Academic literature on the topic 'Epoxy-based laminates'
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Journal articles on the topic "Epoxy-based laminates"
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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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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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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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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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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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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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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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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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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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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.
Dissertations / Theses on the topic "Epoxy-based laminates"
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Rosetti, Yann. "Multiscale morphologies of epoxy-based composite matrices from combination of TP-tougheners." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0140.
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Les composites stratifiés à matrice organique thermodurcissable (TD) et renforts fibreux continus se sont progressivement imposés dans le monde de l’aéronautique depuis bientôt 50 ans. Ces matériaux, malgré de nombreux avantages ayant permis de remplacer les alliages métalliques précédemment utilisés, ont néanmoins un point faible majeur, à savoir une tolérance aux dommages limitée. De nombreuses solutions de renforcement ont vu le jour, dont l’ajout de polymères thermoplastiques (TP) présentant une ductilité supérieure à la matrice TD. Les travaux réalisés concernent une matrice représentative de composites stratifiés employés aujourd’hui. Elle est constituée d’un système époxy-amine menant à un réseau de haute Tg, ainsi que deux TP utilisés comme agents renforçants : un polyéthersulfone (PES) initialement soluble dans le système, et un polyamide (PA) sous forme de microparticules préformées. Un état de l’art sur les mélanges TD/TP cristallins et l’utilisation de TP comme agents renforçants dans les composites stratifiés est présenté en préambule des résultats expérimentaux. L’étude s’est focalisée sur le comportement de ces deux TP vis-à-vis du réseau époxy-amine en construction lors de la polymérisation. L’intérêt porte sur la compréhension des phénomènes reliant les différents composants du mélange entre eux. Dans un premier temps, le comportement du PES dans le système époxy-amine est étudié en fonction des conditions de polymérisation, à savoir le cycle de température appliqué. Le phénomène de séparation de phase induite par polymérisation (RIPS) ayant lieu étant en compétition avec la gélification du réseau TS, et ces deux phénomènes étant liés à la température, différents types de morphologie ont pu être obtenus. L’approche concernant le PA est différente. En effet, ce polymère initialement insoluble dans le système époxy-amine peut être compatibilisé après avoir réagi avec les monomères époxy. De plus, l’affinité physique entre le PA et le durcisseur aminé employé entraîne une modification du comportement du PA à la fusion. Des systèmes binaires modèles époxy-PA et amine-PA ont donc été étudiés pour bien découpler et comprendre toutes ces interactions. Enfin, les morphologies et propriétés résultantes du système époxy-amine modifié simultanément avec le PES et le PA ont été suivies et contrôlées grâce à un choix pertinent de différents cycles de polymérisation. La compréhension du développement d’un mélange si complexe, en termes de morphologie et de mécanismes réactionnels, a été rendue possible grâce aux études préliminaires sur systèmes modèlesFiber-reinforced thermosetting (TS) matrix-based composites, and more particularly laminates, have progressively imposed themselves in the aeronautic field for nearly 50 years. Nevertheless, despite numerous advantages making them an elegant solution to replace metallic alloys, such composites have a huge drawback: a low damage tolerance. Various toughening solutions have been developed, including the addition of thermoplastic (TP) polymers which exhibit a much higher ductility than the TS matrix. The present work relates on a representative matrix of currently considered laminates. It is constituted of an epoxy-amine system leading to a high Tg network, and two TP used as reinforcing agents: a polyethersulfone (PES) initially soluble in the system, and a polyamide (PA) preformed in micro-particles. A literature review about TS/semi-crystalline TP blends and TP reinforcement agents used in laminates is given previously to the experimental results. The study focuses on the behavior of these two TP in regard to the growing epoxy-amine network during its polymerization. The interest is put in the understanding of the phenomena linking all the matrix components together. In a first time the PES behavior in the epoxy-amine system dependence on curing conditions (i.e. the applied cure schedule) is studied. The reaction-induced phase separation (RIPS) phenomenon being competitive with the TS network gelation, and taking into account that both phenomena are temperature dependent, various types of morphologies were obtained. Apprehension of PA behavior is different. In fact, this polymer is initially soluble in the epoxy-amine system and may be compatibilized after chemical coupling with epoxy prepolymers. Moreover, physical affinities between PA and the considered amine hardener impact the PA melting behavior. Consequently, binary epoxy-PA and amine-PA model systems have been studied to uncouple and understand all these interactions. Finally, resulting morphologies and properties of the epoxy-amine system, simultaneously modified with both PES and PA, have been monitored and controlled thanks to a choice of suitable cure schedules. The understanding of the development of such a complicated system, in terms of morphologies and curing mechanisms, was made possible thanks to the preliminary studies on the model systems
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Van, Rooyen Louis Johann. "Epoxy-based coatings with reduced gas permeation : formulation and properties." 2012. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000471.
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M. Tech. Polymer Technology.The gas permeability of composite epoxy resins formulated with graphene platelets and glass flakes was investigated. The purpose of researching the gas permeability of the composite resins was to develop a possible coating system that could prevent or limit the release of radioactive gases like tritium from irradiated graphite waste which may accumulate in underground repositories. Helium was used as a substitute gas to simulate the diffusive properties of tritium gas.
Books on the topic "Epoxy-based laminates"
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Center, Langley Research, ed. Experimental verification of a progressive damage model for composite laminates based on continuum damage mechanics. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1994.
Find full textBook chapters on the topic "Epoxy-based laminates"
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Gerharz, J. J., and H. Idelberger. "A Method To Predict Residual Strength and Fatigue Ufe of Impact Damaged Carbon/Epoxy Laminates." In Durability of Polymer Based Composite Systems for Structural Applications, 445–54. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3856-7_37.
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Saitta, Lorena, Eugenio Pergolizzi, Claudio Tosto, Claudia Sergi, and Gianluca Cicala. "Fully-Recyclable Epoxy Fibres Reinforced Composites (FRCs) for Maritime Field: Chemical Recycling and Re-Use Routes." In Progress in Marine Science and Technology. IOS Press, 2022. http://dx.doi.org/10.3233/pmst220010.
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The maritime transport is guilty for about 2.5% of global greenhouse gases emission, since 940 million tonnes of CO2 are emitted around every year. Moreover, even though now the 96% of ships can be recycled, current recycling practices cause negative environmental impacts. Indeed, researches carried out on ‘ships graveyard’ showed a concentration of petroleum hydrocarbons 16,793% higher than at the control. Epoxy Fibres Reinforced Composites (FRCs) are sustainable candidates in this field. In fact, having the FRCs structures a light weight, fuel-efficient ships can be built. The global epoxy composites market size was valued at USD 25.32 billion in 2019 and is expected to expand at a compound annual growth rate (CAGR) of 6.2% from 2020 to 2027. In this sense, in the next few years, the market is expected to rapidly replace conventional materials with epoxy composites in several fields, including the marine one. However, concerns about their non-recyclability are rising more and more. In this study, by following a twofold “design for recycling” and “design from recycling” approach the chemical recycling process for thermoset polymer composites developed by Connora Technologies (California, USA) was considered as solution to overcome this issue. Moreover, the adoption of natural fibres, i.e. flax, and bio-based epoxy resin was used as environmentally-friendly solution to even avoid the use of petroleum based raw materials. To follow the first approach, i.e. “design for recycling”, Flax FRCs with bio-epoxy matrices were first produced via hand lay-up with vacuum bagging. Next, they were chemically treated to obtain a recycled thermoplastic (rTP). Then moving on the “design from recycling” approach, a reuse strategy was developed by exploiting the Electrospinning technique and producing electrospun fibers suitable for the interlaminar toughening of composite laminates.
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Roy, Subhankar, and Tanmoy Bose. "Defect Detection in Delaminated Glass-Fibre/Epoxy Composite Plates Using Local Defect Resonance Based Vibro-Thermography Technique." In Acoustic Emission - New Perspectives and Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.101178.
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In the present scenario, composites are widely used for various applications in the field of aerospace, automobile, marine, sports, construction and electrical industries. The need of damage inspection for these composite structures has been of great importance. Complicated defects like delaminations present in the composite laminates can be detected effectively using nonlinear acoustic wave spectroscopy (NAWS). One of the NAWS techniques of detecting the delamination is based on intensification of vibration amplitudes at the delamination location, known as local defect resonance (LDR) technique. In this chapter, a numerical investigation for detecting delamination in glass fibre reinforced polymer (GFRP) composite based on vibrothermography technique will be discussed. A single periodic LDR frequency excitation is used to excite the GFRP plate, resulting in a local temperature rise at delamination region due to frictional heating at the damage interface. An explicit dynamic temperature displacement analysis will be carried out for a specific time period of LDR excitation. Subsequently, a heat transfer analysis will be performed to observe the temperature difference at top surface of the delaminated GFRP plate. Thus a numerical investigation will be carried out based on LDR excitation for high contrast imaging of delamination in composite materials using vibro-thermography.
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Acosta Flores, Mario, Eusebio Jiménez López, and Marta Lilia Eraña Díaz. "Obtaining of a Constitutive Models of Laminate Composite Materials." In Elasticity of Materials [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.100607.
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The study of the mechanical behavior of composite materials has acquired great importance due to the innumerable number of applications in new technological developments. As a result, many theories and analytical models have been developed with which its mechanical behavior is predicted; these models require knowledge of elastic properties. This work describes a basic theoretical framework, based on linear elasticity theory and classical lamination theory, to generate constitutive models of laminated materials made up of orthotropic layers. Thus, the models of three orthotropic laminated composite materials made up of layers of epoxy resin reinforced with fiberglass were also obtained. Finally, by means of experimental axial load tests, the constants of the orthotropic layers were determined.
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Sarasini, Fabrizio, Jacopo Tirillò, Vincenzo Fiore, Antonino Valenza, Lorena Saitta, Claudio Tosto, Gianluca Cicala, et al. "Environmentally Friendly Composites and Surface Treatments for Metal-to-Composite Hybrid Joints for Marine Application." In Progress in Marine Science and Technology. IOS Press, 2022. http://dx.doi.org/10.3233/pmst220053.
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In this study, the use of natural fibres (flax and basalt) in combination with a recyclable epoxy matrix based on cleavable amines is suggested for improving the sustainability of marine industry. In addition, a new and eco-friendly anodizing process based on tartaric sulfuric acid solution (TSA) and a pore widening step in a NaOH aqueous solution was carried out on aluminium alloy (AA5083) to evaluate its effect on the adhesion strength and damage tolerance after low velocity impact of co-cured adhesive joints with a basalt fibre reinforced and recyclable laminate. The durability in marine environment was simulated by exposing samples to salt-fog spray conditions over a period of 90 days. Results highlighted the potential of the proposed natural fibre composites, even though the interfacial adhesion with the recyclable matrix needs to be improved, while the anodizing treatment significantly increased the damage tolerance of the joints irrespective of ageing, impact energy and temperature compared to the reference joints.
Conference papers on the topic "Epoxy-based laminates"
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Filippini, Mauro. "Identification of the Mechanical Properties of Composite Materials by Inverse Analysis." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-25101.
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A procedure based on the principles of inverse analysis has been employed to identify the elastic material parameters and the strength characteristics of epoxy carbon fiber reinforced composite laminates. By adopting a classical optimization algorithm, elasticity parameters are chosen by minimizing the mean squared error between the values predicted by the classical theory of elastic laminates and the experimentally observed ones. The average modulus of the laminate has been calculated from elastic parameters of laminas by implementing the classical equations of anisotropic elasticity in a subroutine, in order to speed up the optimization process. In a similar fashion, even though under strongly simplifying hypothesis, the strength characteristic parameters of laminas have been identified by inverse analysis, with the aim of assessing the strength of the composite laminates in the case of complex stress state.
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Gupta, V., Dan Potter, and Serge Hoart. "Mechanisms-Based Failure Laws for Graphite/Epoxy Laminates Under Compression." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-1160.
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Abstract Micromechanisms of failure were studied to determine the influence of specimen size and fiber constraint effects with end loading, and with a view to develop the failure laws. For this study, [±10]12s and [±15]12s, [±30]12s, and [±45]12s specimens with various aspect rations (height/width) were tested with an end loading fixture. Failure modes varied depending on the fiber orientation of the laminate layers to the loading axis. Failure transitioned from shear slipping along the fibers in the [±45]12s and [±30]12s samples to global delamination in the [10]12s samples. Geometry and size effects were also investigated by comparing samples with various aspect ratios. In addition to simply changing the geometry of the samples, adjusting the aspect ratio varied the amount of fibers constrained at the specimen ends against the platen interfaces. For all of the fiber orientations tests, low aspect ratio specimens had a lower elastic modulus but a higher ultimate strength compared to the larger aspect ratio specimens. Stress concentration and fiber constraint effects introduced by the end loading explain these results. These effects highlight the importance of specimen geometry and fixturing considerations for off-axis compression testing and the sensitivity of stress/strain behavior to specimen size. Biaxial compression testing was also conducted on [±45]12s and [±30]12s samples with a cruciform material testing machine. Samples were loaded with platens slightly smaller than the sample widths. The confinement ratio R, the ratio of stress applied to the secondary to primary sample axes, was varied from 0.25 to 1 to measure the sensitivity of sample failure mechanisms and stress/strain behavior to different stress states. Failure modes for both fiber orientations transitioned from the uniaxial failure mode to massive delamination with an increasing confinement ratio. Results indicate that the shear stress oriented along the fiber direction dictates failure for confinement ratios from 0 to 0.5, since the shear stress at failure is relatively constant. Above R = 0.5, failure moves toward delamination since the fiber aligned axial stresses that produce buckling begin to dominate the decreasing shear stresses along the fibers. These investigations lead to further understanding of the coupling between failure modes and stress/strain results for biaxial compression testing to allow development of failure models. A simple local matrix shear criterion in the micromechanical model captured the nucleation of fiber-aligned longitudinal cracks rather well. The saturation cracking state that ensured was determined in terms of the length of the two wing-cracks that nucleated from the edges of the main longitudinal crack due to its mode-III sliding along the fiber axis direction. The stress intensity factor at the wing crack tip was determined in terms of the friction sliding resistance, matrix fracture toughness, and the attendant compressive stress state near the main sliding crack. The model captured the results obtained with different biaxiality ratios and also explained the changes in the failure model to axial delamination.
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Hauert, Serge, Daniel S. Potter, and Vijay Gupta. "Micromechanics-Based Modeling of Uniaxially and Biaxially Compressed Graphite/Epoxy Laminates." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0369.
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Abstract Uniaxial and in-plane biaxial testing were conducted on cross-ply graphite/epoxy laminates with different orientations. Results from these investigations are presented here only for the [±45]12s samples under different stress states. The stress-strain behavior is related to microscopic events through micromechanics-based modeling. It is shown that crack nucleation starts in the matrix when the local shear stress exceeds the shear strength of the epoxy. Depending on the stress state in the plies, two types of cracks form: (i) transverse cracks and (ii) angled out-of-plane cracks. While transverse cracks slide and allow the sample to accommodate large strains, angled cracks lead to massive delamination and an overall brittle behavior.
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Trabelsi, W., V. Bellenger, and E. Ghorbel. "Anisothermic Oxidation of Carbon/Epoxy Laminates." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13352.
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This work deals with the ageing of a carbon epoxy composite material for aeronautic and supersonic applications. One of the main parameters which governs the durability of this kind of materials is the matrix oxidation, which is limited to surface layers. The long-term behaviour of organic matrix composites includes combined effects of ageing: matrix oxidation occurring at high temperature and matrix cracking due to thermo-mechanical ply stresses induced by differential expansion between matrix and fibers or between the various plies. For some years ENSAM has developed for isothermal conditions a kinetic model of radical chain oxidation coupled with the equation of oxygen diffusion. This model is based on a "close-loop" oxidation mechanistic scheme and gives access to the concentration profile of oxidation products in the sample thickness. In this work we expressed the temperature by a Fourier series and we simulate the oxidative behaviour of samples exposed to the following thermal cycles: -50°C/+180°C, -50°C/+150°C and +50°C/+180°C. The weight loss of the oxidised samples was chosen as indicator of oxidation. Numerical results are compared to experimental ones to check the validity of the model. Good agreement between experimental and numerical results is obtained.
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Rahman, Mosfequr, Saheem Absar, F. N. U. Aktaruzzaman, Abdur Rahman, and N. M. Awlad Hossain. "Effect of Ply Stacking Sequence on Structural Response of Symmetric Composite Laminates." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-37217.
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In this work, the effect of ply stacking sequence on the structural response of multi-ply unidirectional fiber-reinforced composite laminates was evaluated using finite element analysis. The objective of this study was to develop a computational model to analyze the stress response of individual plies in a composite laminate for a given stacking sequence. A laminated composite plate structure under tensile loading was modeled in ANSYS. Stress profiles of the individual plies were obtained for each lamina. An Epoxy matrix with both unidirectional Graphite and Kevlar fibers was considered for the model. Three dimensional sectioned shell elements (SHELL181) were used for meshing the model. Several sets of stacking sequences were implemented, symmetrical to the mid-plane of the laminate. Symmetric stacking configurations of 6 layers stacked in ply angles of [0/45/-45]s, [0/60/-60]s, [0/45/90]s, and an 8-layered arrangement of [0/45/60/90]s were modeled for the analysis. The layer thickness was maintained at 0.1 mm. The results were compared against an analytical model based on the generalized Hooke’s law for orthotropic materials and classical laminate theory. A numerical formulation of the analytical model was implemented in MATLAB to evaluate the constitutive equations for each lamina. The stress distributions obtained using finite element analysis have shown good agreement with the analytical models in some of the cases.
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Regalla, Sabrina, Bianca Pinheiro, Ilson Pasqualino, Luiz Daniel Lana, and Valber Perrut. "Fatigue Assessment of Damaged Pipelines After Glass Fiber and Epoxy Matrix Laminate Repairs." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62112.
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The aim of this work is to evaluate the residual fatigue life enhancement of damaged pipelines after the execution of composite material repairs made of laminates of epoxy matrix reinforced with glass fibers. In view of structural performance and cost concerns, the more suitable repair thickness should be proposed. The work comprises a numerical and experimental study on the stress concentration of damaged pipes under internal pressure before and after repair. A numerical model is developed, based on the finite element method, to provide stress concentration factors of damaged pipes (plain dent defect), under cyclic internal pressure, before and after applying glass fiber and epoxy matrix laminate repairs with varying thicknesses. Small-scale steel pipe samples are submitted to denting and the resulting stress concentration in the damaged region is estimated under cyclic internal pressure, before and after repair execution. From correlation between numerical and experimental results, the finite element model is calibrated and validated. A parametric study is carried out to evaluate stress concentration factors of dented pipes repaired with varying laminate thickness. Stress concentration factors of dented pipes under internal pressure after repair can be used in a fatigue assessment methodology from correction of S-N curves. The effect of repair thickness on the reduction of stress concentration factors is evaluated in view of the residual fatigue life enhancement of damaged pipes, beside repair procedure costs. Based on results of the parametric study, recommendations about the repair procedure using laminates of epoxy matrix reinforced with glass fibers will be proposed, comprising indications of the more suitable repair thickness, as a function of pipe and damage dimensions, in view of fatigue performance and cost concerns.
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SNYDER, ALEXANDER D., ZACHARY J. PHILLIPS, and JASON F. PATRICK. "SELF-HEALING OF WOVEN COMPOSITE LAMINATES VIA IN SITU THERMAL REMENDING." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35785.
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Fiber-reinforced polymer composites are attractive structural materials due to their high specific strength/stiffness and excellent corrosion resistance. However, the lack of through-thickness reinforcement in laminated composites creates inherent susceptibility to fiber-matrix debonding, i.e., interlaminar delamination. This internal damage mode has proven difficult to detect and nearly impossible to repair via conventional methods, and therefore, remains a significant factor limiting the reliability of composite laminates in lightweight structures. Thus, novel approaches for mitigation (e.g., self-healing) of this incessant damage mode are of tremendous interest. Self-healing strategies involving sequestration of reactive liquids, i.e. microcapsule and microvascular systems, show promise for the extending service- life of laminated composites. However, limited heal cycles, long reaction times (hours/days), and variable stability of chemical agents under changing environmental conditions remain formidable research challenges. Intrinsic self- healing approaches that utilize reversible bonds in the host material circumvent many of these limitations and offer the potential for unlimited heal cycles. Here we detail the development of an intrinsic self-healing woven composite laminate based on thermally-induced dynamic bond re-association of 3D-printed polymer interlayers. In contrast to prior work, self-repair of the laminate occurs in situ and below the glass-transition temperature of the epoxy matrix, and maintains >85% of the elastic modulus during healing. This new platform has been deployed in both glass and carbon-fiber composites, demonstrating application versatility. Remarkably, up to 20 rapid (minute-scale) self-healing cycles have been achieved with healing efficiencies hovering 100% of the interlayer toughened (4-5x) composite laminate. This latest self-healing advancement exhibits unprecedented potential for perpetual in-service repair along with material multi-functionality (e.g., deicing ability) to meet modern application demands.
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Reddy, S. Indrasena, and L. Prabhu. "Experimental investigation on mechanical behavior of synthetic based bidirectional reinforced hybrid epoxy laminates." In PROCEEDINGS OF INTERNATIONAL CONFERENCE ON RECENT TRENDS IN MECHANICAL AND MATERIALS ENGINEERING: ICRTMME 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0025072.
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Soutis, Costas, and Maria Kashtalyan. "Analysis of Fatigue Damage Mechanisms and Residual Properties of Polymer Matrix Composites." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2161.
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Abstract Resin dominated damage modes such as matrix cracking in the off-axis plies and matrix crack-induced local and edge delaminations are common failure mechanisms in composite laminates under tensile or thermal fatigue. Accurate prediction of the laminate stiffness and strength must consider all the above-mentioned damage modes. In the present paper, an approach is developed for the analysis of cross-ply laminates damaged by transverse and longitudinal cracks and transverse and longitudinal delaminations that initiate and grow along these cracks. It is based on the Equivalent Constraint Model (ECM) of the damaged ply and employs an improved 2-D shear lag method to determine the stress field in the cracked and locally delaminated ply. The method is applied to predict residual stiffness properties of cross-ply graphite/epoxy laminates using experimentally observed damage patterns.
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Carlone, Pierpaolo, and Gaetano S. Palazzo. "A Simulation Based Metaheuristic Optimization of the Thermal Cure Cycle of Carbon-Epoxy Composite Laminates." In THE 14TH INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING: ESAFORM 2011. AIP, 2011. http://dx.doi.org/10.1063/1.3589483.
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