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The construction of lunar stations for research and habitation requires high-performance building materials that can adapt to the harsh lunar environment. One of the feasible building materials is fiber-reinforced composites, for which the composition of glass fibers can be designed like lunar soils, i.e., terrestrial basalt, and in turn the "lunar glass" can be drawn into fibers. Because of a wide variation of TiO 2 in lunar soils, our study focused on a series investigation on the effect of TiO 2 (0.55 wt%-6.14 wt%) on fiber spinnability and strength of the simulated "lunar glass and glass fibers". The baseline glass composition was derived from a simulated TiO 2 -lean lunar soil and other glasses were made at different TiO 2 doping levels. The addition of TiO 2 was found to reduce the thermal stability of the melt, there appears a TiO 2 threshold (6.14 wt%), at which fibers cannot be drawn without breakage because of melt devitrification. The fiber tensile strength exhibits a nonlinear characteristic with an apparent maximum at 1.52 wt% TiO 2. FTIR and Raman spectroscopic studies were carried out to investigate the glass network structure responses to TiO 2 modifications and show TiO 2 functions as a network modifier, depolymerizing the silicate network. Statistical structure (FTIR & Raman based)–property modeling was attempted to further elucidate the effect of TiO 2 -induced structure change on T g and fiber tensile strength. Good agreements were found between the model predictions and the measured values. [ABSTRACT FROM AUTHOR]

Glass fiber reinforced composite aerogel felt is an important thermal insulation material, but its thermal insulation performance is often compromised due to the limitation of preparation methods. In this study, the high performance glass fiber composite silica aerogel insulation thin felt was successfully prepared by in-situ sol-gel impregnation and combustion drying process for the first time. Especially, the drying time for the whole procedure is extremely quick, only taking a few minutes. The composite felt shows the characteristics of light weight, porous, hydrophobic, and has good mechanical properties. More importantly, due to the unique composite structure of the prepared felt, it has extremely low thermal conductivity (0.016 W/(m·K)) and thermal stability. The infrared thermal imager further confirmed that glass fiber composite silica aerogel thin felt has excellent thermal insulation ability, and has promising application potential in the thermal management system of power battery. Finally, the preparation process and drying mechanism based on sol-gel impregnation combined with combustion drying technology were discussed. Compared with the common technology, the preparation method has significant advantages of high efficiency and low cost, which offer an innovative technical approach for producing composite aerogel felt. [ABSTRACT FROM AUTHOR]

Since high costs restrict the wide-range implementation of green hydrogen production capacities based on proton exchange membrane water electrolysis (PEMWE), efforts on cost reduced components need to be made. Beside the necessary noble metal catalyst, the membrane material is a main cost driver. In this work, a novel glass fibre reinforced PFSA/ssPS composite membrane is investigated as an alternative to widely used Nafion®. These membranes are processed into membrane-electrode-assemblies (MEAs) in conjunction with catalyst-coated substrates, prepared via electrochemical catalyst deposition. This approach is promising to reduce costs due to less expensive raw materials and due to increasing catalyst utilization by graded catalyst layers. Characterisation of the components and entire MEAs was performed ex-situ as well as in-situ via PEMWE operation. Novel MEAs revealed 2.0 V at 0.5 A cm2, which indicates good potential, but still requires further development efforts. • PEM based on Aquivion ionomer, glass fibre fabric and crushed ion exchange resin. • CCM based on glass fibre reinforced composites reveals 2 V at 2 A cm−2. • Ti-PTL/ATO/Ir anode unveils 2 V and GDL/CNF/Pt cathode 2.3 V at 2 A cm−2. • Electrodeposited electrodes maintain 2.2 V during 62 h of operation at 2 A cm−2. [ABSTRACT FROM AUTHOR]

• Two conductive coatings consisting of CNTs and MXene with randomly mixed structure (MS) and laminated structure (LS) on the fiber surface are prepared by EPD, respectively. • Conductive coatings strengthen the mechanical properties of the single fibers and their composites. • Fiber sensors with conductive coatings depict excellent sensitivity and cyclic stability for monitoring the manufacturing process and structural health of composites. Monitoring the structural health of fiber-reinforced composites from fabrication to in-service is important. Herein, two types of glass fibers (GF) coated with hybrids carbon nanotubes (CNTs) and Ti 3 C 2 T X (MXene) were developed for life-long structural health monitoring. Two conductive layers consisting of CNTs and MXene laminated structure (LS) and randomly mixed structure (MS) were constructed on the single glass fiber surface by electrophoretic deposition (EPD). Compared to pristine GF, LS and MS improved the tensile strength of single fibers by 20.2% and 25.4% for GF with LS (GFL) and GF with MS (GFM), respectively. They also enhanced the interfacial shear strength of the GFL-based and GFM-based composites by 10.11% and 34.22%, respectively. This enhancement was attributed to multiple interactions between CNTs and MXene, such as the mechanical interlocking effect and chemical bonds. Additionally, they could detect the in-situ curing information of the resin, effectively capturing the resin phase change, enabling the monitoring of resin flow, and detection of dry spots. The porous mixed CNTs/MXene layer, which had more voids for resin infiltration, resulted in a superior peak of Δ R / R 0 change (1000%) for MS. Furthermore, both conductive layers could monitor the damage and warn of failure, accurately reflecting the details and crack growth under tensile action. The continuous laminated MXene nanosheets in LS enabled GFL to exhibit excellent cyclic stability and high sensitivity to tensile strain. In sum, by rationally designing the conductive structures, the unique requirements of the sensing fibers for life-long structural health monitoring at different stages were satisfied. [ABSTRACT FROM AUTHOR]

The fiber geometry is a crucial determinant of the fiber reinforced polymer composites' mechanical properties. Specifically, the manufacturing process of stretching and gradual curving in pultruded composites invariably results in complex 3D fiber geometries. Despite its significance, there is still lacking a statistical method to accurately describe these spatially curved fiber shapes. This paper presents a novel multi-scale mathematical approach for modeling the complex 3D fiber geometry in pultruded glass fiber reinforced polymer (GFRP) composites, which includes the analysis of fiber misalignment and waviness at two scales. At the mesoscopic level, a modified elliptical symmetry angular Gaussian (ESAG) model effectively characterizes the fiber misalignment. Simultaneously, at the micro scale, a cosine series representation is employed for capturing local fiber waviness. The approach is verified with XCT scanning results of pultruded GFRP specimens. The current statistical modeling method provides a multi-scale approach for geometry analysis and further simulation of pultruded composite materials. [Display omitted] [ABSTRACT FROM AUTHOR]

This study aims to experimentally investigate the impact resistance of Textile Reinforced Concrete (TRC) panels under high-velocity impact loading. 54 control and TRC panels were fabricated using a standard (29 MPa) and a high (101 MPa) compressive strength concrete, as well as Ultra-High-Performance Fibre Reinforced Cementitious Composites (UHPFRCCs) (132 MPa). 36 out of 54 TRC panels were reinforced with carbon and glass textiles. The mechanical properties of all types of composite systems were investigated under four-point bending test. All specimens were subjected to a high-velocity impact load from a hemispherical steel projectile travelling with an initial impact velocity ranging from ∼60 m.s−1 to ∼160 m.s−1. A high-speed camera was used to track the projectile and record the impact process. The level of impact damage to the TRC panels was quantified by the mass loss, penetration depth and scabbing diameter. The results demonstrated that the standard compressive strength concrete had a flexural toughness 17 % higher than that of the higher compressive strength. The most efficient system in reducing crack propagation and local damage against high-velocity (160 m.s−1) projectile impact load was the UHPFRCCs reinforced with carbon textiles, resulting in maximum penetration depth 25 % lower compared to unreinforced UHPFRCCs panels. • We investigate the impact resistance of Textile Reinforced Concrete (TRC) panels. • We investigate the effect of concrete strength and type of textile on impact resistance. • The UHPFRCCs reinforced with carbon textiles were the most effective against high-velocity impact. • Existing empirical formulas for predicting penetration depth were found to be insufficient for samples with reinforcement. [ABSTRACT FROM AUTHOR]

Epoxy/glass fibre composites possess excellent mechanical and electrical properties and are widely utilised in electrical and electronic power equipment. However, the composites exhibit relatively poor thermal conductivity, causing the temperature of the composites to increase during the operation of power equipment, resulting in a significant reduction in the electrical breakdown strength. Although the effects of thermal aging on polymeric materials have been widely studied, its influence on electrical strength mechanisms has not been investigated at the molecular level. In this study, epoxy/glass fibre composite specimens were subjected to accelerated thermal aging treatment for 360 h at 180 °C. Functional groups, molecular chain dynamics, and electrical breakdown are characterised using infrared spectroscopy, dielectric spectroscopy, and breakdown measurement. Subsequently, electrical breakdown mechanism and life prediction of the thermally aged composites are discussed. During thermal aging, the epoxy resin molecular chains undergo continuous oxidation and chain scission, which generate numerous polar functional groups and short chains and an increase in the free volume. This triggers an enhancement in the chain segmental dynamics, thereby significantly reducing the activation energy of the epoxy resin. After 360 h, activation energy decreased from 0.78 eV to 0.67 eV. The DC breakdown voltages of the specimens decreased from 168.28 kV/mm to 134.91 kV/mm. An insulation life prediction model for thermally aged epoxy/glass fibre composites is established based on the time-temperature equivalence theory. The prediction results indicate that the service life of the operational composites is approximately 11.2 years at 353 K, which is consistent with engineering experience. [Display omitted] • Obtain chain dynamic parameters of thermal-aged composites by dielectric spectrum. • Clarify the effects of thermal aged chemical structure on chain dynamic characteristics. • Demonstrate the influence mechanisms of chain dynamics on electrical breakdown. • Establish a life prediction model based on chain dynamics and breakdown. [ABSTRACT FROM AUTHOR]

Fiber reinforced thermoplastic composites have many advantages, such as repeated molding, high toughness, durability and recyclability, which made them a potential substitute as engineering strengthening materials for thermosetting composites. However, their long-term performances under complex service environments are not well understood, hindering its durability design. In the present paper, glass fiber reinforced polypropylene (GFRPP) plate was studied on its mechanical property evaluation subjected to water immersion (distilled water) and bending (bending strains of 0.54 % and 1.04 %) at elevated temperatures (40 °C, 60 °C and 80 °C) up to 180 days. Water uptake, mechanical properties, thermal properties and microstructure tests were further carried out to reveal the effects of water uptake content, immersed temperature and bending loading level on the properties. The results showed the water absorption curve at three temperatures presents a two-stage diffusion behavior. After the longest immersion time of 180 days, the strength retention of plate at 40 °C, 60 °C and 80 °C were 88.2 %, 58.3 % and 31.8 % for tensile strength, 83.6 %, 67.8 % and 47.9 % for flexural strength and 70.6 %, 61.7 % and 41.4 % for in-plane shear strength. Higher immersion temperature accelerated the swelling effects of polypropylene. Higher bending loading levels accelerated the crack or defects formation and propagation in the resin as well as at the interface. When the strength retention rates were 50 %, the longest service life of plate exposed in service environment of Da Lian (T=9.2 °C) were 23.9 years (tensile strength), 12.8 years (flexural strength) and 3.0 years (in-plane shear strength) without the bending strain. Through comparing with thermosetting composites, glass fiber reinforced polypropylene has almost close or higher tensile strength retention rate and service life for certain service conditions. • The maximum water absorption and diffusion coefficient of composites were lower than epoxy or polyurethane based composites. • Higher immersion temperature accelerated the swelling effects of polypropylene. • Higher bending loading levels accelerated the crack or defects propagation in the resin as well as at the interface. • When the strength retention rates were 50 %, the longest service life of tensile strength were 23.9 years. [ABSTRACT FROM AUTHOR]

• Vinylester-Urethane resin with high density E-glass fibre fabrics composite. • Elastic Modulus, Flexural strength, Interlaminar Shear Strength. • Mode II interlaminar fracture toughness, Strain Energy Release Rate. • Accelerated curing schedule. The influence of the curing process on the interlaminar shear strength and mode II toughness of Vinylester-Urethane resin composites with high density glass fibre plain fabric is shown in this work. There is a shorter curing treatment that achieves similar mechanical properties compared to the treatment proposed by the resin manufacturer. This is of industrial interest as shortening time leads to savings in production costs. [ABSTRACT FROM AUTHOR]

Wind turbine blades are mainly made from E-glass fiber (GF) epoxy composites, because of their good ratio of strength to weight and costs. With the increase in blade length and tip speed, the problem of leading edge erosion is becoming more severe, reducing annual energy production and raising maintenance cost. It was recently shown that nanodiamond-treated flax fiber (FF ND) composites have significantly less erosion than GF composites and could be an alternative for GF in the turbine blade aeroshells. However, FF ND alone might not be suitable for manufacturing turbine blades at the large scale of modern wind turbines. Here, we show that a hybrid composite with a thin layer of only 1.5 mm of FF ND on a GF base, can achieve the same superior results as bulk material FF ND composite. In addition, we show and explain why aramid fibers, that are known for impact resistance, do not perform well as erosion protection. Our research shows the great potential of this technology to be implemented as a low-cost, lightweight skin layer on the leading edge. Acting as damage-tolerant failsafe layer, negligible ∼ 0.04 % extra weight of the FF ND could increase the blade's base erosion resistance by a factor of 60±20 compared to plain GF, expanding the repair window, reducing costs, and enhancing reliability. [Display omitted] • FF ND /GF hybrid composite has same superior erosion resistance as bulk FF ND composite • Acoustic energy measurements indicate material failure as main energy absorption channel. • High energy absorption and mass loss disqualify AFs for erosion protection. • Low-cost, lightweight FF ND skin layer can increase erosion resistance of turbine blades by a factor of 60±20. [ABSTRACT FROM AUTHOR]

In this study, two kinds of fiber reinforced thermoset composites (glass and carbon fiber) were fabricated with almost same volume fraction and thickness and bonded with epoxy adhesives (ADs) with various weight contents of nano hexagonal boron nitride (nano-h-BN) (0, 1, 2 and 3 wt%). The single-lap shear (SLS) tests were conducted on bonded joints with ADs. The effects of nano-h-BN contents on the morphology and micro-structure of the epoxy ADs were studied by scanning electron microscope (SEM). The specimens with the glass fiber reinforced composites with 2-wt% nano-h-BN showed the highest results of SLS strength characteristics with an improvement of 23.6 % and 37.2 % in the SLS strength compared to the specimens with the glass fiber and without nano-h-BN in 0° and 90° directions. Furthermore, the specimens with the carbon fiber reinforced composites with 2-wt% nano-h-BN showed an improvement of 191.7 % and 78.3 % in the SLS strength compared to the specimens with the carbon fiber and without nano-h-BN in 0° and 90° directions. [ABSTRACT FROM AUTHOR]

This article presents the application of cubic Statistical Volume Elements (SVEs) to homogenize the elasticity tensor of epoxy matrix chopped glass fiber composites using displacement boundary conditions. A virtual microstructure reconstruction algorithm is used to reconstruct three large domains of the composites with different fiber orientation distributions. A non-iterative parallel meshing algorithm, named CISAMR, is then implemented to generate high-fidelity finite element models and simulate the linear elastic response of 1536 SVEs extracted from these domains. While the fiber orientations imply transversely isotropic elasticity stiffness matrices, for the SVE sizes considered, the composite is not quite transversely isotropic. We propose two indices of transverse isotropy to (1) determine the orientation at which a given property most closely matches the transversely isotropic assumption for an SVE, (2) quantify the corresponding transversely isotropic discrepancy, and (3) state the extent of transverse isotropy by measuring the difference between transverse and average normal quantities. The former can be applied to any orientation-dependent quantity such as strength, whereas the latter only applies to the elasticity tensor. We demonstrate the superiority of the latter for elastic properties and use the former to show that a proposed initiation fracture strength is farther away from its transversely isotropic limit compared to the directional elasticity normal stiffness. • A virtual reconstruction algorithm is used to synthesize realistic composite microstructures. • Thousands of statistical volume elements (SVEs) are extracted from each composite model. • An automated meshing algorithm is employed to generate finite element models of SVEs. • Two indices are introduced to quantify the transverse isotropy of the elastic tensor. • A statistical analysis shows the superiority of these indices in quantifying the SVE properties. [ABSTRACT FROM AUTHOR]

Geopolymer (GP) materials are attracting increasing interest as a promising alternative to conventional cement-based materials, due to their beneficial characteristics. This article presents the preparation of two series of GP composites based on natural pozzolan (Pz), reinforced with varying percentages (0, 0.5, 1, 1.5, and 2 %) of short fiberglass waste rich in zirconia (Zr-GFW). Two alkaline activation solutions were used with a 1:1 ratio: NaOH (10 M): Na 2 SiO 3 for the first series, and NaOH (12 M): Na 2 SiO 3 for the second series. The effect of Zr-GFW incorporation on the structural, physical, mechanical, and chemical properties was investigated. Besides, a comparison between the two series with the different concentrations of alkaline solutions was also discussed. XRD analysis shows that no significant reaction occurred between zirconia and Pz-based GP matrix. The results show that a 1 % Zr-GFW is sufficient for excellent mechanical strength, up to 65 MPa, and good physical properties. Furthermore, based on the Box-Behnken design statistical method, the developed response surface methodology model shows a strong fit to the experimental data, with high values of R² (0.9998). In this model, the compressive strength studied is 64.28 MPa. After exposure to an 80 % solution of acetic acid for 60 days, the evaluation of chemical durability showed that the dense structure of the studied GP composites resisted the acid attack tests, as confirmed by SEM analysis. The percentage weight loss (%W L) of the GP composites ranges from 14.66 % to 16.15 %, resulting in a decrease in compressive strength of up to 55 %. However, this reduction is better than several previous works. The findings suggest that these GP composites not only contribute to waste management but also enhance the energy performance of buildings. [Display omitted] • GP composites were prepared with pozzolan and varying amounts of short fiberglass. • Alkaline activators included aqueous solutions of NaOH (10 or 12 M): Na 2 SiO 3. • GPs reinforced with 1 % fiberglass have the highest compressive strength. • After 60 days in an 80 % acetic acid solution, the %W L varies from 14.66 % to 16.15 %. • These new GP composites enhance building energy performance and waste management. [ABSTRACT FROM AUTHOR]

This study reports a carbonyl iron/glass fiber cloth composites for radar-infrared compatible stealth in a wide temperature range. All-in-one design strategy breaks the multi-layer design limitation of traditional multi-spectrum stealth materials, which not only obtains better electromagnetic stealth effect with thinner thickness but also shows excellent flexibility and tensile strength simultaneously. [Display omitted] • All-in-one design is proposed to achieve radar-infrared compatible stealth for FCI/GF cloth in a wide temperature range. • Orientation distribution structure achieves synergistic optimization of microwave loss and impedance characteristics. • FCI/GF cloth demonstrates effective bandwidth of 5.82 GHz and excellent infrared stealth properties at high temperature. Multispectral camouflage in a wide temperature range is still a challenging issue owing to the incompatibility of stealth mechanisms corresponding to different spectra. Herein, we develop a flexible flaky carbonyl iron (FCI)/glass fiber (GF) cloth, using all-in-one design of microwave absorption and infrared (IR) stealth to eliminate the above contradictions. Due to micron-scale gaps and height differences on the surface of GF cloth modified with Fe 3 O 4 , FCI gains a special vertical structure, which not only induces multiple eddy centers in FCI to enhance magnetic loss but also reduces the microwave reflection area, achieving a synergistic improvement in attenuation and impedance characteristics. Therefore, FCI/GF cloth with a thickness of 2.0 mm obtains a maximum effective absorbing bandwidth of 5.82 GHz in a range of 25–400 °C. On the other hand, combination of FCI and GF cloth decreases IR emissivity while maintaining wonderful heat insulation performance, allowing objects over 250 °C to obtain promising thermal IR camouflage. The all-in-one design successfully breaks barriers faced by traditional hierarchical radar-IR compatible stealth materials such as strong reflection, great thickness, loss and impedance mismatch. [ABSTRACT FROM AUTHOR]

Thermoplastic composites suffer from weak inter-tape bonding during high-rate laser-assisted automated fiber placement (L-AFP). Here, we propose a strategy to simultaneously enhance the laser heating efficiency and fracture toughness of glass fiber-reinforced polypropylene prepreg tape for L-AFP process by depositing carbon nanotubes (CNTs) on the tape surface by a low-cost bath coating process. CNTs function as efficient light absorbing and photothermal coating to promote molecular inter-diffusion and interfacial healing between successive tapes, as well as toughen the weak interface by CNT pull-out and rupture. A 56 % increase in the near-infrared laser absorption of tapes results in a 946 % improvement in the laydown rate. CNTs also remarkably improve transverse temperature uniformity. Furthermore, double cantilever beam and pants tearing tests show that 0.5 wt% CNTs improve the mode I interlaminar fracture toughness and mode III fracture strength by 17 % and 52 %, respectively, attributed to the enhanced molecular inter-diffusion and CNT bridging effect. [Display omitted] [ABSTRACT FROM AUTHOR]

The fiber hybridization in high-strength composites is one of the most researched strategies to enhance their limited toughness. In this work, hybrid composites at laminate level by stacking together plies of carbon and glass fiber were prepared using fused filament fabrication (FFF) technique. The large void content and the poor adhesion between layers attributed to this technology are overcome by the addition of an optimized thermo-pressurized treatment. The analysis of post-processing temperature effects on the microstructural, thermal and interlaminar properties of additive manufactured hybrid composites, revealed a progressive porosity reduction preserving the dimensional accuracy. The enhancement of mechanical properties is due to different contributions that occurred during post-processing: (i) drying effect, which reduces the plasticization of the composites; (ii) improvement of interface adhesion due to the miscibility of polymers; and (iii) significant porosity reduction (below 1 %). This work opens a wider space of possibilities, since FFF allows more complex designs than traditional composite manufacturing, and additionally provides an approach to promote molecular diffusion at the interface, which is the most critical region of FFF parts. [ABSTRACT FROM AUTHOR]

• Set up of a method to test curved composites in mode I fracture toughness. • Fracture toughness for carbon and glass curved composites. • Mode-I fracture behaviour under harsh conditions. • Environmental conditioning plays a key role on R-curves. • Samples with off-set angles have several crack modes, mainly fibre bridging. This work aims to assess the effect of hygrothermal ageing on the Mode-I fracture toughness behaviour of glass/epoxy and carbon/epoxy composites manufactured by filament winding. Cylinders (136 mm in diameter) are manufactured using various winding angles (±0°, ±15°, ±30° and ± 45°), and the specimens are aged in water at room temperature and 70 °C. Water uptake was monitored until equilibrium, which varies with the material, temperature, and winding angle, being the highest for the ± 45° sample, reaching 1.10 % for glass/epoxy and 1.74 % for carbon/epoxy at room temperature, and 1.30 % and 2.95 % at 70 °C. These results are related to the void content, which is 3.20 % and 3.41 %, respectively. Glass/epoxy composites show superior performance in terms of peak load and strain energy release rate, but carbon/epoxy shows higher fracture toughness for the same winding angle and ageing. Specimens aged at room temperature are less prone to delamination than those at 70 °C. In addition, aged samples at room temperature show higher peak force and strain energy release rates compared to non-aged composites, which is attributed to matrix plasticisation. Samples aged in hot water have poorer behaviour compared to those non-aged or aged at room temperature. The curved double cantilever beam (CDCB) samples have more complex fracture mechanisms compared to flat samples, attributed to their curvature and difficulty in keeping symmetry throughout the test. [ABSTRACT FROM AUTHOR]

Fiber reinforced thermoplastic composite bars offered the advantages of repeated molding, high toughness, and recyclability, making them a promising alternative to steel bars. For the stirrups applications in concrete structures, it was essential to develop efficient bending technologies for producing high-quality thermoplastic bending bars. In the present paper, the bending properties of glass fiber reinforced polypropylene (GFRPP) composite bars were investigated by experimental and theoretical methods. A novel bending fixture of GFRPP bars was specifically designed for GFRPP bars to ensure the reliable bending of the bars. Finite element simulation was employed to analyze the stress distribution of GFRPP bars, providing valuable insights into their mechanical behavior. Additionally, a bending strength model was developed based on the material mechanics, offering a theoretical framework for understanding and predicting the bending strength of GFRPP bars. Finally, the bending mechanism of bars was further revealed according to experimental and theoretical findings. The results of the study demonstrated that the specially designed bending fixture was successful in minimizing damage to the bending section of the GFRPP bars, leading to a significant improvement in bending strength retention of up to 43.2 %. Furthermore, the theoretical results and experimental test have a good agreement in terms of stress distribution and failure mode. The maximum strain in the transition zone between the straight section and the bending section of the GFRPP bars was nearly double that of the straight section at the same stress levels. With the increase of bending radius to diameter ratio from 3.0 to 7.0, the tensile strength of GFRPP bending bars increased by ∼7.9 %. The study identified the transition area between the bending section and straight section of GFRPP bars as the most critical failure point. The strength degradation mechanism during the bending were attributed to the shrinkage and torsion of inner fibers owing to the compression caused the local stress concentration, which caused the inner resin matrix to crack and interface debonding of fiber/resin, leading to the premature tensile failure. • The bending fixture can achieve the high bending strength retention up to 43.2 %. • Theoretical and experimental results verified the most unfavorable failure point. • Larger bending radius contributed to the decrease ∼7.9 % of tensile strength. • Fiber distortion and interface debonding led to tensile failure of bending bars. [ABSTRACT FROM AUTHOR]

• The impact response of carbon/glass intralaminar hybrid braided pipes was studied. • Impact behaviors of hybrid pipes with and without internal pressure were compared. • The damage extension mechanisms were analyzed by micro-CT 3D damage reconstruction. • Ductile and brittle hybrid fibers restrict each other and promote impact resistance. • The hybrid fiber layout and the internal pressure had a synergistic effect. This study investigated the low-velocity impact behaviors of intralaminar hybrid carbon/glass braided composite pipes under internal pressure. The effects of intralaminar fiber layout and internal pressure on the mechanical responses, damage extension, and material cost-effectiveness were analyzed. The internal damage distribution of composite pipes with different hybrid fiber alternating numbers but identical mix ratios was evaluated through Micro-CT three-dimensional damage reconstructions. The yarn splitting of brittle carbon fiber materials was mutually prevented by the induction of intra-yarn debonding and delamination damages by hybridization with ductile glass fiber materials, which were prone to produce out-of-plane displacement and shear stresses under impact loading. A smaller hybrid fiber alternating unit was conducive to exploiting the hybrid impact toughening effect by avoiding pure reinforced fiber materials aggregated under the impactor. Internal pressure had a supporting effect on the composite pipe and was effectively synergistic with the hybridization effect. The change in the dominant damage mode resulted in significant reductions in impact deformation and damage severity compared to the unpressurized case. [ABSTRACT FROM AUTHOR]

This study investigates the use of hemp/glass fiber reinforced epoxy composites for designing automotive front bumper beams, focusing on crashworthiness and pedestrian safety. The composite bumper beam model is evaluated through low- and high-velocity crash simulations and pedestrian leg form impact tests using LS-DYNA software. Optimal stacking sequences are analyzed, with high-strength glass fibers positioned on the outer layers to bear impact loads and low-density hemp fibers in the middle. The hybrid hemp (H)/glass (G) fiber composite laminate can absorb up to 90 % of the impact energy absorbed by a glass fiber composite, with a ± 45° fiber orientation, showing exceptional energy absorption capabilities. The [G(±45°) 4 , H(±45°) 4 ] S composite bumper beam offers superior impact performance, safety, and a weight reduction of 49.2 % compared to a commercial steel bumper beam. This study highlights the potential of natural fiber composites as sustainable alternatives in automotive design. [ABSTRACT FROM AUTHOR]

The research object is a scaled ship model based on the actual size of the naval ship. The ship model's superstructure is made of fiberglass sandwich composite structure and integrated design method. Firstly, based on the theory of composite sandwich panel, the magnitude and distribution of stresses and deformations of the measuring points on the model are analyzed by using the static loading test with four-point bending method under the hogging and sagging cases. The work finds that when the integrated superstructure participates in the total longitudinal bending of ships, its sandwich composite material structure has low stress and coordinated deformation. Therefore, when there are no elastic joints, the superstructure can be constructed into a continuous integrated structural form. After that, the composite stiffness degradation correction model is proposed, the USDFLD subroutine for the failure criterion of the composite shell elements is written, and the damage modes, damage regions and extension paths of the superstructure are obtained by applying different proportions of displacement loads and calculating based on the finite element model of progressive damage. Finally, the work further analyzes the influence of the thickness and orientation of fiber layer in skin, the structural materials of superstructure, the material types and layup thickness of stiffeners in superstructures, and the structural form with or without deck opening and transverse bulkheads on the bearing characteristics and mechanical properties of the integrated superstructure. • Sandwich composites show low stress in ship bending. Non-elastic joints enable continuous structural form. • The study found transmission traits of the composite superstructure vertically and at the hull interface. • The study introduces a composite degradation model, USDFLD subroutine, and analyzes damage in the superstructure. • Showing how factors like skin thickness, layering, material, and structure affect load-bearing. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) are widely used in aerospace applications due to their excellent properties. Green and efficient laser cleaning technology has a broad development prospect in the paint removal treatment of aerospace composites. However, the lack of theoretical analysis and guidance has prevented the industrial application of laser paint removal technology. An infrared nanosecond laser is used to clean the paint layer on the surface of CFRP and GFRP, and the best paint removal process parameters are explored. Surface micromorphology and 3D morphology of CFRP and GFRP after cleaning are observed to reveal the cleaning quality. The FTIR spectrum is used to verify the cleanliness of the paint layer. In addition, the contact angle and bonding force are tested, and the experimental results show that the surface wettability of both surfaces is enhanced after cleaning, and the paint adhesion of both surfaces is improved after repainting. Temperature monitoring, acoustic signal monitoring and high-speed photography monitoring are used to monitor the two cleaning processes respectively. The temperature, amplitude intensity, and plasma size of the two in the cleaning process are compared and analyzed. Based on the monitoring results, it is found that the cleaning mechanism of fiber-reinforced composites includes thermal ablation, vibration effect and plasma impact effect. [ABSTRACT FROM AUTHOR]

Short glass fibre injection moulded composites, used in interior and exterior automotive parts, are exposed to complex stress states, for example during a crash. As the fibre scale dominates the composite's material properties, numerical models need to account for the local fibre orientation. In recent years, mould flow simulation results have been exploited to predict the fibre orientations for finite element models, albeit with limited accuracy. Alternatively, X-ray computed tomography can be used to directly image and analyse fibre orientations. Traditionally, achieving the necessary resolution to image individual fibres restricts the imaging to small regions of the component. However, this study takes advantage of recent advancements in imaging and image analysis to overcome this limitation. As a result, it introduces, for the first time, a reliable, fast, and automated fibre orientation mapping for a full component based on image analysis at the individual fibre level; even for cases where the pixel size is significantly larger than the fibre diameter. By scanning at lower resolutions, a drastically larger volume of interest can be achieved. The resulting fibre orientation analysis and mapping algorithm, based on X-ray computed tomography, is well matched to the level of information required for automotive crash modelling with a standard element-size of a few millimetres. The entire process, encompassing image acquisition, image analysis and fibre orientation mapping, can be directly integrated into an industrial full component application in a matter of hours. [ABSTRACT FROM AUTHOR]

[Display omitted] This work evaluates several mechanisms of separation of surfactant-stabilized emulsified water droplets from diesel fuel using high surface area (50–370 m2/g) and high porosity (>90 %) filter media fabricated by combining aerogels and glass fiber mats. Specifically, high surface area, porous gels of syndiotactic polystyrene (sPS) and silica are developed inside glass fiber mats via dip coating in corresponding sol followed by sol–gel transition. The resultant materials are supercritically dried to obtain aerogel-coated separation media. The abundant meso- and macropores of the aerogel network and the different surface energy of sPS and silica produce cooperative functioning of the mechanisms of size exclusion, coalescence filtration, surfactant adsorption, and volumetric water absorption for removal of emulsified water droplets from ultralow sulfur diesel fuel under continuous flow conditions. The role of each separation mechanism is elucidated in this paper. The results reveal high water separation efficiency of ∼92 % compared to ∼30 % for the glass fiber mats. [ABSTRACT FROM AUTHOR]

This paper developed smart composite structures with screen-printed piezoelectric composite energy harvesters. P(VDF-TrFE) based composites with BaTiO 3 particles of different concentrations were deposited via screen printing and studied regarding surface morphology, crystalline structure, piezoelectric, dielectric and mechanical properties. It was identified that P(VDF-TrFE) with 5 wt% BaTiO 3 addition exhibited the best piezoelectric property. Even with a monotonic reduction in the β phase crystallisation as the BaTiO 3 concentration was increased, a 5 wt% inclusion of BaTiO 3 led to the rise of d 33 from −28.63 pC/N to −33.90 pC/N. This was attributed to the enhanced interfacial polarisation and the stress concentration induced by the addition of the ceramic particles. Subsequently, the printed piezoelectric composites were co-cured with glass fibre reinforced composites (GFRPs) and carbon fibre reinforced composites (CFRPs). The assembled harvesters were tested under both sinusoidal excitation and real industrial vibration. It was found that the smart composites with 5 wt% BaTiO 3 always manifested the best energy harvesting performance. For the optimised generator, maximum power of 2 μW and 1.5 μW could be obtained when using GFRPs and CFRPs as substrates under 1 g peak-peak sinusoidal excitation, respectively. The harvested energy could be used to power a commercial accelerometer with the help of a power management system. When exciting the GFRP-based energy harvester with an optimised printed piezoelectric generator at 7 g p-p acceleration, the power harvested was sufficient to maintain the operation of the accelerometer for 0.34 s. [ABSTRACT FROM AUTHOR]

• Automatic defect detection in glass composites using terahertz radiation. • Time-domain spectroscopy reflective scanner with an electronically controlled optical sampling scheme. • Pre-selection of C-scans with defect-related features. • Thresholding method based on Gaussian histogram fitting. • Size and depth of inclusions and delaminations determined with high accuracy. We developed a method for automatic detection of defects in glass fibre reinforced polymer (GFRP) based on a terahertz time-domain spectroscopy (TDS) system. Two GFRP specimens with round defects of different sizes (inclusions and delaminations) were measured by means of a high-speed TDS reflective scanner with an electronically controlled optical sampling scheme. The algorithm provided a series of C-scans, which were then pre-selected to identify only those with features potentially associated with defects. A thresholding method based on Gaussian fitting of the histogram was developed. The results showed that 87 % of defects were detected for the specimen with inclusions and 100 % for the specimen with delaminations. The algorithm also provided information about the depth of defects, as each C-scan was assigned to a time slice. The results demonstrate that the TDS-based system, along with the proposed histogram-based method, can automatically detect defects in GFRP. © 2017 Elsevier Inc. All rights reserved. [ABSTRACT FROM AUTHOR]

The manufacturing process of composite structures permits fully embedding acoustic emission (AE) sensors. While the embedding process may pose challenges, its advantages, if proven, can outweigh the challenges. The increased sensitivity resulting from embedding acoustic emission sensors in composites is still not definitively established. A test was set up with pre-determined AE initiation locations (surface and sub-surface) and pre-determined receiving sensor's location (surface and sub-surface) to ensure any sensitivity increase was evident. The receiving sensor's attenuation along (at 90°) and across the fibres (at 45°) was assessed using two test methods: pencil lead breaking (PLB) and actuator methods. The actuator method involved using two pulse generators, the TGP110 pulse generator and the Mistras FieldCal. A range of specific frequencies were utilised, 30, 60, 150 and 300 kHz, using the FieldCal. The results obtained from the test methods were not in agreement with each other. For example, comparing the sensitivity using surface cracks, the PLB method showed decreased sensitivity when embedding the receiving sensor compared to the actuator method, which demonstrated minimal changes in sensitivity. The research aims to clarify the sensitivity increase obtained when embedding an AE sensor while taking into account the crack's position and frequency. [Display omitted] • The receiving sensor's sensitivity was different concerning the artificial surface and integrated cracks. • Different frequency outputs were observed between the signal-generating techniques: PLB and TGP pulse generator. • The amplitude registered along the fibres (at 90°) was greater than across the fibres (at 45°). • The Frequency of the AE signal impacted the sensor's sensitivity. • The fully embedded receiving sensor had little to no improved sensitivity. [ABSTRACT FROM AUTHOR]

This study addresses the mechanical limitations of concrete fabricated with recycled brick and concrete as partial replacement of coarse aggregates, which exhibit inferior strength and stiffness compared to those with natural aggregates. To rectify this, a cost-effective approach involving low-cost glass fiber-reinforced polymer composites (LOC-GFRP) is proposed. The key parameters considered were the plain concrete compressive strength and the quantity of LOC-GFRP layers. The compressive strength of LOC-GFRP-confined concrete increased with the number of layers, with greater improvements observed in lower-strength plain concrete. Moreover, the improvement in ultimate strain was more significant than the improvement in compressive strength. The compressive strength and ultimate strain were improved by 271% and 478%, respectively. LOC-GFRP confinement resulted in a bilinear compressive stress vs. strain response, showcasing increased ductility and strength with more LOC-GFRP layers. The study evaluated various existing analytical expressions for fiber-reinforced polymers but found them inadequate in predicting parameters accurately. As a result, nonlinear regression analysis was carried out to propose expressions for predicting compressive strength and ultimate strain of LOC-GFRP-confined concrete for different aggregate types. The calculated coefficient of determination values ≥ 0.90 confirmed the good correlation among experimental and predicted values. ● Low-cost glass fiber-reinforced polymer composites (LOC-GFRP) were proposed. ● LOC-GFRP confinement resulted in bilinear compressive stress-strain responses. ● Strength and strains of LOC-GFRP-confined concrete specimens were predicted. [ABSTRACT FROM AUTHOR]

• The glass fiber filler is adopted as the filler. • The composition of the PVDF-glass fiber composites and the film formation are simple. • Within a specific content range, the BDS synchronously increase with the ε of the material. To make the product commercially viable and applicable, the inclusion of glass fiber filler with a low cost and medium dielectric constant (ε) is adopted as the filler. Synchronously, representative polyvinylidene fluoride (PVDF) with high permittivity and breakdown strength is selected as optimal polymer matrix. And surface modifying agent is employed as organic coatings to weaken the surface energy of glass fiber and boost the interfacial inter-action. An investigation of dielectric properties was conducted by preparing flexible composites consisting of various content of glass fiber. The ε of composites can be significantly enhanced in the PVDF composites with glass fiber, and the breakdown strength (BDS) is remained at a high level. Moreover, within a specific content range, glass fiber makes the ε and BDS of the material increase synchronously. This work provides a facile strategy for the development of excellent performance, simple preparation and low-cost flexible composites. [ABSTRACT FROM AUTHOR]

Lightweight, glass fiber reinforced plastic composites (GFRP) have gained a broad, global acceptance in commercial markets, among which wind turbine blade for the renewable energy sector is one of the fastest growing areas. The usfsupplee of longer wind turbine blades can effectively reduce the cost of energy generation. However, it requires a fiberglass product with a higher tensile modulus to make the blades stiffer to meet the blade deflection requirement under severe weather conditions. Traditional wind turbine blades are made from conventional E-Glass fibers with and without boron. E-Glass is primarily composed of CaO-Al 2 O 3 -SiO 2 (CAS) with and without minor components of MgO (less than 4 %) and/or B 2 O 3 (less than 1 %). Glass with higher modulus belongs to MgO (>7 %) -CaO-Al 2 O 3 -SiO 2 (MCAS) system or R-Glass. Our study focuses on the effects of selective key oxides on the glass network structure by using Raman spectroscopic technique. The Raman derived plausible structure groups are then used to build statistical structure (S) – property (P) models. The S-P models are then compared with the conventional statistical C-P models. A good agreement between S-P and C-P models led to the final construction of C-S-P model platform for future glass design. [ABSTRACT FROM AUTHOR]

• The baking soda abrasive jetting method as a new surface material stripping method for glass fiber reinforced materials (GFRP) was studied. • The jetting effects of different abrasives were compared, and the advantage of low damage of baking soda abrasives was highlighted. • Chemical stripping method was used to compare cleanliness. • The surface material of GFRP stripping process was simulated using LS-DYNA. Glass fiber reinforced composites (GFRP) working in a specific environment require regular inspection and maintenance. It is necessary to remove the surface material of fiber reinforced composites to check the fracture of fibers and the damage to matrix that binds fibers in this process. In this paper, the baking soda abrasive jetting was utilized to strip the surface material of glass fiber reinforced epoxy resin (GFREP). The stripping effects of baking soda abrasive jetting technology under different jetting parameters (fiber orientation, jet angle, jet pressure) were explored, and the optimum stripping conditions were determined as parallel to the fiber, 30°, 0.4 MPa. Compared with the chemical stripping method (phenol-dichloromethane), baking soda abrasive jetting can better retain epoxy resin between glass fibers. The LS-DYNA was applied to simulate the erosion process of a single abrasive particle under the optimum stripping condition. The plastic deformation of the matrix and the slight bending deformation of the glass fiber under abrasive impact were observed. [ABSTRACT FROM AUTHOR]

• Mode I fracture process is characterized for GFRP-steel bi-material interface. • Double-cantilever beam experiments supplemented by detailed DIC measurement. • Accurate modeling of crack initiation, fiber bridging and propagation by new CZM. • Four-linear traction-separation law derived from DIC measurements and iterative FEA. Debonding is characterized as the governing failure mode in the innovative wrapped composite joints made with glass fiber composite material wrapped around steel hollow sections without welding. The prerequisite for predicting debonding failure of wrapped composite joints is to obtain fracture behavior of the composite-steel bonded interface. The mode I fracture behavior of the bonded interface was experimentally investigated using glass fiber composite-steel double cantilever beam (DCB) specimens. The crack length a and the crack tip opening displacement (CTOD) during the test were accurately measured by analyzing the digital image correlation (DIC) data while the strain energy release rate (SERR) was calculated through the extended global method (EGM). The cohesive zone modeling (CZM) was utilized in the finite element model with the proposal of a four-linear traction-separation law to simulate the mode I fracture process. An approach is introduced to determine the critical stages of the proposed four-linear cohesive law by combining accurate measurements of crack length a and CTOD, along with SERR values. The validity of the four-linear cohesive law and the introduced approach to determine the critical stages were confirmed by good agreement in both global and local behavior between the testing and the FEA results. [ABSTRACT FROM AUTHOR]

To address the deficiencies in traditional communication towers in mobile communication engineering, such as heavy weight, easy corrosion and poor durability, this study proposes replacing traditional communication towers with GFRP communication lattice towers with lightweight, high-strength and good durability. Firstly, GFRP material test and GFRP circle tube bending capacity test are conducted. The maximum bending moment that can be subjected to the anchorage end of GFRP circular tube is 18.20 kN·m. Finite element analysis of GFRP circular tubes verifies the accuracy of the bending test results. Secondly, a GFRP communication lattice tower with a height of 25 m is designed adopting GFRP circular tubes as tower columns. Through the bending test of the GFRP tower, it is verified that the connection between the columns and web members of the GFRP tower is reliable and the force pattern of the GFRP tower is reasonable. The large deflection theory can be adopted to the displacement of GFRP towers accurately. Thirdly, according to the actual engineering requirements, the finite element analysis of 25 m-high GFRP tower under the basic wind pressure of 0.45 kN/m2 is carried out by using 3D3S (a spatial structure design software). It can be obtained that the vibration mode of the GFRP communication tower shows two forms of lateral bending and axial torsion. 0° wind load direction has the greatest influence on the displacement of the GFRP tower. The stress ratio of each component in the GFRP tower is less than 1, indicating that no damage occurs in the GFRP tower. Finally, GFRP towers have good economic benefits, good environmental performance and wide range of application after comparing the GFRP tower and traditional steel tower. The demonstration project of the GFRP communication lattice tower is established in Qingyuan City, Guangdong Province, China. When subjected to a typhoon with a wind speed of 17.26 m/s, The horizontal displacement of the GFRP tower top is 10 m, which is about 2/5 of the height of GFRP tower. Although the displacement is large, the GFRP tower is still not destroyed. It can be concluded from the research in this paper that GFRP towers have low cost, good mechanical properties, good durability, and wide application range, which can promote the rapid construction of 5 G communication base stations. [Display omitted] • The bending moment of the GFRP tube can reach 18.20 kN·m. The finite element analysis match well with bending test. • A 25-m-high GFRP lattice tower is designed. The deformation of GFRP tower can be calculated by large deflection theory. • The vibration mode of the GFRP tower shows two deformation forms: lateral bending and axial torsion around the z-axis. • The GFRP tower has a large displacement but no damage, when subjected wind with the speed of 17.26 m/s. • Applying GFRP tower can effectively improve the construction efficiency of 5 G communication base station. [ABSTRACT FROM AUTHOR]