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This study aims to investigate the crashworthiness properties of thin-walled foam-filled Auxetic metal/composite cellular tubes under quasi-static and low-velocity impact axial loading. The specimens were fabricated using thin-walled steel tubes and Glass Fiber Reinforced Composite (GFRC) laminates. The crashworthiness characteristics including peak load, absorbed energy, specific absorbed energy, and failure mechanisms of the hybrid structures were studied and compared with individual hollow section and foam-filled Auxetic tubes. In addition, detailed FE simulations were performed using LS-DYNA software, which was verified by the experiments. [ABSTRACT FROM AUTHOR]

Leaf springs play a vital role in heavy-duty vehicles by offering substantial load support, durability, and convenient maintenance. Lightweight leaf springs enhance vehicle performance, offering benefits like improved fuel efficiency and a smoother ride. Glass fiber reinforced composites enhance fuel efficiency and durability, providing corrosion resistance. Their design flexibility improves ride comfort, and damping properties enhance vehicle stability. The examination conducted through finite element analysis, utilizing ANSYS software, demonstrated a substantial 75.32% decrease in weight for the E-Glass-Epoxy composite leaf spring (GECLS), affirming its efficacy in enhancing strength, reducing weight, and enhancing stiffness. This underscores its superiority as a viable alternative to traditional steel leaf springs (SLS) in vehicular applications. The mono-GECLS exhibited a natural frequency that was found to be 1.9 times higher than that observed in the traditional SLS. It indicates the potential to mitigate resonance issues. After analysing the SLS and GECLS using ANSYS, it was observed that the GECLS exhibits greater values in deflection, natural frequency, and strain energy, measuring 4.659 mm, 29.98 Hz, and 440.68 mJ, respectively, compared to its steel counterpart. Conversely, the SLS demonstrates elevated values in stress, mass, and density, with readings of 283.84 MPa, 3.7695 kg, and 5920 kg/m³, respectively. [ABSTRACT FROM AUTHOR]

Highlights The use of composite materials, particularly glass fiber‐reinforced polymers (GFRP), has considerably increased. The present investigation seeks to ascertain how sodium hydroxide (NaOH) treatments and the incorporation of graphene nano‐particulates (GNP) in GFRP flat‐joggle‐flat (FJF) composite joints. The experiments demonstrated that surface treatment with 0.1 N NaOH and the addition of 0.25, 0.50, and 0.75 wt% GNP reinforcement to the resin considerably enhanced the shear behavior of the FJF joints by 5.48%, 16.04%, and 32.77%, respectively, as compared to plain GFRP specimens, due to the improved chemical bonding and excellent IR radiation retention. 0.2 N NaOH treated with the same GNP concentrations lowered the shear strength compared to 0.1 N NaOH due to the linear reduction in fiber size. Field emission scanning electron microscopy gives a clear failure analysis of the FJF joint specimens. Fourier transform infrared spectroscopy investigation determines the chemical structure of GFRP materials based on distinctive peak intensities in the infrared range and different functional groups contained in the composite materials. Atomic force microscopy testing was done to evaluate the surface textures. The vibration analysis firm that the FJF joint having 0.1 N NaOH with 0.75 wt% of graphene had the highest natural frequency. The effect of NaOH treatment and graphene influence on FJF joints. Shear analysis of the FJF composite joints. FTIR and AFM techniques were adopted to analyze the surface properties. Modal analysis is used to evaluate the natural frequencies. [ABSTRACT FROM AUTHOR]

Owing to the outstanding properties of boron carbide (B4C) particles, material researchers have shown potential in filler‐reinforced polymer composites. The present work studied the implication of B4C fillers on the mechanical and ballistic properties of glass fiber epoxy reinforced composites. Two different weight percentages of 2 and 4 wt% B4C fillers were used to modify the epoxy resin. The composite samples with glass fabric woven were made through compression molding. The results show that the tensile, flexural, interlaminar, impact strength and hardness of glass fiber composite were improved by addition of 2 wt% of B4C. The high‐velocity ballistic tests were conducted on the unfilled and B4C filler‐reinforced composites using a 9 mm parabellum projectile with an initial striking of 372 ± 15 m/s. The least back face signature (BFS) and highest specific energy absorption (SEA) were observed for 2 wt% B4C filler composite. Adding B4C filler enhanced matrix toughening and interfacial bonding between fiber and matrix. Matrix cracking and fiber breakage result in the least ballistic resistance for unfilled composite. Fracture behavior was studied on tensile, impact, and ballistic‐tested samples using scanning electron microscopy. The fractured surfaces of filler‐reinforced composite demonstrated good interfacial bonding, matrix hardening, and fiber pullouts. Highlights: The addition of B4C with epoxy up to 2 wt% improves the mechanical and ballistic properties of the composites.The least back face signature and highest specific energy absorption were observed for 2 wt% B4C filler composite.B4C filler enhanced matrix toughening and interfacial bonding between fiber and matrix.Failure of unfilled glass fiber composites is a combination of matrix cracking, fiber pullout, and interface debonding. [ABSTRACT FROM AUTHOR]

Hybrid kenaf/glass fiber reinforced polymer composites have emerged as promising structural materials, garnering significant attention due to their unique blend of natural kenaf fibers and synthetic glass fibers. However, despite their potential, there remains a gap in the comprehensive understanding of their quasi‐static mechanical behavior, creep resistance, and fatigue performance. This paper addresses this gap by presenting recent advancements in studying these key properties of hybrid composites. Studies reveal that the combination of kenaf and glass fibers results in enhanced tensile, flexural, and impact strengths compared to individual fiber composites. Additionally, the hybridization offers improved creep resistance, with the glass fibers reinforcing the polymer matrix against deformation under sustained loads. Furthermore, investigations into fatigue properties demonstrate the resilience of hybrid composites to cyclic loading, contributing to prolonged service life in high‐stress environments. By elucidating the interplay between kenaf and glass fibers, this review underscores the potential of hybrid composites in various structural applications. The synergistic effects between natural and synthetic fibers offer a balance between sustainability, performance, and durability, making hybrid kenaf/glass fiber reinforced polymer composites a compelling choice for industries seeking lightweight, high‐performance materials in which aligns with the sustainable development goals (SDGs) especially on Goal 12. Highlights: In composite engineering, combining glass and kenaf fibers could cut production costs, yield high‐performance materials, and promote green technology.Substituting part of the glass fiber with kenaf can enhance the strength‐to‐weight ratio and promote greater biodegradability in current synthetic composites.Quasi‐mechanical properties of hybrid kenaf/glass‐based composites was enhanced by optimal stacking sequences, filler addition, and fiber treatment.Failures due to fatigue and creep can be reduced by hybridizing kenaf/glass fiber composites can prevent in polymer composite due to enhance elastic modulus.Enhanced tribological performance of hybrid kenaf/glass‐based composites due to less damage in microstructure via good interlocking of kenaf and glass in matrix. [ABSTRACT FROM AUTHOR]

The development of dental materials needs to be supported with sound evidence. This in vitro study aimed to measure the fracture toughness of a short fibre-reinforced composite (sFRC), at differing thicknesses. In this study, 2 mm, 3 mm and 4 mm depths of sFRC were prepared. Using ISO4049, each preparation was tested to failure. A total of 60 samples were tested: 10 samples for each combination of sFRC and depth. Fractured samples were viewed, and outcomes were analysed. EXF showed greater toughness than EXP, with a mean of 2.49 (95%CI: 2.25, 2.73) MPa.m1/2 compared to a mean of 2.13 (95%CI: 1.95, 2.31) MPa.m1/2, (F(1,54) = 21.28; p < 0.001). This difference was particularly pronounced at 2 mm depths where the mean (95%CI) values were 2.72 (2.49, 2.95) for EXF and 1.90 (1.78, 2.02) for EXP (Interaction F(2,54) = 7.93; p < 0.001). Both materials performed similarly at the depths of 3 mm and 4 mm. The results for both materials were within the accepted fracture toughness values of dentine of 1.79–3.08 MPa.m1/2. Analysis showed crack deflection and bridging fibre behaviour. The optimal thickness at the cavity base for EXF was 2 mm and for EXP 4 mm. Crack deflection and bridging behaviour indicated that restorations incorporating sFRCs are not prone to catastrophic failure and confirmed that sFRCs have similar fracture toughness to dentine. sFRCs could be a suitable biomimetic material to replace dentine. [ABSTRACT FROM AUTHOR]

Highlights The bio‐sandwich composites are lightweight, economical, recyclable, and easily obtainable. Sandwich panels comprising glass fiber/epoxy face sheets and hemp fiber/epoxy core with varying fiber orientations, thickness, and montmorillonite nanoclay are prepared by stirring the epoxy/clay mixture to have uniform dispersion followed by compression molding. The sandwich and monolithic composites are loaded under quasi‐static punch shear. The sandwich panel with 3 wt.% nanoclay shows optimum quasi‐static tensile modulus and strength than the neat panel. Energy absorption, and specific energy absorption of sandwich panels G0/H(0)5/G0‐0%, G0/H(0)10/G0‐0%, G0/H(0)15/G0‐0% are 2%, 76%, 111%, and 28%, 132%, 183% higher than same weight glass/epoxy composites G(0)5‐0%, G(0)8‐0%, G(0)10‐0%. Energy absorption and specific energy absorption of panels G0/H(0)3/G0‐3%, G0/H(0)7/G0‐3%, G0/H(0)9/G0‐3% are similar, 25%, 24%, and 18%, 55%, 57% higher than same thickness composites G(0)5‐0%, G(0)8‐0%, G(0)10‐0%. The energy absorption of sandwich panel G0/90/H(0)15/G90/0‐0% is 49% lower than same weight composite G0/90/(0)9/90/0‐0%. Similar behavior is observed for panels with ±45° face sheets, 0° core, and 0°/90° face sheets, ±45° core compared to composites. Therefore, sandwich panels with 0° face sheets and core outperform composites and can replace them in structural applications in automotive. Particularly, panels show greater improvement over same‐weight composites than same‐thickness ones. Energy absorption of sandwich panels having 0° and ±45° cores is comparable while it is higher than a panel with 0°/90° core, each of 0°/90° face sheets. This is observed for monolithic composites as well. The quasi‐static indentation response of bio‐sandwich composites is examined. Bio‐sandwich composites outperform synthetic composites, each of the same weight. Bio‐sandwich panels with 3 wt. % nanoclay perform better than the same thickness synthetic composites. The behavior of sandwich and monolithic composites varies with fiber orientations. [ABSTRACT FROM AUTHOR]

Glass fiber reinforced phenolic composites (GFRP) are an advanced composite material with good processability, fatigue resistance, corrosion resistance and stability, and are widely used in the production of structural parts for aircraft and ships. Our research described in this article explores the performance changes of GFRP in different aging media with prolonged aging time using GFRP with different fiber/matrix ratios. The research results indicated that aging time had the most significant impact on the various properties of the composite materials among all variables. With the extension of aging time, the bending strength of our composite materials decreased significantly, with a maximum decrease of 33%. The water absorption rate gradually increased and tended to stabilize, but the thermal decomposition temperature remained at 300 °C, and the mass residual rate remained stable at around 61% with little change. As the content of GF was increased, the aging of the composite gradually slowed down, and the rate of decline in its bending strength gradually decreased. In addition, the influence of different aging media on the performance was also studied, and it was found that the presence of NaCl in artificial seawater could cause changes in the osmotic pressure at the interface of the composite materials and the sea water, thus exacerbating interface damage and affecting the material's performance. [ABSTRACT FROM AUTHOR]

This study investigates the residual tensile behaviour of hybrid Carbon Glass fibers reinforced thermoplastic PEEK laminates after they were exposed for 5 min to a hydrogen/oxygen flame. This flame results in a severe thermal aggression characterized by a wall temperature ranging from 900 to 1270 °C and with different heat fluxes (from 200 to 800 kW/m2). The thermally-induced damages were examined by means of microscopic observations and micro CT analyses. The results show that the mass loss linearly depends on the measured heat flux for a 5 min exposure. Depending on the fire testing conditions, the mechanical properties in tension (stiffness and strength) are totally degraded after exposure to the highest heat fluxes (600 and 800 kW/m2) but the retention of the tensile properties is moderate (about −35 to −60% decrease in strength and stiffness, respectively) after exposure to a 200 kW/m2 heat flux. The residual tensile properties of CG/PEEK laminates follow master curves representing the correlations between the mass loss and the changes in the tensile properties regardless the heat flux. These master curves provide a relevant design rule for composite parts to be used under critical service conditions (H 2 /O 2 flame exposure). • The influence of a H 2 /O 2 flame on the behaviour of composite materials was studied. • Wall temperature ranges from 900 to 1270 °C for heat fluxes from 200 to 800 kW/m2. • The mechanical properties are totally degraded after exposure to 600–800 kW/m2. • The changes in the tensile properties are correlated to the mass loss. • Master curves provide a criterion to design composite parts under H 2 /O 2 flame. [ABSTRACT FROM AUTHOR]

Metallic glass fibers have high strength, poor plasticity and low Young's modulus. In this study, it was used as a reinforcement to prepare metallic glass fiber reinforced epoxy composites with different fiber volume contents (20%, 30%, 40%, and 50%). The effect of fiber volume contents on the tensile properties of the metallic glass fiber reinforced epoxy composites was studied by experiment and the finite element analysis method. The experiment and simulation results are in good agreement. The tensile strength and plasticity of the metallic glass fiber reinforced epoxy composites increase with the increase of fiber volume contents. When the fiber volume content is 40% or 50%, a sharply necking feature appeared on the fibers and exhibited improved plasticity, due to the formation of interacting and arresting events of shear bands occurring at the interface between the metallic glass fibers and the epoxy. In addition, the strain hardening due to plastic deformation of the metallic glass fibers further enhanced the tensile strength of the metallic glass fiber reinforced epoxy composites. This is a first step toward toughening the inherently brittle metallic glass fibers under tensile conditions. Highlights: A novel CoFeSiB metallic glass fiber reinforced epoxy resin compositeThe increase of fiber volume fraction improves the tensile strength and plasticity of fiber reinforced composites.The strain hardening due to plastic deformation of the metallic glass fibers further enhanced the tensile strength of the metallic glass fiber reinforced epoxy composites. [ABSTRACT FROM AUTHOR]

This article aims to investigate the mechanical properties and substrate adhesion of the pull-off method in polymer mortars modified with styrene-butadiene resin polymer (SBR) containing glass powder and composite fiber-reinforced slag. Different mix designs were investigated with and without SBR, taking into account different amounts of glass powder and slag separately and in combination, along with the effect of glass, polypropylene, and steel fibers alone and in combination. The flexural performance and energy absorption of beams retrieved with these layers were also assessed. The results revealed significant differences and increases in the substrate adhesion of the restored modified polymer layers containing SBR compared to the polymer-free repair overlays. Furthermore, an improvement was observed in the adhesion performance of the repair overlay using a combination of slag and glass powder and the glass and polypropylene fiber composite. The highest adhesion was related to the modified polymer mortar design containing composite fibers of glass, polypropylene, and steel with 25% replacement of SBR polymer for 10% glass powder, 10% slag, and 5% slag with 5% glass powder. The adhesion was increased by about 3.74, 3.72, and 3.78 times compared to the repair overlay of the control design. Modified polymer mortars had a higher T 150 D toughness. Moreover, the energy absorption was significantly improved by the presence of SBR polymer. The highest toughness values were found in the beams restored with modified polymer mortars containing polypropylene, glass, and steel composite fibers with an increase of 48.51%-66.42% compared to the samples without polymer as a result of the pozzolans used in this mix. [ABSTRACT FROM AUTHOR]

Highlights Recently, thermosetting epoxy resin is expected to be substituted by thermoplastic featured from green circular economy. Poly(methyl methacrylate) (PMMA) has been well known as one promising thermoplastic resin, although its mechanical property needs to be further investigated. In this paper, the free radical polymerization of methyl methacrylate (MMA) was initiated by lauroyl peroxide/N,N‐dimethylaniline (LPO/DMA) and lauroyl peroxide/N,N‐dimethyl‐p‐toluidine (LPO/DMT) redox system at room temperature, respectively. The PMMA (n(MMA:LPO:DMA) = 200:1.2:1) exhibited excellent mechanical properties, and the tensile strength was 66.5 MPa, the bending strength was 118.0 MPa. The tensile strength increased to 78.9 MPa at −40°C, which suggested a promising application at low temperature. The resin was applied to fabricate continuous glass fiber reinforced PMMA (GF/PMMA) composites by vacuum‐assisted resin infusion. The 0° tensile strength and modulus were 1.17 and 43.7 GPa and 90° tensile strength and modulus were 48.3 MPa and 13.2 GPa, respectively. The mechanical properties of GF/PMMA composites are higher than GF/epoxy. Moreover, PMMA resin and glass fiber can be recycled from GF/PMMA composites by MMA as solvent, which is more energy‐efficient and environment‐friendly. This work is of great significance for preparing sustainable resin and composites. GF/PMMA composites were fabricated by vacuum perfusion. GF/PMMA composites showed higher mechanical properties than GF/epoxy. GF/PMMA composite was recycled with MMA and closed‐loop recovery was achieved. [ABSTRACT FROM AUTHOR]

Highlights Two‐phase hybrid modification has been used as an advanced method to improve the strength and toughness of composite. An interfacial modification strategy for simultaneous strengthening, toughening, and damage monitoring of glass fiber (GF)/epoxy composite is proposed by coating rigid multi‐walled carbon nanotubes (MWCNT) and flexible thermoplastic polyurethane (TPU) on the glass fiber surface. The fiber pull‐out and out‐of‐plane experiments were performed to investigate the interfacial modification effect of rigid/flexible hybrid modifier. The results show that the hybrid modifier with a MWCNT/TPU mass ratio of 3:1 (MT@GF‐3/epoxy composite) realizes the most significant enhancement. Specifically, in comparison to GF/epoxy composites, MT@GF‐3/epoxy composite has an increment of 36.52%, 60.96%, 29.56%, and 80.36% in interfacial shear strength (IFSS), transverse fiber bundle test (TFBT) strength, interlaminar shear strength (ILSS) and interlaminar fracture toughness (GIC), respectively, and a significant enhancement in impact resistance. The enhanced interfacial strength and toughness are attributed to the mechanical interlocking, deflection of cracks, and plastic stretching generated by MWCNT and TPU. Results show that the two modifiers interact in a mutually reinforcing way with regard to the strengthening/toughening effects. In addition, multiple mechanical tests confirm the MT@GF/epoxy composites have an excellent damage monitoring ability by recording the resistance change based on the MWCNT's conductive characteristics. This strategy for interfacial modification coating a rigid‐flexible MWCNT/TPU hybrid modifier would offer valuable guidance for improving the strength and toughness of glass fiber/epoxy composites, as well as monitoring and locating the damage. A rigid/flexible hybrid modifier is proposed for modifying the GF/EP composites. The modifier achieves the greatest enhancement at a 3:1 mass ratio of MWCNT/TPU. The mutual reinforcing mechanism between the rigid/flexible phases is analyzed. Damage monitoring is realized for the modified GF/EP composites. [ABSTRACT FROM AUTHOR]

Highlights A detailed investigation was employed on the manufacturing process of Glass Fiber (GF) reinforced poly‐L‐lactide (PLLA) composites (GFRP) during in‐situ PLLA polymerization using Resin Transfer Molding (RTM). The lower viscosity of lactide, in comparison to PLLA, led to a strong interaction between PLLA and GF as a result of improved penetration into the fiber matrix, resulting in a high conversion rate of 100% for GFRP and 91.9% for PLLA. GF incorporation into the composite material resulted in an improved crystallinity of 55.65% for GFRP, where PLLA showed crystallinity of 36.5%. A GFRP composite with exceptional mechanical properties, including 122.3 MPa tensile strength and 4.485 GPa modulus, was achieved. Both surface and bulk erosion were seen during the breakdown of these composites. These composites seem to be a viable substitute for metallic implants in biological applications. In situ, resin transfer molding of poly‐l‐lactide and GF composite. Higher volume fraction such as 40% w/v loading of GF into composites. 1% conversion of GFRP is achieved. GFRP shows the machinal strength of 122 MPa and harness of 4.2 GPa. Biocompatibility of GFRP composites in body stimulated conditions. [ABSTRACT FROM AUTHOR]

This research aimed to understand how the incorporation of nanocarbon powder (NCP) influences the crashworthiness performance of glass fiber‐reinforced epoxy (GFRE) tubular components, potentially offering insights into improving the safety and resilience of structures or vehicles. Consequently, the crashworthiness behaviors of circular tubes made of GFRE with varying amounts of NCP was studied. Utilizing wet‐wrapping through hand lay‐up technique, GFRE tubes were fabricated with various weight percentages of NCP, that is, 0, 0.25, 0.50, 1, 2, 3, and 4 wt.%. Following that, the crashing load, total absorbed energy against displacement responses, and deformation histories of these tubes under quasi‐static axial loading conditions were calculated and tracked. As part of the crashworthiness analysis, critical indicators were evaluated, including initial peak load (Fip), total absorbed energy (U), mean crash force (Fm), crash force efficiency (CFE), and specific energy absorption (SEA). The findings reveal that the maximum Fip, U, Fm, and SEA were noted at 0.5 wt.% of NCP, with increasing percent's of 30.80, 12.17, 12.16, and 7.50, respectively, compared to the unfilled tube. While, the CFE was recorded by 3 wt.% of NCP with an enhancement of 16.67%. It is worth to note that, the findings reveal that the inclusion of NCP increases crashworthiness metrics up, that is, Fip, U, Fm, and SEA to a concentration of 0.50 wt.% NCP. However, beyond this point, there's a notable decline in performance. Highlights: The GFRE tubes were filled with various wt.% of NCP.The planned tubes were made using hand lay‐up methods.The tubes were subjected to axial compression loads to examine their crashing behavior.The crashing load and absorbed energy versus displacement responses for tubes were exposed.The experimental results were analyzed and discussed. [ABSTRACT FROM AUTHOR]

In this study, high loadings of boron nitride (BN) nanoplatelets were added to silica fiber-reinforced phenolic composites to study the multifunctional impact of BN loading and manufacturing processing on the subsequent mechanical, thermal, and thermomechanical properties. A series of high-quality laminates were made with various loadings of BN using compression-molded out-of-autoclave processing. Three-point bend and short beam shear testing determined the relationship between BN loading and mechanical performance. The fracture properties were analyzed using optical and scanning electron microscopy. The thermal conductivity performance was increased up to a 93% improvement, indicating the thermal management multifunctionality of the modified composites without changing the crosslinking ability or glass transition temperature significantly. The modified performance of hybrid silica/phenolic/BN composites is demonstrated through micromechanical multiscale modeling, where BN loading and particle stress concentrations impact the modulus and strength of the composite. [ABSTRACT FROM AUTHOR]

Short-fiber reinforcement is a potent approach to improving the material properties of injection-molded parts. The main consideration in such reinforced materials is to preserve the fiber length, as this is the major influence on the properties of a given composite. The aim of this work was to investigate the different influencing parameters in injection molding processing on the properties of short carbon and glass fiber-reinforced polypropylene. We investigated parameters like melt temperature and back pressure, but also machine size and pre-heating regarding their influence on the tensile properties. We found that adjustments of melt temperature and back pressure only yield small improvements in the fiber length and the tensile properties, also depending on machine size, but a pre-heating step of the granules can significantly improve the properties. [ABSTRACT FROM AUTHOR]

The paper deals with the influence of the brittleness of glass fibers on the selected performance properties of the fibrous polymer composite. Understanding the fatigue behavior of fiber-reinforced plastics is desirable for exploiting their features in safe, durable, and reliable industrial components. Based on the proposed methodology, it is possible to assess the impact of material reuse on selected mechanical and rheological properties. To verify the methodology by experimental analysis, homopolymer PP reinforced with chemically grafted glass fiber (30 wt%) was selected. The proposed methodology was subsequently verified by experimental analysis and evaluated statistically. The morphology of the fracture surfaces was evaluated, and the fiber-polymer matrix adhesion was monitored at the interface of the fracture surfaces. Based on the measured and evaluated values and fracture surfaces, we can say that the brittleness of the fibers significantly affects the performance properties of the tested polymer composite. [ABSTRACT FROM AUTHOR]

This study evaluates the effects of sodium hydroxide (NaOH) treatment on tensile properties of sugar palm 'ijuk' (SPI) fibre-reinforced polymer (FRP) composites, with and without an open hole that acts as a stress concentrator. The NaOH treatment is aimed to improve the interfacial adhesion between SPI fibres and polymer matrix. Composite specimens were prepared using the hand lay-up method, incorporating SPI fibres in various orientations, and featuring a 6 mm diameter hole. Tensile tests were conducted to evaluate the mechanical performance of SPI FRP composite, including ultimate tensile strength, Young's modulus, and elongation at break. The research also compared the properties of SPI to those of synthetic glass fibre in fibre-reinforced polymer composites. The results showed that NaOH treatment significantly improves the fibre-matrix adhesion with 26% increase in tensile strength, leading to enhanced tensile properties in both samples, regardless of hole presence. The 0° orientation provides the highest strength and stiffness when the load is applied in the direction of the fibres. While for the 90° orientation, strength reduces by 14%. The impact of the hole on stress concentration and the subsequent mechanical behaviour of the open-hole specimens is substantial. The findings of this study offer insightful perspectives on the potential use of NaOH-treated SPI fibre in structural and other applications, demonstrating its ability to withstand tensile stresses, even with geometric discontinuities like holes. [ABSTRACT FROM AUTHOR]

This research explores the scratch resistance of polymer composites reinforced with hybrid glass and basalt fibers under repeated loadings. By examining the behavior across 1–10 repetitions using Rockwell and Vickers indenters, the study delves into the complex interplay between composite matrices and the fibers' configurations. Through Scanning Electron Microscope (SEM) imaging and 3D profilometry, it reveals how different fibers influence the composite's surface post‐scratch tests. Basalt fibers are found to offer superior scratch protection over glass fibers, although both types' of effectiveness declines with increased loading cycles, showing significant material loss and surface damage respectively. Composites with these fibers display enhanced resistance, especially when basalt fibers are optimally positioned on the surface. The study underscores the critical role of fiber‐matrix bonding in scratch resistance and the significant impact of mechanical stress. It was found that the scratch hardness values reduced with more repeats in the scratch tests utilizing Vickers and Rockwell indenters. The sample with the label G4B6G4 has the greatest hardness values, which is noteworthy. After 10 repeats, the scratch hardness values for this sample reduced to 225 N/mm2 and 75 N/mm2, respectively, from roughly 340 N/mm2 and 225 N/mm2 at both ends for a single repetition. In addition, ANOVA for penetration depth is dominated (66.01%) by the repetition factor. The most common kind is indenter (42.79%), with low p‐values. Despite material and indenter effects, groove area study confirms the significance of repetition (65.72%). Highlights: Basalt fibers enhance scratch resistance more than glass fibers.Increased scratch repetitions lead to fiber breakage and material loss.Hybrid fiber layers distribute load and minimize surface damage.Strong fiber‐matrix adhesion is crucial for reducing damage severity.Research informs the design of durable, fiber‐reinforced composites. [ABSTRACT FROM AUTHOR]

Highlights Glass fiber reinforced polymer (GFRP) composites can be subjected to different environmental conditions such as temperature, humidity, ultraviolet radiation, hydrothermal cycle, acidic and alkaline solution in environments where they operate. These environmental conditions cause different damage mechanisms in composites such as pore formation, micro‐cracks, delamination, fiber breakage, fiber/matrix interface separation, plasticization, swelling and surface color change. In this study, wear properties of hybrid glass fiber reinforced polymer composites exposed to various environmental conditions for constant load (60 N), speed (500 rpm) and 2 h were examined comprehensively, depending on material content and environmental conditions. In this experimental study, the service conditions in glass fiber reinforced composites were simulated using different artificial aging environments such as acidic environment, hydrothermal cycle and UV radiation. In addition to the material content, it appears that the environmental conditions to which composites are exposed has a significant effect on friction coefficient. Considering environmental conditions, it is seen that the acid environment and hydrothermal cycle have reduced wear resistance of GFRP composites, while UV radiation improved wear resistance of the composites. In C2 sample, the wear rates under different conditions are 1.87 × 10−14 m3/Nm in non‐treated sample, 6.05 × 10−14 m3/Nm in acid environment, 4.79 × 10−14 m3/Nm in hydrothermal cycle and 0.59 × 10−14 m3/Nm in UV radiation. Friction coefficient of glass fiber reinforced polyester (GFRP) is higher under aged condition compared to non‐treated. Glass fibers used in correct proportions can reduce friction coefficient in GFRP. GFRP exposed to environmental conditions has an important effect on wear. Acid environment and hydrothermal cycle has reduced wear resistance of GFRP. UV radiation improved wear resistance of GFRP composite. [ABSTRACT FROM AUTHOR]

Purpose: Additive manufacturing of polymer composites is a transformative technology that leverages the benefits of both composite material and 3D printing to produce highly customizable, lightweight and efficient composites for a wide range of applications. Design/methodology/approach: In this research work, glass fiber-reinforced polylactic acid (PLA) filament is used to print the specimen via fusion deposition modeling process. The process parameters such as infill densities (40%, 50% and 60%) and raster angle/orientations (0°, 45° and 90°) are varied, and the specimens for tensile, flexural, impact, hardness and wear testing are prepared as per their respective ASTM standards. Findings: The results revealed that with an increase in infill density, the mechanical properties of glass fiber-PLA specimens increase progressively. Optimal tensile properties and flexural properties are obtained at 0° and 90° raster angle orientations and 60% infill density. Minimum wear rate is achieved at 0° raster angle orientation and it increases at 45° and 90° raster angle orientations. Originality/value: Using SEM, the microscopic analysis of the fractured specimen was analyzed to study the interface between the fibers and matrix and it indicates the presence of good adhesion between the layers at 60% infill density and 0° print orientation. [ABSTRACT FROM AUTHOR]

There is a growing drive in replacing conventional non-renewable fibres such as glass and carbon reinforced composites with more sustainable and renewable reinforcements such as flax, hemp, jute in biobased composites in key industry sectors such as automotive, marine, building and construction motivated by lower carbon footprint and sustainability. Despite this drive, flammability characteristics of these sustainable biobased composites are not fully understood. Through an up-to-date review, this article meticulously discusses the theme of bio-based and eco-friendly flame retardants (FRs), delving into their intricate mechanisms, flammability testing methodologies, and emerging research trends. It underscores the pivotal necessity of developing tailor-made eco-friendly FRs customised for a diverse range of materials to bolster fire safety in sustainable material applications. Furthermore, it illuminates the limitations associated with prevalent methods for assessing flammability and advocates for advancements in dynamic testing and multi-scale analyses to more accurately simulate real-world fire scenarios. This review also highlights the key characteristics of natural plant fibres and their composites critical for the development of sustainable and fire safe materials for key applications areas. Additionally, it highlights the diverse spectrum of strategies employed in the realm of flame-retardant materials research, emphasizing a pronounced shift towards eco-friendly alternatives, innovative coatings, and the ongoing exploration of synthetic biopolymers, nanocomposites, and fibres in the pursuit of heightened fire safety. Amidst the inherent challenges, this comprehensive review unequivocally underscores the pivotal role of interdisciplinary research collaboration in driving forward fire safety within the domain of sustainable materials. [ABSTRACT FROM AUTHOR]

The effects of geometric scaling on the strain rate sensitivity of unidirectional and [+45/−45]s laminates under uniaxial tensile loading has been investigated experimentally. Two material systems, Toray T800/3900-2B carbon/epoxy unitape and Newport NB321/7781 fiberglass/epoxy fabric, were used in the study. The nominal strain rates investigated ranged from quasi-static (0.0002 s−1) to moderate strain rates of 50 s−1 across the scaled specimen geometries. The geometric scaling effects at different strain rates were quantified in terms of the Weibull modulus. At each strain rate, the average failure stress of [0]4 carbon, [0]4 fiberglass, and [±45]s fiberglass showed a declining trend with increasing specimen size. However, the percentage of the strength reduction was less significant at higher strain rates compared to the quasi-static strain rate. In contrast to the other stacking sequences, [+45/−45]s carbon specimens showed a maximum percentage in strength reduction at a high strain rate compared to the quasi-static strain rate, indicating increased scaling effect with strain rate. The magnitude of Weibull modulus (m) for the specimens increased with strain rate indicating diminishing scaling effects, while [+45/−45]s carbon specimens exhibited an opposite trend. [ABSTRACT FROM AUTHOR]

This study investigates the potential of natural fibers, commonly used as cost-effective fillers in the plastic industry, as replacements for glass fibers in composite materials. Despite their advantages, these natural fibers possess a strong polar nature, causing compatibility issues with certain thermoplastic platforms, particularly aromatic compounds. Surface-level treatments, though not cost-effective, offer a solution to this issue. This research focuses on optimizing and qualifying two treatment methods, the acetyl method and stearic treatment, applied to two types of flax fibers: long and short. Examining variables such as temperature, treatment duration, and compound recovery, this study employed diffraction and gas chromatography techniques to evaluate treated and untreated fibers. Results revealed that both treatments effectively reduced non-crystalline segments within the fibers, altering surface topography. Notably, the acetyl method increased fiber surface energy, while the stearic treatment decreased it. These findings underscore the significant impact of the acetyl method and stearic treatment on modifying fiber properties, particularly surface characteristics and energy levels. The study sheds light on the potential applications of these treatments in enhancing the compatibility of natural fibers with thermoplastic platforms, despite their inherent polarity. Incorporating visuals depicting the treatment processes would further enrich the study's authenticity and engagement, providing a tangible representation of the methods employed. [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]

This study was focused on developing and evaluating the impacts of wood and graphite fillers on an E-glass fibre-reinforced polyester composite. The fillers employed in this study include teak, casuarina, psuedon wood dust, graphite, and hybrid fillers such as casuarina and graphite fillers. They tested for tension, flexural, impact, hardness, and dynamic mechanical analysis. In the current work, the optimum loading level is 15 wt% which was determined through testing at various loading levels. The experimental results have shown that the mechanical, physical, and thermomechanical properties of glass fiber reinforced polyester composites improvement mechanism analysis depend upon chemically treated wood dust fillers by avoiding surface delamination during fabrication. By using the hand layup method, composites were created by maintaining the fibre constant while distributing the fillers following the rule of mixture; a hybrid composite has a filler distribution of 1:1. Hybrid composite has exhibited increased flexural strength and hardness by 72.77%, 63.33% compared to casuarina wood of 15 wt% by avoiding incompatibility of casuarina wood filler with the resin. The glass transition value of the hybrid composite was increased by 1.4% compared to the above said casuarina wood composite, making it a more thermally resistant material. The hardness of the hybrid composite has increased by 2.78% compared to the teak wood of 15 wt% composite. [ABSTRACT FROM AUTHOR]

Hand layup was used to fabricate the glass fibre reinforced aluminium foam epoxy composites in this study. On the manufactured materials, dry sliding wear experiments were performed. The effect of wearprocess parameters such asapplying load (kg), speed (m/s), and sliding distance (m) on specific wear rate (Ws) was investigatedand the obtained results were compared with neat glass fibre reinforced epoxy composite in this work. The outcome of these results showed that specific wear rate (Ws) of glassfibre epoxy composite containing aluminium foam decreased as compared with neat glass fibre reinforced polymer composites. Experimental results showed that a minimum wear rate of 10.1 µm was attained for the sliding velocity (1.5 m/s), Applied load (2 kg), and sliding distance (1000 m) in the fabricated composite laminates. It was observed thatthe resistance to wear in glass fibre reinforced aluminium foam composite was mainly due to the bond strength between aluminium foam and epoxy. [ABSTRACT FROM AUTHOR]

This study investigates the effect of stress amplitude on the damage sensing characteristic of glass fibre reinforced (GFRP) composites under fatigue loading using the electrical resistance change (ERC) method. The electrical conductivity of GFRP composites was achieved by incorporating 0.3 wt.% multi-walled carbon nanotubes (MWCNTs) into epoxy resin by ultrasonication method. In-situ electrical resistance measurements during fatigue tests of MWCNT-filled GFRP (MWNCT/GFRP) composites were conducted at two different stress amplitudes, S = 0.6 and S = 0.5. The average stiffness losses at failure were observed as 28% and 25% for S = 0.6 and S = 0.5 respectively. The corresponding ERC ratios at failure were found as 153% and 59% for S = 0.6 and S = 0.5, respectively. A two-parameter Weibull analysis, based on the ERC ratios corresponding to 40%, 60%, 80%, and 100% (failure) fatigue life, was implemented to establish reliability curves at the two stress amplitudes. The ERC ratios at failure with a 95% reliability for S = 0.6 and S = 0.5 were determined as 64% and 23%, respectively. Finally, the remaining fatigue life and the stiffness loss of composite specimens at the ERC ratios corresponding to various Weibull reliability were found for both stress amplitudes. [ABSTRACT FROM AUTHOR]

Highlights The goal of this project was to recycle the waste forming in the production of a flexible, multilayer food packaging film. The film consists of five layers, two polyamides containing three different polymers, a polyethylene and two adhesive layers of maleated polyethylene. The type of the components and the exact composition are not disclosed because they represent proprietary information. The key to recycling is the selection of an appropriate strategy and target product. In this case, glass fiber reinforced PA composites were produced with an acceptable property profile. The properties of the recycled product are comparable to those of commercial composites available on the market. The crucial question was the selection of the glass fiber grade with the appropriate sizing. The selection was further complicated by the possible interaction of the functionalized polymer with the sizing of the fiber. The implementation of the solution is feasible technologically, the properties of the product are comparable to those available on the market, and its price is very advantageous. An engineering material can be produced from flexible multilayer packaging waste. The properties of the recycled product are comparable with those on the market. The selection of the glass fiber is crucial for mechanical properties. The solution is feasible technologically and the final price is competitive. [ABSTRACT FROM AUTHOR]

Highlights Interfacial adhesion properties are a key factor affecting the mechanical properties of composites. It is a very effective way to improve the low‐velocity impact resistance of composites by improving the interfacial adhesion properties. To improve the fiber/matrix interfacial adhesion properties of GF/PA6 (glass‐fiber/polyamide 6) composites, polyethyleneimine (PEI) and γ‐aminopropyltriethoxysilane (KH550) were used to co‐modify GF together in this study. The GF/PA6 composites with different modifications of glass‐fiber (GF) were also prepared using a hot pressing process, and then their flexural strength, shear strength, pendulum impact strength, and low‐speed impact resistance were investigated. Next, the relationship between fiber/matrix interfacial adhesion and mechanical properties of GF/PA6 composites was investigated by combining x‐ray photoelectron spectroscopy, scanning electron microscopy, and x‐ray computed tomography test results. The results showed that the GF‐reinforced PA6 matrix composite with co‐modified GF by PEI and KH550 (PEI‐KH550‐GF/PA6) had the best mechanical properties, with flexural, shear, and pendulum impact strengths of 660.7 MPa, 53.1 MPa, and 261.6 kJ/m2, respectively. Furthermore, the low‐velocity impact resistance was measured in terms of stress peak, absorbed energy, residual stress, and damage extension, and the results showed that the low‐speed impact resistance of PEI‐KH550‐GF/PA6 composites was also substantially improved that the Fmax increased from 7402.1 to 10414.0 N. Due to the poor surface activity of GF, in this experiment, GF was co‐modified with PEI and KH550 to achieve better fiber/matrix interfacial adhesion and successfully improve the mechanical properties of the composites; Different modification methods are used to improve the interfacial adhesion of the fiber/matrix interface. The relationship between the interface and impact strength of composites has been studied; The relationship between fiber/matrix interfacial adhesion and internal cracking in composites was investigated using X‐CT and SEM and other test results. [ABSTRACT FROM AUTHOR]

This study investigates the mechanical properties of continuous carbon/glass hybrid fiber‐reinforced polylactic acid (PLA) composites (HFRC) produced through the three dimensions (3D) printing process, comparing them with single carbon fiber‐reinforced PLA composites (CFRC). Initially, composite prepreg filaments are prepared using an impregnation device, followed by fabrication using a 3D printer. The mechanical performance results reveal a 13% increase in tensile strength for HFRC compared with CFRC. Due to differing elongation rates of carbon and glass fibers, HFRC exhibits two strength peaks, while CFRC demonstrates a 37% higher bending strength than HFRC. Scanning electron microscope images indicate that the tensile failure mechanism involves fiber brittle fracture and fiber‐matrix interface debonding, while the bending failure mechanism includes fiber pullout, fiber debonding, fiber cluster buckling, and interlayer interface failure. Highlights: To realize the moldless rapid manufacturing of continuous hybrid fiber‐reinforced PLA composites.The stress–strain curves of single fiber‐reinforced composites and hybrid fiber‐reinforced composites are obviously different.Elucidating the effect of single fiber/hybrid fiber in composites on mechanical properties and failure mechanism according to micro‐morphology. [ABSTRACT FROM AUTHOR]

Hole quality in composite materials is gaining interest in aerospace, automotive, and marine industries, especially for structural applications. This paper aims to investigate the quality of holes performed without a backup plate, in thin plates of glass fiber-reinforced polymer (GFRP). The samples were manufactured by two different technologies: vacuum bagging and an innovative method named vacuum mold pressing. Three experiments were designed choosing the control factors that affect the maximum cutting force, delamination factor, and surface roughness of drilled holes in composite materials based on twill fabric layers. Quality analysis of the hole features was performed by microscopy investigations. The effects of the main factors on the targets are investigated using the statistical design of experiments, considering control factors, such as support opening width, weight fraction (wf), feed per tooth, and hole area. The results showed that the feed per tooth and hole area had a more significant influence on the delamination factors and surface roughness (Sa). The best quality of the holes drilled in twill-based GFRP was achieved for a lower feed rate of 0.04 mm/tooth and used a support opening width of 55 mm. [ABSTRACT FROM AUTHOR]

In this study, two types of composites, polybutylene terephthalate (PBT) and epoxy resin (ER), reinforced with 20% of glass fiber (GF) are used as the comparative research objects. Their mechanical properties after thermal aging at 85~145 °C are evaluated by tensile strength and fracture morphology analysis. The results show that the composites have similar aging laws. The tensile strength of GF/PBT and GF/ER decrease gradually with the increase of aging temperature, while their elastic moduli are independent of the thermal treatment temperature. Scanning electron microscopy study of the fracture surface shows that separation of glass fiber from PBT and ER matrix becomes more obvious at higher aging temperature. The fibers on the matrix surface appear clear and smooth, and the whole pulled out GFs can be observed. As a main mechanical strength degradation mechanism, the deterioration of interface adhesion between the matrix and GF is discussed. A large difference in coefficients of thermal expansion of the matrix and GF is a main factor of the mechanical degradation. [ABSTRACT FROM AUTHOR]

Highlights Polyimide composites are easily degraded in high temperature and high humidity environments for long service, which reduces their reliability and stability in aerospace, electronic components, weapons, and other fields. In this paper, the inorganic and organic multiphase double‐layer coating was prepared. The insulating layer was made of vinyl polysilazane resin as the base material and hollow glass microspheres as the filler. The hydrophobic layer consisted of polydimethylsiloxane as the base material, hollow phenolic microspheres, and nano‐TiO2 as the filler. The heat resistance, hydrophobic properties, and aging resistance of the coated polyimide resin matrix composites were studied. The results showed that the thickness of the double‐layer coating was about 200 μm. Under the 200°C thermal insulation test, the maximum temperature drop can be achieved at 59.7°C. After adding 5 wt% TiO2, the static contact angle of composites was increased from 86.2° to 127.7°. Significantly, the hydrophobic performance was improved by 48.1%, which was due to the construction of micro‐nano structures in the surface layer coating. In the accelerated hydrothermal aging tests, the bending properties of coated composite materials can be improved by 8.5%, 3.2%, and 8.7% in water, alkali, and acid environments, respectively. The moisture absorption of glass fiber and the pyrolysis of polyimide led to the degradation of the mechanical properties. The existence of heat‐resistant and hydrophobic coating could effectively eliminate this adverse effect, which was of great significance for polyimide composites to cope with various service environments. A novel coating consisting of thermal insulating and hydrophobic layers was developed on glass fiber reinforced polyimide composites (G/PI) composites. The maximum temperature drop of coating can be achieved at 59.7°C. The static contact angle of coated G/PI composites was increased from 86.2° to 127.7°. In the aging tests, the protective effect of the coating resulted in improved mechanical strengths of G/PI composites. The microscopic damage morphology was performed to analyze the anti‐aging properties of the coating. [ABSTRACT FROM AUTHOR]

This research aims to develop fiber-reinforced composites (FRC) with enhanced fire resistance, which can be particularly useful for the transport industry (e.g., aviation, automotive, and train production). The fire retardation was achieved through epoxy matrix modification with hexachlorocyclotriphosphazene (HCTP). First, the fire-resistant and mechanical properties of the epoxy matrix filled with different HCTP contents (4.8, 7.2, and 9.5 wt.%) were studied to select the most effective HCTP content for the impregnation of FRC. Then, glass, basalt, and carbon fiber fabrics were impregnated with epoxy filled with 7.2 wt.% of HCTP, and the fire resistance, flexural, and interlaminar fracture properties were studied to select the most effective HCTP-modified type of fiber reinforcement based on the test results. It was concluded that basalt fiber impregnated with epoxy filled with HCTP could be selected as the most effective reinforcement type, allowing excellent mechanical and flame-retardant properties. [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]

Hybridizing the natural fibers with stronger synthetic fibers could significantly improve the properties of the natural fiber-reinforced composites. The improved mechanical capabilities of fiber reinforced polymers result from the fiber's capacity for withstanding a more substantial portion of the mechanical load compared to the matrix it replaces. In order to guarantee the efficient transfer of the mechanical load from the matrix to the reinforcement, it is necessary to incorporate a fibrous filler. Transference takes place when the length of the fiber is longer than a specific critical length. Fibers which are shorter than the critical length will pull out from the matrix when tested to a tensile load. In some cases, complete transfer of the load is not performed. The goal of this study is to learn more about flax (FF), glass (GF), and mixtures of flax and glass (FF + GF) short fiber-reinforced PLA-PBS composites. This is performed to find out how the flax/glass combination affects the mechanical properties of PLA-PBS-reinforced short fiber composites. In order to extend their use for industrial applications, these composites were manufactured via extrusion and, afterward, injection molding. Fiber aspect ratios were followed after compounding and injection processing. The analysis of fiber lengths reveals a noteworthy observation: the proportion of fibers exceeding their critical length of 531 µm and 772 µm for FF and GF, respectively, is more significant when flax fibers (FF) and glass fibers (GF) are combined compared to when they reinforce the composite individually. Specifically, the composite containing both FF and GF exhibits a higher percentage of fibers surpassing their critical length, compared to their individual reinforcement in the composite. The results reveal that 27% of individually extracted single FF exceed their critical length, whereas a higher proportion, at 34%, is observed when FF is part of the composite mixture. In contrast, the critical length is surpassed by only 4% of individually extracted single GF, whereas the combined presence of GF in the composite results in a notably higher percentage, at 19%. The tensile properties of these composites were investigated considering the effect of the hybridization by flax/glass short fibers. It was noted that the tensile properties of the hybrid composites increase comparing to the flax composites from 42.4 MPa to 53 MPa for the tensile strength and from 4.9 GPa to 5.4 GPa for the tensile modulus. In contrast, the elongation at break of the hybrid composites decreases from 1.7% to 1.5% with the incorporation of glass fibers. The experimental results were compared with the predictions of the mixture law and the Cox-Krenchel model. The findings indicate that mixing synthetic fibers with natural fibers is an excellent approach to enhancing mechanical properties. [ABSTRACT FROM AUTHOR]

The characterization of the flexural performances of short glass fiber reinforced polyether‐ether‐ketone (SGFR‐PEEK) composites fabricated by injection molding is a crucial and challenging task due to the process‐induced fiber orientation at different locations, resulting layered shell‐core‐shell microstructures and exhibiting large variations in mechanical performances. This article proposes a method for predicting the bending performance of SGFR‐PEEK and indicates the influence of fiber orientation on its bending behavior. This article reports a new scheme that combines multiscale homogenization with periodic microstructures and presents an experimental investigation of the flexural properties of SGFR‐PEEK composites. The distributions of fiber orientation through the thickness extracted from the micro‐computed tomography (μCT) were analyzed and reproduced with a layered skin‐shell‐core structure along the thickness at meso‐scale finite element model within representative volume elements (RVEs) of the macroscopic composites. Then, the effective properties of the RVEs were predicted using the homogenization method with the periodic boundary condition. The elastic modulus of skin‐shell‐core layers in the direction of flow are 4260.51, 4541.27, 4628.52, and 4630.84 MPa, respectively. The classical laminate theory (CLT) and the second homogenization implementation were then utilized in conjunction with the obtained mechanical properties of RVEs to predict the effective macrostructural behavior. The flexural modulus of the composite material was determined to be 5448.7 MPa through a three‐point bending test. The results obtained through lamination plate reinforcement theory and finite element simulation were 5887.4 and 5785.9 MPa, respectively, showing good agreement with the experimental findings. It is shown that the proposed multiscale scheme yields satisfactory agreement with experimental measurements. In addition, the effect of layered skin‐shell‐core microstructures on the flexural behavior was discussed. Highlights: RVEs of layered shell‐core‐shell microstructures were generated with specified fiber orientations.The homogenization scheme with the periodic boundary condition was adopted to accurately predict each layer mechanical properties.The proposed multiscale scheme was compared with experimental results and yielded satisfactory predictions.The effect of layered skin‐shell‐core microstructures on the flexural behavior was thoroughly studied by the multiscale analytical approach. [ABSTRACT FROM AUTHOR]

The effect of the incorporation of dolomite based geopolymer on the tensile and flexural properties of glass fibre reinforced epoxy composite were investigated. Composites containing different weight percentages of fillers (2.5, 5.0 and 7.5 wt.%) were fabricated using hand lay-up and vacuum bagging techniques. The experimental results showed that the dolomite based geopolymer contributed to the detrimental effect on tensile strength of the composite with 2.5 wt.% incorporation of the filler contributed to the least detrimental effect. 2.5 wt.% incorporation of dolomite based geopolymer meanwhile improved flexural strength by 13.04%. [ABSTRACT FROM AUTHOR]

The development of wind power has brought about increasing challenges in decommissioning, among which DWTBs (decommissioned wind turbine blades) are the most difficult component to deal with. To enable the cost-effective, energy-efficient, and environmentally friendly large-scale utilization of DWTBs, an experimental study on thermogravimetric and pyrolysis characteristics of DWTBs was carried out. A new process involving recycling glass fiber with pyrolysis gas re-combustion and flue gas recirculation as the pyrolysis medium was innovatively proposed, and the simulation calculation was carried out. Thermogravimetric experiments indicated that glass fiber reinforced composite (GFRC) was the main heat-generating part in the heat utilization process of blades, and the blade material could basically complete pyrolysis at 600 °C. As the heating rate increased, the formation temperature, peak concentration, and proportion of combustible gas in the pyrolysis gas also increased. The highest peak concentration of CO gas was observed, with CO2 and C3H6 reaching their peaks at 700 °C. The solid product obtained from pyrolysis at 600 °C could be oxidized at 550 °C for 40 min to obtain clean glass fiber. And the pyrolysis temperature increased with the increase in the proportion of recirculation flue gas. When the proportion of recirculation flue gas was 66%, the pyrolysis temperature could reach 600 °C, meeting the necessary pyrolysis temperature for wind turbine blade materials. The above research provided fundamental data support for further exploration on high-value-added recycling of DWTBs. [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]

Fiber composite materials are key components of numerous future technologies. This results in a strongly increased demand and also in increasing amounts of waste in the upcoming years. Thus, recycling of fiber composite materials has become an intensively researched topic. At 95 wt %, glass fiber‐reinforced plastics make up the largest part. This review article will provide an overview of the state of the art of common recycling strategies and technologies, with particular focus on the advantages and challenges of glass fiber‐reinforced polymer recycling. [ABSTRACT FROM AUTHOR]

This study aims to assess the hybridization effect on the perforation threshold of Low-Velocity Impact (LVI) in thermoplastic glass composite laminates, incorporating layers of resin-impregnated stainless-steel mesh. Reinforcing methodologies such as hybridization are recently being adopted as a practical approach to increasing the energy-absorbing capacity of polymer composites. In the current paper, a multi-step hot press lamination method has been employed to fabricate the hybrid composite laminates strengthened with stainless-steel mesh layers. Several stacking sequences, metal mesh wire sizes, orientation and position relative to the impactor have been examined under various LVI energies. It was revealed that the LVI penetration energy was increased for the thermoplastic-based composite laminates reinforced with stainless-steel mesh layers. Furthermore, the LVI penetration energy threshold was significantly influenced by the metal mesh wire size, orientation and stacking sequence. Finally, the backlight method capability was assessed to detect the after-impact interlaminar damages. [ABSTRACT FROM AUTHOR]