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Cemented soil commonly faces issues regarding strength, cracking resistance, and water stability when used in airstrip pavements. Three kinds of soil samples (low-liquid limit clay, high-liquid limit clay, and clayey sand), four kinds of fibers (basalt fiber, glass fiber, fine polypropylene fiber, and coarse polypropylene fiber), and one curing agent (cement) were analyzed in a systematic investigation of the compressive strength of fiber-reinforced cemented soil based on unconfined compressive strength (UCS), water stability, and failure mode. When 38 mm coarse polypropylene fiber at 0.3% content was mixed with 12 mm fine polypropylene fiber at 0.3% content, the hybrid fiber-reinforced cemented soil prepared after 7 d of saturated curing achieved UCS values of 4.18 (low-liquid limit clay), 4.36 (high-liquid limit clay), and 4.16 MPa (clayey sand), which satisfied airstrip requirements for the strength of base course. In this study, coarse polypropylene fiber was adopted and mixed with fine fiber to give full play to their respective advantages and effectively enhance the mechanical properties of cemented soil. The research results improved the understanding of the mechanical properties and reinforcement mechanism of coarse and fine fiber reinforced cemented soil in theory, and enriched the materials and methods of airstrip construction in engineering. [ABSTRACT FROM AUTHOR]

This laboratory study investigates the feasibility of using geopolymer-based stabilization of base soil and reclaimed asphalt pavements (RAP) to fully replace cement in road rehabilitation projects. Geopolymer is an environment-friendly material that is based on the alkaline activation of aluminosilicate precursors. The performance of Portland cement as a chemical stabilizer for the full depth reclamation (FDR) of asphalt pavements is well established. However, Portland cement manufacturing has a high carbon footprint and other significant environmental impacts. Furthermore, there is a shortage of cement available for FDR projects across many country regions. Simultaneously, there is a strong motivation to explore various industrial wastes such as ponded ash, slag, ground glass fibers, etc., as replacements for Portland cement in construction. Therefore, a geopolymer based on ground glass fibers (GGF), either separately or combined with ponded fly ash (PFA) or slag (S), was studied to replace cement in FDR. All mixtures were tested for unconfined compressive strength (UCS), flexural strength, and drying shrinkage, wetting/drying, freezing/thawing, and tube suction tests. The results showed promising performance of geopolymer-based stabilized mixtures as compared to control. However, some test methods related to FDR with cement need to be modified to suit the mixtures of FDR with geopolymer. [ABSTRACT FROM AUTHOR]

In order to improve the performance of desert sand concrete, polypropylene fiber (PF) and glass fiber (GF) were used to prepare desert sand concrete (DSC) with different fiber and volume content, and the basic mechanical properties, such as cube compressive, tensile and flexural strengths, were tested and studied. Based on the mercury injection method (MIP) and scanning electron microscopy (SEM), the evolution of pore structure and interface structure was analyzed. The mechanism of fiber toughening was revealed at the microscopic level. The results show that the slump of DSC decreases with the increase in fiber content. The slump of glass-fiber-reinforced DSC (GFRDSC) is smaller than that of polypropylene-fiber-reinforced DSC (PFRDSC). The strength enhancement of DSC by fibers is in the order of flexural strength > split tensile strength > compressive strength. The flexural strength of hybrid-fiber-reinforced DSC (HyFRDSC) (0.1% PF + 0.1% GF) is increased by 40.7%. Meanwhile, fibers can improve the toughness of DSC. The MIP results show that the porosity of HyFRDSC decreased by 50.01%, and the addition of fiber can effectively refine the large pore size. The SEM results show that the incorporation of PF and GF causes the formation of a uniform and dense structure between the fibers, cement and aggregate. The two can give full play to the crack-resisting and toughening effect in different loading stages, thus improving the macromechanical properties of DSC. [ABSTRACT FROM AUTHOR]

This paper focuses on the development of thin-walled panels with specific properties for applications such as water-tight structures. The authors propose the use of textile-reinforced concrete (TRC) as a composite material and highlight its advantages, which include high tensile strength, improved crack resistance, and design flexibility. The study presents a novel approach which combines TRC with reactive powder concrete (RPC) as a matrix and a lightweight aggregate. RPC, known for its brittle behaviour, is reinforced with glass fibres and a textile fabric to increase its flexural strength. The research includes a comprehensive analysis of the physical and mechanical properties of both the unreinforced RPC matrix and the TRC composite. In particular, the lightweight aggregate RPC matrix has a porosity of 41%, and its mechanical properties, such as flexural and compressive strength, are discussed. The TRC composites, produced in thicknesses ranging from 1 mm to 4 mm, are subjected to flexural tests to evaluate their behaviour under load. The thicker elements show typical damage phases, while the thinner elements show greater flexibility and elasticity. SEM observations confirm good adhesion between the glass fibres and the RPC matrix. Water permeability tests show that the TRC composite, despite its highly porous structure, achieves a water permeability two orders of magnitude higher than that of a reference material, highlighting the roles of both the porous aggregate and the matrix hydration. The paper concludes with a proof of concept—a canoe called the PKanoe, which is constructed from the developed TRC composite. The design of the canoe is supported by numerical analysis to ensure its optimal shape and structural integrity under load. The research contributes to the exploration of innovative materials for sustainable civil engineering applications and addresses both structural and environmental considerations. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive analysis of emission in erbium-doped and erbium and ytterbium co-doped fluoroindate glasses has been presented. The luminescence of the erbium transitions and the effect of ytterbium co-doping under 488, 808 and 976 nm laser excitation have been discussed. Optimization of rare-earth (RE) ions doping concentration and the energy transfer processes related to the sensibilization effect in Er3+/Yb3+ co-doped fluoroindate glasses focusing on the reciprocal distribution of radiative transitions, energy transfer parameters, and lifetimes have been analyzed. The luminescence consists of several bands in the visible (525, 546 and 660 nm) and the infrared (1550 and 2700 nm) spectral regions that correspond to characteristic radiative energy transitions within the erbium ions. In glasses co-doped with the Er3+/Yb3+ system, an augmentation in the emission intensity was observed in the visible and at 1550 nm, while a decrease was observed in the 2700 nm infrared band. The increase of the Yb3+: 2F 5/2 lifetime under 488, 808 and 976 nm excitation showed significant Er3+: 4I 11/2 → Yb3+: 2F 5/2 back energy transfer. Based on the analysis of the available literature, it can be concluded that energy transfer upconversion and cooperative energy upconversion play a significant role in modulating luminescence intensity values within the examined emission bands. This effect is likely enhanced due to the incorporation in a low phonon energy glass matrix. As a result of the above optimization, a glass optical fiber co-doped with 0.8 YbF 3 /1.4 ErF 3 (in mol%) was drawn and characterized, showing a strong emission at 2.77 μm. The optimized Er3+/Yb3+ co-doped fluoroindate glass and glass optical fiber confirmed their ability to be used in the visible and near-infrared spectral regions as efficient optical fiber sources. [ABSTRACT FROM AUTHOR]

In this contribution a comprehensive spectroscopic study of Dy3+ doped fluoroindate glass samples and glass fiber is presented. The mid-infrared (MIR) emission from DyF 3 doped bulk glass samples (0.2, 0.4, 0.8, 1.2, 1.4, 1.6 mol.%) is investigated when pumping at 1320 nm. A broadband mid-infrared emission spanning from 2800 nm to 3500 nm with 0.88 ms emission lifetime of the 6H 13/2 level in 0.2 mol.% glass sample was observed. Also 0.2 mol.% of DyF 3 doped fluoroindate glass fiber was drawn and its photoluminescence properties were studied showing the emission spectrum to 3500 nm and the 6H 13/2 level lifetime of 0.91 ms. The results obtained show that fluoroindate glass is a good candidate for further development of tunable fiber lasers and broadband mid-infrared spontaneous emission fiber sources. [ABSTRACT FROM AUTHOR]

Fast preparation of Fe precisely regulated 3D dandelion spore-like Fe 1 -Ni 1 P@GF self-supported electrode by one-step mild electroless plating for efficient ultra-stable overall water splitting at ultra-high current density in harsh environments such as quasi-industrial conditions (6.0 M KOH + 0.5 M NaCl), high salt (1.0 M KOH + 3.0 M NaCl) and simulated domestic wastewater (1.0 M KOH + 0.5 M urea). [Display omitted] • Successful preparation of large-size, robust and stable Fe 1 -Ni 1 P@GF bifunctional catalytic electrodes with Fe element precisely regulated by one-step mild electroless plating on corrosion-resistant glass fiber surface. • The precise regulation of Fe improves the electronic conductivity and charge transfer capability, significantly reduces the overpotential, and promotes the generation of OER active materials. • Fe 1 -Ni 1 P@GF not only has excellent electrocatalytic activity, but also has long-term stability in extreme environments such as quasi-industrial conditions, simulated domestic wastewater and high salt. Construction of ultra-stable, flexible, efficient and economical catalytic electrodes is of great significance for the seawater electrolysis for hydrogen production. This work is grounded in a one-step mild electroless plating method to construct industrial-grade super-stable overall water splitting (OWS) catalytic electrodes (Fe 1 -Ni 1 P@GF) by growing loose and porous spore-like Fe 1 -Ni 1 P conductive catalysts in situ on flexible glass fibre (GF) insulating substrates with precise elemental regulation. Cost-effective Fe regulation boosts the electronic conductivity and charge transfer ability to achieve the construction of high intrinsic activity and strong electron density electrodes. Fe 1 -Ni 1 P@GF exhibits remarkable catalytic performance in hydrogen and oxygen evolution reaction (HER and OER), providing current densities of 10 mA cm−2 for HER and 100 mA cm−2 for OER at overpotentials of 51 and 216 mV, respectively. Moreover, it achieves 10 mA cm−2 at 1.42 V for OWS, and exhibits stable operation for over 1440 h at 1000 mA cm−2 in quasi-industrial environment of 6.0 M KOH + 0.5 M NaCl, without any performance degradation. This strategy enables the preparation of universally applicable P-based electrodes (ternary, quaternary, etc.) and large-area flexible electrodes (paper or cotton), significantly expands the practicality of the electrodes and demonstrating promising potential for industrial applications. [ABSTRACT FROM AUTHOR]

Basalt fibres are gaining interest in the fibre-reinforced thermoplastic industries around the world. In this work, basalt and glass short fibres reinforced polypropylene composites were produced using twin-screw extrusion and followed by injection molding. To carry out a comprehensive study on physical and mechanical properties, the composites were produced with different proportions of fibre loadings (for both fibres 5, 10, and 20 wt %). Composites were characterized and studied for tensile (at different strain rates), flexural (at different speeds), impact, dynamic mechanical analysis, density, tensile-relaxation, melt flow index test, and rheometric properties. Results indicate that tensile, flexural, dynamic mechanical analysis, and tensile-relaxation properties increased with increasing fibre proportions in the polypropylene matrix. The melt flow and rheometric behaviors of polypropylene decreased significantly with the addition of short fibres into the matrix. The overall results showed that basalt fibres can be potentially used as replacements for glass fibre to develop these thermoplastic composites. [ABSTRACT FROM AUTHOR]

The heat resistance of adhesive joints of SVM heterocyclic aramid fibers and cyanoacrylate glue has been studied based on the adhesion failure temperature in an adhesion cell formed by a loop tightened into a knot. For the first time, data on the heat resistance of adhesive joints of fibers with a polymer matrix under static load with constant shear stress have been obtained. Using the example of two types of glue, the influence of filler in the glue and fibers on the glass transition temperature of polycyanoacrylate and the heat resistance of the adhesive joint is shown. The activation energy of adhesion failure was calculated, and the dependence of the thermal stability of the adhesive joint on the shear stress was shown to be of the Arrhenius type. [ABSTRACT FROM AUTHOR]

Lunar glasses with different origins act as snapshots of their formation processes, providing a rich archive of the Moon's formation and evolution. Here, we reveal diverse glasses from Chang'E-5 (CE-5) lunar regolith, and clarify their physical origins of liquid quenching, vapor deposition and irradiation damage respectively. The series of quenched glasses, including rotation-featured particles, vesicular agglutinates and adhered melts, record multiple-scale impact events. Abundant micro-impact products, like micron- to nano-scale glass droplets or craters, highlight that the regolith is heavily reworked by frequent micrometeorite bombardment. Distinct from Apollo samples, the indigenous ultra-elongated glass fibers drawn from viscous melts and the widespread ultra-thin deposited amorphous rims without nanophase iron particles both indicate a relatively gentle impact environment at the CE-5 landing site. The clarification of multitype CE-5 glasses also provides a catalogue of diverse lunar glasses, meaning that more of the Moon's mysteries, recorded in glasses, could be deciphered in future. [ABSTRACT FROM AUTHOR]

Orthotropic rectangular plates, featuring central cutouts and subjected to in-plane loading, are extensively employed across various engineering fields, including mechanical, automobile, aerospace, and marine. The introduction of a cutout inevitably leads to stress concentration within the plate. Incorporating carbon nanotubes (CNTs) into the polymer matrix composite has been noted to induce significant heterogeneity in stress fields. Functioning as bridges between the fibers and the matrix, CNTs can effectively mitigate stress concentration and enhance the damage tolerance of the composite. However, accurately determining stress concentration in CNT-based composites requires comprehensive understanding of the geometric discontinuity edge and well-defined evaluation techniques. Among these, the finite element method emerges as a straightforward yet precise approach for studying stress concentration around geometric discontinuities. The present work harnesses the finite element method to investigate stress concentration in CNT-based multiscale composite plates (Glass Fiber/CNT/Epoxy) with central cutouts under static in-plane loading. To validate the model, the derived results are compared with analytical data from conventional composite materials. Moreover, the impact of cutout size on stress concentration is examined for three distinct configurations: plates with a central circular cutout, plates with an elliptical central cutout (major axis in the longitudinal direction), and plates with an elliptical central cutout (major axis in the transverse direction). Preliminary findings suggest a correlation between increased cutout size and augmented percentage reduction in stress concentration. Notably, the maximum percentage reduction in stress concentration is observed in the case of plates hosting an elliptical cutout at the center with the major axis aligned in the transverse direction. [ABSTRACT FROM AUTHOR]

A variety of 3D printing parameters have been investigated including reinforcement material and print orientation, as well as reinforcement pattern, distribution and volume. From these evaluated parameters, the optimal values are taken into account to select the highest compressive properties. By using Scanning Electron Microscopy (SEM) imaging, reinforcement and thermoplastic layers have been clearly identified alongside sample flaws. Horizontally printed samples exhibited higher mean values with less standard deviation than vertically printed ones for compressive modulus and compression strength. For the sample set with the Nylon and carbon fibre; concentric and isometric fill patterns were compared in three different fibre distributions. Concentric fill pattern with equidistantly fibre distribution exhibited the highest compressive modulus as 1.8 GPa. It also exhibited a higher proportional limit of 12.80% and compressive modulus of 11.64% than its counterpart with the isometric fill pattern. For the set with 12.5% fibre volume, Onyx + CF (matrix + reinforcement) exhibited higher compressive modulus and compressive strength than Nylon + CF by 18.5%, and 28.1%, respectively. Within the experimental set of different reinforcements (carbon fibre, Kevlar, fibreglass), and different fibre volumes (6.25%, 12.5%, 25%) with Onyx matrix; Onyx thermoplastic with fibreglass reinforcements and a fibre volume of 25% exhibited the highest compressive properties. [ABSTRACT FROM AUTHOR]

Aluminium oxide was designed and synthesised with three different diamines, including production and/or diamino diphenyl sulfoxide, as well as p-phenylenediamine, to improve the adhesion properties of lightweight carbon composites. For 3-ply composite production, manual lay-up was utilised as a straightforward process. The fibre content ratios of 30:70 with fibre inclinations of 0, 45 and 90 degrees were employed in sample processing. Both Al2O3 and many fibre layers were first distributed in the epoxy coating and then the Al2O3 and carbon-strengthened epoxy were immediately inserted into that same carbon fibre to increase the mechanical properties. The Al2O3 and fibre glass compositions ranged from 0.1 to 0.5%wt. The mechanical qualities of hybrid composites are found to be primarily determined by the kind of derivatization, followed by the proportion of altered Al2O3. As a consequence, the Al2O3 additive dramatically improves both flexural and tensile forces. Because of Al2O3 good mechanical properties, both tensile strength and flexural strength and elastic modulus are boosted by Al2O3 filling inside the adhesives. [ABSTRACT FROM AUTHOR]

This experimental study aims to create innovative hybrid composites (HCs) for aerospace applications using the hand lay-up technique. Different volume fractions (Vf%) of distinctive natural (white clay (W) and red clay (R)) and synthetic (alumina (A) and woven glass fibers (E-GFW) reinforcing unsaturated polyester (UP). The mechanical and physical characterizations of these innovative HCs were estimated according to the American Society for Testing and Materials (ASTM) standards. The findings show that adding more white clay, red clay, and alumina to the HCs makes a big difference in improving their mechanical properties, such as Hardness Shore D (HSD), True Tensile Strength (Ttσ), Impact Strength (iσ), and Fracture Toughness (Kc). Analysis of variance (ANOVA) revealed noteworthy variations in the assessed parameters, emphasizing the potential suitability of these materials for aeronautical applications. This research contributes to the ongoing progress in material engineering, specifically in enhancing the mechanical resilience of composites utilized in the aerospace industry. [ABSTRACT FROM AUTHOR]

The natural and synthetic fibers are combined in a single composite to achieve a balance between the desired strength and cost considerations. In this study, the vacuum resin transfer moulding process was used to prepare an epoxy‐based composite. The composite consisted of grewia optiva as the natural fiber and glass fiber as the synthetic fiber, both with a fixed weightage of 10 %. Dolomite was used as a filler with varying content (0 %, 5 %, 10 %, and 15 weight %). The physical, mechanical, erosion wear and morphological behavior of the epoxy‐based composite were investigated. The inclusion of dolomite filler significantly increased the composite hardness and impact strength but reduced its tensile and flexural strength. At a dolomite filler content of 10 weight %, the erosive wear was reduced, while it increased at higher dolomite filler contents. The composite was examined using the L16 array, and the minimum wear rate was observed at an impingement angle of 30°, a velocity of 10 m/s, and an erodent size of 150 μm. Morphological studies were conducted to explore the possible mechanism for the variation in erosive wear at different dolomite contents in the hybrid composites. [ABSTRACT FROM AUTHOR]

Optimizing the mechanical characteristics of cemented tailings backfill (CTB) and quickly identifying its damage state under external loading, this study compares and prepares CTB specimens without fiber, doped with polypropylene fiber (PF), doped with glass fiber (BL), and doped with polypropylene and glass blended fiber (PB). Uniaxial compression and acoustic emission (AE) monitoring experiments are also conducted. Based on the cumulative energy of AE, the damage ontology model of CTB was developed. As shown by the study's findings, adding various fibers can greatly enhance the filler body's uniaxial compressive strength (UCS). BL has the greatest effect, followed by PB, while PFs have the least effect. Furthermore, the fibers primarily prevent the growth of crack extension by extending or breaking themselves, The results of the tests on acoustic emission revealed that the fiberless filler's signals were more active prior to the peak point and less intense in the later stages of the damage, whereas the fiber-doped filler's signals began to increase following the peak point and remained high. Thus, the damage model curves of various fiber-filled bodies are constructed based on the cumulative energy of acoustic emission, and the experimental data verification shows that the two have good consistency, suggesting that the established theoretical model can serve as a basis of reference for assessing the filled bodies' damage state. [ABSTRACT FROM AUTHOR]

The usability of glass fibers as immobilization support with a porous open structure was investigated. We developed a method to immobilize the enzyme β-galactosidase on special glass fiber rolls. The new method is simple, non-expensive and industrially applicable. Glutaraldehyde was used as a non-specific cross-linking agent for the covalent binding of β-galactosidase on modified glass fibers. The efficiency of immobilization was tested with the known hydrolysis of lactose. All experiments were performed in a continuous laboratory reactor. The influence of the reaction temperature (20, 25 and 30 °C), the substrate flow rate (1, 2 and 3 mL/min) and the pH of the reaction medium (6, 7 and 8) on the conversion was investigated. The reaction efficiency was monitored by measuring the glucose concentration with a spectrophotometer. High immobilization efficiency, enzyme activity and stability were obtained. The optimal reaction temperature, substrate flow rate and pH were found. The activity and stability of the enzyme entrapped on the glass fiber rolls remained almost unchanged during reuse, which is promising for potential industrial applications. [ABSTRACT FROM AUTHOR]

Different types of additives are used in asphalt modification to enhance several properties within the asphalt pavement. In various cases, modification is needed by using multiple additives, which is called composite modification. In this study, glass fibre and nano clay were used to modify the asphalt pavement. The amount of these two additives, together with the optimum bitumen content, was determined by the response surface methodology (RSM). Central composite method (CCD) was used for determining the optimum amount of independent variables (nano clay, glass fibre, bitumen content), by evaluating the dependent variables. Marshall mixture design criteria and minimum bitumen content, were the optimal conditions. As a result, the mixture containing 0.2% glass fibre, 3.693% nano clay and 4.096% bitumen content, was predicted to give the most desirable characteristics. Additionally, verification tests were conducted to evaluate the adequacy of the predicted model. The results were within the 95% confidence intervals for all response variables, which demonstrates the validity of the model obtained in the study. Consequently, CCD can be used to obtain design optimisation of asphalt modification with less mixture production for experimental stages. This is a substantial advantage, which supports human safety and environment- friendly practices. [ABSTRACT FROM AUTHOR]

Silica, a principal component of waste glass powder (GP) reacts with calcium hydroxide to form the hydration products, and the process is affected by the fineness of GP and the percentage of cement replaced. This study investigates the structural behavior of concrete incorporating GP in reinforced concrete members by 0%–25% (by weight) replacement of cement with GP along with 0%–0.45% addition of glass fibers (GFs). The compressive and tensile strengths, strength activity index (SAI), and failure mode of treated concrete mixtures have revealed the optimum values as 15% replacement of cement with GP with 0.3% of GF. In the second stage of experiment, reinforced concrete beams were cast at various percentages of GP and GF to investigate the load–deflection response. It was observed that the beam specimen treated with GP exhibited considerably less mid‐span deflection (14.8 mm) at failure as compared to the control beam (with no GP and GF) which failed at 29.4 mm. The beam specimen treated with GP only showed significant degradation in stiffness after the peak load due to the fact that a part of GP remains unreacted and acts as a filler. Moreover, the beam specimen cast at optimum percentages of GP (15%) and GF (0.3%) showed large mid‐span deflection and higher failure load as compared to the control beam. These results suggest that the partial replacement of cement with GP should be accompanied by the addition of fibers to avoid unwanted brittle responses of GP concrete, with the additional advantage of reducing the non‐biodegradable waste. [ABSTRACT FROM AUTHOR]

The development of fifth‐generation technology has resulted in increased demand for materials with low dielectric losses and superior thermal and mechanical properties. However, ensuring the widespread use of such materials by investigating their aging mechanisms and operating lifetimes remains challenging. In this study, a glass‐fiber (GF)‐reinforced acrylate‐styrene‐acrylonitrile/polycarbonate (ASA/GF/PC) composite is designed and comprehensively investigated its aging behavior, mechanism, and service lifetime under long‐term hygrothermal conditions. Based on the general Peck model, the composite maintains a high level of quality for over 10 years, including under harsh conditions of 40 °C and 80% relative humidity. The aging mechanism is primarily ascribed to cracking between the GF fibers and matrix, the breaking of chemical bonds, the generation of new cross‐linked domains, and physical aging. These findings provide valuable insights into the long‐term utilization of ASA/GF/PC composites in harsh environments. [ABSTRACT FROM AUTHOR]

Y-shaped sealing rings of a 140-MPa cage throttle valve were studied at temperatures of − 46 °C, 25 °C, and 180 °C. First, we determined the constitutive model parameters of the ring materials (polytetrafluoroethylene (PTFE), PTFE with 5% carbon fiber, PTFE with 5% carbon fiber and 5% glass fiber, PTFE with 10% carbon fiber (10C-PTFE), and PTFE with 10% carbon fiber and 10% glass fiber) at three temperatures through uniaxial tensile testing. Next, we investigated the influence of interference, lip front angle, and lip back angle on sealing performance and determined the maximum von Mises stresses and maximum contact stresses of the inner and outer lips. Based on those results, 10C-PTFE was established as the best material for Y-shaped sealing rings. A sealing ring with an interference of 0.25 mm, a lip front angle of 75°, and a lip back angle of 16° can simultaneously meet the sealing requirements at all three temperatures and has the best sealing performance. Finally, the obtained optimal sealing ring parameters were used to produce sealing parts, and a testing device was designed to complete the PR1 (Performance Requirements 1) testing. The testing results show that the Y-shaped sealing ring developed here can achieve 140-MPa sealing capability at − 46 °C, 25 °C, and 180 °C with qualified sealing performance. [ABSTRACT FROM AUTHOR]

This paper presents experimental results on the behavior of a class of glass fiber composites under low velocity impacts, in order to analyze their usage in designing low velocity impact-resistant components in car and marine industries. Also, a finite element model at the meso level (considering yarn as a compact, homogenous and isotropic material) was run with the help of Ansys Explicit Dynamics in order to point out the stages of the failure and the equivalent stress distribution on the main yarns in different layers of the composite. The composites were manufactured at laboratory scale via the laying-up and pressing method, using a quadriaxial glass fiber fabric (0°/+45°/90°/−45°) supplied by Castro Composites (Pontevedra, Spain) and an epoxy resin. The resin was a two-component resin (Biresin® CR82 and hardener CH80-2) supplied by Sika Group (Bludenz, Austria). The mass ratio for the fabric and panel was kept in the range of 0.70–0.77. The variables for this research were as follows: the number of layers of glass fiber fabric, the impact velocity (2–4 m/s, corresponding to an impact energy of 11–45 J, respectively) and the diameter of the hemispherical impactor (Φ10 mm and Φ20 mm) made of hardened steel. The tests were performed on an Instron CEAST 9340 test machine, and at least three tests with close results are presented. We investigated the influence of the test parameters on the maximum force (Fmax) measured during impact, the time to Fmax and the duration of impact, tf, all considered when the force is falling to zero again. Scanning electron microscopy and photography were used for discussing the failure processes at the fiber (micro) and panel (macro) level. At a velocity impact of 2 m/s (corresponding to an impact energy of 11 J), even the thinner panels (with two layers of quadriaxial glass fiber fabric, 1.64 mm thickness and a surface density of 3.51 kg/m2) had only partial penetration (damages on the panel face, without damage on panel back), but at a velocity impact of 4 m/s (corresponding to an impact energy of 45 J), only composite panels with six layers of quadriaxial fabric (5.25 mm thickness and a surface density of 9.89 kg/m2) presented back faces with only micro-exfoliated spots of the matrix for tests with both impactors. These results encourage the continuation of research on actual components for car and naval industries subjected to low velocity impacts. [ABSTRACT FROM AUTHOR]

Thin-walled and thick-walled microcellular moldings were obtained by MuCell® technology with nitrogen as a supercritical fluid. 2 mm thick polyamide 6 (PA6) with 30% wt. glass fiber (GF) samples were cut from automotive industrial elements, while 4 mm, 6 mm, and 8.4 mm thick moldings of PA6.6 with 30% wt. GF were molded into a dumbbell shape. The internal structure was investigated by scanning electron microscopy (SEM) and X-ray computed microtomography (micro-CT) and compared by numerical simulations for microcellular moldings using Moldex3D® 2022 software. Young's modulus, and tensile and impact strength were investigated. Weak mechanical properties of 2 mm thick samples and excellent results for thick-walled moldings were explained. SEM pictures, micro-CT, and simulation graphs revealed the tendency to decrease the cell size diameter together with increasing sample thickness from 2 mm up to 8.4 mm. [ABSTRACT FROM AUTHOR]

Composites are materials that are widely used in industry, including yachting, railway and aviation. The properties of these materials can be modified by changing the type of reinforcement, the type of matrix, as well as the use of additives in the form of fillers and nanofillers that improve their mechanical or specific parameters. Due to the fact that these materials are often used for important structures, computational models using FEM tools may not be sufficient to determine the actual strength parameters, and what is more, to check them during operation. When designing structures made of composite materials, it is necessary to use high safety factors due to their behavior under several different types of loads, which is still difficult to determine precisely. This situation makes these structures much heavier and characterized by much higher strength properties than those that would actually be needed. In this article, the Kolmogorov-Sinai (K-S) metric entropy was used to determine the transition from the elastic to the viscoelastic state in GFRP (glass fiber reinforced polymer) composite materials without and with the addition of nanoaluminum, during a static tensile test. Additionally, the acoustic emission method was used during the research. This signal was further processed, and graphs were made of the number of events and the amplitude as a function of time. The obtained values were plotted on tensile graphs. The influence of the nano-filler on these parameters was also analyzed. The presented results show that it is possible to determine additional parameters affecting the strength of the structure for any composite materials. [ABSTRACT FROM AUTHOR]

The potential benefits of using zinc borate powder as filler material in the production of glass fiber‐reinforced composites were explored in this study. The epoxy matrix was filled with zinc borate powder at 5%, 10%, and 15% by weight, as part of the hand lay‐up approach followed by a compression molding process. Ultrasonication was used to mix the epoxy resin with zinc borate fillers. Both the elemental composition and morphological characteristics were studied using a scanning electron microscope and energy‐dispersive X‐ray analysis. The composite's density, tensile behavior, flexural behavior, impact resistance, and hardness were all measured experimentally. The potential incorporation of zinc borate particles resulted in a modest reduction in the void contents, in addition to enhancing the interfacial bonding in glass fiber‐reinforced composites as also a significant improvement in both the mechanical and thermal properties of the hybrid composites produced. The 10 wt.% zinc borate‐ filled glass fiber‐reinforced composites exhibited a significant rise in both ultimate tensile strength (227 MPa), ultimate compressive strength (239 MPa), and ultimate flexural strength (406 MPa) compared to the unfilled counterpart. The performance of the laminated composites was greatly improved by adding zinc borate powder particles to the matrix. Highlights: In the present work glass fiber was reinforced with zinc borate to explore the morphological, mechanical, and thermal properties.Ultrasonication was used to mix the epoxy resin and zinc borate fillers and the composites were manufactured by compression molding process.The addition of zinc borate resulted in an increase in tensile strength, flexural strength, and compressive strength.The thermal stability of the composites was increased by the addition of zinc borate to the glass matrix.The good bonding between the matrix and fiber resulted in improvements in various properties. [ABSTRACT FROM AUTHOR]

Composite laminates have found extensive application in various industries, and numerous studies have been conducted to investigate their behavior in flat sheet configurations. The present study aims to extend this research by examining the behavior of convex composite specimens subjected to high velocity impact (HVI), and comparing their energy absorption and failure area to that of flat sheets made of glass fibers. Additionally, we seek to investigate the influence of curvature diameter on the energy absorption and fiber failure percentage of the composite specimens. Four series of composite laminates with distinct geometries, comprising a flat specimen and three convex composite specimens, were fabricated with nine layers each and diameters of 10, 15, and 20 cm. All specimens were fully clamped and subjected to empirical gas gun impact tests at three different velocities of 200, 250, and 300 m/s. The velocity values before and after the impact were measured using velocity sensors, and the energy absorption of the laminates was computed. Of the tested composite specimens, those with smaller diameters and greater curvature exhibited reduced fiber damage percentage and increased energy absorption. Compared to the flat specimens made of glass fibers, the convex specimens with a diameter of 10 cm exhibited an energy absorption increase of approximately 47%, while the specimens with diameters of 15 and 20 cm showed approximately energy absorption increases of 42% and 7%, respectively. The results were confirmed through simulation using finite element software ABAQUS/Explicit. Highlights: Curved E‐glass laminates studied under high velocity impact which is done experimentally and numerically.Convexity increases energy absorption capacity of E‐glass reinforced epoxy composites.The results show that convexity can absorb more energy compared to flat panels.The damaged area of curved laminates are smaller than the flat one.The findings suggest that convexity can be a useful design feature for improving impact resistance in various applications. [ABSTRACT FROM AUTHOR]

In this work, the effect of the kind of reinforcement on the sliding wear performance of a polyester matrix composite reinforced with glass fiber and pineapple leaf fiber is investigated. The purpose of this study is to ascertain the effects of the type of reinforcement on the sliding wear performance of a polyester matrix composite reinforced with glass fiber and pineapple leaf fiber. By using hot press molding and the 30% weight fraction of fiber reinforcement, polyester composites with four distinct compositions—PPP, GGG, PGP, and GPG—have been created. These composites' dry sliding wear experiment is carried out using a Pin on Disc wear testing device. The following parameters are used in experiments: a track radius of 50 mm, a sliding distance (SD) of 500 m, an applied load of 50, 70, or 90 N, and a sliding velocity of 3.14, 4.71, or 6.28 m s−1. For dedicated (PPP, GGG) and hybrid (PGP, GPG) polyester composites, the effects of load, sliding velocity (SV), and wear rate (WR) are studied. At 50 N and 3.14 m s−1 the COF for PPP and GGG dedicated composites is 0.68 and 0.70, respectively, whereas for PGP and GPG hybrid composites, it is 0.41 and 0.64. The PGP/GPG hybrid composites have a minimal wear rate of 3.34e‐8 m3 s−1 and are 80% more effective than dedicated composites. Utilizing the Analysis of Variance (ANOVA) and Taguchi L9 orthogonal array, regression models are created to optimize the influence of various parameters, such as load, sliding velocity, and composition. Results of confirmation tests show excellent agreement with predictions generated using the developed mathematical model. [ABSTRACT FROM AUTHOR]

This review paper presents tribological and mechanical characteristics of hybrid polymer composite materials that exhibit low friction and low wear. Polymer fiber reinforced materials possess low weight and high specific quality along with high specific stiffness. This study targets a critical review of wear and frictional characteristics of hybrid polymer composite materials. Tribological properties have been evaluated by various researchers using a rotating pin‐on‐disc tribometer and reciprocating wear testing machine. Most likely filler materials are carbon, graphite, nano silica, bronze, glass fibers, MoS2, and polytetrafluoroethylene (PTFE) added in the polyether ether ketone (PEEK), polyamide 66, thermoses polymer, etc. It improves mechanical and tribological properties of hybrid composite materials. This review paper aims to highlights the comparative study of various fillers added in PEEK, Polyamide 66, and thermoses polymer hybrid materials. Recently hybrid composites are used in wide range of applications since it has light weight and high strength. [ABSTRACT FROM AUTHOR]

The vacuum bagging is a common but critical step of various manufacturing process chains for Carbon/Glass Fibre reinforced polymers (C/GFRP). Whilst developing a new generation of vacuum bagging, significant efforts have been made to deeply understand the relevant physics fields, process variables involved and to provide predictive approaches to support dimensioning and scaling exercises prior to implementation into real production process. Main features of the new bagging system are, (1) the reduction of material diversity through merging of various properties within one single layer and, (2) the suppression of critical folding steps by using thermoforming for pre-shaping purposes. This paper will mainly focus on considerations of heat transfer during the pre-shaping of the film, directly on the CFRP part short before the curing step. For the better risk assessment of the short time exposition of an uncured composite part to the heat flow, a problem of transient coupled field analysis involving heat transfer via conduction, convection and radiation is formulated and solved by using Finite Element Analysis in COMSOL under consideration of realistic process conditions. Further a section dedicated to the comparison of the obtained results with measurements performed on a system including an IR-emitter, the bagging material, a ground plate and in some studies as well a CFRP sample is included. During the study the influence of time, power output of the emitter, distance between emitter and surface as well as irradiation angle has been assessed including a comparison of simulated results and performed measurements. [ABSTRACT FROM AUTHOR]

The main purpose of this study is to investigate usability of resistance welding joining method for poly (aryletherketone) (PAEK) thermoplastic matrix/carbon fiber (CF) reinforced composite laminates (PAEK/CF). For this purpose, effects of six different Interlayer Forms having different stainless steel meshes as Heating Elements and different woven glass fiber forms as Insulating Layers were studied. After determining welding parameters for each specimen group, performance of the resistance welding operations was compared by ultrasonic inspection, microscopic examination, DSC analyses, and by three different interlaminar mechanical tests. Analyses and tests generally revealed that use of stainless steel meshes as Heating Elements could supply proper amperage level for the heating, melting and crystallization stages of the PAEK matrix during welding consolidation. Depending on the lay-up configuration of Interlayer Forms, "amperage levels" determined for the heating, melting dwell and crystallization dwell were in the ranges of 46–100 A, 40–90 A and 25–50 A, respectively, It was also observed that in order to prevent Current Leakage problem to the other layers in the composite laminate, rather thicker and heavier woven glass fiber forms as Insulating Layers should be used. Otherwise, not only voids could form in the thermoplastic matrix, but also delamination might occur in the upper or lower PAEK/CF composite laminates being welded. When thicker and heavier insulating layer was used; interlaminar mechanical properties of Single Lap Shear Strength, Fracture Toughness under Mode-I and Mode-II were determined as high as 36.77 MPa, 3.76 kJ/m2 and 4.71 kJ/m2, respectively. [ABSTRACT FROM AUTHOR]

Nowadays, additive manufacturing techniques such as the Fused Filament Fabrication appear to be among the most promising methods for enabling modern industry to produce components of high geometrical complexity. The main characteristic of this method is the deposition of thermoplastic polymers that can be further reinforced with chopped and/or continuous fibers that attribute to the product some unique structural characteristics. Nevertheless, the process is susceptible to a variety of defects that are derived from the fabrication process parameters, such as porosity, insufficient fiber impregnation with the polymer and fiber disorientation. On the other hand, since the applicability of the process depends on the development of numerical tools for assessing the effects of these defects, the accurate detection and quantification of them is a crucial part of it. In the present work, these defects are studied experimentally by implementing an X-ray computed tomography testing campaign. The manufacturing defects are identified using well-established techniques while a complete analysis of the distribution of porosity is presented for various zones of Onyx, Onyx/Carbon and Onyx/Glass fiber reinforced structures. Finally, the tendency of the overall pore content to increase with increasing number of continuous fiber reinforcement was identified as well as porosity variations in printing direction are presented. [ABSTRACT FROM AUTHOR]

Conventional PMMA bone cement, and more lately BisGMA (bisphenol A-glycidyl methacrylate) composite bone cement, is employed in various bone augmentation procedures such as vertebroplasty. Problems with these materials include high curing exotherm and shrinkage, leakage of toxic components after insertion and exhibition of a modulus mismatch between bone cement and weak bone. A novel high molecular weight dimethacrylate, polypropylene glycol dimethacrylate (PPG), was used in combination with urethane dimethacrylate, hydroxyethyl methacrylate, silica glass particles and fibres to create PPG fibre composite (PFC) dual paste materials. This study was designed to ascertain whether PFCs are a viable alternative to Cortoss™ composite bone void filler and Simplex P™ PMMA bone cement for osteoporotic vertebroplasty and fracture fixation applications. The degree of monomer conversion and curing kinetics of the PFCs and commercial bone cements were found using FTIR, while the mechanical properties were found through biaxial flexural testing. An equation was derived to describe the curing profiles of the PFCs and commercial bone cements. The curing profiles and equations and mechanical properties of the PFCs, Cortoss™ and Simplex P™ bone cements were compared. It was found that PFC materials had more complete monomer conversion, and faster cure than Cortoss™ and Simplex P. The flexural strength of some of the PFC materials was comparable to Cortoss™ and Simplex P. Incorporating fibres into the PFC materials prevented brittle fracture exhibited by Cortoss™ and mimicking the fracture behaviour of Simplex P. [ABSTRACT FROM AUTHOR]

In this study, fatigue properties of a novel continuous glass fiber reinforced composite with an acrylic-based thermoplastic matrix Elium®, have been investigated and S-N curves were obtained. The effect of various fiber orientations of the plies with glass fibers of 0°/90°/±45°, 0°/90°, and ±45° alignment has been evaluated. The highest fatigue strengths have been recorded for composites with 0°/90° glass fiber ply orientations. Composite with ±45° alignment has the lowest fatigue strengths in S-N curves. Stiffness degradation of the composites with 0°/90° and 0°/90°/±45° at medium fatigue stress levels was calculated and showed higher degradation for stacking having more off-axis plies, i.e. 0°/90°/±45° alignment. Temperature increase during fatigue testing was measured using an IR camera for a medium fatigue stress level for 0°/90°/±45° alignment. Temperature increases were calculated for all stress amplitudes for composites with 0°/90°/±45° and 0°/90° alignment cross-ply sequences. The temperatures obtained were all below the glass transition temperature of the material. The 0°/90°/±45° plies had a higher temperature effect than 0°/90° plies in both analytical calculations and observations. [ABSTRACT FROM AUTHOR]

Modern industrialisation and the need for low-density material initiated the up-gradation of material for the necessity of sustainability, and the same goes for engineering materials as well. Right from ancient times, composites have an important place in the field of engineering materials, but now demand for such materials, especially fibre-reinforced polymer (FRP) composites, proliferates just to improve the quality of materials as well as the quality of life. The present work provides a comprehensive literature review on hybrid FRP composites, techniques involved in its fabrication, machining and variation in mechanical properties due to hybridisation. The main focused fibre-reinforced composite are glass fibre, carbon fibre, basalt fibre and Kevlar fibre-reinforced polymeric composites. The paper includes recent work that showcases the hybridisation behaviour and their field of application. [ABSTRACT FROM AUTHOR]

A coupled initial-boundary value problem of thermoelastoplastic deformation of flexible reinforced plates is formulated. The possibility of weak resistance of structures of this kind to transverse shear is taken into account within the framework of the Ambartsumyan theory. The geometric nonlinearity is taken into account in the von Kármán approximation. The temperature over the thickness of the plates is approximated by polynomials of different orders. The solution to the two-dimensional problem is constructed using an explicit numerical scheme. We investigate the dynamic thermoelastoplastic behavior of plane criss-cross and spatially reinforced fiberglass and metal-composite plates bending under the action of an air blast wave. It is shown that, in order to adequately determine temperature in these structures, it should be approximated by polynomials of the 6–7th orders over the thickness of the plates. It is demonstrated that relatively thin composite plates are heated to a greater extent than relatively thick plates for the same maximum values of the intensity of deformations in the binder. The level of heating of reinforced structures is insignificant: for fiberglass plates, the temperature increment is 2–18°C, while for metal-composite structures, it is equal to 30°C. Therefore, the dynamic calculations of fiberglass plates under the action of loads, such as air blast waves, can be carried out without taking into account the thermal effect in the absence of additional heat sources of nonmechanical nature. In calculating the metal-composite plates, it is necessary to take into account the thermal effect but their thermal sensitivity can be ignored. [ABSTRACT FROM AUTHOR]

Abstract Asymmetric sandwich panels (ASPs) with tapered transitions are effective configurations for connecting them with other structural elements. However, fiber reinforced composite panels are susceptible to impact events and thus it is imperative to gain a comprehensive understanding of the impact failure mechanisms of ASPs. This article investigates the failure mechanisms of ASPs subjected to low-velocity impacts experimentally and numerically. Low-velocity impact tests are conducted at two energy levels to induce barely visible impact damage (BVID) and visible impact damage (VID). A non-linear finite element (FE) model is developed to elucidate the damage behavior and failure mechanisms of ASPs. The numerical results are compared with experimental data to validate the FE model. Additionally, a parametric study is undertaken to explore the failure mechanisms of ASPs subjected to penetration. This study also investigates the influence of impactor diameter, impactor angle, foam core thickness, face sheet stacking sequence, and face sheet thickness on impact response through numerical simulations. The reported results hold potential significance for safety design ASPs. [ABSTRACT FROM AUTHOR]

Cultivated natural fibers have a huge possibility for green and sustainable reinforcement for polymers, but their limited load-bearing ability and flammability prevent them from wide applications in composites. According to the beam theory, normal stress is the maximum at the outermost layers but zero at the mid-plane under bending (with (non)linear strain distribution). Shear stress is the maximum at the mid-plane but manageable for most polymers. Accordingly, a laminated composite made of hybrid fiber-reinforced shape memory photopolymer was developed, incorporating strong synthetic glass fibers over a weak core of natural hemp fibers. Even with a significant proportion of natural hemp fibers, the mechanical properties of the hybrid composites were close to those reinforced solely with glass fibers. The composites exhibited good shape memory properties, with at least 52% shape fixity ratio and 71% shape recovery ratio, and 24 MPa recovery stress. After 40 s burning, a hybrid composite still maintained 83.53% of its load carrying capacity. Therefore, in addition to largely maintaining the load carrying capacity through the hybrid reinforcement design, the use of shape memory photopolymer endowed a couple of new functionalities to the composites: the plastically deformed laminated composite beam can largely return to its original shape due to the shape memory effect of the polymer matrix, and the flame retardancy of the polymer matrix makes the flammable hemp fiber survive the fire hazard. The findings of this study present exciting prospects for utilizing low-strength and flammable natural fibers in multifunctional load-bearing composites that possess both flame retardancy and shape memory properties. [ABSTRACT FROM AUTHOR]

Cultivated natural fibers have a huge possibility for green and sustainable reinforcement for polymers, but their limited load-bearing ability and flammability prevent them from wide applications in composites. According to the beam theory, normal stress is the maximum at the outermost layers but zero at the mid-plane under bending (with (non)linear strain distribution). Shear stress is the maximum at the mid-plane but manageable for most polymers. Accordingly, a laminated composite made of hybrid fiber-reinforced shape memory photopolymer was developed, incorporating strong synthetic glass fibers over a weak core of natural hemp fibers. Even with a significant proportion of natural hemp fibers, the mechanical properties of the hybrid composites were close to those reinforced solely with glass fibers. The composites exhibited good shape memory properties, with at least 52% shape fixity ratio and 71% shape recovery ratio, and 24 MPa recovery stress. After 40 s burning, a hybrid composite still maintained 83.53% of its load carrying capacity. Therefore, in addition to largely maintaining the load carrying capacity through the hybrid reinforcement design, the use of shape memory photopolymer endowed a couple of new functionalities to the composites: the plastically deformed laminated composite beam can largely return to its original shape due to the shape memory effect of the polymer matrix, and the flame retardancy of the polymer matrix makes the flammable hemp fiber survive the fire hazard. The findings of this study present exciting prospects for utilizing low-strength and flammable natural fibers in multifunctional load-bearing composites that possess both flame retardancy and shape memory properties. [ABSTRACT FROM AUTHOR]

This work aims to scrutinize the effect of the silanization of glass fibers (GF) on the mechanical properties and cathodic disbonding resistance of an epoxy composite coating. Successful silanization was approved based on different characterization techniques, including Fourier transform infrared spectra, field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. Tensile strength measurement exhibited a significant effect of silanization on the mechanical performance of the fiber-reinforced polymer (FRP). FE-SEM cross-sectional images illustrated improved interfacial bonding between the epoxy matrix and GF upon silanization. Pull-off measurements revealed improved wet adhesion strength of the FRP to the mild steel surface after exposure to the salt spray chamber when the GF were silanized. In addition, silanization revealed enhanced resistance to cathodic delamination (CD). Electrochemical impedance spectroscopy and electrochemical noise assessments proved silanization's significant influence on the FRP's CD resistance. [ABSTRACT FROM AUTHOR]

Zn metal batteries have garnered considerable scientific and technological interests. However, the widespread commercial application of these batteries is impeded by the uncontrollable dendrite growth and consequent severe side effects. Herein, a functionalized separator is prepared by spraying polyaniline‐modified graphene oxide (denoted as NPGO)/polyvinylidene difluoride solution directly on one side of a common separator of glass fibers (GFs). The reversible transition between protonated and deprotonated states of quinolone imide on NPGO nanosheets can facilitate the rapid desolvation and transfer of Zn2+. Therefore, the spatial electric field as well as the Zn2+ flux is effectively homogenized due to the ion‐sieving effect of NPGO nanosheets that are oriented toward Zn anode. This engineering design of the NPGO@GFs separator harvests excellent rate and cycling performance (over 3000 cycles at 20 mA cm−2) for Zn metal symmetric batteries. Meanwhile, it provides an impressive commercial prospect (500 cycles with a capacity retention of 91.6% under 2000 mA g−1) for MnO2||Zn full batteries. Such a strategy can be generalized as a common way to protect metal anodes (Na, Zn, and K) in rechargeable batteries, which is highly cost‐effective and scalable. [ABSTRACT FROM AUTHOR]