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Laser glass deposition is an additive manufacturing method to produce individualized glass components. This process uses a CO2 laser with a defocused beam as a heat source to additively melt-fused silica filaments. The fiber filament is fed laterally in the process zone and is deposited layer-by-layer to form 3D structures. The formation of boundary layers in conventional 3D-printing methods is a usual byproduct of the process. In this paper, the boundary layer formation of deposited fused silica filaments is investigated in detail by means of varying different process parameters such as, laser power, feed rate, laser spot diameter, and printing strategy. This involves examining both thin-walled and thick-walled test specimens. Quality characteristics like the surface roughness and the optical transmission are analyzed for the printed specimen. Finally, fully transparent structures with surface roughness below 100 nm and a transparency of 90% could be printed boundary layer-free and without post-processing. [ABSTRACT FROM AUTHOR]

Alkali-free aluminoborosilicate glasses without (GDMC-Si) and with La2O3 addition (GDMC-La) were fabricated with an aim to develop low dielectric glass fibers for use in printed circuit boards (PCBs) as a reinforcing material in high-speed 5G/6G telecommunications application. This study presents the structural, thermo-physical, and dielectric properties of the glasses. The decrease in glass transition temperature (Tg) and the increase in coefficient of thermal expansion (CTE) were found by the addition of SiO2 and La2O3 in the present glass system, which are due to the depolymerization of the glass networks confirmed by the FTIR analysis. The dielectric constants (Dk) and the dissipation factors (Df) of the glasses were investigated at a high frequency of 10 GHz. The Dk values of the GDMC-Si and GDMC-La glass systems reached a minimum of 4.50 and 4.75, while their Df values reached a minimum of 2.86 × 10−3 and 3.01 × 10−3, respectively. Notably, the Dk and Df values of the present glasses were lower than the commercial E-glass (Dk: 6.9, Df: 7.0 × 10−3 at 10 GHz) and L-glass (Dk: 4.8, Df: 3.0 × 10−3 at 10 GHz). Glass fibers with a diameter of 10 μm were successfully drawn by the continuous melt-spinning process and their mechanical properties were investigated. [ABSTRACT FROM AUTHOR]

Environmental awareness has driven a crucial search for biodegradable materials. Over the past few decades, the machining of these materials, particularly through drilling, has garnered significant research interest. This study presents an evaluation of the drilling performance of a hybrid composite (jute/glass), considering factors such as the concentration of chemical treatment with sodium bicarbonate, the type of glass fiber (random or woven), the degree of hybridization between the jute and glass fibers, and cutting parameters like rotation speed, feed rate, and drill diameter. Drilling operations were conducted to determine the maximum temperature in the cutting zone, the surface roughness of the drilled holes, and the maximum delamination factor. A Sobol sensitivity analysis was performed to identify the input parameters influencing these responses studied. Predictive modeling of the results based on the input factors was then conducted using the deep neural network (DNN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) approaches. The results show that the type of glass fiber significantly affects surface roughness, while rotation speed primarily influences cutting temperature. Similarly, the drill diameter directly impacts the maximum delamination factor. Finally, the predictive modeling demonstrates that the ANN-IGWO models provide the best predictions of drilling parameters compared to the ANN-GA and ANFIS models, with mean absolute errors ranging from 1.22 to 12%. [ABSTRACT FROM AUTHOR]

Polyamide (PA) composites exhibit excellent properties such as stiffness, impact resistance, chemical resistance, and thermal stability, making them widely used in automotive interiors, engine parts, and bodywork. To leverage these advantages, high-content composite materials that enhance the wettability and interfacial adhesion between polyamide 66 (PA66) and glass fiber are essential. In this study, we synthesized linear and hyperbranched amide-based flow modifiers to improve the flowability of PA66 composites. H-NMR and FT-IR analyses confirmed the successful preparation of these structures. FT-IR analysis confirmed the successful synthesis of flow modifiers, showing characteristic amide peaks at 1650 cm−1 and the absence of -NH2 peaks at 3300 cm−1. Five flow modifiers were mixed with PA66 in various ratios using a micro-compounder, and viscosity reduction was confirmed by rotational rheometer measurements. Tensile strength and DMA indicated that PA66 composites with flow modifiers showed improved mechanical properties without significant reduction. Notably, PA66 composites with ACDA exhibited a superior viscosity reduction effect while maintaining mechanical strength. The DMA results indicated that the mechanical properties of PA66 composites with flow modifiers showed no significant reduction. The tensile strength of samples with flow modifiers ranged from 208 to 212 MPa, and the elongation at break was between 8.94 and 9.18%. These findings demonstrate that the synthesized flow modifiers improve the viscosity of PA66 composites while maintaining or enhancing mechanical properties. [ABSTRACT FROM AUTHOR]

The design and development of efficient microwave-absorbing and electromagnetic interference (EMI) shielding materials and structures to conceal electromagnetic (EM) waves remains a consistent and challenging task. Despite advancements in materials science and microwave engineering, there is a need for optimized materials that offer both effective microwave absorption and EMI shielding while minimizing material layer thickness. This research aims to address this gap by utilizing the firefly algorithm (FFA) to predict the optimal medium properties and thickness of microwave-absorbing and EMI shielding materials under specific constraints. In this context, a comprehensive investigation was carried out at the X-band involving numerical and experimental EM characterization of novel lightweight fiber-based samples. Additionally, the FFA has been applied to optimize these fiber-based microwave structures within the given constraints. Two separate objective functions (OBF) targeting minimum sample thickness, maximum microwave absorption, and shielding effectiveness (SE) bandwidth have been integrated into the FFA to address the thickness–bandwidth trade-off issue. Subsequently, resistive ink-coated glass fiber (IGF) and ink-coated mesh fiber (IMF) were developed and characterized based on the optimal solutions provided by the FFA. Consequently, an optimized IMF sample provides a minimum reflection coefficient (RC) of −19.0 dB at 10.7 GHz with a bandwidth of 2.8 GHz (9.6 to 12.4 GHz) below the −10 dB threshold. Besides, the optimal IGF sample achieves maximum SE of 11 dB at thickness of only 0.8 mm and covers the entire operating band. Furthermore, the response of the proposed structure was assessed for various oblique angles of incidence, revealing significant potential for various practical applications. A strong correlation between measured and theoretical findings underscores the potential of the proposed approach in realizing efficient microwave stealth and EMI shielding materials. [ABSTRACT FROM AUTHOR]

Sandwich panels with trapezoidal metal/glass fiber cores are increasingly popular due to their lightweight and energy-absorption properties. This study employs response surface methodology (RSM) and Box-Behnken design to investigate the effects of core angle, fiber orientation, and MCM-48 nanoparticles on the panels' energy absorption and peak force, developing regression models with high R2 values of 0.9027 and 0.9228, respectively. Experimental tests were conducted to validate these models, showing minimal deviation from predicted values. Results indicate that increasing the fiber orientation angle from 30° to 90° enhances energy absorption and peak force by 72.18 and 46.9%, respectively, and adding MCM-48 nanoparticles up to 0.25% weight improves energy absorption by 60.8%. A core angle of 52° balances energy absorption and peak force, while integrating a metal wire mesh within the panels significantly enhances energy absorption and reduces core brittleness. The optimal parameters for maximum energy absorption and minimum peak force include a core angle of 58°, fiber orientation of 73.5°, and no nanoparticles. These findings provide valuable insights into the design and optimization of sandwich panels for various applications. [ABSTRACT FROM AUTHOR]

Polymer matrix composites are extensively used in numerous industrial and engineering applications, and utilization of these materials has been extended to different and novel areas where it is essential to study and improve their mechanical properties. In this paper, the hand layup technique is used to prepare composites from a vinyl ester resin matrix filled with 4 wt.% chopped glass fiber and different silicon nitride particle contents with concentrations of 1.5, 2, 2.5, 3, 3.5, and 4 wt.% are used to study erosive wear, flexural, compression, and hardness tests. The air-jet-type test rig is used to measure erosive wear rate under four factors: weight fraction of both glass fiber and silicon nitride particles, impingement angles 30°, 45°, 60°, and 90°, size sand particles 250, 450, 650, and 850 μm, and standoff distance 18, 20, 22, and 24 cm at constant 15 hours. MINITAB (L16) is utilized for erosive wear parameter analysis. It is observed that the specimens (vinyl ester–4% chopped glass fiber–4% silicon nitride) have better erosive resistance properties as compared to other specimens. Moreover, the addition of 4 wt.% silicon nitride particles in the vinyl ester resin filled with chopped glass fiber improved the values of flexural strength, compressive strength, and hardness shore D significantly. The signal-to-noise results showed that the 4% weight ratio of silicon nitride particles, 90° impingement angles, 250 μm sand size, and 22 cm standoff distance gave the best erosive resistance. The analysis of variance showed that specimens (A), size of sand particles (C), and standoff distance (D) are the most important factor affecting the erosive rate, while the angle (B) factor has less effect on the erosive rate. Also, the interaction plot for all control parameters showed an important effect on erosive wear. It is observed that the properties of vinyl ester resin have improved after being strengthened with chopped glass fibers and silicon nitride particles, which can proposed for specific applications such as sewage pipes, helicopter fan blades, and desert structures. [ABSTRACT FROM AUTHOR]

This paper proposes a multi-objective optimization method for injection molding, combining the random forest (RF) model optimized using the light spectrum optimizer (LSO) with the non-dominated sorting whale optimization algorithm (NSWOA), to tackle the quality defects of warpage deformation and volume shrinkage commonly observed for the glass fiber injection molded product. Based on the simulation results of central composite face centered design (CCF), the model for control of injection molding quality defects using LSO-RF is constructed. NSWOA is used for multi-objective optimization to obtain the Pareto solutions, and the critic method is employed to determine the optimal process parameter scheme. Then, the optimal process parameter scheme is inputted to Moldflow for simulation verification. The validation results demonstrate that the LSO-RF model achieves prediction errors within 3 % for warpage deformation and volume shrinkage, indicating good predictive accuracy. The optimized warpage deformation and volume shrinkage are 0.3519 mm and 7.0930 %, respectively. Compared to the pre-optimized state, the warpage deformation decreased by 32.57 % and the volume shrinkage decreased by 15.93 %, indicating a significant improvement in molding quality for the glass fiber injection molded product. [ABSTRACT FROM AUTHOR]

Geopolymer lightweight cellular concrete (GLCC) combines the advantages of geopolymer and LCC but also suffers from the inherent deficiency of low strength, which can be improved by introducing suitable reinforcing materials such as fibers. This paper investigated the mechanical properties and microstructure of fly ash-slag-based GLCC reinforced with glass fibers (GLCCRGF), aiming to reveal the strengthening mechanism of glass fibers. The effects of different fiber contents (0.0, 0.3, 0.6, 0.9, and 1.2%), fiber lengths (3, 6, 9, 12, and 15 mm), and fiber-blending methods (G-R, G-W, and G-S) on the mechanical properties of GLCCRGF were analyzed. The results showed that the fiber incorporation had no significant or even negative effect on the compressive strength but significantly improved the splitting tensile strength. The optimal results of fiber content, fiber length, and fiber-blending method are 0.6%, 9 mm, and G-R, respectively. From the microstructure perspective, optical tests were conducted to explore the evolution rules of pore size, pore shape factor, and fractal dimension of pore distribution of GLCCRGF. The results showed that the incorporation of glass fibers (0.6%, 9 mm, and G-R) improved the pore characteristics and contributed to more uniform pore distribution. Furthermore, scanning electron microscopy (SEM) was employed to observe the micromorphology of the skeleton structure of GLCCRGF. The SEM results showed excellent interfacial bonding between glass fibers and the geopolymer matrix. Due to good bonding quality and crack-bridging effect, the presence of glass fibers enhanced the strength and crack resistance of the matrix. [ABSTRACT FROM AUTHOR]

In this study, glass-carbon hybrid fibre reinforced polymer matrix composite is proposed to use in solar greenhouse dryer trays. The effects of hybridization on compressive instability failure are analysed by varying the glass fiber volume percentage in a composite. The study examines the compressive instability failure of the composite, considering the non-linear constitutive behaviour of the polymer matrix and initial morphological defects. Each glass and carbon fiber is modelled using 3D finite element micromechanical models. Linear buckling analysis is conducted with appropriately scaled faults. The Thermal analysis to determine heat distribution over the tray, carried out using COMSOL Multiphysics tool, solar greenhouse dryers are used to dehydrate agricultural products, preserving them for longer periods and improving their market value. The materials used in these dryer trays must meet specific performance criteria to ensure optimal drying conditions. In Greenhouse solar dryers, two commonly used tray configurations such as Stable Tray-Assisted Dryer (STAD) and Rotatable Tray-Assisted Dryer (RTAD) are considered in this study and the glass-carbon hybrid composite used in solar greenhouse dryer trays Introduced as Hybrid composite Rotatable Tray-Assisted Dryer (HRTAD), offers significant contributions by ensuring uniform and effective moisture removal and their excellent strength-to-weight ratio, corrosion resistance, heat resistance, sustainability, and long life. These properties make them a dependable and effective solution for building solar dryer components, assuring optimal performance and contributing to the overall success of solar greenhouse systems. Hybrid glass fiber composites offer several advantages that make them particularly suitable for this application. [ABSTRACT FROM AUTHOR]

To ensure a strong adhesive bond, most standards and adhesive manufacturers specify a maximum adhesive gap of 1 mm when bonding fiber reinforced composite structures. In manufacturing large components, such as joining two halves of wind turbine blades, meeting this gap tolerance specification is impractical; gaps larger than 10 mm are common in large adhesively bonded composite structures using state-of-the-art manufacturing techniques. Currently, there is a lack of fundamental understanding of the failure mechanics of adhesive gaps larger than 3 mm. To create such understanding, glass fiber – acrylic thermoplastic composite panels bonded using different epoxy adhesives within single-lap joint samples with adhesive thicknesses of 0.1 mm, 0.3 mm, 1 mm, 3 mm, 5 mm, and 10 mm were sheared to failure. A transition from cohesive to adhesive failure was observed to occur about 1 mm to 3 mm joint thicknesses. Plotting the shear stress normalized by the ratio of the joint width to thickness as a function of the joint thickness normalized by the joint length is shown to result in the ability to fit simple empirically derived models of the cohesive-to-adhesive failure transition, regardless of the adhesive. Furthermore, using these normalized variables, all the observed cohesively failed specimens collapse to a single master curve, as do the adhesively failed specimens. [ABSTRACT FROM AUTHOR]

Aiming at the merits of highly integrated and free styling of the inner and exterior panels for electric vehicles, an integrated third-generation glass fiber reinforced plastic tailgate (GFRPT) lightweight technology based on structural design, performance optimization, and process manufacturing is proposed. GFRPT preliminary structural data and 3D model are drawn, and modal, stiffness, and concavity resistance simulation analyses are carried out in combination with CAE technology to verify whether the initial data meet the performance requirements. A simulation technique for coupling the injection molding process with part properties is formed by dynamic simulation of glass fiber orientation. Simultaneously, the dimensional deformation is strictly controlled based on the simulation of high and low temperature deformation, combined with the correction of structural profiling and integrated bonding process. Ultimately, through the complete industry chain to develop prototype parts and test verification. The results demonstrate that GFRPT meets all performance requirements, the economic and social benefits are in line with energy saving and emission reduction requirements. The weight reduction rate is 37% and the single sample cost is measured to be reduced. With the gradual maturity of lightweight technology and market, the application ratio of GFRPT will be gradually expanded. [ABSTRACT FROM AUTHOR]

Thermoplastic composite pipe is gaining popularity in the oil and gas and renewable energy industries as an alternative to traditional metal pipe mainly due to its capability of being spooled onto a reel and exceptional corrosion resistance properties. Despite its corrosion-proof nature, this material remains susceptible to various defects, such as delamination, fiber breakage, matrix degradation and deformation. This study employed the phased array ultrasonic testing technique with the implementation of the classical time-corrected gain method to compensate for the significant spatial signal attenuation beyond the first interface layer in the thick multi-layered thermoplastic composite pipe. Initially, the ultrasonic signals from the interface layers and back wall were detected with good signal-to-noise ratios. Subsequently, flat-bottom holes of varying depths, simulating one-sided delamination, were bored and the proposed method effectively identified ultrasonic signals from these holes, clearly distinguishing them from the background noise and interface layer signals. Finally, a defect deliberately fabricated within the composite laminate layers during the pipe manufacturing process was successfully identified. Subsequently, this fabricated defect was visualized in a three-dimensional representation using the X-ray computed tomography for a qualitative and quantitative comparison with the proposed ultrasonic method, showing a high level of agreement. [ABSTRACT FROM AUTHOR]

A straightforward mixing approach that involves incorporating glass fiber into cement-based materials is frequently carried out at construction sites. This practice can have adverse effects on both the fresh and hardened properties of cement mixtures. The lack of quality control measures often leads to the production of fiber-reinforced cement mixtures that do not perform as intended. Additionally, the inherent variations in commercially available glass fibers of the same type add complexity to mixing, making it difficult to consistently reproduce desired effects for in situ casting. Therefore, this research aims to accomplish three main objectives. Firstly, characterizing E-glass and AR-glass fibers to enable a practical replication of performance using these specific variants. Secondly, assessing the impact of five different mixing methods on water absorption, flowability, setting time, compressive, and flexural strength in cement mixtures embedded with these glass fibers. Lastly, evaluating the fiber-matrix interaction within the hardened samples for each mixing method. The results revealed that various mixing methods yielded distinct advantages in the fresh and hardened properties. This highlights the variability in mixing approaches, indicating that the choice of method should be tailored to meet the specific construction requirements of engineers. In essence, the study underscores the importance of selecting an appropriate mixing technique based on the desired outcomes for both the fresh and hardened states of cement mixtures. [ABSTRACT FROM AUTHOR]

Leaf springs are designed to bear loads as well as shocks in automotive vehicles. Two leaves of glass fiber-reinforced composites (GFRCs) of various shapes sandwiched between steel plates were analyzed for application in a minitruck. Computer-aided engineering analysis was performed for five different types of GFRC material leaf springs: flat leaf, flat and parabolic leaf, both parabolic leaf, both parabolic leaf springs with aluminium alloy bushes at the eye-end and spring steel multi-leaf springs. A silencer pad was used in the parabolic leaf spring to reduce delamination and vibration at contact points of the mating leaf. The various shapes and combinations of leaves provided varying parameters, namely, the deformation, maximum equivalent strain, maximum equivalent stress and fatigue life. The CAE results showed that compared with the other combinations, the flat leaf and parabolic leaf combinations provided the maximum equivalent strain, maximum equivalent stress and fatigue life. [ABSTRACT FROM AUTHOR]

The desire for lightweight, carbon-negative materials has been increasing in recent years, particularly as the transportation sector reduces its global carbon footprint. Natural fibers, such as flax fiber and their composites, offer a compelling combination of properties including low density, high specific strength, and carbon negativity. However, because of the low modulus and high variability in performance, natural fibers can't compete with glass fibers as structural reinforcements in polymer composites. In this study, flax technical fibers were treated in supercritical CO2 (scCO2), and the effects of this treatment on the morphology and properties of flax fibers are reported. Treatment in scCO2 successfully resulted in higher fiber modulus and strength by 33% and 40%, respectively. Fiber porosity was reduced by 50% and morphological changes to the fibers were observed. Specifically, fiber lumen collapsed during treatment and micro/mesoporosity was reduced by 27%. Treated flax fibers were used to create 30 vol% unidirectional flax-epoxy composites. ScCO2 treatment raised composite modulus and strength by 33% and 25%, respectively. Because of the dependence between technical fiber size and mechanical properties, the relationship between fiber modulus and fiber size were created and applied to the rule-of-mixtures. This relationship were found to be viable representations of the fiber performance within each composite. Overall, the treatment developed in this study has the potential to significantly improve natural fiber properties, enabling their consideration for use in lightweight, semi-structural composites. [ABSTRACT FROM AUTHOR]

The main challenges of using fiberglass composites are poor impact resistance and understanding of damage mechanisms during loading. This work focuses on improving the indentation resistance of glass/epoxy composites by the incorporation of industrial waste iron fillers with maximum concentration of 50 µm in size. Moreover, the quasi-static indentation test with acoustic emission (AE) monitoring was employed to study the damage initiation and propagation of baseline and optimized 10 wt.% of filler-loaded composites. Post-indentation performance was evaluated by conducting compression after indentation test. The result reveals that the stiffness, absorbed energy and strain energy density were increased by 32%, 59.2% and 18.02% in filler-loaded composites, whereas the residual dent was reduced from 0.9 to 0.5 mm as compared with baseline. As compared with 3 mm indentation displacement, the % of AE hits related to delamination and fiber failure was significantly reduced to 3.6% and 1% during 6 mm, respectively. Further, the sentry function results that shown very small two PII functions indicate a better indentation resistance in filler-loaded composites, which were well correlated with rear side photographic images. Besides, the filler-loaded composites exhibited least reduction in the residual compressive strength of 3.71% and 4.33% for 3 mm and 6 mm indented displacements, respectively. However, the microstructural analysis was used to validate the effect of iron fillers on glass/epoxy composites. Finally, this study concludes that the impact resistance of fiberglass composites was greatly improved by the addition of industrial waste iron fillers. [ABSTRACT FROM AUTHOR]

Owing to the importance of fibre architectures in the design of textile composite materials, understanding their effect on the failure mechanisms of these composites have taken more considerations. In this regards, non-crimp preform and 2/2 twill fabric have been manufactured from glass fibre by using pin-board and power loom machines respectively, and subsequently composites laminates from both preforms are manufactured via vacuum assisted resin infusion method. In addition, quasi-static tensile and compressive strength tests have been conducted for the composite laminates that have same volume fraction. Damage failure mechanisms that occurred in compressive strength in both composites have been examined by using scanning electronic machine (SEM). Findings show that the mechanical properties are primly determined by fibre architectures and the presence of fibre crimp can further weaken tensile and compressive strength values. It was noticed that the tensile strength of non-crimp composite was 610 MPa whereas that of twill fabrics composite laminates it was found to be 350 MPa and 440 MPa in warp and weft directions respectively. Moreover, in case of twill fabric composites, fibre crimp has a considerable effect on the mode and characteristics of damage in the compressive loading; this leads to fibre fracture and kinks that primarily happened in the intersection point of warp and weft yarns. Results also showed improved ductility, strain to failure and absorbing energy in the twill fabric composites compared to non-crimp composites under in-plane shear strength test. [ABSTRACT FROM AUTHOR]

In this study, the axial compressive stresses of hollow circular composite tubes were investigated. For this purpose, hollow circular composite tubes with various inner diameters (Ø12 and Ø13 millimeters), a height of 80 millimeters, and an outer diameter kept constant at Ø17 millimeters were fabricated using a fiber winding process. In the production of hollow circular tubes, epoxy was used as resin, and glass fiber, carbon fiber, and Kevlar fiber were used as reinforcement materials. Experimental investigations were carried out for three different reinforcement materials, two thin-wall thicknesses, and five orientation angles. Axial compression tests were performed to research the influences of reinforcement materials, thin-wall thickness, and orientation angles on the compressive stresses. The axial compressive strength of the samples was observed experimentally by applying the load in the vertical direction. The reinforcement material, orientation angle, and thin-walled thickness had an important influence on the axial compressive stress. The glass/epoxy reinforcement material was found to have the highest axial compressive strength at 204 Mpa. When the orientation angle increased from 45° to 88°, the axial compressive stress increased by 2.27 times in glass/epoxy, 2.36 times in carbon/epoxy, and 2.37 times in Kevlar/epoxy specimens, respectively. In addition, by increasing the specimen wall thickness by 0.5 millimeters, the axial compressive stress at an 88° orientation angle increased by 9.67 % glass/epoxy, 11.85 % carbon/epoxy, and 7.14 % Kevlar/epoxy specimens. [ABSTRACT FROM AUTHOR]

The use of fiber-reinforced metal laminates (FML) is increasing due to their special mechanical properties. Their properties depend on the type and thickness of the metal and reinforcing fibers. In this study, the mechanical properties of FML sheets with a 2 mm thickness stainless steel 420 intermediate layer reinforced with six layers of Woven and Mat glass fibers were investigated. The fibers were impregnated with a polyester resin and produced as three layers on the front and back of the steel sheet with different fiber angles (0°, 15°, 30°, and 45°). Finally, samples with 8 mm thickness were cut by water jet. Mechanical properties including static tensile and bending tests were performed, and after that a low-cycle dynamic tensile and bending test was also performed according to the obtained maximum static tensile and bending force for each sample. The obtained results varied depending on the fibers' angle, but in all tests, the highest strength was obtained for samples with fibers arranged at 0°. A charpy impact and high speed pressure test were performed to determine toughness and confirm the strength and adhesion between the samples' layers. SEM imaging of the fracture surface showed good adhesion and bonding between layers. [ABSTRACT FROM AUTHOR]

The sandwich panels are widely used in many industrial applications due to their high mechanical properties. Their core design is most important parameter in enhancing their mechanical strength. Flexibility in the design of the core structure leads to the achievement of high strength and light structures. In this paper, the results of the optimized geometry in the previous work are used to investigate the capability of the core geometry design with different materials. Therefore, using the different materials, the peak enhancement of strength-to-weight ratio in sandwich panels besides core behavior during pressure testing are investigated. To this end, a new lattice core is brought forth as the first level; then, three types of materials including AL3105, glass, and innegra fiber/epoxy composites are used to fabricate the cores, in order to compare the compressive strength and the peak. The Nano-clay cloisite 20A is also utilized in construction of sandwich panels. The result indicates that the AL3105 lattice core has the highest strength-to-weight ratio, while the innegra fiber composite core has the highest toughness. Applying curve studies and the SEM Fig. 13, it is concluded that the addition of Nano-clay to composites leads to an increase in both of the strain and the core strength. Comparing the results of experimental and finite element modeling (FEM) data (in ABAQUS software) represented that there is a suitable compliance between them. Our results with the positional variation in core design can pave way in designing advanced engineered sandwich structures in aerospace, shipping, automotive industries. Therefore, these structures will have wide applications in the field of light structure, heat and fluid transfer, sound and vibration control. [ABSTRACT FROM AUTHOR]

An experimental study on reinforced concrete one-way slabs strengthened by various methods and materials is introduced in this paper. Innovative anchorage procedures are presented and evaluated to prevent the strengthening elements with FRP system from de-bonding at the initial stages. Externally bonded embedded in concrete cover (EBECC) strengthening technology was proposed to save the fiber strips from being subjected to heat, degradation, and sabotage. Nine RC one-way slabs, including a control slab and eight strengthened slabs, were cast. One RC slab was strengthened using externally bonded embedded in concrete cover (EBECC), whereas the other tested RC slabs were strengthened using either externally bonded (EB) or near-surface mounted (NSM) procedures. The following test variables are used in this study: the proposed anchors, the area of steel, the kind of material utilized in NSM rods (carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), and steel), and the strengthening scheme. The ultimate and initial cracking loads, load–deformation response, cracking patterns, and failure behavior were recorded and discussed. Additionally, a comparison of the stiffness, ductility, and energy absorption of the examined slabs was reported. The strengthened slabs by various techniques showed a boost in flexural strength that varied from 67 to 107% compared to the control slab. In addition, RC slabs strengthened by NSM-CFRP bars showed a maximum flexural capacity when compared with slabs strengthened by GFRP and steel bars. Also, the results supported the superiority of a novel end anchorage. The ABAQUS program was employed to conduct a finite element analysis (FEA) employing 3-D geometries to compare and assess the numerical performance of the identical slabs under similar test settings. The results showed good agreement between the experimental and numerical findings. [ABSTRACT FROM AUTHOR]

Canines are widely used for real-time detection of explosives and have proven to be on par with instrumental methods. Canines are thought to rely largely upon detection of volatile chemical constituents of the explosives, though not necessarily the explosive itself. Hence, it is crucial to understand the odor available to them as generated by training aids. Previous studies have established that the Training Aid Delivery Device (TADD) developed by SciK9 is a reliable training aid that reduces cross-contamination and doubles as a storage device. A TADD comprises a standardized container, a synthetic membrane, a membrane holder, and a lid. In the work presented, activated charcoal strips were placed above and below the TADD membrane to determine the relative amounts of volatiles emitted by dynamite (i.e., ethylene glycol dinitrate (EGDN) and trinitroglycerin (NG)). The strips were eluted and the extracts tested using gas chromatography–mass spectrometry in negative ion chemical ionization mode. A series of t-tests at 95% confidence level were performed to determine any differences in vapor composition above and below the membranes. Nine synthetic membranes and six glass fiber membranes were tested in this study. It was expected that the relative concentration of volatiles would remain the same on both sides of the membrane; however, selective removal of nitroglycerin by some membranes was observed. Synthetic membranes with larger pore sizes showed no alteration in the vapor composition. Both synthetic and glass fiber membranes did not show a significant change in relative concentration of the other volatile compound in dynamite, i.e., EGDN. Out of all the membranes tested, three synthetic membranes and four glass fiber membranes showed selective alteration in odor availability of nitroglycerin in dynamite. For training purposes, membranes that do not alter the vapor composition should be used in the training aid. [ABSTRACT FROM AUTHOR]

The present work deals with analyzing the effect of silicon dioxide on mechanical and thermal stability of hybrid polymer composite. Compression molding is adopted to develop the hybrid composite with constant 0.5 wt.% of graphene and varying wt.% of silicon dioxide (2, 4 & 6 wt.%). Modified hummers method is used to synthesis graphene by chemical exfoliation of graphene from graphite flakes. Mechanical properties of developed composite is investigated using tensile, flexural, impact and interlaminar shear testing follow by fracture surface analysis of tested samples. Thermal stability is examined by thermogravimetric analysis and functional group confirmation is carried out using Fourier transform infrared spectroscopy (FTIR). Investigation over mechanical properties of fabricated composite reveals that addition of silicon dioxide up to 4 wt.% depicted higher flexural and tensile strength. Increment in silicon dioxide percentage improves the toughness of composite. FTIR results confirms the presence of asymmetric stretching vibrations due the after effect of hybrid fillers. Thermogravimetric analysis results depict that incorporation silicon dioxide increases the activation of energy of matrix from ~ 24.2 to 31.5 kJ/mol. [ABSTRACT FROM AUTHOR]

A product class characterization was requested on some plastic granular waste samples, already reduced in fine form with particles < 20 mm, derived from waste electrical wires and PC cables. The product class discrimination was worked out by visual characterization with the aid of optical stereomicroscopy and confirmation by electron scanning microscopy (SEM) and microanalysis. Characterization at a micro-scale level evidenced predominance of plastic materials with presence of metal wires, paper, textile and glass fibres at residual levels in the main fraction (0.5–4 mm). The fractions < 0.5 mm, when present, cannot easily be distinguished at sight and only approximate qualitative information can be extracted by SEM analysis. The described approach has been carried out effectively due to major shape and material differences between plastic particles and metal wires and other materials. However, this approach may not work in every case, or it may not lead to usable results with every type of waste. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental and numerical investigations on water ingress trapped in aircraft honeycomb panels. The ingress of atmospheric water during aircraft service may cause minor or major damages of airplane crucial components. The percentage of water/ice filling honeycomb cells is an important factor related to possible cell damage. This study is focused on the analysis of the following inspection parameters: (1) influence of panel orientation (horizontal, vertical and Inclined at 30°, 45° and 60°) on the efficiency of water detection, (2) efficiency and optimization of a heating technique in evaluating water ingress, (3) influence of water/ice phase transformation on detectability of water ingress. The numerical analysis was conducted by using the ThermoCalc-3D software in order to evaluate the detectability of water ingress in the cases where a test panel is placed in different spatial orientations. The samples with water and ice were tested and analysed by using several data processing algorithms available in the ThermoFit software to enhance water detection performance. The signal-to-noise ratio concept was used to compare efficiency of image processing algorithms in the inspection of water ingress in honeycomb panels with varying water content, spatial orientation and water/ice phase transformation. [ABSTRACT FROM AUTHOR]

The advantages of carbon nanotubes (CNTs) in fortifying the glass fiber reinforced polymeric (GFRP) composites are discussed in this paper. Bolted steel straps are utilized at the edges of composite plate to establish clamped conditions in the test setup. To minimize uncertainties caused by bolt attachments, a genetic algorithm-based model updating approach has been implemented by introducing artificial linear springs at the margins to achieve a better balance between theory and reality. The accuracy of the plate's results (natural frequencies and mode shapes) is verified, and the mechanical properties of randomly dispersed CNTs are incorporated in the formulations of folded plates. Remarkably, the motion equations are brought forward by the first order shear deformation theory (FSDT). Thereafter, two-directional generalized differential quadrature (2D-GDQ) technique is employed to determine natural frequencies from available motion, continuity, and boundary equations. The results of the folded plate are validated first by an experimental modal testing and finally some effective parameters such as folding angle, CNT weight ratio, boundary condition and flange-shape length are examined. [ABSTRACT FROM AUTHOR]

This study aims to explore the flexural behavior of crushed clay brick (CCB) lightweight concrete (LWC) beams strengthened with rubberized strain-hardening cementitious composite reinforced with glass fiber textile mesh layers (GFTM-RSHCC) at the tension side. For this purpose, an experimental investigation consisting of seven simply supported beams, including one un-strengthened specimen, was produced and tested using a monotonic 4-point loading scheme. All specimens had a 120 × 250 mm cross-section, a total length of 2400 mm, and a loaded span of 2200 mm. The studied parameters were the number of GFTM inside the RSHCC (1, 2, or 3) and the thickness of GFTM-RSHCC layer (30 or 40 mm). All the following aspects were tracked: crack pattern, ultimate load, mid-span defection, and ductility. The results show that increasing the number of layers of GFTM and the thickness of RSHCC generally leads to an increase in the ultimate loads and ductility, up to 68% and 83%, respectively, compared to the control beam. Finally, a proposed equation considering the contribution of the GFTM-RSHCC layer was developed to predict the flexural capacity of the strengthened beams. The proposed equation showed good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

This study aims to synthesize TiC + TiB2 reinforced epoxy/glass fiber composites to enhance mechanical properties and resistance to wear and erosion. For this purpose, TiC + TiB2 particles were added to the epoxy matrix in contents of 0, 2.5, 5, 12.5, and 20 wt.%, and the composites were then created through the hand-layout technique. The mechanical, wear, and erosion properties were eventually analyzed. The wear mechanisms of samples were evaluated by scanning electron microscope (SEM) images. The findings indicated that adding 2.5 wt. % of particles maximized the modulus, increasing the tensile and flexural modulus rates by 26 and 17%, respectively. The hardness also improved when TiC + TiB2 particles were added. In fact, it reached the maximum level (58%) once 12.5 wt.% of particles were added. The wear resistance of the composites increased with the TiC + TiB2 content where adding 20 wt.% of the particles enhanced the abrasion resistance by 86% while lowering the friction coefficient. The erosion resistance was analyzed with a rotating device in an abrasive slurry under different variables such as rotation speed, impact angle, and sand rate. The maximum erosion resistance was observed in a composite sample containing 12.5 wt.% of TiC + TiB2 particles. [ABSTRACT FROM AUTHOR]

Composite materials are an effective way to realize the lightweighting of automobiles. The molding process parameters have significant effects on the mechanical properties of the products. In this paper, continuous glass fiber reinforced polypropylene plastics (CGFRPP) laminated boards were prepared through compression molding. The influence of process parameters on the mechanical properties of CGFRPP products was investigated. The material preheating temperature was found to have the greatest influence by the extreme difference analysis method. Typical products were selected for microscopic observation to investigate the microscopic mechanism of the influence of material preheating temperature on CGFRPP products. The results show that the optimal process parameters for compression molding are 95 °C, 570 kN, 90 s, 9 mm/s, 195 °C and 600 s for mold temperature, compression pressure, holding time, mold-closing speed, material preheating temperature, and material preheating time, respectively. Afterward, a confirmation test was performed to validate the optimum parameters. [ABSTRACT FROM AUTHOR]

In defense and military applications, the growing use of radar technology necessitated the development of effective stealth solutions for military equipment like drones and fighter jets. This paper explored a new approach that glass fiber mat coated with various concentrations of grapheme embedded polyvinylidene fluoride (PVDF) nanofibers using electrospinning technique and stacked the Graphene/PVDF/Glass fiber mat layers by epoxy resin and hardener to form the glass fiber laminate composite by hand layup technique to enhance the electromagnetic wave absorption. These research findings demonstrated that composite materials were more successful than metals at absorbing electromagnetic waves. The tailored composite showed above 80% increase in electromagnetic absorption over conventional metal in the X-band (8–12 GHz), although having a minimum thickness of 3 mm. According to X-ray diffraction, PVDF/Graphene nanofibers had improved electroactive β-phase behavior when compared to pure PVDF nanofibers. The PVDF/graphene nanofibers which have an average diameter of 80–160 nm, were seen using scanning electron microscopy. The tailored composites also had simple configuration and mechanical characteristics that were improved when compared to plain glass fiber laminate composite. In comparison to all other configurations, experimental findings showed that the composite with 0.5 wt% Gp/PVDF had a wide band absorption of above 90% in all the frequencies. This innovative method of fabrication of the tailored Gp/PVDF nanofibers coated glass fiber laminate composite provided a promising strategy in the manufacture of military equipment and stealth fighters. [ABSTRACT FROM AUTHOR]

The migration and transformation of bromine in the pyrolysis process of copper-containing glass fiber resin (CGFR) under microwave heating have been studied, and the pyrolysis products analyzed. With the increase of microwave power, the solid-phase yield and the bromine content in the solid-phase product showed a trend of first decreasing and then increasing. Under the optimized conditions (700°C, 1000 W, 60 min), the solid yield was 74.41%, the bromine content in the solid product was 78 ppm, and the removal rate of bromine was 14.19% higher than that of conventional pyrolysis. Bromine mainly exists in organic form and is encapsulated in CGFR polymers. Microwave pyrolysis can heat the CGFR as a whole, promote the release of bromine in these organic inclusions, and ultimately improve the removal rate of bromine. However, the higher microwave power will cause the CGFR to violently pyrolyze, and the organic matter will carbonize, which will hinder the release of bromine. In this study, the migration and transformation mechanism of bromine in microwave pyrolysis of CGFR has been proposed, which proves that microwave pyrolysis plays a positive role in the recovery process of CGFR, improved its recovery and utilization efficiency. [ABSTRACT FROM AUTHOR]

Hybrid components consisting of continuous fiber reinforced thermoplastic (CFRT) and steel components exhibit promising potential in advanced lightweight construction. However, the joining operation presents a significant challenge due to the materials' distinct physical and chemical properties. This paper studies a joining method in which dual pin arrays protruding from the surface of the metal component are inserted into the locally heated CFRT component to create a form-fitting joint. The primary objective is to scrutinize the influence of various CFRT materials on joint formation and quantify the resulting properties. The fiber type (glass and carbon) and fiber architecture (unidirectional and bidirectional reinforcement) are varied. All materials could successfully be joined via the direct pin pressing process, while depending on the CFRT material, distinct characteristic fiber morphologies could be identified. Bidirectionally reinforced carbon fiber reinforced samples showed the highest overall strength, while unidirectionally glass fiber reinforced samples showed the highest energy absorption and second highest ultimate strength. [ABSTRACT FROM AUTHOR]

With the current development of the 5G infrastructure, there presents a unique opportunity for the deployment of battery-less mmWave reflect-array-based sensors. These fully-passive devices benefit from having a larger detectability than alternative battery-less solutions to create self-monitoring megastructures. The presented 'smart' skin sensor uses a Van-Atta array design enabling ubiquitous local strain monitoring for the structural health monitoring of composite materials featuring wide interrogation angles. Proof-of-concept prototypes of these 'smart' skin millimeter-wave identification tags, that can be mounted on or embedded within common materials used in wind turbine blades, present a highly-detectable radar cross-section of − 33.75 dBsm and − 35.00 dBsm for mounted and embedded sensors respectively. Both sensors display a minimum resolution of 202 μ -strain even at 40 ∘ off-axis enabling interrogation of the fully-passive sensor at oblique angles of incidence. When interrogated from a proof-of-concept reader, the fully-passive, sticker-like mmID enables local strain monitoring of both carbon fiber and glass fiber composite materials. The sensors display a repeatable and recoverable response over 0–3000 μ -strain and a sensitivity of 7.55 kHz/ μ -strain and 7.92 kHz/ μ -strain for mounted and embedded sensors, respectively. Thus, the presented 5G-enabled battery-less sensor presents massive potential for the development of ubiquitous Digital Twinning of composite materials in future smart cities architectures. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced cement-based material incorporating hollow glass beads (GFRC-HGB) is an innovative lightweight building material with exceptional energy-saving properties. Based on the framework of variational asymptotic homogenization theory, a micromechanical model is developed for predicting the effective elastic properties and recovering the local fields of unidirectional GFRC-HGB. This model starts with expressing the displacements of the heterogeneous GFRC-HGB in terms of those of the corresponding homogeneous material and fluctuation function. Then, the principle of minimum potential energy is used along with variation asymptotic method to formulate the governing variational statement for the micromechanics model, the micromechanical model is used to quantitatively investigate the influence of internal structural parameters of HGB on the elastic properties of unidirectional GFRC-HGB. The numerical results demonstrate the effectiveness and accuracy of the micromechanical model in predicting the effective elastic modulus and local fields. The numerical simulation and SEM images of the tensile fracture prove that the local stress distributions are closely related to the loading direction, and the transverse deformation is restrained by glass fibers. [ABSTRACT FROM AUTHOR]

To simultaneously endow thermal conductivity, high glass transition temperature (Tg) and healing capability to glass fiber/epoxy (GFREP) composite, dynamic crosslinked epoxy resin bearing reversible β-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth (GFC@BNNSs). The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated BNNSs. Then, the GFC@BNNSs were impregnated with the mixture of lower concentration (3-glycidyloxypropyl) trimethoxysilane grafted BN micron sheets, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride, which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical performances. The resultant GFREP composite containing less boron nitride particles (17.6 wt%) exhibited superior in-plane (3.29 W·m−1·K−1) and through-plane (1.16 W·m−1·K−1) thermal conductivities, as well as high Tg of 204 °C (Tg of the unfilled epoxy=177 °C). The reversible transesterification reaction enabled closure of interlaminar cracks within the composite, achieving decent healing efficiencies estimated by means of tensile strength (71.2%), electrical breakdown strength (83.6%) and thermal conductivity (69.1%). The present work overcame the disadvantages of conventional thermally conductive composites, and provided an efficient approach to prolong the life span of thermally conductive GFREP laminate for high-temperature resistant integrated circuit application. [ABSTRACT FROM AUTHOR]

The damage mechanism of 2D woven fiberglass panels under random vibration loadings was investigated by means of an experimental analysis and compared with the damage mechanism under constant-amplitude loadings. Based on experimental observations, it was found that the failure mode under vibration loadings was delamination, and predicting the vibration fatigue life using the traditional S – N curve would result in significant errors. Therefore, a prediction method was proposed to accurately estimate the vibration fatigue life of a 2D woven fiberglass panel by modifying the conventional S – N curve. An experimental verification showed that this method has a high level of prediction accuracy. [ABSTRACT FROM AUTHOR]

The effects of thermal aging on the failure behavior of single-lap bonded joint composites were investigated experimentally. The single-lap bonded joints specimens were made of [0]8 layered woven glass fiber/epoxy composite plates joined together by adhesive. Two different thermal aging processes were applied to adhesive- bonded single-lap joints specimens. In the first process, temperatures of 75, 100, and 150°C were applied during the aging time of 4 h. In the second process, a constant temperature of 150°C was applied for aging times of 2, 4, and 8 h. Additionally, this study was carried out in a temperature-controlled oven, without considering humidity, using three different adhesive thicknesses (0.2, 0.4, and 0.6 mm) and three different overlap lengths (15, 30, and 45 mm). After the thermal aging process, the specimens were subjected to a tensile test to determine the failure loads. Furthermore, the hardness values of both the adhesive and the composite plate were investigated under the conditions of 4 h at 150°C. The failure loads and microstructural changes determined were compared with the results for control specimens kept at room temperature (25°C). It was found that the increase in hardness values positively affected the strength of both the adhesive and the composite. With increasing the thermal aging time, temperature, and overlap length, the failure loads increased by 8.4 to 79.1%, 14.4 to 79.1%, and 9.5 to 50.9%, respectively. However, an increasing the adhesive thickness resulted in a decreasing the failure loads by 4.6 to 23.8%. [ABSTRACT FROM AUTHOR]

United Nations SDGs-11 focuses on safe, resilient, sustainable cities and human settlement. Importance given to implement the Disaster Risk Reduction strategy where the number of death and economic loss to be reduced. Seismic disaster risk reduction is one of the major task in SDGs., The occurrence of earthquake in the Himalayan region is continuous and infrastructures are highly affected. The study aims to suggest a suitable seismic retrofitting technique for infrastructures in Sikkim Himalayan region by In-situ and laboratory based analysis. In the lab environment, geoinformatic based geospatial databases have been generated to understand the seismological characteristics of the study area and a seismic retrofitting experiment has been conducted with the help of plaster of Paris column wrapping with glass fiber to test the strengthening of the column specimen. Also, In-situ field observation data has been collected and analyzed to recognize the vulnerable infrastructures which have the probability to get damaged during an earthquake and relevant seismic retrofitting technique has been suggested for vulnerable infrastructures by incorporating with lab based structural analysis. The experimental result shows that the first crack is developed in the Specimen-I without wrapping while the applied load is 320N, deflectometer reading is 555 mm. At a load of 640N, the column developed crack. The complete failure of the column has also been recognized from this specimen while the applied load is 832N and deflectometer reading is 924 mm. In the fiber wrapped specimen (Specimen- II), it is observed that the crack is not developed in the specimen-II column till it has been completely uprooted from the base when the load reached 320N the corresponding deflection was found to be 350 mm which is very much less than Specimen I. The experimental result indicates that the glass fiber wrapped specimen appears stronger with an increasing load than without wrapped specimen. It can be inferred that the seismic retrofitting technique using GFRP wrap in concrete structure can improve the strength of the buildings in the study region. The proposed technique is suggested for different concrete infrastructures in the study region to improve the strength of the columns and beams for protecting infrastructures. [ABSTRACT FROM AUTHOR]

The use of renewable lightweight materials and the adoption of cleaner production are two effective approaches to reduce resource consumption, which contributes to meeting the industry's environmental impact targets. In a previous study we found, that a miscanthus fibre reinforced cellulose acetate (CA-Miscanthus, 25 wt.%) can be a bio-based alternative to glass fibre reinforced polypropylene (PP-GF, 20 wt.%), as both materials exhibit similar mechanical properties. However, only limited information on the environmental benefits of using bio-based composites instead of their petroleum-based counterparts are available. In this study, we compare the environmental impact of ready to use compound of both materials in the cradle to gate system boundaries, including fibre cultivation, fractionation and refining, fibre pretreatment, and compounding. The functional unit is chosen based on the equivalent function of both materials. The environmental impact is determined using the Product Environmental Footprint (PEF) methodology. The results reveal that the CA-Mis composite has a higher environmental impact than the PP-GF composite in all categories observed, despite its biomass origin. As the primary reason for the high impact, the acetic anhydride use during CA production is identified. The study indicates that, though the bio-composite CA-Mis has mechanical properties comparable to PP-GF composites, it is not as eco-friendly as we initially assumed it to be. [ABSTRACT FROM AUTHOR]

The present study investigates the flexural failure properties of a hybrid laminate beam subjected to three-point bending. A symmetrically laminated hybrid beam is constructed using high-strain and inexpensive glass fibre on the top layers and low-strain and expensive carbon fiber on the middle layers. Classical lamination plate theory is used to find the stress and strain distribution that occurs due to the bending moment on the compressive side. The theoretical failure limits of the laminated hybrid beam are analyzed considering the targeted span-to-depth ratios, volume fractions of the fibers and hybrid ratios using the Tsai-Wu failure criterion and Matlab codes. Using the graph of failure index versus hybrid ratios, the minimum thickness of carbon fiber needed for the delay of failure and cost efficiency of the laminated hybrid beam is identified by applying the linear interpolation method. The numerical results indicate that the failure index increases with the increasing loading span and decreases when the volume fraction of fiber increases. In particular, the placement of glass fiber on the top layer of the laminated hybrid beam might have contributed to obtaining higher strains and curvatures before the catastrophic failure properties of carbon fiber. The flexural stiffness of the laminates is found to increase when the hybrid ratio increases. Overall, it is noted that the theoretical analysis is one method that is less time-consuming and cost-effective than other alternative approaches, such as finite element methods and experimental tests to estimate the minimum thickness of high-stiffness and the expensive material needed to maintain the strength and stiffness of the hybrid composite structures over long periods. [ABSTRACT FROM AUTHOR]

Composites have gained acceptance in an extensive range of applications owing to their unique characteristics. But, machining of these materials is often challenging due to improved bonding between matrix and fibre when fillers are added. Since the machinability is an important aspect for any material for its successful utilization, it is essential to analyse the effect of secondary phase on machinability. However, investigations on the effect of fillers on machinability of polymer composites are minimal. In this research, hybrid fillers, namely boron nitride (BN) and montmorillonite (MMT) nanoclay, were added to epoxy/glass fibre composite through compression moulding, in which quantity of MMT is fixed and BN is varied from 2 to 6 wt%. Abrasive water jet machining (AWJM) is a leading method for machining polymer composites in which transverse speed, stand-off distance, pump pressure and filler percentage are key factors and are considered as input variables. To assess the machinability, material removal rate (MRR), surface roughness (Ra) and kerf taper (Kt) are chosen as response variables. Experimental planning is done through Taguchi method, and Criteria Importance Through Intercriteria Correlation (CRITIC)-weighted Complex Proportional Assessment (COPRAS) technique is utilized for optimization. The results revealed that addition of BN reduces the MRR while it improves the surface finish and reduces the Kt. Transverse speed has the most influence over all the considered output responses, stand-off distance and water pressure mainly affect the MRR and Ra while filler addition mainly affects the Kt. The hybrid CRITIC-COPRAS approach–recommended optimal control factors resulted in 16.20 mm3/min MRR with 0.29° Kt and 3.86 µm Ra. The recommended optical condition can be utilized for effective machining of polymer composite with MMT/BN fillers. [ABSTRACT FROM AUTHOR]

An evaluation of the interlaminar fracture toughness of polyamide/glass fiber laminates with various layups is reported. Due to large differences in thermal expansion coefficients of fiber and binder the laminates with layups where single layers are swapped exhibit high warping. A technique for avoiding this is proposed, allowing evaluating interlaminar fracture toughness of various angle interfaces. Two different layups for evaluating the Mode I and II interlaminar fracture toughness are tested. The differences of delamination behavior of a number of different-angle fiber interfaces are shown and analyzed. The applicability of the proposed testing technique is discussed. [ABSTRACT FROM AUTHOR]

The present scenario forces researchers to reduce raw material usage for future conservation and imposes a responsibility to reuse the waste by converting it into valuable products. With a state of potential, the components are put forward for reusing the diamond-cutting waste as effective filler particles in the polyepoxide-glass laminated hybrid composite. The polymer composites were prepared using the hand lay-up process under hydraulic loading conditions. The composites were formulated by changing the diamond filler fraction (1, 3, 5 and 10 wt%) and keeping a constant glass weight percentage of 20%. The composite's mechanical, thermal stability and erosion properties were evaluated to study the effect of diamond filler material in glass fibre composites. With the addition of 5% diamond particles, the tensile, flexural, and Shore D hardness were improved by a maximum of 48, 34 and 26%, respectively, compared to the polyepoxide glass fibre composite, due to the restraint on deformation of polymer chains. There was minor diamond particle aggregation due to fines in more than 5% of the diamond filler, reducing the rate of improvement of the mechanical behaviour. The higher thermal conductivity and increased strength offered by diamond filler improved thermal resistance and slowed down the thermal degradation of composites. The sand erosion test reveals that diamond particles boosted the erosive wear resistance of the composites by offering high mechanical strength, which could change the erosion wear mechanism. Erosion morphology determined through SEM analysis found that high-volume diamond particles reduced erodent-polymer matrix interaction at the micro level, decreasing the erosion wear of diamond-filled composites. [ABSTRACT FROM AUTHOR]

The efficient modeling of 3D-printed parts, especially long fiber-reinforced composite parts, is a significant concern. This paper discusses finite-element modeling using the embedded element technique to simulate the mechanical behavior of specimens reinforced with long glass fibers. The study considered the concentric deposition mode of the fibers, the walls, and the solid filling pattern of the printed parts as parameters. In addition, classical numerical modeling of the composites using 2D Shell elements and an analytical prediction of the Young's modulus using the rule of mixtures were implemented. The results showed that both the classical 2D Shell modeling and the law of mixtures predict the Young's modulus with acceptable prediction error. However, these approaches have limitations in predicting the overall behavior of the specimens. The use of the embedded element technique allowed for the prediction of both the Young's modulus and the global behavior of the specimens with acceptable prediction error. [ABSTRACT FROM AUTHOR]

The manufacture of large wind turbine blades requires well-controlled processing conditions to prevent defect formation and thus produce high-quality composite blades. While the physics-based models provide accurate computational capabilities for the resin infusion and curing process for the glass fiber composites, they suffer from high computational costs, making them infeasible for fast optimization computation and process control during manufacturing. In light of the limitations, we describe a machine learning (ML) approach that employs a deep convolutional and recurrent neural network model to predict the spatio-temporal temperature distribution during the vacuum assisted resin infusion molding (VARIM) process. The ML model is trained with the "big data" generated from the physics-based high-fidelity simulations. Once fully trained, it serves as a digital twin of the blade manufacturing process. Validation is made by comparing simulation results with experimental data on a unidirectional glass fiber composite laminate plate (44 plies, 2 m long and 0.5 m wide). The trained and validated ML model is then extended to evaluate the role of critical VARIM processing parameters on temperature distribution. With the predictive accuracy of 94%, at over 100 times faster computational speed than the physics-based simulations, the ML approach established herein provides a general framework for a digital twin for temperature distribution in the composite manufacturing process. [ABSTRACT FROM AUTHOR]

Degradation of polymer composites is a significant problem in many engineering aspects. Due to the interaction of various degradation factors during the exploitation of composites, a synergistic effect of destruction is observed. The article describes the phenomena occurring in glass fiber reinforced polyester laminates under the influence of ultraviolet radiation (UV) in an aquatic environment. The laminates were exposed to UV-A, UV-B and UV-C radiation for 1000 h in free-air and underwater conditions. During the test, the materials were immersed at stable depth of 1 mm and 10 mm, respectively. The three-point bending tests performed on the samples after being exposed to UV showed an increase in the flexural strength of the composites. Simultaneously, degradation of the outer surface layer was observed. The degradation removed the thin resin film from the surface which resulted in a direct exposure of the reinforcing fibers to the environment. The transformations taking place in the deeper layers of the composite increased the mechanical strength due to the additional cross-linking reactions excited by the energy arising from the radiation. Moreover, the formation of polymer structures from free styrene remaining after the technological process and the occurrence of free radical reactions as a result of the cage effect was also observed. [ABSTRACT FROM AUTHOR]

This research paper presents the synthesis of Glass-Fiber Reinforced Plastic (Glass-FRP) and Natural Fiber-Hybrid Composites (NFHC) using Hand Lay-up techniques. The aim of the this research is on assessing mechanical characteristics of composites made from different natural fibers, including jute, flax, coir, and hair fibers. The study sought to evaluate the influence of natural fiber addition on mechanical characteristics of the composite material and to emphasize the significance of altering fiber type, orientation, resin type, and curing conditions to optimize composite characteristics for particular applications. The mechanical characteristics of these composites were evaluated using tensile and flexural testing. This study significantly enhances the mechanical properties of Glass-FRP composites by incorporating Jute fibers, showcasing a superior tensile strength of 71.29 MPa and the highest flexural strength of 67.73 MPa. The investigation showed that the combination of natural and glass fibers may produce a lightweight, highly-strengthen composite material with enhanced mechanical characteristics that can be employed in a wide range of technical applications. [ABSTRACT FROM AUTHOR]

Composite manufacturing demands mould tooling to produce dimensionally accurate parts, adding substantial capital costs to their production. Recent developments in advanced manufacturing of fibre-reinforced polymer composite elements have seen the implementation of mould-free technologies that can produce complex shaped parts off a flat tool. This paper presents eccentric fibre prestress as a novel mould-free method for producing curvatures within carbon fibre and glass fibre laminates. Tailoring the flexural rigidity along the primary orientation of the laminate is shown to result in predictable compound curvature profiles with a low average root mean square error of 1.39 across the four geometries tested. An analytical model based on Euler–Bernoulli beam theory is proposed and proven to correlate closely with the experiential laminates. Finally, an inverse design approach based on a genetic algorithm is demonstrated to design an accurate laminate configuration, achieving the top surface of a NACA 4412 aerofoil section with a low root mean square error of 1.98 using the proposed eccentric fibre prestress. [ABSTRACT FROM AUTHOR]

Sustaining the resilience of the environment against climate change volatilities is fast becoming a herculean task considering the vulnerabilities of the ecosystem and disruption of the global value chain. Environmental crisis emanating from improper containment of synthetic materials is a major impediment facing the world today, and the situation could get worse if urgent measures are not devised to mitigate the quantity of waste synthetic materials that find its ways to the environment. These wastes are released in the form of toxins, posing danger to the environments, causing biodiversity loss and the degradation of already battered-climate. In this paper, the authors apprise existing containment measures of synthetic waste materials taking a preliminary and on-the-spot assessment of their impacts and effectiveness of their application leading to their operation. The prospect of waste glass fiber in automotive part replacement is given utmost interest in this paper, in which, a significant quantity of glass fiber could be used as part of automotive materials to reduce their overbearing environmental carnage. By this approach, the emerging automotive parts may have their strength and durability enhanced against impact and corrosion. Mindful of the non-biodegradable properties of glass fibers, the paper captures how effective these fibers could be used as automotive parts against the traditional materials. This paper also reflects on the response of the natural fiber in terms of their sustainability, as natural forest faces severe extinction occasioned by anthropogenic activities. [ABSTRACT FROM AUTHOR]