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Abedin I. Gagani
Siemens Digital Industries Software, Via Werner von Siemens 1, 20128 Milan, Italy

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Review
Published: 15 January 2021 in Journal of Composites Science
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Recently, significant events took place that added immensely to the sociotechnical pressure for developing sustainable composite recycling solutions, namely (1) a ban on composite landfilling in Germany in 2009, (2) the first major wave of composite wind turbines reaching their End-of-Life (EoL) and being decommissioned in 2019–2020, (3) the acceleration of aircraft decommissioning due to the COVID-19 pandemic, and (4) the increase of composites in mass production cars, thanks to the development of high volume technologies based on thermoplastic composites. Such sociotechnical pressure will only grow in the upcoming decade of 2020s as other countries are to follow Germany by limiting and banning landfill options, and by the ever-growing number of expired composites EoL waste. The recycling of fiber reinforced composite materials will therefore play an important role in the future, in particular for the wind energy, but also for aerospace, automotive, construction and marine sectors to reduce environmental impacts and to meet the demand. The scope of this manuscript is a clear and condensed yet full state-of-the-art overview of the available recycling technologies for fiber reinforced composites of both low and high Technology Readiness Levels (TRL). TRL is a framework that has been used in many variations across industries to provide a measurement of technology maturity from idea generation (basic principles) to commercialization. In other words, this work should be treated as a technology review providing guidelines for the sustainable development of the industry that will benefit the society. The authors propose that one of the key aspects for the development of sustainable recycling technology is to identify the optimal recycling methods for different types of fiber reinforced composites. Why is that the case can be answered with a simple price comparison of E-glass fibers (~2 $/kg) versus a typical carbon fiber on the market (~20 $/kg)—which of the two is more valuable to recover? However, the answer is more complicated than that—the glass fiber constitutes about 90% of the modern reinforcement market, and it is clear that different technologies are needed. Therefore, this work aims to provide clear guidelines for economically and environmentally sustainable End-of-Life (EoL) solutions and development of the fiber reinforced composite material recycling.

ACS Style

Andrey E. Krauklis; Christian W. Karl; Abedin I. Gagani; Jens K. Jørgensen. Composite Material Recycling Technology—State-of-the-Art and Sustainable Development for the 2020s. Journal of Composites Science 2021, 5, 28 .

AMA Style

Andrey E. Krauklis, Christian W. Karl, Abedin I. Gagani, Jens K. Jørgensen. Composite Material Recycling Technology—State-of-the-Art and Sustainable Development for the 2020s. Journal of Composites Science. 2021; 5 (1):28.

Chicago/Turabian Style

Andrey E. Krauklis; Christian W. Karl; Abedin I. Gagani; Jens K. Jørgensen. 2021. "Composite Material Recycling Technology—State-of-the-Art and Sustainable Development for the 2020s." Journal of Composites Science 5, no. 1: 28.

Journal article
Published: 06 December 2019 in Fibers
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Understanding the strength degradation of glass and carbon fibers due to exposure to liquids over time is important for structural applications. A model has been developed for glass fibers that links the strength reduction in water to the increase of the Griffith flaw size of the fibers. The speed of the increase is determined by regular chemical dissolution kinetics of glass in water. Crack growth and strength reduction can be predicted for several water temperatures and pH, based on the corresponding dissolution constants. Agreement with experimental results for the case of water at 60 °C with a pH of 5.8 is reasonably good. Carbon fibers in water and toluene and glass fibers in toluene do not chemically react with the liquid. Subsequently no strength degradation is expected and will be confirmed experimentally. All fiber strength measurements are carried out on bundles. The glass fibers are R-glass.

ACS Style

Andreas T. Echtermeyer; Andrey E. Krauklis; Abedin I. Gagani; Erik Sæter. Zero Stress Aging of Glass and Carbon Fibers in Water and Oil—Strength Reduction Explained by Dissolution Kinetics. Fibers 2019, 7, 107 .

AMA Style

Andreas T. Echtermeyer, Andrey E. Krauklis, Abedin I. Gagani, Erik Sæter. Zero Stress Aging of Glass and Carbon Fibers in Water and Oil—Strength Reduction Explained by Dissolution Kinetics. Fibers. 2019; 7 (12):107.

Chicago/Turabian Style

Andreas T. Echtermeyer; Andrey E. Krauklis; Abedin I. Gagani; Erik Sæter. 2019. "Zero Stress Aging of Glass and Carbon Fibers in Water and Oil—Strength Reduction Explained by Dissolution Kinetics." Fibers 7, no. 12: 107.

Journal article
Published: 09 November 2019 in Polymers
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Long-term creep properties and the effect of water are important for fiber reinforced polymer (FRP) composite materials used in offshore applications. Epoxies are often used as a matrix material in such composites. A typical design lifetime of offshore FRP structures is 25 or more years in direct contact with water leading to some deterioration of the material properties. Knowing and predicting the extent of the material property deterioration in water is of great interest for designers and users of the offshore FRP structures. It has been established that the time–temperature superposition principle (TTSP) is a useful tool for estimating changes in properties of polymer materials at long times or extreme temperatures. In this work, a time–temperature–plasticization superposition principle (TTPSP) is described and used for predicting the long-term creep behavior of an epoxy compound. The studied epoxy does not degrade chemically via hydrolysis or chain scission but is negatively affected by plasticization with water. The methodology enables prediction of the long-term viscoelastic behavior of amorphous polymers at temperatures below the glass transition (Tg) using short-term creep experimental data. The results also indicate that it is possible to estimate the creep behavior of the plasticized polymer based on the short-term creep data of the respective dry material and the difference between Tg values of dry polymer and plasticized polymer. The methodology is useful for accelerated testing and for predicting the time-dependent mechanical properties of a plasticized polymer below the glass transition temperature.

ACS Style

Andrey E. Krauklis; Anton G. Akulichev; Abedin Gagani; Andreas T. Echtermeyer. Time–Temperature–Plasticization Superposition Principle: Predicting Creep of a Plasticized Epoxy. Polymers 2019, 11, 1848 .

AMA Style

Andrey E. Krauklis, Anton G. Akulichev, Abedin Gagani, Andreas T. Echtermeyer. Time–Temperature–Plasticization Superposition Principle: Predicting Creep of a Plasticized Epoxy. Polymers. 2019; 11 (11):1848.

Chicago/Turabian Style

Andrey E. Krauklis; Anton G. Akulichev; Abedin Gagani; Andreas T. Echtermeyer. 2019. "Time–Temperature–Plasticization Superposition Principle: Predicting Creep of a Plasticized Epoxy." Polymers 11, no. 11: 1848.

Journal article
Published: 27 June 2019 in Composites Science and Technology
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This work investigates the combined effect of water immersion and temperature on the interlaminar shear static and fatigue strength of glass fiber epoxy composites. Interlaminar shear tests were performed on I-beam shaped samples which enable faster fluid saturation at 20, 40 and 60 °C, both in air and in immersion. Analysis of fatigue parameters and optical micrography enabled understanding the phenomena that govern the static and fatigue degradation for each case. The dry properties are dominated by the matrix resistance at room temperature and by fiber/matrix interface strength for higher temperature. The immersed properties are dominated by the fiber/matrix interface degradation. An analytical model based on Arrhenius theory is presented for building a fatigue mastercurve that accounts for both temperature and water immersion. The effect of water immersion is modeled by accounting for the change of glass transition temperature of the material. The results show that the mastercurve describes well the conditions tested, provided that the material remains below its glass transition temperature.

ACS Style

Abedin I. Gagani; Anna B. Monsås; Andrey E. Krauklis; Andreas T. Echtermeyer. The effect of temperature and water immersion on the interlaminar shear fatigue of glass fiber epoxy composites using the I-beam method. Composites Science and Technology 2019, 181, 107703 .

AMA Style

Abedin I. Gagani, Anna B. Monsås, Andrey E. Krauklis, Andreas T. Echtermeyer. The effect of temperature and water immersion on the interlaminar shear fatigue of glass fiber epoxy composites using the I-beam method. Composites Science and Technology. 2019; 181 ():107703.

Chicago/Turabian Style

Abedin I. Gagani; Anna B. Monsås; Andrey E. Krauklis; Andreas T. Echtermeyer. 2019. "The effect of temperature and water immersion on the interlaminar shear fatigue of glass fiber epoxy composites using the I-beam method." Composites Science and Technology 181, no. : 107703.

Journal article
Published: 19 April 2019 in Coatings
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Glass fiber-reinforced composites are exposed to hydrolytic degradation in subsea and offshore applications. Fiber-matrix interphase degradation was observed after the matrix was fully saturated with water and typical water absorption tests according to ASTM D5229 were stopped. Due to water-induced dissolution, fiber-matrix interphase flaws were formed, which then lead to increased water uptake. Cutting sample plates from a larger laminate, where the fibers were running parallel to the 1.5 mm long short edge, allowed the hydrolytic degradation process to be studied. The analysis is based on a full mechanistic mass balance approach considering all the composite’s constituents: water uptake and leaching of the matrix, dissolution of the glass fibers, and dissolution of the composite interphase. These processes were modeled using a combination of Fickian diffusion and zero-order kinetics. For the composite laminate studied here with a saturated epoxy matrix, the fiber matrix interphase is predicted to be fully degraded after 22 to 30 years.

ACS Style

Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. Long-Term Hydrolytic Degradation of the Sizing-Rich Composite Interphase. Coatings 2019, 9, 263 .

AMA Style

Andrey E. Krauklis, Abedin I. Gagani, Andreas T. Echtermeyer. Long-Term Hydrolytic Degradation of the Sizing-Rich Composite Interphase. Coatings. 2019; 9 (4):263.

Chicago/Turabian Style

Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. 2019. "Long-Term Hydrolytic Degradation of the Sizing-Rich Composite Interphase." Coatings 9, no. 4: 263.

Journal article
Published: 06 April 2019 in Composite Structures
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A novel method is proposed for interlaminar shear testing of marine composites, which accelerates fluid saturation: the I-beam short beam shear test. A layered finite element (FE) model is employed to explain the nonlinear behavior of the short beam shear experiment. Using this model, rectangular and I-beam short beam shear results are compared, yielding consistent results. Dry and saturated specimens are also compared for the I-beam geometry proposed. The model can simulate these effects and enables attributing the nonlinear behavior of the composite interlaminar shear response to the plasticity of the resin rich inter-ply. In both dry and saturated conditions, the interlaminar shear strength of the composite can be estimated mainly from the matrix properties.

ACS Style

Abedin I. Gagani; Andrey Krauklis; Erik Sæter; Nils Petter Vedvik; Andreas T. Echtermeyer. A novel method for testing and determining ILSS for marine and offshore composites. Composite Structures 2019, 220, 431 -440.

AMA Style

Abedin I. Gagani, Andrey Krauklis, Erik Sæter, Nils Petter Vedvik, Andreas T. Echtermeyer. A novel method for testing and determining ILSS for marine and offshore composites. Composite Structures. 2019; 220 ():431-440.

Chicago/Turabian Style

Abedin I. Gagani; Andrey Krauklis; Erik Sæter; Nils Petter Vedvik; Andreas T. Echtermeyer. 2019. "A novel method for testing and determining ILSS for marine and offshore composites." Composite Structures 220, no. : 431-440.

Journal article
Published: 12 March 2019 in Fibers
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Glass fibres slowly degrade due to dissolution when exposed to water. Such environmental aging results in the deterioration of the mechanical properties. In structural offshore and marine applications, as well as in the wind energy sector, R-glass fibre composites are continuously exposed to water and humid environments for decades, with a typical design lifetime being around 25 years or more. During this lifetime, these materials are affected by various temperatures, acidity levels, and mechanical loads. A Dissolving Cylinder Zero-Order Kinetic (DCZOK) model was able to explain the long-term dissolution of R-glass fibres, considering the influence of the pH, temperature, and stress corrosion. The effects of these environmental conditions on the dissolution rate constants and activation energies of dissolution were obtained. Experimentally, dissolution was measured using High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). For stress corrosion, a custom rig was designed and used. The temperature showed an Arrhenius-type influence on the kinetics, increasing the rate of dissolution exponentially with increasing temperature. In comparison with neutral conditions, basic and acidic aqueous environments showed an increase in the dissolution rates, affecting the lifetime of glass fibres negatively. External loads also increased glass dissolution rates due to stress corrosion. The model was able to capture all of these effects.

ACS Style

Andrey E. Krauklis; Abedin I. Gagani; Kristine Vegere; Ilze Kalnina; Maris Klavins; Andreas T. Echtermeyer. Dissolution Kinetics of R-Glass Fibres: Influence of Water Acidity, Temperature, and Stress Corrosion. Fibers 2019, 7, 22 .

AMA Style

Andrey E. Krauklis, Abedin I. Gagani, Kristine Vegere, Ilze Kalnina, Maris Klavins, Andreas T. Echtermeyer. Dissolution Kinetics of R-Glass Fibres: Influence of Water Acidity, Temperature, and Stress Corrosion. Fibers. 2019; 7 (3):22.

Chicago/Turabian Style

Andrey E. Krauklis; Abedin I. Gagani; Kristine Vegere; Ilze Kalnina; Maris Klavins; Andreas T. Echtermeyer. 2019. "Dissolution Kinetics of R-Glass Fibres: Influence of Water Acidity, Temperature, and Stress Corrosion." Fibers 7, no. 3: 22.

Journal article
Published: 12 January 2019 in Journal of Composites Science
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Swelling in fiber-reinforced composites is anisotropic. In this work, dealing with glass fiber epoxy composite immersed in distilled water, swelling coefficients are obtained in each direction experimentally. Swelling behaviour in the fiber direction was constrained by the non-swelling fibers and was close to null, while swelling in the transverse directions was found to occur freely—similar to the unconstrained polymer. An analytical method for predicting anisotropic swelling in composites from the swelling of the matrix polymer is reported in this work. The method has an advantage that it is simple to use in practice and requires only a swelling coefficient of the matrix polymer, elastic constants of the matrix and fibers, and a known fiber volume fraction of the composite. The method was validated using finite element analysis. Good agreement was obtained and is reported between experimental hygroscopic swelling data, analytical and numerical results for composite laminates, indicating the validity of this predictive approach.

ACS Style

Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. Prediction of Orthotropic Hygroscopic Swelling of Fiber-Reinforced Composites from Isotropic Swelling of Matrix Polymer. Journal of Composites Science 2019, 3, 10 .

AMA Style

Andrey E. Krauklis, Abedin I. Gagani, Andreas T. Echtermeyer. Prediction of Orthotropic Hygroscopic Swelling of Fiber-Reinforced Composites from Isotropic Swelling of Matrix Polymer. Journal of Composites Science. 2019; 3 (1):10.

Chicago/Turabian Style

Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. 2019. "Prediction of Orthotropic Hygroscopic Swelling of Fiber-Reinforced Composites from Isotropic Swelling of Matrix Polymer." Journal of Composites Science 3, no. 1: 10.

Journal article
Published: 20 November 2018 in Open Engineering
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Fiber-reinforced polymers (FRP) are widely used in structural applications. Long-term properties of such materials exposed to water are of high concern and interest, especially for subsea and offshore applications. The objective of this study is to identify the mechanisms and to identify whether drop in properties of diamine-cured mixed DGEBA-HDDGE is reversible upon drying the material to its initial water content. The properties of interest are mechanical strength, elastic properties and fatigue performance, as well as changes in chemical structure. The effect of absorbed water on the properties of the resin is evaluated, and hygrothermal effects and aging mechanisms are discussed. Furthermore, it is shown experimentally that the tension fatigue S-N curve of a wet epoxy resin can be estimated by shifting the S-N curve of a dry material proportionally to a reduction in static tensile strength due to hygrothermal effects.

ACS Style

Andrey Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. Hygrothermal Aging of Amine Epoxy: Reversible Static and Fatigue Properties. Open Engineering 2018, 8, 447 -454.

AMA Style

Andrey Krauklis, Abedin I. Gagani, Andreas T. Echtermeyer. Hygrothermal Aging of Amine Epoxy: Reversible Static and Fatigue Properties. Open Engineering. 2018; 8 (1):447-454.

Chicago/Turabian Style

Andrey Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. 2018. "Hygrothermal Aging of Amine Epoxy: Reversible Static and Fatigue Properties." Open Engineering 8, no. 1: 447-454.

Journal article
Published: 13 October 2018 in International Journal of Fatigue
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Exposure to marine environment causes a degradation of the interlaminar shear performance of composites. This effect has been reported in several studies, but the mechanisms that lead to failure in composites subjected to cyclic loading under water exposure are still not fully understood. In this work a novel test method, the I-beam short beam shear, was used to determine shear properties and accelerate fluid saturation in glass fiber epoxy specimens. The interlaminar shear performance of the material was studied experimentally. From the analysis of the cyclic parameters recorded during the test and from optical micrographs it was possible to observe a change in failure mode between dry samples and conditioned samples. The failure of dry samples was a creep dominated effect, which led to inter-ply cracks, while the failure of conditioned samples was a damage growth dominated effect, which led to intra-ply failure. Optical micrographs showed that fiber/matrix debonding occurs in conditioned samples prior to mechanical loading, which are potential damage onset spots.

ACS Style

Abedin I. Gagani; Emeric P.V. Mialon; Andreas T. Echtermeyer. Immersed interlaminar fatigue of glass fiber epoxy composites using the I-beam method. International Journal of Fatigue 2018, 119, 302 -310.

AMA Style

Abedin I. Gagani, Emeric P.V. Mialon, Andreas T. Echtermeyer. Immersed interlaminar fatigue of glass fiber epoxy composites using the I-beam method. International Journal of Fatigue. 2018; 119 ():302-310.

Chicago/Turabian Style

Abedin I. Gagani; Emeric P.V. Mialon; Andreas T. Echtermeyer. 2018. "Immersed interlaminar fatigue of glass fiber epoxy composites using the I-beam method." International Journal of Fatigue 119, no. : 302-310.

Journal article
Published: 26 September 2018 in Composites Part A: Applied Science and Manufacturing
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Finite elements simulations of fluid diffusion for composite structures are becoming more common in marine and offshore applications. Input parameters for such simulations are the orthotropic diffusion constants for the materials. Diffusivity in fiber direction is faster than diffusivity in transverse direction; it is therefore important to determine all these constants to predict long-term fluid diffusion in composite structures. Current standards for the determination of the diffusion constants prescribe a sample geometry that enforces 1-D diffusion, but thin samples are not easy to fabricate, especially from thick laminates. Edges with metallic coatings are also prescribed, which can influence the calculation of the moisture saturation content and may detach during the experiments. Furthermore, axial symmetrical structures are often used offshore, requiring 3-D diffusion analysis in cylindrical coordinates. The aim of this paper is to provide a 3-D theory and methods for obtaining diffusion constants for plates, rods and pipes.

ACS Style

Abedin I. Gagani; Andrey Krauklis; Andreas T. Echtermeyer. Orthotropic fluid diffusion in composite marine structures. Experimental procedure, analytical and numerical modelling of plates, rods and pipes. Composites Part A: Applied Science and Manufacturing 2018, 115, 196 -205.

AMA Style

Abedin I. Gagani, Andrey Krauklis, Andreas T. Echtermeyer. Orthotropic fluid diffusion in composite marine structures. Experimental procedure, analytical and numerical modelling of plates, rods and pipes. Composites Part A: Applied Science and Manufacturing. 2018; 115 ():196-205.

Chicago/Turabian Style

Abedin I. Gagani; Andrey Krauklis; Andreas T. Echtermeyer. 2018. "Orthotropic fluid diffusion in composite marine structures. Experimental procedure, analytical and numerical modelling of plates, rods and pipes." Composites Part A: Applied Science and Manufacturing 115, no. : 196-205.

Journal article
Published: 11 September 2018 in International Journal of Solids and Structures
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Multidirectional composite laminates are often used in marine and offshore applications. Upon cyclic loading, cracks appear early in the off-axis plies and generate delaminations, which accelerate fluid diffusion. In this work, a theoretical model was developed for the prediction of fluid diffusion in laminates having cracks and delaminations. The model is based on the definition of a representative volume element subjected to Fickian diffusion. The geometry and dimensions of the representative volume element are determined by the crack density and the length of delaminations. Experiments were performed on both statically loaded samples having transverse cracks and fatigue loaded samples having transverse cracks and delaminations. The presence of delaminations increased the apparent diffusivity of the laminate by 5.4 times. The experimental results showed good agreement with the theory.

ACS Style

Abedin I. Gagani; Andreas T. Echtermeyer. Influence of delaminations on fluid diffusion in multidirectional composite laminates – Theory and experiments. International Journal of Solids and Structures 2018, 158, 232 -242.

AMA Style

Abedin I. Gagani, Andreas T. Echtermeyer. Influence of delaminations on fluid diffusion in multidirectional composite laminates – Theory and experiments. International Journal of Solids and Structures. 2018; 158 ():232-242.

Chicago/Turabian Style

Abedin I. Gagani; Andreas T. Echtermeyer. 2018. "Influence of delaminations on fluid diffusion in multidirectional composite laminates – Theory and experiments." International Journal of Solids and Structures 158, no. : 232-242.

Journal article
Published: 01 May 2018 in Marine Structures
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Carbon fiber composite plastic (CFRP) rods immersed in water present a pronounced anisotropic diffusion behavior. Understanding and predicting this behavior is important as the mechanical properties of the material are influenced by the moisture content. A simple experimental procedure allowing identification of both radial and axial diffusivity is presented. The diffusivities are calculated based on a new anisotropic analytical or numerical analysis. The diffusivity in the axial direction was found to be 14.3 times the diffusivity in radial direction. The analytical and numerical approaches show a good agreement. A practical engineering case study is also presented: the moisture content profile of a carbon fiber rod inside a cylindrical metal end fitting for long exposure times (5, 10, 25 and 50 years).

ACS Style

Abedin Gagani; Andrey Krauklis; Andreas T. Echtermeyer. Anisotropic fluid diffusion in carbon fiber reinforced composite rods: Experimental, analytical and numerical study. Marine Structures 2018, 59, 47 -59.

AMA Style

Abedin Gagani, Andrey Krauklis, Andreas T. Echtermeyer. Anisotropic fluid diffusion in carbon fiber reinforced composite rods: Experimental, analytical and numerical study. Marine Structures. 2018; 59 ():47-59.

Chicago/Turabian Style

Abedin Gagani; Andrey Krauklis; Andreas T. Echtermeyer. 2018. "Anisotropic fluid diffusion in carbon fiber reinforced composite rods: Experimental, analytical and numerical study." Marine Structures 59, no. : 47-59.

Journal article
Published: 01 May 2018 in Composites Science and Technology
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Composite structural components are often subjected to service loads that cause cracks in off-axis layers, without compromising the load bearing capability of the structure. In marine or humid environments fluid ingress in the material can be accelerated by the presence of such cracks, leading to further strength degradation. Several studies have been dealing with the effect of cracks on fluid diffusion in composites, sometimes with contradictory results. In this work the difference between cracks on the external and internal plies of the laminate has been addressed both experimentally and analytically, showing that the first ones have a strong influence on diffusivity, while the second have a negligible effect.

ACS Style

Abedin I. Gagani; Andreas T. Echtermeyer. Fluid diffusion in cracked composite laminates – Analytical, numerical and experimental study. Composites Science and Technology 2018, 160, 86 -96.

AMA Style

Abedin I. Gagani, Andreas T. Echtermeyer. Fluid diffusion in cracked composite laminates – Analytical, numerical and experimental study. Composites Science and Technology. 2018; 160 ():86-96.

Chicago/Turabian Style

Abedin I. Gagani; Andreas T. Echtermeyer. 2018. "Fluid diffusion in cracked composite laminates – Analytical, numerical and experimental study." Composites Science and Technology 160, no. : 86-96.

Journal article
Published: 11 April 2018 in Materials
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Monitoring water content and predicting the water-induced drop in strength of fiber-reinforced composites are of great importance for the oil and gas and marine industries. Fourier transform infrared (FTIR) spectroscopic methods are broadly available and often used for process and quality control in industrial applications. A benefit of using such spectroscopic methods over the conventional gravimetric analysis is the possibility to deduce the mass of an absolutely dry material and subsequently the true water content, which is an important indicator of water content-dependent properties. The objective of this study is to develop an efficient and detailed method for estimating the water content in epoxy resins and fiber-reinforced composites. In this study, Fourier transform near-infrared (FT-NIR) spectroscopy was applied to measure the water content of amine-epoxy neat resin. The method was developed and successfully extended to glass fiber-reinforced composite materials. Based on extensive measurements of neat resin and composite samples of varying water content and thickness, regression was performed, and the quantitative absorbance dependence on water content in the material was established. The mass of an absolutely dry resin was identified, and the true water content was obtained. The method was related to the Beer–Lambert law and explained in such terms. A detailed spectroscopic method for measuring water content in resins and fiber-reinforced composites was developed and described.

ACS Style

Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. Near-Infrared Spectroscopic Method for Monitoring Water Content in Epoxy Resins and Fiber-Reinforced Composites. Materials 2018, 11, 586 .

AMA Style

Andrey E. Krauklis, Abedin I. Gagani, Andreas T. Echtermeyer. Near-Infrared Spectroscopic Method for Monitoring Water Content in Epoxy Resins and Fiber-Reinforced Composites. Materials. 2018; 11 (4):586.

Chicago/Turabian Style

Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. 2018. "Near-Infrared Spectroscopic Method for Monitoring Water Content in Epoxy Resins and Fiber-Reinforced Composites." Materials 11, no. 4: 586.

Research article
Published: 03 December 2017 in Journal of Composite Materials
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Fluid diffusion in fiber reinforced composites is typically anisotropic. Diffusivity in the fiber direction is faster than in the transverse direction. The reason for this behavior is not yet fully understood. In this work, dealing with glass fiber epoxy composite immersed in distilled water, an experimental procedure for determination of anisotropic diffusion constants from a laminate is presented. The method has the advantage that it does not require sealing of the samples edges because 3-D anisotropic diffusion theory is implemented for obtaining the diffusion constants. A microscale model is presented, where matrix and fiber bundles are modeled separately. The matrix properties have been obtained experimentally and the fiber bundle properties have been deduced by the composite homogenized diffusivity model. The analysis indicates that the anisotropic diffusion of the composite is due to inherent anisotropic properties of the fiber bundles.

ACS Style

Abedin Gagani; Yiming Fan; Anastasia H Muliana; Andreas T Echtermeyer. Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites. Journal of Composite Materials 2017, 52, 2321 -2335.

AMA Style

Abedin Gagani, Yiming Fan, Anastasia H Muliana, Andreas T Echtermeyer. Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites. Journal of Composite Materials. 2017; 52 (17):2321-2335.

Chicago/Turabian Style

Abedin Gagani; Yiming Fan; Anastasia H Muliana; Andreas T Echtermeyer. 2017. "Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites." Journal of Composite Materials 52, no. 17: 2321-2335.

Chapter
Published: 19 September 2017 in Internal Variables in Thermoelasticity
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Fibre-reinforced plastics are praised for their good corrosion resistance. However, when this resistance needs to be documented for safety-critical applications extensive and time-consuming test programmes are needed. A better quantitative understanding of the fundamental mechanisms behind degradation should help to reduce the testing effort. A multiscale approach for modelling degradation in water and hydrocarbons is described. The environmental degradation happens on the scale of the constituent materials: fibres, matrix and sizing (interface). Local concentration profiles of the fluid inside the material need to be known to predict degradation. The global engineering properties are then calculated from the constituents using finite element analysis and homogenisation. Describing degradation with the multiscale approach is a promising method for reducing the current test effort. Much more work is needed to create enough confidence in the models that then can be used for designing real components. The first steps are described here showing the models and how they can be connected.

ACS Style

Andreas T. Echtermeyer; Abedin Gagani; Andrejs Krauklis; Tobiasz Mazan. Multiscale Modelling of Environmental Degradation—First Steps. Internal Variables in Thermoelasticity 2017, 244, 135 -149.

AMA Style

Andreas T. Echtermeyer, Abedin Gagani, Andrejs Krauklis, Tobiasz Mazan. Multiscale Modelling of Environmental Degradation—First Steps. Internal Variables in Thermoelasticity. 2017; 244 ():135-149.

Chicago/Turabian Style

Andreas T. Echtermeyer; Abedin Gagani; Andrejs Krauklis; Tobiasz Mazan. 2017. "Multiscale Modelling of Environmental Degradation—First Steps." Internal Variables in Thermoelasticity 244, no. : 135-149.

Review
Published: 01 April 2016 in American Journal of Engineering and Applied Sciences
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Fracture of the breakable isostatic graphite is concerned using the experimental and theoretically, the plates containing nicks holes key subject to varying degrees of mixed task. The main purpose of this work is a double one. In the first place, in order to offer a new set of experimental results on fracture of samples of graphite scored, with different values of the load mixed and radii notch and which may be helpful for researchers, as it enlarges the very limited data available; and secondly, to provide a criterion fracture of the polycrystalline graphite under the conditions mentioned above. The main purpose of this work is to offer a new set of experimental results (70 new data) on the fracture of the samples of the loose graphite of key holes, the different values of mixed loading, the tilt angle and radii notch and which may be of help as widens the very limited data available. By using the value of the average density of the stem of energy in a well defined, a criterion of fracture of the polycrystalline graphite under the conditions referred to above, it is proposed to predict the static resistance of the samples taken into account. The third part of the work deals with the analysis of the direction of initiation of fracture and spread of the crack in the early. The average value of the stem density of energy in a well defined is used to predict the static resistance of the samples taken into account. Good agreement is found between the experimental data for the tasks critical failure and the theoretical predictions based on average constant strain density of energy on the volume of the material.

ACS Style

Filippo Berto; Abedin Gagani; Relly Victoria V. Petrescu; Florian Ion T. Petrescu. Key-Hole Notches in Isostatic Graphite: A Review of Some Recent Data. American Journal of Engineering and Applied Sciences 2016, 9, 1292 -1300.

AMA Style

Filippo Berto, Abedin Gagani, Relly Victoria V. Petrescu, Florian Ion T. Petrescu. Key-Hole Notches in Isostatic Graphite: A Review of Some Recent Data. American Journal of Engineering and Applied Sciences. 2016; 9 (4):1292-1300.

Chicago/Turabian Style

Filippo Berto; Abedin Gagani; Relly Victoria V. Petrescu; Florian Ion T. Petrescu. 2016. "Key-Hole Notches in Isostatic Graphite: A Review of Some Recent Data." American Journal of Engineering and Applied Sciences 9, no. 4: 1292-1300.