generated, and its cluster variation was analyzed at each degree of aging.
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15

Kim, Won Seok, Sang Hoon Kim, and Jung Ju Lee. "Structural Health Monitoring of Composite Laminates by Using Embedded FBG Optical Fiber Sensors." Key Engineering Materials 297-300 (November 2005): 2158–63. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.2158.

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In this paper, a new Structural Health Monitoring (SHM) technique for composite laminates through the use of embedded FBG sensors is presented. This method monitors the ply stress states of a laminate and compares them with failure criteria continuously during structures’ service time. The ply stress state of each ply composing the composite laminate can be obtained by embedding three FBG sensors in the laminate based on the classical lamination theory. In this study FBG sensor embedded graphite/epoxy composite laminate specimens were fabricated. With ply stress states being monitored, tension and fatigue tests were performed until laminates’ failure. Experimental results show that laminates experience fracture when the ply stress states are beyond the boundaries of failure criteria. Embedded FBG sensors had good fracture strain and reliability. Therefore, critical damage can be detected by the ply stress states which are close to the boundaries of failure criteria.
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16

Kang, Ki Weon, Seung Yong Yang, J. H. Kim, Jung Kyu Kim, Heung Seob Kim, and H. J. Kim. "Impact Damage Behavior of Glass/Epoxy Laminates for Railway Vehicle at Low Temperature." Key Engineering Materials 326-328 (December 2006): 1793–96. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1793.

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This paper deals with the damage behavior of glass/epoxy composite laminates subjected to low-velocity impact at various temperatures. For this goal, the impact tests were performed by using an instrumented impact-testing machine at three temperatures: +20°C, -10°C and -40°C. And the resultant damages were inspected through the scanning acoustic microscope (SAM). Also, based on the impact force history and the damage configuration of the laminates, the impact resistance parameters were employed to evaluate damage resistance of glass/epoxy laminates. As results, it was found that the temperature changes affect the damage resistance capacity of glass/epoxy laminates.
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17

Raju, D. Dhanunjaya, and Dr V. V. Subba Rao. "Effect of Carbon Nanotubes Volume Fraction on the Deflections and Stresses of Laminated Hybrid Composite Plates using First-Order Shear Deformation Theory." International Journal of Innovative Technology and Exploring Engineering 11, no. 9 (August 30, 2022): 67–73. http://dx.doi.org/10.35940/ijitee.g9248.0811922.

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Carbon Nanotubes reinforced composite materials are widely used in aerospace engineering due to high strength-to-weight ratios, which can be tailored per requirements. The behaviour of the composite structures depends on various factors like, Lamination scheme, Ply orientation and loading conditions. In the present work, Static deflection and stresses analysis of a Carbon Nano Tube reinforced laminated hybrid composite plate extends the First Order Shear Deformation Theory with variable ply angles and volume fractions of CNT. A micromechanics model based on the Mori-Tanaka method is used to calculate the properties of CNT reinforced laminate. In this analysis, hybrid composite plates mainly consist of Graphite/epoxy, Kevlar/epoxy and CNT/ polystyrene sub-laminates. The lamination scheme and CNT volume fraction play a vital role in the non-dimensional deflections and stresses. The main intention of this work is to enhance the suitability of CNT reinforced Hybrid composite plates under static loading for structural applications.
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18

Tomková, B., M. Pechočiaková, and J. Novotná. "Modification of Glass/Epoxy laminates using micro/nano particles from carbon wastes." Journal of Physics: Conference Series 2413, no. 1 (December 1, 2022): 012014. http://dx.doi.org/10.1088/1742-6596/2413/1/012014.

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This study is focused on the influence of a modified matrix on glass fiber reinforced laminates, which inherently have different material properties than carbon fiber composites. For this study we modified the green epoxy resin with 2.5wt% of carbon based fillers (synthesized graphene nanopellets, and milled recycled carbon fibres), which were subsequently applied to the glass multifilaments, and vacuum cured to obtain fiber/epoxy UD laminates. The prepared samples were further tested on the mechanical, thermo-mechanical and electrical properties, to evaluate the filler influence on the studied type of glass/epoxy laminates. Aim of this work is to study the influence of carbon fillers on overall composite properties, and evaluate its applicability for the improvement of UD glass epoxy laminates without having to significantly change the weight of component and the technology of the composite production.
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19

Evran, Savaş. "Experimental and statistical free vibration analyses of laminated composite beams with functionally graded fiber orientation angles." Polymers and Polymer Composites 28, no. 7 (June 27, 2020): 513–20. http://dx.doi.org/10.1177/0967391120938210.

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In this experimental and statistical study, free vibration behavior of laminated composite beams with functionally graded fiber orientation angles was investigated under clamped-free boundary conditions. The beams were manufactured using E-glass/epoxy. Fiber orientation angles of the beams were analyzed based on Taguchi’s L9 (33) orthogonal array. The effect of fiber orientation angles and beams with optimum levels were assessed using analysis of signal-to-noise ratio. Significant laminates of the beams and their percent contributions on the free vibration responses were obtained using analysis of variance. According to this study, the increase of fiber orientation angle from 0° to 80° causes a decrease in the fundamental frequency behavior of laminated composite beams. The most effective control factors were found to be the first and the second laminates symbolized as L1 with 85.86% contribution, the third and the fourth laminates symbolized as L2 with 12.29% contribution, the fifth and the sixth laminates symbolized as L3 with 1.84% contribution, respectively. This study can be used as a reference for free vibration analysis of cantilever laminated composite beams made of functionally graded fiber orientation angles as experimentally and statistically.
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20

Goto, Keita, and Tetsuya Matsuda. "Free Edge Stress Analysis of Unidirectional CFRP Laminates Based on a Homogenization Theory for Time-Dependent Composites." Key Engineering Materials 535-536 (January 2013): 397–400. http://dx.doi.org/10.4028/www.scientific.net/kem.535-536.397.

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In this study, distributions of microscopic stress at free edges of unidirectional carbon fiber-reinforced plastic laminates (CFRP laminates) are analyzed three-dimensionally, based on a homogenization theory for time-dependent composites. For this, the homogenization theory is reconstructed for free edge problems using a traction-free boundary condition. Then, an analysis domain is reduced using the point-symmetry of the internal structure of the unidirectional CFRP laminate. Moreover, the substructure method is newly introduced into the theory to reduce the computational costs required for the analysis. The present method is then applied to the elastic-viscoplastic microscopic stress analysis at free edges of unidirectional carbon fiber/epoxy laminates subjected to an in-plane uniaxial tensile load. It is shown that complex microscopic stress distributions occur in the vicinity of the free edge, especially around fiber/matrix interface regions.
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21

Paleari, Lorenzo, Mario Bragaglia, Francesco Fabbrocino, and Francesca Nanni. "Structural Monitoring of Glass Fiber/Epoxy Laminates by Means of Carbon Nanotubes and Carbon Black Self-Monitoring Plies." Nanomaterials 11, no. 6 (June 11, 2021): 1543. http://dx.doi.org/10.3390/nano11061543.

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The health monitoring of structures is of great interest in order to check components’ structural life and monitor damages during operation. Self-monitoring materials can provide both the structural and monitoring functionality in one component and exploit their piezoresistive behavior, namely, the variation of electrical resistivity with an applied mechanical strain. In this work, self-monitoring plies were developed to be inserted into glass-fiber reinforced epoxy-based laminates in order to achieve structural monitoring. Nanocomposite epoxy-based resins were developed employing different contents of high surface area carbon black (CB, 6 wt%) and multiwall carbon nanotubes (MWCNT, 0.75 and 1 wt%), and rheologically and thermomechanically characterized. Self-monitoring plies were manufactured by impregnating glass woven fabrics with the resins, and were laminated with non-sensing plies via a vacuum-bag process to produce sensored laminates. The self-monitoring performance of the laminates was assessed during monotonic and cyclic three-point bending tests, as well as ball drop impact tests. A higher sensitivity was found for the CB-based systems (Gauge Factor 6.1), while MWCNTs (0.55 and 1.04) ensure electrical percolation at lower filler contents, as expected. The systems also showed the capability of being used to predict residual life and damage occurred under impact.
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22

Oide, Kohei, and Tetsuya Matsuda. "Macro/Meso/Micro Elastic-Viscoplastic Analysis of Plain-Woven Laminates Using Homogenization Theory." Key Engineering Materials 626 (August 2014): 365–71. http://dx.doi.org/10.4028/www.scientific.net/kem.626.365.

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In this study, macro/meso/micro elastic-viscoplastic analysis of plain-woven laminates is conducted based on a homogenization theory for nonlinear time-dependent composites. For this, a plain-woven laminate is modeled with respect to three scales by considering the laminate as a macrostructure, fiber bundles (yarns) and a matrix in the laminate as a mesostructure, and fibers and a matrix in the yarns as a microstructure. Then, an elastic-viscoplastic constitutive equation of the laminate is derived by dually applying the homogenization theory for nonlinear time-dependent composites to not only the meso/micro but also the macro/meso scales. Using the present method, the elastic-viscoplastic analysis of a plain-woven glass fiber/epoxy laminate subjected to on-and off-axis loading is performed. It is shown that the present method successfully takes into account the effects of viscoplasticity of the epoxy in yarns on the elastic-viscoplastic behavior of the plain-woven GFRP laminate. It is also shown that the results of analysis are in good agreement with experimental data.
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23

Samajdar, S., and Kishore. "Fracture surface characterization of epoxy-based GFRP laminates." Journal of Materials Science 26, no. 4 (January 1, 1991): 977–84. http://dx.doi.org/10.1007/bf00576775.

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24

Gopal, P., L. R. Dharani, and S.-C. Yen. "Measurement of Delamination Fracture Energy Using Stepped Laminates." Advanced Composites Letters 1, no. 4 (July 1992): 096369359200100. http://dx.doi.org/10.1177/096369359200100402.

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Delamination is often the mode of failure in laminated composites. Therefore the quantification of delamination fracture energy is of vital importance. In this work, externally stepped graphite/epoxy (T300/934) laminates are tested in flexure, resulting in a series of delaminations at 0/90 interface. The delamination fracture energy is calculated based on the strain energy released and is found to be 535 J/m2. This value is in good agreement with the mode II strain energy release rate obtained by other workers.
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25

Huang, Zheng-Ming, X. C. Teng, and S. Ramakrishna. "Progressive Failure Analysis of Laminated Knitted Fabric Composites Under 3-Point Bending." Journal of Thermoplastic Composite Materials 14, no. 6 (November 2001): 499–522. http://dx.doi.org/10.1106/uw1g-83l2-91w9-g47y.

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The bending behavior of laminated beams reinforced with differently arranged plain-weft knitted fabrics has been investigated in this paper. Experiments were carried out to measure the bending stiffness and strength of six layers knitted fabric rein-forced epoxy composite laminates under 3-point bending. The laminate lay-ups of [0/0/0/0/0/0], [90/90/90/90/90/90] and [0/-45/45/45/-45/0] have been taken into account, where 0 denotes that the fabric wale direction is arranged along the beam axial direction. A simulation procedure is presented to analyze the bending property of the laminated beams based on the bridging micromechanics model and the classical lamination theory. It has been found that the use of a stress failure criterion only is no longer enough for estimating the ultimate bending strength of the laminate. An additional critical deflection condition is also required. By using only the constituent properties, which were measured using bulk material specimens independently, and the fabric knitting and lay-up parameters, the predicted stiffness and strength agree favorably with the experimental data.
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26

Pichler, Stefan, Günter Wuzella, Thomas Hardt-Stremayr, Arunjunai Raj Mahendran, and Herfried Lammer. "High-Performance Natural Fiber Composites Made from Technical Flax Textiles and Manufactured by Resin Transfer Molding." Key Engineering Materials 742 (July 2017): 263–70. http://dx.doi.org/10.4028/www.scientific.net/kem.742.263.

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In the present work it is shown that the resin transfer molding (RTM) is a beneficial technique to manufacture natural fibers into high-performance natural fiber composites. At first, three different types of weaves were produced by using low-twist flax yarns and standard-twisted flax yarns. Laminates based on the weaves and a petrochemical derived epoxy thermoset were fabricated by RTM process. For each laminate different numbers of plies (4, 5, 6, and 7) were used to achieve a broad range of vf (from 32 % up to 55 %) which are having a pore volume fraction, vp, as low as possible (min. 0.7 % - max. 2.7 %). For the laminates, flexural properties in warp and weft direction were determined (ISO 14125) and the effect of respective yarn type on flexural properties was investigated. The best properties were achieved for the laminate based on weave2 with vf = 55 % (strength=303 MPa, modulus=19.3 GPa). When laminates were tested again after half of the year the modulus and strength were reduced, but the strainincreased. The laminates were immersed into a water bath (ASTM D570) to test the influence of vf and vp on the water absorption behavior. The maximum water uptake (4-7 wt.-%) and the maximum thickness swelling (3-12 %) were observed for the samples with higher vf. Laminates based on weave1 were immersed again into the water bath to investigate the extent of deterioration of flexural properties with respect to water absorption at various time intervals. The laminates were tested immediately after removing from the water bath and after re-drying.
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27

Franco-Urquiza, Edgar Adrián, Raúl Samir Saleme-Osornio, and Rodrigo Ramírez-Aguilar. "Mechanical Properties of Hybrid Carbonized Plant Fibers Reinforced Bio-Based Epoxy Laminates." Polymers 13, no. 19 (October 7, 2021): 3435. http://dx.doi.org/10.3390/polym13193435.

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In this work, henequen and ixlte plant fibers were carbonized in a horizontal quartz tube furnace. Several carbonized and non-carbonized fiber fabric configurations were impregnated with a bio-based epoxy resin through the infuseon process. The infrared spectra revealed characteristic bands of styrene instead of organic compounds, representing that the carbonization procedure was adequate to carbonize the plant fibers. The porosity volume ratio for the non-carbonized henequen laminates showed the highest number of voids >1.9%, and the rest of the composites had a similar void density between 1.2–1.7%. The storage modulus of the non-carbonized and carbonized henequen laminates resulted in 2268.5 MPa and 2092.1 MPa, respectively. The storage modulus of the carbonized ixtle laminates was 1541.4 MPa, which is 37.8% higher than the non-carbonized ixtle laminates and 12% higher than henequen composites. The laminates were subject to thermal shock cycling, and tomography scans revealed no alterations on the porosity level or in the cracks after the cycling procedure. Thermal shock cycling promoted the post-curing effect by increasing the glass transition temperature. The viscoelastic results showed a variation in the storage modulus when the carbonized fiber fabrics were located between natural fiber fabrics, which was attributed to more excellent compaction during the infusion process. Variations in the viscoelastic behavior were observed between the different types of natural fibers, which influenced the mechanical properties.
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Sales, Rita de Cássia Mendonça, Silas Rodrigo Gusmão, Ricardo Francisco Gouvêa, Thomas Chu, José Maria Fernandez Marlet, Geraldo Maurício Cândido, and Maurício Vicente Donadon. "The temperature effects on the fracture toughness of carbon fiber/RTM-6 laminates processed by VARTM." Journal of Composite Materials 51, no. 12 (November 25, 2016): 1729–41. http://dx.doi.org/10.1177/0021998316679499.

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The increasing use of composite in the aircraft industry has raised the interest for a better understanding of the failure process in these materials, which can be also influenced by the manufacturing process of the laminate. Some materials used in vacuum assisted resin transfer molding process have been studied in the open literature but very few data have been published for resin transfer molding-6 epoxy based laminates, in particular studies showing the influence of the temperature on the interlaminar fracture behavior of this type of laminates. The aim of this article is to investigate the interlaminar fracture behavior of resin transfer molding-6 based carbon composite laminates manufactured by vacuum assisted resin transfer molding subjected to Modes I and II at 25℃ and 80℃. The results show the influence of the temperature on the interlaminar fracture toughness of composites and provide a database to design composite aerostructures subjected to temperatures commonly experienced in civil aviation. The fracture aspects of the tested laminates were also investigated and directly related to the trend in results found for the fracture toughness values.
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29

Ren, Hua, and Xiang Kang Meng. "Preparation of Z-Pin from Different Resin and Evaluation of Interlaminar Reinforcement Effect by Pullout Test." Advanced Materials Research 486 (March 2012): 444–48. http://dx.doi.org/10.4028/www.scientific.net/amr.486.444.

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A specific type of bismaleimide resin (BMI) was synthesized and a kind of epoxy resin was formulated to prepare Z-pins reinforced by T300 carbon fiber with diameters of 0.3 mm and 0.5 mm, respectively. Glass transition temperature (Tg) was measured by dynamic mechanical thermal analysis (DMTA) and interlaminar shear strength of Z-pins was tested by short beam shear method. The combination force between Z-pins and laminates was characterized by a special pullout test. The adhesion force/maximum pullout force per unit area between Z-pins and laminates was compared and the combination forces between the Z-pins and laminates were characterized. The results showed that Z-pins based on BMI resin exhibited higher interlaminar reinforcement effect toward T700/5429 composite, concluding that co-bonding between Z-pins and prepreg plays an important role in reinforcing the laminated composites.
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30

Abdellah, Mohammed Y., Mohamed K. Hassan, Abdel-Aziz AlMalki, Ahmed F. Mohamed, and Ahmed H. Backar. "Finite Element Modelling of Wear Behaviors of Composite Laminated Structure." Lubricants 10, no. 11 (November 18, 2022): 317. http://dx.doi.org/10.3390/lubricants10110317.

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Three different laminated composites are used in this study: carbon fiber, woven glass fiber, and glass-fiber-reinforced epoxy. The composite laminate structures were fabricated using the hand lay-up technique at room temperature. The laminates were reinforced with epoxy resin, carbon fibers (CFRP), woven glass fibers (GFRP-W), and random-orientation glass fibers (GFRP-R) to obtain laminates with eight layers. The wear test was performed using a pin-on-disc tribometer with five different loads of 10, 20, 30, 40, and 50 N at room temperature and a constant speed of 3 m/s. In addition, three different surfaces were lubricated: dry, with grease, and with oil. The effect of lubrication on the weight loss of the laminates was measured. The linear elastic finite element model FEM was derived to simulate the pin on the disc and the failure mode in shear mode for the case of dry lubrication. In addition, the FEM allows the friction force to be measured to determine the friction coefficient numerically. For validation, a simple analytical model based on the shear stress induced by the laminates at the interfaces was extracted to measure the friction coefficients. Tensile strength is a characteristic property that is very important for the purpose of material description from FEM and the analytical model. Therefore, it was determined experimentally with a simple tensile test. The results show that the wear rate is better with GFRP-R composites. Moreover, the wear rate with grease is lower than with oil or dry. The FEM showed that the coefficient of friction decreases with normal force to a minimum value of 0.02 for the case of 50 N normal force and for GFRP-R, while the maximum value of the coefficient of friction was 0.55 for CFRP at 10 N normal load and the FEM results were in good agreement with the analytically determined data.
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31

Sun, B. A., K. P. Cheung, J. T. Fan, J. Lu, and W. H. Wang. "Fiber metallic glass laminates." Journal of Materials Research 25, no. 12 (December 2010): 2287–91. http://dx.doi.org/10.1557/jmr.2010.0291.

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The fabrication and properties of fiber metallic glass laminates (FMGL) composite composed of Al-based metallic glasses ribbons and fiber/epoxy layers were reported. The metallic glass composite possesses structural features of low density and high specific strength compared to Al-based metallic glass and crystalline Al alloys. The material shows pronounced tensile ductility compared to monolithic bulk metallic glasses.
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32

Yusuf, N., J. M. Kaura, A. Ocholi, and M. Abbas. "Experimental assessment of the performance of reinforced concrete beams strengthened with carbon fiber reinforced polymer laminates." Nigerian Journal of Technology 39, no. 1 (April 3, 2020): 105–12. http://dx.doi.org/10.4314/njt.v39i1.11.

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In this study, experimental research is carried out to assess the flexural performance of RC beams strengthened with different amount of CFRP laminates at the tension face. Twelve rectangular RC beams were fabricated and three are un-strengthened and used as reference beams and the remaining nine are strengthened with different amount of CFRP varying from single to triple layers and all are tested to failure under three points bending test. The increase of ultimate strength provided by the bonded CFRP laminates is assessed and failure modes is identified and compared to the un-strengthened RC beams. The results indicated that the flexural capacity of the beams was significantly improved as the amount of the laminates increases that ranged from 20% to 52% increased for single to triple layers laminates. It is concluded that the attachment of CFRP laminates has substantial influence on the performance of CFRP strengthened RC beams. Based on the observed results, recommendations are made that externally application of CFRP laminates can be used for a significant enhancement of the strength deficient RC beams in increasing the ultimate load carrying capacity. Keywords: CPRP laminate, Reinforced concrete, ductility, index, epoxy resin, flexural strengthening
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33

Sotiropoulos, Dimitris G., and Konstantinos Tserpes. "Interval-Based Computation of the Uncertainty in the Mechanical Properties and the Failure Analysis of Unidirectional Composite Materials." Mathematical and Computational Applications 27, no. 3 (April 29, 2022): 38. http://dx.doi.org/10.3390/mca27030038.

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An interval-based method is presented to evaluate the uncertainty in the computed mechanical properties and the failure assessment of composite unidirectional (UD) laminates. The method was applied to two composite laminates: a carbon/epoxy and a glass/epoxy. The mechanical properties of the UD lamina were derived using simplified micromechanical equations. An uncertainty level of ±5% was assumed for the input properties of the constituents. The global minimum and maximum values of the properties were computed using an interval branch-and-bound algorithm. Interval arithmetic operations were used to evaluate the uncertainty in the Hashin-type failure criteria in a closed form. Using the closed-form uncertainties of intervals and sets of stresses obtained by finite element analysis, the uncertainty in the failure assessment was quantified for the two composite laminates. For the assumed uncertainty level of ±5%, the computed uncertainty for the mechanical properties ranges from 6.64% to 10.63% for the carbon/epoxy material and from 6.72% to 12.28% for the glass/epoxy material. For evaluating the uncertainty effect on the efficiency of failure criteria, a probability of failure function, which employs interval boundaries, was defined and proved capable of evaluating the whole spectrum of stresses.
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34

Castro, Oscar, Kim Branner, and Nikolay Dimitrov. "Assessment and propagation of mechanical property uncertainties in fatigue life prediction of composite laminates." Journal of Composite Materials 52, no. 24 (March 22, 2018): 3381–98. http://dx.doi.org/10.1177/0021998318765626.

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A probabilistic model for estimating the fatigue life of laminated composite materials considering the uncertainty in their mechanical properties is developed. The uncertainty in the material properties is determined from fatigue coupon tests. Based on this uncertainty, probabilistic constant life diagrams are developed which can efficiently estimate probabilistic ɛ-N curves at any load level and stress ratio. The probabilistic ɛ-N curve information is used in a reliability analysis for fatigue limit state proposed for estimating the probability of failure of composite laminates under variable amplitude loading cycles. Fatigue life predictions of unidirectional and multi-directional glass/epoxy laminates are carried out to validate the proposed model against experimental data. The probabilistic fatigue behavior of laminates is analyzed under constant amplitude loading conditions as well as under both repeated block tests and spectral fatigue using the WISPER, WISPERX, and NEW WISPER load sequences for wind turbine blades.
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35

Ávila, Antonio F., Lázaro V. Donadon, and Horácio V. Duarte. "Modal analysis on nanoclay epoxy-based fiber-glass laminates." Composite Structures 83, no. 3 (May 2008): 324–33. http://dx.doi.org/10.1016/j.compstruct.2007.05.003.

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36

Srivastava, S. K., and I. P. Singh. "Mechanical Properties of Glass Fibre-Epoxy Based Polymer Nanocomposites." Journal of Nano Research 15 (September 2011): 41–49. http://dx.doi.org/10.4028/www.scientific.net/jnanor.15.41.

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The experimental studies are conducted in this paper to optimize the three parameters for development of nanocomposite, namely (i) clay loadings, (ii) magnetic stirring time, and (iii) sonication time. Firstly polymer nanocomposites of varying contents nanoclay were prepared by using a mechanical stirrer and an ultrasound sonicator. The weight percentage of nanoclay in the nanocomposite with fixed stirring and sonication time was optimized for maximum intercalation within the polymer. After optimization of clay percentage, glass fiber based epoxy nanocomposite laminates were prepared. Nanocomposite structure was characterized by using X-Ray Diffraction and Transmission Electron Microscopy, which revealed the intercalated morphology of clay layers. Nanocomposites with 2.0% nanoclay content showed better intercalation with an increased interlayer spacing. The mechanical properties (impact and flexural property) were studied using an impact tester and three point bending tester. The flexural and impact properties of laminates with nanoclay contents were found to be better.
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37

Ostapiuk, Monika, Jarosław Bieniaś, and Barbara Surowska. "Analysis of the bending and failure of fiber metal laminates based on glass and carbon fibers." Science and Engineering of Composite Materials 25, no. 6 (November 27, 2018): 1095–106. http://dx.doi.org/10.1515/secm-2017-0180.

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AbstractThe purpose of this paper is to investigate the mechanisms of cracking and failure in fiber metal laminates (FMLs) subjected to 3-point bending. Two types of laminates, based on the glass/epoxy and carbon/epoxy composites, were selected for the study. The paper presents the failures of matrix and fibers as well as the effects of different thicknesses of metal layers on the tested laminates. The mechanisms of failure observed for the two tested types of fibers with uniform thickness of aluminum sheets seem similar. The results demonstrate that the tested laminates exhibit the following failure modes: fiber breakage, matrix cracking, fiber/matrix debonding, delamination, and anodic layer failure. Given the behavior of aluminum under the compressive and tensile stresses, the aluminum layer acts as a barrier preventing FML failure during bending. In addition to aluminum layer thickness, the fiber type and composite layer directions are also important factors to be considered.
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38

Jen, Yi-Ming, and Yu-Ching Huang. "Improvement in Tensile Quasi-Static and Fatigue Properties of Carbon Fiber-Reinforced Epoxy Laminates with Matrices Modified by Carbon Nanotubes and Graphene Nanoplatelets Hybrid Nanofillers." Nanomaterials 11, no. 12 (December 20, 2021): 3459. http://dx.doi.org/10.3390/nano11123459.

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The monotonic and cyclic properties of carbon fiber-reinforced epoxy (CFEP) laminate specimens with matrices modified by multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) were experimentally studied. The laminate specimens were fabricated by the hand lay-up procedure and six MWCNT:GNP weight ratios, i.e., 0:0, 10:0, 0:10, 5:5, 9:1, and 1:9, were considered to prepare the nanoparticle-modified epoxy resin by using an ultrasonic homogenizer and a planetary centrifugal mixer. Then, these laminate specimens with their matrices modified under various nanofiller ratios were employed to investigate the influence of the number of nanofiller types and hybrid nanofiller ratios on the quasi-static strength, fatigue strength, and mode I fracture toughness. The experimental results show that adding individual types of nanoparticles has a slight influence on the quasi-static and fatigue strengths of the CFEP laminates. However, the remarkable synergistic effect of MWCNTs and GNPs on the studied mechanical properties of the CFEP laminates with matrices reinforced by hybrid nanoparticles has been observed. Examining the evolution of stiffness-based degradation indicates that adding hybrid nanoparticles to the matrix can reduce the degradation effectively. The high experimental data of the mode I fracture toughness of hybrid nano-CFEP laminates demonstrate that embedding hybrid nanoparticles in the matrix is beneficial to the interlaminar properties, further improving the fatigue strength. The pushout mechanism of the MWCNTs and the crack deflection effect of the GNPs suppress the growth and linkage of microcracks in the matrix. Furthermore, the bridging effect of the nanoparticles at the fiber/matrix interface retards the interfacial debonding, further improving the resistance to delamination propagation.
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39

Ravandi, M., U. Kureemun, M. Banu, WS Teo, Liu Tong, TE Tay, and HP Lee. "Effect of interlayer carbon fiber dispersion on the low-velocity impact performance of woven flax-carbon hybrid composites." Journal of Composite Materials 53, no. 12 (October 23, 2018): 1717–34. http://dx.doi.org/10.1177/0021998318808355.

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This work investigates the effects of interlayer hybrid fiber dispersion on the impact response of carbon-flax epoxy hybrid laminates at low carbon volume fractions, and benchmarks the mechanical performance enhancement against the non-hybrid flax epoxy. Five hybrid laminate stacking sequences with similar carbon-to-flax weight ratio were fabricated and subjected to low-velocity impact at three different energy values, generating non-perforated and perforated damage states. A virtual drop-weight impact test that models intralaminar failure based on continuum damage mechanics approach, and delamination using cohesive elements, was also implemented to evaluate the material behavior and damage development in the composites. Simulation results were then verified against experimental data. Results suggested that positioning stiffer carbon plies at the impact face does not necessarily lead to enhancement of the hybrid's impact properties. On the contrary, flax plies at the impacted side lead to significant improvement in impact resistance compared to the non-hybrid flax composite with similar thickness. Results of finite element analysis showed that carbon plies play a significant role in the hybrid laminate's energy absorption characteristics due to lower failure strain.
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40

Ramírez-Herrera, Claudia A., Isidro Cruz-Cruz, Isaac H. Jiménez-Cedeño, Oscar Martínez-Romero, and Alex Elías-Zúñiga. "Influence of the Epoxy Resin Process Parameters on the Mechanical Properties of Produced Bidirectional [±45°] Carbon/Epoxy Woven Composites." Polymers 13, no. 8 (April 14, 2021): 1273. http://dx.doi.org/10.3390/polym13081273.

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This work focuses on investigating the curing process of an epoxy-based resin—Aerotuf 275-34TM, designed for aerospace applications. To study the curing degree of Aerotuf 275-34TM under processing conditions, woven carbon fiber fabric (WCFF)/Aerotuf 275-34TM composite laminates were produced by compression molding using different processing temperatures (110, 135, 160, and 200 °C) during 15 and 30 min. Then, the mechanical behavior of the composite laminates was evaluated by tensile tests and correlated to the resin curing degree through Fourier-transform infrared spectroscopy (FTIR) analysis. The results show the occurrence of two independent reactions based on the consumption of epoxide groups and maleimide (MI) double bonds. In terms of epoxide groups, a conversion degree of 0.91 was obtained for the composite cured at 160 °C during 15 min, while the measured tensile properties of [±45°] WCFF/Aerotuf 275-34TM laminates confirmed that these epoxy resin curing processing conditions lead to an enhancement of the composite mechanical properties.
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41

Manik, Parlindungan, Agus Suprihanto, Sri Nugroho, and Sulardjaka Sulardjaka. "The effect of lamina configuration and compaction pressure on mechanical properties of laminated gigantochloa apus composites." Eastern-European Journal of Enterprise Technologies 6, no. 12 (114) (December 22, 2021): 62–73. http://dx.doi.org/10.15587/1729-4061.2021.243993.

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This study aims to investigate the mechanical properties of bamboo apus (gigantochloa apus) as a natural reinforced composite material. Bamboo’s laminates of gigantochloa apus were used as reinforcement on the epoxy resin matrix. The parameters examined in this study are the configuration of lamina and compaction pressure. Laminate configuration varies in the number, thickness and direction of the lamina. Compaction pressures of 1.5 MPa, 2 MPa, and 2.5 MPa were used to fabricate the Laminated Bamboo Composites (LBCs). The stem of bamboo with a length of 400 mm was split to obtain bamboo lamina with a size of 400×20 mm. The thickness of bamboo lamina is varied between 1 mm, 1.5 mm, and 2 mm. The bamboo lamina is then preserved by watering it with a preservative solution in the form of 2.5 % sodium tetraborate solution and dried in an oven until the water content reaches 10 %. LBCs were made with a hand lay-up method. After the LBCs were molded, they were pressed with 3 variations of dies compaction 1.5 MPa, 2 MPa and 2.5 MPa. The tensile and bending tests were carried out on the LBCs. Tensile testing is performed in accordance with ASTM standard D3039 and the bending tests were conducted based on ASTM standard D7264. The results show that at each compaction pressure, the highest tensile and bending strength was achieved by LBCs with a thickness of 1 mm of bamboo lamina and 7 layers of bamboo laminates. The LBC with thinner bamboo lamina reinforcement and more layers has the highest tensile strength and bending strength, even it has a lower mass fraction. The LBCs with laminates oriented 0° exhibited greater tensile and bending strengths than the LBCs with laminates structured –45°/+45° and 0°/90°. The LBCs with the 0° laminates direction is matrix fracture followed by lamina fracture. In the 0°/90° direction, matrix fracture is followed by delamination in the 90° and 0° laminates direction. Delamination and lamina clefting were observed in LBCs with laminates oriented +45°/–45°.
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42

Qiu, Ang, Cheng Bi Zhao, You Hong Tang, and Wei Lin. "Rapid Predicting the Impact Behaviors of Marine Composite Laminates." Materials Science Forum 813 (March 2015): 19–27. http://dx.doi.org/10.4028/www.scientific.net/msf.813.19.

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There are challenges of using composite laminates in the marine engineering, i.e., composites are frequently suffering from the effects of impaction including wave impaction, ship or other objects hitting, missiles or bullets hitting and other especially conditions. It is significant to understand the impact behaviors of laminates, in this research, the impact responses of typical laminates are investigated numerically. The delamination responses among the plies and fibre and/or matrix damage responses within the plies are simulated to understand the impaction behaviours of laminates under impaction conditions. The impact damage of composite laminates in the form of intra-and/or inter-laminar cracking is modelled by using stress-based criteria for damage initiation, and fracture mechanics technique is used to capture its evolution. Interface cohesive elements are inserted between plies with appropriate mixed-mode damage laws to predict the delamination. A group of graphite fibre/epoxy laminates with impact energies of 5, 10, 15 and 20 J, respectively, are simulated with a full scale FE model and a simplified FE model respectively. Through comparing the simulation results with each other, we find out that the impact behaviors obtained in the simplified FE model is comparable to experiments with a short computing time, but the simplified model cannot represent the properties of laminate after impact.
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43

Kang, Ki Weon, H. J. Kim, J. H. Kim, Heung Seob Kim, Yong Su Kim, and Young Min Do. "Impact Damage Resistance of Glass/Epoxy Laminates with Embedded Shape Memory Alloy." Key Engineering Materials 345-346 (August 2007): 1529–32. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.1529.

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This paper deals with the damage resistance of glass/epoxy laminates with embedded shape memory alloy (SMA) subjected to low-velocity impact at various temperatures. For this goal, the impact tests were performed by using an instrumented impact-testing machine at three temperatures: +20°C, -10°C and -40°C. And the resultant damages were inspected through the scanning acoustic microscope (SAM). Also, based on the impact force history and the damage configuration, the impact resistance parameters were employed to evaluate damage resistance of laminates with embedded SMA wires. As results, it was found that the damage resistance of glass/epoxy laminates with embedded SMA wires is dependent on the service temperature.
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44

Jakubczak, P., B. Surowska, and J. Bieniaś. "Evaluation of Force-Time Changes During Impact of Hybrid Laminates Made of Titanium and Fibrous Composite." Archives of Metallurgy and Materials 61, no. 2 (June 1, 2016): 689–94. http://dx.doi.org/10.1515/amm-2016-0117.

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AbstractFibre metal laminates (FML) are the modern hybrid materials with potential wide range of applications in aerospace technology due to their excellent mechanical properties (particularly fatigue strength, resistance to impacts) and also excellent corrosion resistance. The study describes the resistance to low velocity impacts in Ti/CFRP laminates. Tested laminates were produced in autoclave process. The laminates were characterized in terms of their response to impacts in specified energy range (5J, 10J, 20J). The tests were performed in accordance with ASTM D7137 standard. The laminates were subjected to impacts by means of hemispherical impactor with diameter of 12,7 mm. The following values have been determined: impact force vs. time, maximum force and the force at which the material destruction process commences (Pi). It has been found that fibre titanium laminates are characterized by high resistance to impacts. This feature is associated with elasto-plastic properties of metal and high rigidity of epoxy - fibre composite. It has been observed that Ti/CFRP laminates are characterized by more instable force during impact in stage of stabilization of impactor-laminate system and stage of force growth that glass fibre laminates. It has been observed more stable force decrease in stage of stress relaxation and withdrawal of the impactor. In energy range under test, the laminates based on titanium with glass and carbon fibres reinforcement demonstrate similar and high resistance to low-velocity impact, measured by means of failure initiation force and impact maximum force.
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45

Alejandro Rodríguez-González, Julio, Carlos Rubio-González, José de Jesús Ku-Herrera, Lourdes Ramos-Galicia, and Carlos Velasco-Santos. "Effect of seawater ageing on interlaminar fracture toughness of carbon fiber/epoxy composites containing carbon nanofillers." Journal of Reinforced Plastics and Composites 37, no. 22 (September 4, 2018): 1346–59. http://dx.doi.org/10.1177/0731684418796305.

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This work reports the influence of seawater ageing on the mode I and mode II interlaminar fracture toughness ([Formula: see text] and [Formula: see text]) of prepreg-based unidirectional carbon fiber/epoxy laminates containing carbon nanofillers. Double cantilever beam and end notched flexure specimens were fabricated from composite laminates containing multiwalled carbon nanotubes and/or reduced graphene oxide at their middle plane interface. Experimental results showed that the addition of carbon nanofillers moderately increased the [Formula: see text] and [Formula: see text] propagation of composite laminates before and after their immersion in seawater with respect to the reference laminate under dry condition. For double cantilever beam and end notched flexure specimens aged in seawater, it was observed that [Formula: see text] and [Formula: see text] increased by 57% and 13% for specimens with multiwalled carbon nanotube/reduced graphene oxide hybrid combination, 39% and 4% for specimens with multiwalled carbon nanotubes and 53% and 8% for specimens with reduced graphene oxide respectively, as a consequence of the plasticization effect of seawater immersion on the matrix. Fracture surface examination by scanning electron microscopy revealed interlaminar failure associated to mode I and mode II delamination and toughening mechanisms produced by the multiwalled carbon nanotubes and reduced graphene oxide at delaminated regions of composite laminates.
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46

Sarasini, Fabrizio, Jacopo Tirillò, Luca Ferrante, Claudia Sergi, Pietro Russo, Giorgio Simeoli, Francesca Cimino, Maria Ricciardi, and Vincenza Antonucci. "Quasi-Static and Low-Velocity Impact Behavior of Intraply Hybrid Flax/Basalt Composites." Fibers 7, no. 3 (March 22, 2019): 26. http://dx.doi.org/10.3390/fib7030026.

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In an attempt to increase the low-velocity impact response of natural fiber composites, a new hybrid intraply woven fabric based on flax and basalt fibers has been used to manufacture laminates with both thermoplastic and thermoset matrices. The matrix type (epoxy or polypropylene (PP) with or without a maleated coupling agent) significantly affected the absorbed energy and the damage mechanisms. The absorbed energy at perforation for PP-based composites was 90% and 50% higher than that of epoxy and compatibilized PP composites, respectively. The hybrid fiber architecture counteracted the influence of low transverse strength of flax fibers on impact response, irrespective of the matrix type. In thermoplastic laminates, the matrix plasticization delayed the onset of major damage during impact and allowed a better balance of quasi-static properties, energy absorption, peak force, and perforation energy compared to epoxy-based composites.
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47

Hsieh, Tsung-Han, Yau-Shian Huang, and Ming-Yuan Shen. "Dynamic properties of carbon aerogel/epoxy nanocomposite and carbon fiber-reinforced composite beams." Journal of Reinforced Plastics and Composites 36, no. 23 (August 25, 2017): 1745–55. http://dx.doi.org/10.1177/0731684417728585.

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Carbon aerogels are a promising candidate for vibration insulation due to their three-dimensional networked structures interconnected with carbon nanoparticles. However, the effect of adding carbon aerogels to polymer-based composites on their dynamic properties remains unclear. In this study, an epoxy polymer matrix was modified with carbon aerogels, and this modified matrix was used to manufacture nanocomposite plates and carbon fiber-reinforced polymer composite laminates to investigate its dynamic properties. Force vibration tests were performed on cantilever beams of the composite beams. The frequency responses of the composite beams were measured experimentally and analytically; the half-power method was used to calculate the damping ratio for each vibration mode. According to the experimental results, the presence of carbon aerogel in the nanocomposites and laminates steadily increased the natural frequencies. Differences within 10% of the natural frequencies were obtained between the experimental and numerically. Furthermore, the damping ratios of the nanocomposite and laminate beams increased significantly with the increase in aerogel loading. For a nanocomposite with 0.3 wt% aerogel, a damping ratio approximately 44% greater than that of unmodified nanocomposite was obtained. The maximum damping ratio was 4.682% for the laminate with 0.5 wt% aerogel—an 88% increase compared with the unmodified laminate.
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48

Chen, Ling Fei, Li Chen, and Guo Li Zhang. "Finite Elemental Simulation on Flexural Process of Carbon Fiber/Epoxy Composite Laminates." Advanced Materials Research 332-334 (September 2011): 1105–8. http://dx.doi.org/10.4028/www.scientific.net/amr.332-334.1105.

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A 3D finite element model of three-point flexure test of carbon fiber/epoxy composite laminates is developed and analyzed with the finite element software ANSYS. Based on the Hashin criterion, a stiffness degradation method is adopted to predict the progressive failure properties of the carbon fiber/epoxy composite laminates. For carbon fiber/epoxy composite, five failure modes: fiber tensile failure, fiber compressive failure, matrix tensile cracking, matrix compressive cracking and fiber-matrix shear-out failure are included in the present model. The calculated load-displacement curve and the final flexural failure strength are compared with the experimental result, and the finite element results are in good agreement with the experimental values.
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49

Ying, Sun, Tang Mengyun, Rong Zhijun, Shi Baohui, and Chen Li. "An experimental investigation on the low-velocity impact response of carbon–aramid/epoxy hybrid composite laminates." Journal of Reinforced Plastics and Composites 36, no. 6 (December 20, 2016): 422–34. http://dx.doi.org/10.1177/0731684416680893.

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In the current study, the low-velocity impact response of hybrid-laminated composites based on the twill woven fabrics was investigated experimentally. The following five different types of carbon–aramid/epoxy hybrid laminates were produced and tested, (a) two types of interply hybrid, (b) two types of sandwich-like interply hybrid, and (c) intraply hybrid. Non-hybrid carbon and aramid twill woven laminates were also tested for comparison. The effects of the hybrid structure on the impact properties such as the peak load, the ductility index, and damage area were discussed. The impact damage resistances of specimens were evaluated by comparing damage images taken from both the impacted and the non-impacted surface. The damage and failure mechanisms were analyzed from the impact damage morphologies using ultrasonic C-scan and three-coordinate measuring device. Under the same impact energies, the interply hybrid laminates with carbon fabric on the impact surface have higher impact damage resistance. It can be concluded that placing of high stiffness carbon fabric at highly stressed regions as reinforcement would result in enhanced properties, and the damage tolerance performance of composites with interply hybrid structure are better than those of other hybrid composites.
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50

Bayati Chaleshtari, Mohammad Hossein, Mohammad Jafari, and Hadi Khoramishad. "Effect of cutout geometry on the failure strength of symmetric laminates under uniform heat flux." Journal of Reinforced Plastics and Composites 41, no. 3-4 (October 14, 2021): 81–98. http://dx.doi.org/10.1177/07316844211048772.

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The present work aims to investigate the thermal stress distribution in an infinite symmetrical laminated composite plate with a polygonal cutout to determine the laminate failure strength based on the first ply failure according to Hashin–Rotem and Tsai–Wu criteria. Lekhnitskii’s solution technique has been used to obtain the required potential functions. The extension of the technique used for the circular and elliptical cutouts into polygonal cutouts was performed using conformal mapping function in accordance with the procedure of complex variables. The main parameters such as cutout orientation, bluntness factor, the aspect ratio of the cutout, as well as stacking sequences in composite plates with symmetrical laminates made of glass/epoxy material containing triangular, square, pentagonal, and hexagonal cutouts have been examined. According to the research findings, it is possible to improve the failure strength of perforated plates by appropriate selection of cutout shapes along with the optimum values of the effective parameters. The unexpected result was that circular geometry was not always the best choice for the cutout because the selection of appropriate values for the parameters under consideration for a laminate with non-circular cutout leads to higher failure strength compared to the same plate with circular cutout.
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