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Highlights Despite the low density and high specific strength properties, the fiber‐reinforced composites are characterized by a relatively low interlaminar fracture toughness and their ultimate properties are strongly affected by the fiber matrix adhesion. This study aims to investigate the influence of fiber surface treatments, such as UV and atmospheric plasma, and of the interfacial shear strength, on the flexural properties and Mode I interlaminar fracture toughness of glass fiber epoxy composites. The vacuum‐assisted resin infusion technique is used for the composite fabrication. Scanning Electron Microscopy analysis is used to observe and to explain the changes in the morphology of the fibers after surface treatment. Remarkably, the results showed an overall reduction in the mechanical properties. The interfacial shear strength values of the UV and plasma‐treated samples were reduced by 34.9% and 49.5% respectively. The flexural strength was reduced by 7.9% and 5.9% respectively. The Mode I fracture toughness values for the UV and plasma‐treated samples were also reduced by 49.8% and 62.2% respectively. UV and plasma treatments were performed on glass fibers to improve performance. Push‐out tests were carried out to evaluate fiber/matrix adhesion. An aerospace grade epoxy resin curing in thermal press‐clave was used. Mechanical tests related Interfacial Shear Strength to composites performance. [ABSTRACT FROM AUTHOR]

Highlights In recent years, there has been a significant emphasis on the development of composite materials that are both high‐performing and environmentally friendly. Hybrid polymer composites that are reinforced by both sisal and glass fibers are introduced in this study. Investigation was conducted to evaluate the combined influence of hybrid reinforcements and Egg Shell Powder (ESP) on the mechanical properties of the composites. The hand layup technique was employed to create hybrid laminates by incorporating variable amounts of ESP (0–15 wt%) and employing various stacking sequences. Various mechanical testing was administered to the composites that had been prepared. The results indicated that the glass/sisal hybrid laminates exhibited superior mechanical properties in comparison to the non‐hybrid sisal laminates, which was attributed to the synergistic benefits of incorporating both sisal and glass fibers. The incorporation of Egg Shell Powder significantly improved the material's mechanical properties. The glass/sisal hybrid laminates with 15% ESP laminate demonstrated the maximum tensile strength (195.23 MPa), flexural strength (150.02 MPa), and ILSS (7.55 MPa). Scanning electron microscopy enabled a comprehensive analysis of the hybrid composites' interfacial adhesion and microstructure. This investigation verified that the ESP was effectively dispersed and had a substantial effect on the interface between the matrix and the fibers. The hybrid composites that are generated are environmentally friendly and exhibit extraordinary potential for a variety of applications, offering a sustainable and high‐performing alternative to conventional synthetic composites. These discoveries promote the utilization of bio‐based resources in the composites industry and advance the development of sustainable materials. The glass/sisal hybrid laminates with 15% ESP laminate showed highest tensile strength of 195.23 MPa Hybrid composites exhibited superior mechanical properties. ESP addition significantly improved interfacial adhesion and strength Water absorption decreased with increasing ESP content up to 15% Development of Eco‐friendly composites suitable for automotive and aerospace applications [ABSTRACT FROM AUTHOR]

Highlights Unique hybrid thermoplastic composites based on polyoxymethylene copolymer (POM C), 10 wt.% glass fiber (GF) and graphite (Grt) filler at 1, 3, and 5 wt.% were developed using injection molding technique. According to the Taguchi L16 orthogonal array, present experiments were carried out with the aim of determining the coefficient of friction (COF) and specific wear rate (SWR) under a range of loads (namely, 5, 10, 20, and 30 N), sliding speeds (namely, 200, 400, 600, and 800 rpm), and run times (namely, 15, 30, 45, and 60 min) with varying wt.% of Grt (namely, 1, 3, and 5 wt.%) throughout the experiment. Analysis of variance (ANOVA) was used to evaluate the most significant factors that affect the output functions (viz., COF and SWR). The findings demonstrated that POM C/10GF composites' tribo‐mechanical, structural, and thermal properties were considerably improved upon by including Grt. Various microscopical methods were also employed to study the wear mechanisms of the composites and the surface morphology of the worn samples. The POM C/10GF with a 3 wt.% of Grt exhibited superior tribological properties owing to its enhanced interfacial bonding characteristics, resulting to increased wear resistance. Injection molded POM C/10GF hybrid composites with 1, 3, and 5 wt.% graphite (Grt) Structural, thermal, chemical, tribo‐mechanical and microstructural studies Design of experiment with variable loads, times, speeds, and Grt compositions COF and specific wear resistance as response Optimization of hybrid composite composition using Taguchi L16 orthogonal array [ABSTRACT FROM AUTHOR]

Thermoplastic polycarbonate provides minimal structural weight and ductility and is a recyclable material. However, investigation of the characteristics of hybrid composites reinforced with woven glass and polycarbonate sheets is limited. This current study investigated the effect of integration of polycarbonate sheets on glass fiber‐epoxy hybrid composite performance. Non hybrid laminate was fabricated from eight layers of woven glass fiber impregnated with epoxy resin (NG). However, the hybrid samples utilized various symmetric stacking patterns which were made by alternating two processed polycarbonate (PC) sheets with six layers of woven glass fiber embedded with epoxy matrix. The manufacturing was made using the hand layup procedure. Mechanical testing includes compressive, tensile, bearing, and hardness was performed on hybrid and non‐hybrid composites. The results showed that employing PC sheets instead of fibers affect the laminate's strength, ductility, bearing capacity, and hardness. Utilization of PC sheets reduces both compressive and tensile strength. However, an enhancement in tensile, compressive, and bearing failure strain was achieved by 2.5%, 31.25% and 31.7%, respectively with hybrid composite having PC in the skin layers as compared with NG. The extent of failure damage is correlated with the position of the PC sheets in the tested samples. Highlights: Novel hybrid composites of woven glass fiber and polycarbonate sheet as reinforcement with various stacking orders were successfully prepared by the hand lay‐up method.The compressive strain of hybrid PC samples are higher than NG sample.The hybrid PC composites showed an improved bearing strength and strain performance.The influence of sample configuration on the damage mechanisms has been investigated. [ABSTRACT FROM AUTHOR]

This study looks at how erosive wear affects hybrid composites made by vacuum infusing glass and basalt fibers into an epoxy matrix. The study uses garnet abrasives and a design experiment method to test how resistant these hybrid composites are to erosion at 30°, 60°, and 90° angles of impact. The analysis included three‐dimensional profilometry and scanning electron microscopy. Results show that glass layers enhance erosion resistance, whereas basalt layers increase wear. Key quantitative findings include erosion rates and mass loss, highlighting impingement angle and erosion time as critical factors. At a 30° angle, basalt exhibited more severe wear (erosion rate: 0.8090 mg/g for 20 s) compared to glass (erosion rate: 0.5683 mg/g). Conversely, at 90°, the erosion rate for basalt decreased to 0.3643 mg/g, indicating a decreased sensitivity to this steeper angle. According to the ANOVA, impingement angle and erosion time account for 30.08% and 50.25% of the erosion rate variance, respectively. These findings advance our understanding of material behavior in hybrid composites and emphasize the strategic selection and layering of materials for enhanced durability. This research contributes to developing more sustainable composites, demonstrating natural fibers' potential to improve mechanical properties and erosion resistance. Highlights: Glass layers enhance durability against erosive forces in hybrid composites.Basalt layers accelerate erosion rates, showing a need for strategic layering.Glass fiber reinforcement significantly improves wear performance.Hybrid constructions with glass a top basalt balance flexibility and durability.Emphasizes eco‐friendly advantages of natural materials in composites. [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]

The boundary condition is a very important factor when characterizing the impact performance of a material or a structure. However, its effect on fiber metal laminate (FML) has been rarely mentioned. In the present investigation, three levels of low‐velocity impact tests were conducted on the glass fiber reinforced aluminum laminate (Glare) under two different boundary conditions, one was that defined in ASTM D7136 and another one was self‐designed that has the same constraint area but different constraint degree. One basis of the experiments, finite element analyses were performed to gain a deeper understanding of the different damage mechanisms. With which another three boundary conditions were investigated for further considering the effect of constraint areas on both the impact and non‐impact sides, including that defined in another commonly used standard ASTM D5628 and two self‐designed cases. It was indicated that the boundary conditions influenced less the force and energy responses of Glare laminate, regardless of the impact damage levels, and hardly on the damage behavior as well when perforation was encountered. However, influences were obtained under lower and intermediate damage levels, and it was the constraint area on the rear side and constraint degree that played the dominant roles, respectively. The results achieved can provide suggestions for reasonably evaluating the low‐velocity impact performance of FML. Highlights: Comparisons were made between the low‐velocity impact behavior of Glare laminates under five different boundary conditions.Boundary conditions influenced hardly on maximum impact force and energy absorbed ratio, but evidently on damage behavior.Constraint area and constraint degree governed damage mechanism under lower and intermediate impact energies, respectively.Influence of boundary conditions on damage behavior disappeared when the impact energy was enough to perforate Glare laminate. [ABSTRACT FROM AUTHOR]

The reliable anchorage and long‐term durability of high‐performance fiber reinforced polymer composites were the decisive factors for engineering applications owing to the anisotropy of materials and the complexity of service environment. In this paper, an innovative glass fiber reinforced polypropylene (GFRPP) self‐anchor plate cable was developed to utilize the high toughness/durability of thermoplastic resin and self‐anchor load‐bearing system. The effects of different reinforcement methods and cable arc angles (10°, 20°, and 30°) on mechanical properties of plate cable were investigated. Water absorption behavior and mechanical properties immersed in alkali solution were tested to evaluate its long‐term service behavior. The thermogravimetric and surface morphology analysis were conducted to reveal the performance evolution mechanism. The results showed through the combination of secondary melting, carbon fiber winding confinement and epoxy reinforcements, the splitting failure of transition zone and interlaminar cracking failure of straight zone for plate cable were effectively avoided. The tensile strength retention of plate cable for arc angles of 10°, 20° and 30° were 45.6%, 41.3%, and 34.0% of GFRPP plate, respectively. Larger arc angle increased the curvature of arc‐straight transition zone and stress concentration near the straight section, leading to interlaminar splitting failure of plate cable at weak transition zone. The tensile strength of plate cable with the immersion time deteriorated obviously until the lowest retention of 29.7%. The degradation mechanism was mainly due to the etching of glass fibers in alkali solution and the formation of pores and internal defects, including fiber/resin interface debonding and resin swelling. The research results were of significance for solving the anchoring problems and promoting the long‐term service reliability in bridge applications. Highlights: The mold can realize reliable molding of glass fiber reinforced polypropylene cables after the reinforcements.The tensile strength retention of plate cable was up to 34.0%–45.6% of plate.Larger arc angle increased the stress concentration near the straight section.Non‐polar polypropylene plate was proved to have better hydrophobic performance.The degradation mechanism of plate cable in alkali solution was revealed. [ABSTRACT FROM AUTHOR]

Highlights In this study, the post‐buckling damage behavior of cylindrical composite tubes was examined experimentally. The samples were reinforced with glass, carbon, and kevlar fibers to obtain glass‐reinforced fiber polymer (GRFP), carbon‐reinforced fiber polymer (CRFP), and Kevlar‐reinforced fiber polymer (KRFP) cylindrical tubes. The samples were produced using 4 stacking layers with filament winding technology. In producing all composite tubes, the outer diameter was kept constant at 17 mm, and two inner diameters of 12 and 13 mm, two wall thicknesses, 5 winding angles, and two lengths were used as parameters. The load was applied to the samples until completely damaged, and the maximum post‐buckling load values obtained were measured on the testing device. The effect of different reinforcement materials, winding angle, wall thickness, and length on the load‐carrying capacity was analyzed and it was understood that they had a significant effect. It was observed that the load‐carrying capacity of GFRP samples was the highest compared to the others, followed by CFRP and KFRP samples, respectively. In all samples, it was observed that a 0.5 mm wall thickness increase increased the load‐carrying capacity, while a 50 mm length increase decreased it. The energy absorption (EA) values of GFRP, CFRP, and KFRP samples were 46.99, 25.22, and 15.48 Joules, respectively. It was understood that the energy absorption of GFRP samples was 1.86 times better than CFRP and 3 times better than KFRP. The samples were produced using the fiber winding method, which is one of the most common production methods in the manufacture of tubes. Three different polymer reinforcement materials were used in the production of the samples. The effects of polymer reinforcement material, winding angle, length, and wall thickness on the maximum post‐buckling load were investigated. Wall thickness was found to have a significant effect on the maximum post‐buckling load. It was observed that GFRP samples had the highest energy absorption feature. [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]

Highlights Environmental hazards caused by the ever‐increasing end‐of‐life (EoL) glass fiber reinforced polymer (GFRPs) composite waste is of major concern for the sustainable development of the industry. Compared to land filling or incineration, pyrolysis is one of the most promising environmentally friendly methods of disposal of EoL GFRPs. Pyrolysis not only results in recovery of clean glass fibers but other valuable products, such as oils. However, long processing time at elevated temperature leads to aggravation of already existed surface flaws along with the structural changes. Therefore, thermal conditioning of glass fibers results in severe deterioration of the strength in recovered fibers and hence limiting the use of recovered fibers to low end‐products. In this study, a new strategy was adopted where instead of complete cleaning of the fibers at pyrolysis stage, the fibers were partially oxidized and the complete removal of char from the surface of glass was done during hot alkaline etching. This strategy was opted to enhance the quality of the required fibers while reducing the processing time. The results showed ~200% increase in strength of fibers after the combined treatment of pyrolysis and post etching compared to the just pyrolyzed samples with etching time of just 1 min. End‐of‐life panels of GFRPs were pyrolyzed under inert environment of Argon. Residual char was partially removed through post oxidation under flowing air. Hot alkaline etching resulted in complete removal of char and surface defects. Partial oxidation and short etching cycles resulted in improved strength of recovered glass fibers. [ABSTRACT FROM AUTHOR]

Highlights Additive manufacturing has enhanced the production of complex parts with greater efficiency. However, inherent drawbacks such as reduced mechanical properties still pose challenges, necessitating further improvements to bridge the gap and meet industry demands. Therefore, this study investigated the use of glass fiber woven fabric with vat‐photopolymerization printing to achieve composite parts with superior mechanical properties. This approach offered an advantage in reducing the production time required for fiber‐reinforced composites by eliminating the need for curing processes or vacuum infusion. The mechanical properties of the composite panels manufactured with this method were investigated using flexural, interlaminar shear (ILSS), impact tests with different fiber orientations, and fiber volume fractions. The results of the mechanical tests showed maximum flexural strength of 295 MPa, impact strength of 174 kJ/m2, and ILSS of 20.58 MPa. In addition, optical images were taken to examine the cross‐section of the printed parts, which revealed a uniform and good wetting of the fibers. The findings suggest that glass fiber woven fabric in vat printing is a promising approach for producing composite parts with enhanced mechanical properties and reduced production rate. Additive manufacturing of glass fiber woven fabric reinforced with VPP printing. Reduced production time and microstructure by using layer‐by‐layer manufacturing. Maximum flexural strength: 295 MPa, impact strength: 174 kJ/m2, ILSS: 20.58 MPa. Consistent porosity values with the increasing number of layers. Promising for producing standard and thick composites with improved properties. [ABSTRACT FROM AUTHOR]

Highlights This paper presents the experimental, analytical, and numerical extensive investigation into the flexural creep performance of pultruded glass fiber reinforced polymer (pGFRP) composites at elevated service temperatures. The experimental phase involved a physical testing program on pGFRP coupons in a four‐point bending setup covering a wide range of loads (12%, 24%, and 37% stress levels) and temperature conditions (20, 40, and 60°C) over a long test duration of 720 h. The analytical Burgers model was employed to provide theoretical insights into the time‐dependent deformation behaviors, while the finite element analysis (FEA) simulations using derived reduction factor validated the accuracy of the proposed procedure. Burgers model was able to capture the experimental data very well and reached the ultimate strain failure limit within about 1.4–50 years depending on the case. The proposed simple FEA procedure yielded a pattern closely resembling the one observed from Burgers model in which they resulted in estimated endurance times with a roughly 15% difference between them. The higher stress and/or temperature, the longer the primary creep stage is. Burgers model is able to capture the experimental data very well in all conditions. Burgers general equation is able to predict failure within about 1.4–50 years. A proposed reduction factor based on Burgers model is utilized in FEA The FEA procedure shows a roughly 15% difference compared to Burgers model. [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]

Glass fiber reinforced polymer (GFRP) composites with chopped strand mat (CSM) and woven roving mat (WRM) reinforcements are widely used in high‐pressure piping due to their favorable strength‐to‐weight ratio. However, cyclic loading from vibrations and pulsating forces can induce internal microstructural damage, ultimately leading to performance degradation. A thorough understanding of this damage mechanism is imperative for its mitigation, necessitating a detailed examination. The present study aims to investigate the fatigue response and damage mechanisms in CSM and WRM composites subjected to tension‐tension cyclic loading. Scanning electron microscopy analysis of edge sections revealed the development of perpendicular microcracks in both composites. CSM composites exhibited fatigue cracks parallel to the loading direction and higher levels of parallel interface debonding compared to perpendicular matrix cracks. Finite element analysis of the representative volume element revealed the role of shear stress in the matrix in initiating parallel cracks, thereby explaining the damage initiation mechanism in CSM. These findings highlight the distinct damage mechanisms arising from the differing fiber arrangements in CSM and WRM composites, providing valuable insights for optimizing their performance under cyclic loading conditions. Highlights: Fatigue response of CSM and WRM was influenced by fiber orientation and weaving pattern.Perpendicular fibers were the most probable fibers to have their interface form a crack.Fatigue cracks parallel to the direction of loading were observed in CSM composites.Quantified the true 3D internal microstructural damages for the first time. [ABSTRACT FROM AUTHOR]

The main objective of this study is to investigate the effect of combining natural and synthetic fibers on the mechanical characteristics of hybrid and novel functionally graded hybrid composites by considering hemp as natural fiber and carbon and glass as synthetic fibers. Before manufacturing, the natural fibers were treated with sodium hydroxide (NaOH) solution to remove the impurities on the fiber surface. The fibers were reinforced in an epoxy‐based matrix using a hand‐layup technique. The volumetric fraction of the hybrid composites was 40% fibers and 60% matrix. Different types of composites, such as plain fiber reinforced polymer (FRP), sandwich hybrid (SH), alternative hybrid (AH), and functionally graded hybrid (FH), were manufactured from hybridizations of hemp/carbon and hemp/glass. In accordance with ASTM standards, the tensile, compression, flexural, short beam shear, water absorption, and wettability properties of composites were determined. FH composites with hemp fiber at the top surface had the highest improvement in tensile strength, stiffness and compressive strength compared with pure hemp FRP (HFRP) composites. Hemp SH composites had the highest improvement in flexural and short beam properties in both hybridizations compared with HFRP composites due to the stacking of synthetic fiber at the outer layers. Scanning electronic microscopic (SEM) studies identified the failure mechanism of the tensile failure specimens and also the effect of mercerization on fiber surfaces. In conclusion, this work identified the structural capacity of hybrid composites and emphasizes that FH and hemp SH composites can replace glass FRP composites in structural applications. Highlights: Treating hemp fiber with 2 g/L of NaOH for an hour had a better impact.Functionally graded composites had better in‐plane strength and stiffness.Composites made with synthetic fiber on the outer layers were good at bending.In structural applications, hemp/carbon hybrid composites can replace GFRP. [ABSTRACT FROM AUTHOR]

Due to the requirements of high stiffness and impact strength of HDPE pipes, in this article, long fiber reinforced HDPE were developed and the effects of fiber length, volume fraction, types, and matrix/fiber interface on the mechanical properties were investigated. Tensile properties, notched impact strength, as well as microstructures were tested. The results showed that fibers increased the tensile strength, modulus, and impact strength, but decreased their plastic deformation. Larger fiber fraction indicates more fibers are involved in load bearing, but easy agglomeration. With ascending fiber length, tensile, and impact strength first increased and then decreased, whereas tensile modulus first increased and then maintained an almost constant value. Carbon fibers showed no advantages over glass fibers and basalt fibers in reinforcing HDPE due to the relatively poor interface bonding strength. Interface modification with KH550 improved the mechanical performance of composites, but the enhancement was limited. More effective methods should be developed for better performance. Highlights: Fiber increases strength and modulus, but decreases plastic deformation.Critical fiber length for basalt LFT is 2.6 mm obtained from SEM.Larger fiber volume and length lead to agglomerations.Difference in BF, CF, and GF reinforced HDPE is determined by interface.Interface modification enhances mechanical properties of LFT but limited. [ABSTRACT FROM AUTHOR]

In the pursuit of sustainable solutions, this study investigates the potential of bio‐based polyamide 5.6 (PA56) as a promising alternative to petroleum‐derived polyamide 6.6 (PA66). Novel composites of PA56 and PA66 were prepared with the incorporation of glass fibers and flame retardant additives by twin screw extruder. Subsequently, these composites were subjected to comprehensive characterization to determine their performance. The physical, mechanical, rheological, thermal, and flammability properties of PA56 composites were investigated and compared with those of PA66 composites with the same formulations. This article aims to unveil the remarkable potential of bio‐based PA56 composites in industrial applications. The results showed that bio‐based PA56 exhibits comparable, and in some cases superior, performance to PA66 while offering the added advantage of environmental sustainability. The findings suggest that bio‐based polyamide 5.6 can serve as a sustainable alternative to petroleum‐derived polyamide 6.6, contributing to a greener future in industrial applications. Highlights: Bio‐based PA56 exhibits comparable properties to petroleum‐derived PA66.Incorporation of glass fibers and flame retardants enhances the properties of PA56.Findings propose PA56 as a sustainable alternative to PA66 in various applications. [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]

The rapid advancement of the electronics industry has continuously increased demands for the E‐glass yarn's quality and production capacity. The twisting and winding process stands out as a crucial step in E‐glass yarn production. Twisted bobbin yarns are produced separately using constant spindle speed technology and constant tension technology in order to address issues such as high yarn breakage rates and excessive yarn hairiness during twisting. By comparing the twisting tension, yarn breakage rates, and yarn hairiness between these two technologies, this study delves into the impact of twisting technology on E‐glass yarn quality and production capacity. The results indicate that, in comparison with constant spindle speed technology, constant tension technology reduces the unevenness ratio of twisting tension from 8.94% to 0.55%, decreases yarn breakage rates from 3.05% to 2.03%, reduces long hairiness by 20.3%, and reduces short hairiness by 25.1%. By reducing the spindle speed when the bobbin yarn's diameter increases, constant tension twisting technology reduces the unevenness ratio of twisting tension, yarn breakage rate, and yarn hairiness. These research findings lay the foundation for the development of high‐end E‐glass yarn products and carry significant practical value in improving yarn quality, enhancing production capacity, and reducing E‐glass yarn losses. Highlights: The twisting and winding principle of E‐glass yarn is revealed.The relationship among four tensions in the twisting and winding process is clarified.The parameters for the constant tension twisting technology are developed.The measurement method for the twisting tension is improved. [ABSTRACT FROM AUTHOR]

The present study investigates the mode‐II fracture resistance and interlaminar shear strength (ILSS) in glass epoxy laminates with the aid of glass‐carbon veils hybrid interleaving technique. Hybrid interleaves were prepared using various areal densities of non‐woven carbon and glass veils. Two methods, specifically inter‐ply and inter‐weaved ply interleaved glass epoxy composite laminates were manufactured by hand layup technique. End notch flexural and short beam test specimens were tested to estimate the mode‐II fracture resistance and ILSS. Test results indicated that the interleaved with inter‐weaved veil composite exhibited ~58% to ~82% and ~13% to ~61% enhancement for inter‐ply veil composite laminates when compared to plain samples. In context with the short beam test, a significant enhancement of approximately 23% in ILSS was noticed for the plain inter‐weaved veil constructed with a lower areal density of the carbon veil. Finally, the plain inter‐weaved interleaving technique has a prominent role in enhancing the resistance to fracture and shear strength in Glass epoxy laminates. Further, the fracture mechanisms of non‐interleaved and hybrid ply interleaved composite laminates were observed by scanning electron microscopic images. Highlights: Interleaving non‐woven microfiber veil is the most promising and cost‐effective strategy to enhance the Interlayer toughness and strength.Interleaving techniques used in this investigation have a significant effect on interlaminar fracture toughness (IFT) and interlaminar shear strength (ILSS).The areal density of high‐modulus carbon veil showed a different phenomenal influence on IFT and ILSS. [ABSTRACT FROM AUTHOR]

Highlights Highly transparent and mechanically robust thermoplastic composites have been developed by hot‐pressing PETG with E‐glass fabrics. The tow‐spreading technique facilitates the reduction of internal defects and fiber crimp angle in the composites, thereby significantly improving their optical and mechanical properties. The optimized composite containing 55.1 vol% glass fibers and 0.4 mm thickness has a high transmittance of 86.1%@616 nm and a low overall haze of 7.2%. Moreover, the 1 mm thick composites exhibit tensile strength of up to 340 MPa and impact strength of up to 86.3 kJ/m2. After 28 days of hygrothermal or UV aging, the composites show minimal changes in their glass transition temperature and thermal degradation temperature. The chemical structure also remains unchanged, with no observed crystallization. In comparison to UV aging, the composites demonstrate better resistance against hygrothermal aging. Specifically, the hygrothermal aged sample displayed a light transmittance retention rate of 93.5% and a bending strength retention rate of 94.3%, while these values were reduced to 73.3% and 90.5%, respectively, in the UV aged sample. The opto‐mechanical properties enhanced mechanism and aging degradation mechanism have been identified by microscopic morphological observation. This work provides an innovative and straightforward approach to fabricate transparent, recyclable, high‐strength thermoplastic composites. Highly transparent, mechanically robust, recyclable glass‐fabric reinforced thermoplastic composites are fabricated. Composites with spread‐tow fabrics exhibits improved transparency. The fabrication route is scalable and cost‐effective. The mechanism for opto‐mechanical properties enhancement are proposed. [ABSTRACT FROM AUTHOR]

Highlights In this paper, the mechanical properties, damage modes, and bolt load distribution of the bonded‐bolted hybrid three‐bolt joint were investigated by a combination of experiments and numerical simulations. Acoustic emission (AE) was used to monitor the tensile process of the connection in real time, and the K‐means clustering algorithm was used to realize the cluster analysis of the damage modes. A numerical simulation model of the tensile process of the joint was established using ABAQUS simulation software. The progressive damage evolution of composite laminates, and adhesive layer was characterized by using the VUMAT subroutine, the B‐K failure criterion, and cohesive element with zero thickness, respectively. The results show that four main damage modes occur in composite laminates during tension: matrix cracking, delamination, fiber pull‐out, and fiber breakage, with corresponding peak frequency ranges of (0–80 kHz), (80–210 kHz), (210–330 kHz), and (330–375 kHz), respectively. The adhesive layer between the laminates mainly exhibits peeling failure because of the secondary bending effect. In the load‐bearing process, the adhesive layer was loaded first and failed, and the bolt loading was delayed. Meanwhile, the results of bolt load distribution showed that the bolts and the adhesive layer at both ends carried greater loads. Damage modes and damage evolution of the bonded‐bolted hybrid joint in tension were analyzed by combining acoustic emission technology and numerical simulation. The simulation of delamination damage in composite laminates was carried out by inserting zero‐thickness cohesive elements into the laminates, and the delamination damage between the carbon fiber layup and the adjacent glass fiber layup was analyzed. The effect of the inclusion of the adhesive layer on the mechanical properties of the joint and the distribution of the bolt load was analyzed. [ABSTRACT FROM AUTHOR]

Highlights In this work, silicone polymer (PSOL)/glass fiber (GF)/epoxy (EP) composites were prepared by employing PSOL as interfacial modifier into GF/EP composites. The mechanical and dynamic mechanical properties of the composites were investigated to determine the optimal PSOL content. The effect of PSOL on the wettability of EP on GF was investigated. The micromorphology of the GF/EP composites was also examined by scanning electron microscope. The results demonstrate that the interfacial bonding between GF and epoxy resin was improved significantly by the addition of PSOL. Specifically, the interlaminar shear strength, tensile strength, elongation at break, and blending strength of the PSOL/GF/EP composites increased by 9.28%, 13.61%, 12.66%, and 19.22%, respectively. Moreover, the original thermal stability of the composites was improved by the incorporation of PSOL. This study highlights the effectiveness of PSOL as an interfacial modifier, enhancing the overall performance of GF/EP composites while improving their thermal stability. Silicone polymer (PSOL)/glass fiber (GF)/epoxy (EP) composite material is made of glass fiber and epoxy resin by hand paste molding. Silicon polymers as interface modifiers can improve the interface between glass fiber and epoxy resin. PSOL/GF/EP composites have good mechanical properties. The glass transition temperature of GF/EP composites was increased by silicon polymer. [ABSTRACT FROM AUTHOR]

Highlights Glass fiber‐reinforced resin matrix composites are widely used and studied for their good mechanical and impact resistance properties. In this paper, five glass fiber reinforced nylon 6 (PA6)‐based composites were prepared by mechanical blending combined with the molding process. The flexural strength, shear strength, pendulum impact strength, and low‐velocity impact properties of five composites were comparatively investigated. The crack extension modes of the composites were characterized and analyzed by light microscopy, scanning electron microscopy (SEM), and computerized X‐ray tomography (XCT), and the effects of different crack extension modes on the mechanical and impact resistance properties of the composites were researched. Experimental results show that: (1) Cracks in the composite material mainly exist in two expansion modes: transverse propagation parallel to the direction of fiber layup and longitudinal propagation perpendicular to the direction of fiber layup; (2) Different crack extension modes will cause different damage situations to the composites, however, the crack extension mode has minimal impact on the flexural, shear and pendulum impact strength of the composites; (3) The flexural and shear strengths of the composites co‐reinforced using fly ash and glass fibers were preferably 484.5 and 46.1 MPa; (4) The crack extension mode has a significant impact on low‐velocity impact performances of the composite material. The composite co‐reinforced with glass beads (GB) and glass fibers had the best impact resistance, with maximum impact force (Pmax), residual impact force (Pr), and absorbed energy (Ea) of 7015.2 N, 6273.6 N and 15.4 J, respectively. The propagation of cracks inside the composites was observed using SEM and XCT etc. A relationship between crack propagation mode and low‐velocity impact resistance of composites was established. The low‐velocity impact properties of composites are carefully analyzed. [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]

Highlights A novel dental fiber post from glass fiber‐reinforced polybenzoxazine (PBZ) composites was developed in this work. The essential properties, that is, chemical characteristics, thermal and biological properties of the PBZ composites were investigated for various glass fiber loadings (10.5, 23.7, 41.2 and 65.1 vol%). Finite element analysis (FEA) was also utilized to observe mechanical behaviors of the tooth model repaired with PBZ composite posts compared to a natural tooth model. The findings reveal that for the fiber‐reinforced PBZ composites not only their thermal properties were significantly improved, but they also showed enhanced cytocompatibility; we found a coefficient of thermal expansion of 12.8 ppm/°C and cell viability of 91.55 for the 65.1 vol% glass fiber‐reinforced PBZ composite. Moreover, samples reinforced with higher glass fiber loadings effectively resulted in the reduction of stress distribution in dentin observed from FEA suggesting protection againt root fractures. Restoration using the PBZ composite post showed the same stress patterns in the dentin‐composite resin‐post interface of the repaired tooth as in the natural tooth model. The results revealed that the glass fiber‐reinforced PBZ composites possess good thermal properties and mechanical behaviors which renders them suitable candidates for biocompatible dental materials. The glass fiber/polybenzoxazine (GF/PBZ) composites had nontoxic properties as evidenced through cell viability, growth and morphology studies. The thermal expansion of the GF/PBZ composite was similar to that of dentin, promoting adaptation at the dentin‐post interface. Mechanical behaviors evaluated by FEA of tooth model restored with GF/PBZ composite post were similar to those restored with commercial glass fiber post. The biocompatible GF/PBZ composite with good thermal and mechanical properties is a promising new candidate material as dental fiber post. [ABSTRACT FROM AUTHOR]

Highlights Polylactic acid (PLA) composites reinforced with rice husk and glass fiber can improve the properties in the aera of the material for vehicle application. In this work, the PLA composite was made and its properties were evaluated using scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). SEM observed that the polymer matrix contained a uniform dispersion of 10 wt% rice husks. The tensile strength and bending strength of the composite are 45.8 and 48.2 MPa, respectively, which are 52% and 41% higher than that of the base material PLA. TGA revealed that the thermal stability of the composite deteriorated with increasing rice husk content. The DTG curve indicated that the incorporation of rice husk and glass fiber led to a reduction in the maximum degradation rate of the PLA matrix. As a result, the thermal degradation of the PLA composite exhibited enhanced stability. The average apparent activation energy (Ea) of the composite, determined using the Friedman (FD), Flynn Wall Ozawa (FWO), Starink (ST), and Kissinger (KS) models, falls within the range of 90 to 120 kJ mol−1. Silane coupling agent was used to improve the interfacial compatibility of fillers. The synergistic action of rice husk and glass fiber fillers enhances the mechanical properties of polylactic acid composites. The mean apparent activation energy (Ea) of the composite was calculated using four models, with values in the range of 90 to 120 kJ mol−1. The Flynn Wall Ozawa and Starink models showed better stability against temperature changes compared to the Friedman model. [ABSTRACT FROM AUTHOR]

Highlights S2‐glass fiber reinforced plastics (S2‐GFRP) and basalt fiber reinforced plastics (BFRP) have emerged as crucial materials due to their exceptional mechanical properties, and milling of composite materials plays an important role in achieving desired properties. However, they have proven challenges due to relative inhomogeneity compared with metals, resulting unpredictability in quality of milling operations. The objective of this work is to investigate the effect of cutting parameters, tool geometry and tool surface materials on the surface quality of composites using burrs as a metric. S2‐GFRP and BFRP composites were produced by the vacuum infusion method. Helical and straight flute end mills were manufactured from high‐speed steel (HSS) and carbide rounds, and half of them were coated with titanium nitride using reactive magnetron sputtering technique. Taguchi L18 orthogonal array is used to determine the effect of tool material, tool angle, coating, cutting direction, spindle speed, and feed rate on the machining quality of S2‐GFRPs and BFRPs with respect to burr formations. Milling experiments were conducted under dry conditions and then the burrs were imaged to calculate the total area and length. Statistical analysis was also performed to optimize the machining parameters and tool type for ensuring the structural integrity and performance of the final composite parts. The results showed that the selection of tool material has the most significant impact on the burr area and length of the machined surface. The novel image analysis allows to analyze the extent of the burr size with a desirable operation speed for industrial applications. Aerospace grade S2‐Glass (S2‐GFRP) and basalt fiber reinforced plastics (BFRP) were manufactured. Carbide and HSS end mills were fabricated and coated with titanium nitride protective layer. FRPs were machined at various process parameters designed by Taguchi method. Distinctive image processing was firstly used to compute milling induced Burr area and length. Statistical analysis was performed to quantify the contribution of parameters and optimize milling. [ABSTRACT FROM AUTHOR]

Highlights Glass fiber reinforced polymer (GFRP) composite tubes have become increasingly popular in crashworthiness applications. On the other hand, square section GFRP tubes are prone to damage in a catastrophic failure mode in the early stages of the crushing process. At this point, triggering mechanisms have great potential to ensure deformation in progressive mode and improve the compression performance of GFRP tubes. Motivated by these facts, this paper aims to optimize the compression performance of square GFRP tubes by implementing notch‐type triggering mechanisms. The effects of notch width, number and length on the axial compression response of tubes were investigated to determine the optimal trigger configurations that would maximize specific energy absorption (SEA) and minimize peak crushing force (PCF). Experiments were conducted based on Taguchi L9 orthogonal array design, and Taguchi coupled Weighted Aggregated Sum Product Assessment (WASPAS) method was employed for optimizing multiple responses. The optimization results revealed that the proposed trigger mechanisms induced progressive crushing by preventing catastrophic failure, thereby significantly improving the compression performance of GFRP tubes. In particular, the results showed that the PCF of intact GFRP tube decreased by up to 38%, while SEA increased by up to 130% with the help of proposed trigger mechanism. The compression performance of square GFRP tubes improved by notch‐type triggering. The notch width, length and number were chosen as design parameters. Taguchi experimental design was used to find the best configuration of design parameters. The optimum configurations were examined through the entropy‐WASPAS approach. The results revealed that significant improvements can be achieved using trigger mechanism. [ABSTRACT FROM AUTHOR]

Highlights 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. 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]

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]

In this paper, a new type of foldcore sandwich panel (tentatively called X‐type foldcore sandwich panel) is proposed by combining the X‐type corrugated sandwich panel and the Miura‐ori sandwich panel. The experimental specimens are prepared by using a glass fiber‐reinforced polymer. To systematically reveal the low‐velocity response mechanism and impact resistance of sandwich panels, a hemispherical impactor is used to impact panels. The effects of impact energy, impact position, diameter of tup, and impact mass on low‐velocity impact performance of X‐type foldcore sandwich panels are considered. The damage morphology, response process, and failure mechanism are analyzed under different working conditions. The results show that under the impact of 75 and 125 J, the impact resistance of the node is better than that of the base. Under 200 J impact, the impact resistance of the base is better than that of the node. Compared with the traditional foldcore sandwich panel, the new configuration reduces the impact resistance difference between two positions (node and base). Highlights: A new foldcore sandwich panel is proposed.The impact effect of energy, mass, position, and tup diameter is investigated.Damage morphology, response process, and impact resistance are analyzed.The new structure reduces differences in impact resistance. [ABSTRACT FROM AUTHOR]

Highlights Wood plastic composite (WPC) is a kind of eco‐friendly material made of agricultural and forest industry waste and residues compounded with thermoplastic. The defects of traditional WPC, such as low strength and high creep, greatly limit its engineering applications. To solve the problem, this paper proposed two methods of glass fiber reinforced polymer (GFRP) reinforced PVC‐based WPC panels (G‐WPC) by bonding GFRP sheets or embedding GFRP bars in the tensile zone of the WPC panels. The effects of the thickness of GFRP sheet and reinforcement ratio of GFRP bar on the flexural property of G‐WPC were comparatively analyzed by carrying out four‐point bending tests and finite element simulations. The results showed that the failure modes of the GFRP sheets reinforced specimens were mainly flexural fracture and interface debonding, and the GFRP bars reinforced specimens were flexural fracture and excessive deformation. The ultimate flexural bearing capacity of both GFRP sheets/bars reinforced specimens could be improved by more than 200%. GFRP bar reinforced specimens had better ductility than reinforced with sheet. The effects of WPC density, GFRP sheet fiber layup angle and GFRP bar diameter on the flexural behavior of G‐WPC were further parametrically analyzed using the finite element model (FEM). Two effective flexural reinforcement methods of WPC were proposed. The optimum thickness of GFRP sheet was obtained based on experimental tests. The suitable reinforcement ratio of GFRP bars was studied by tests and FEM. Effects of WPC density, GFRP fiber layup angle and bar diameter were analyzed. [ABSTRACT FROM AUTHOR]

Highlights 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. A novel CoFeSiB metallic glass fiber reinforced epoxy resin composite The 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]

Highlights This experimental work involves characterization and fractography of a bio‐based epoxy and an in‐situ polymerisable thermoplastic polymer matrix based non‐crimp glass and carbon fiber composites under compressive loading. The laminates are characterized under compression loading using a combined loading compression (CLC) fixture. Laminates made using the thermoplastic matrix exhibit higher compressive strength (approx. 20% along fiber direction) compared to the bio‐epoxy based laminates. Further, both composites exhibit comparable compressive modulus characteristics. The tested composites are subjected to fractography analysis using Scanning Electron Microscopy (SEM) and Computed tomography (CT). SEM results indicate a difference in fiber‐matrix interface characteristics between the thermoplastic matrix and the bio‐epoxy matrix. Additionally, the CT scans reveal a difference in failure modes due to fiber orientations. A difference between failure mode of the exterior and interior plies of the specimens was also noticed. However, no specific influence of matrix type was observed on the overall macroscopic failure behavior. Bio‐epoxy and thermoplastic based laminates were characterized in compression. Post‐test fractography was performed using SEM and x‐ray CT scans. Use of thermoplastic matrix exhibits better fiber‐matrix adhesion compared to bio‐epoxy. Both laminates performed well in compression under laboratory test conditions. [ABSTRACT FROM AUTHOR]

Highlights Fiber‐reinforced polymers (FRP) feature high strength‐to‐weight ratio amongst the emerging class of natural composites. This paper presents the impact of the glass fiber on the tensile strength of the flax epoxy laminate. The mechanical behavior and damping characteristics of flax fiber reinforced polymer (FFRP) and the hybrid flax‐glass fiber reinforced polymer (HFRP) are experimentally investigated. Both the flax and hybrid FRPs are made using vacuum infusion process. The specimens without and with holes of 4, 5, and 6 mm in diameter are subjected to tensile test using acoustic emission monitoring and free vibration test. In the former testing, HFRP resulted in higher peak frequencies and cumulative counts. Also, the natural frequency and damping factor of HFRP vary proportionately with the hole size, as identified in the latter tests. Different damage mechanisms during the tensile test revealed that the presence of glass fibers in HFRP increased resistance for certain damage mechanisms. Adding glass fiber to flax fiber reinforced polymer (FFRP) creates a hybrid FRP (HFRP) with increased resistance to damage and improved damping characteristics. HFRP exhibits a distinction in failure mechanisms compared to FFRP. The study utilizes acoustic emission (AE) to identify various damage mechanisms in the material, providing a more detailed information. The addition of glass fibers in HFRP leads to a more pronounced increase in damping factors. [ABSTRACT FROM AUTHOR]

Highlights 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$$ {\mathrm{F}}_{\mathrm{ip}} $$), total absorbed energy (U), mean crash force (Fm$$ {\mathrm{F}}_{\mathrm{m}} $$), crash force efficiency (CFE), and specific energy absorption (SEA). The findings reveal that the maximum Fip$$ {\mathrm{F}}_{\mathrm{ip}} $$, U, Fm$$ {\mathrm{F}}_{\mathrm{m}} $$, 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$$ {\mathrm{F}}_{\mathrm{ip}} $$, U, Fm$$ {\mathrm{F}}_{\mathrm{m}} $$, and SEA to a concentration of 0.50 wt.% NCP. However, beyond this point, there's a notable decline in performance. 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]

Three‐dimensional multi‐axial warp knitted (3D MWK) reinforced composites are important components of advanced structural composites. The interfacial bonding between fiber and matrix is key to achieving high mechanical properties. In this work, graphene oxide (GO) and poly(oxypropylene) diamines (D400) were grafted on glass fiber (GF) multi‐axial warp knitted (MWK) fabrics to construct a "flexible‐rigid" structure. The surface morphologies of GF were characterized by SEM and EDS. Then, 3D MWK‐reinforced composites were prepared based on four kinds of modified fabrics using the VARTM method. The in‐plane compression properties were obtained at different high temperatures and their failure modes were analyzed. The strain–stress curves showed that the composites exhibited brittle fracture modes. D400 and GO‐modified multi‐scale composites exhibited outstanding compression properties. The strength of the related composited was improved by 55.78%, 76.78%, 52.19%, and 56.78% compared to that of desized composite at 30°C, 60°C, 120°C and 150°C, respectively. The damage to D400‐GO modified and D400 modified composites was the most serious, where shear fracture modes were obvious in addition to layer debonding features. This protocol provides a potential strategy to manufacture of D400 and GO‐modified hierarchical reinforced composites. Highlights: The modified 3D MWK glass fabrics based on poly(oxypropylene) diamines (D400) and graphene oxide (GO) were prepared.The compressive properties of 3D desized, D400‐, D400‐GO‐, and GO‐MWK fabrics reinforced epoxy composites were obtained and analyzed at different temperatures of 30°C, 60°C, 120°C, and 150°C.The failure mechanisms of 3D desized, D400‐, D400‐GO‐, and GO‐MWK fabrics reinforced epoxy composites at different temperatures were analyzed. [ABSTRACT FROM AUTHOR]

The utilization of hollow glass particle‐filled fiber‐reinforced composites in marine applications necessitates a proper understanding of their behavior when exposed to moisture environments. In this study, the glass fiber‐reinforced composites reinforced with 0%–30% volume fraction of glass microspheres were fabricated and immersed in seawater and distilled water conditions for monotonic tensile and flexural testing. The degradation mechanisms were analyzed by dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FT‐IR), and scanning electron microscopy (SEM). Moisture absorption results showed an increasing trend with the inclusion of glass microspheres. A decline in glass transition temperature and storage modulus was observed as a result of moisture absorption. The tensile results of the specimens exhibited a decrease of 13% and 9% in distilled water and seawater solution, respectively when compared with unaged samples, respectively. The flexural results of the aged composite specimens demonstrated a reduction of 24% and 11% in distilled water and seawater solution, respectively when compared with unaged samples. The findings also show that the influence of moisture on the modulus is less pronounced compared to its effect on strength under both environmental conditions. The micrograph results revealed a notable deterioration of the glass microsphere and the fiber/matrix interface in the moist environment. Highlights: Water absorption increases with the addition of glass microspheres.Microsphere degradation and fiber/matrix debonding are the governing mechanism.Retained 89% of tensile strength of their initial properties after exposed in sea water.Increase in microsphere contents decreases the tensile and flexural strength. [ABSTRACT FROM AUTHOR]

In reinforced concrete structures, GFRP bars are becoming acceptable as internal reinforcement subject to compressive load and hygrothermal environments. The paper presents an experimental study on the compressive behavior, thermodynamic properties, and degradation mechanism of the glass fiber‐reinforced polypropylene (GFRPP) bars after aging in distilled water (DW), alkaline solution (AS) and seawater and sea sand concrete (SWSSC) solution at 21, 40, and 60°C up to 120 days. The effect of specimen assembly methods, and slenderness rations (Lu/Db) on the compressive behavior was evaluated on the control GFRPP bars. After immersion, the compressive strength of the GFRPP bars was significantly affected by the type of solution, immersion time, and temperature. Typically, the compressive strength retention was decreased by 25.8%, 30.0%, and 33.0% at 60°C in DW, AS, and SWSSC solutions, respectively. The degradation mechanism of the compressive behavior of GFRPP bars was revealed through SEM images and FTIR spectroscopy analysis, and the debonding of fiber‐resin interfaces, chemical etching of glass fibers, and changes in polypropylene functional groups were confirmed or discovered. Finally, based on the Arrhenius theory, the long‐term life prediction of compression strength in three typical service environments was conducted to provide the design guideline for reinforcement concrete. Highlights: Effect of specimen assembly and Lu/db on compressive behavior of GFRPP barsThermodynamic behavior of the GFRPP bars under different aging environmentsRevealed the degradation mechanism of GFRPP bars under hygrothermal environmentsPredicted the service life of GFRPP bars in typical service environments [ABSTRACT FROM AUTHOR]

The present investigation targets the physical, mechanical, and thermal characteristics of glass fabric‐reinforced vinyl ester/polyester hybrid laminates filled with ferrous, nickel, and tungsten micro‐particles. The metal‐fillers‐glass fabric reinforced vinyl ester/polyester hybrid composites was produced by distributing 1 wt% ferrous, nickel, and tungsten with an ultrasonication probe‐assisted wet layup method. Polyester resin reinforced with glass fabrics and tungsten fillers (PRGT) presents improved mechanical characteristics compared with other hybrid laminates, with tensile, compression, and flexural strength values of 157.89 MPa, 163.74 MPa, and 167.29 MPa, respectively. The fractographic microstructure of tensile fracture PRGT laminates exhibits that glass fibers pull out, microcracks, and lower gaps, because of stronger filler‐fabric‐matrix adhesion when compared with other hybrid laminates. The artificial neural network modeling was conducted to choose the best composite among the various manufactured composites. Statistical analysis was observed from the one‐way ANOVA technique, substantiating that the physical, mechanical, and thermal characteristics of metal fillers‐reinforced hybrid composites were statistically significant. Highlights: Metal‐fillers‐glass fabric reinforced vinyl ester/polyester hybrid composites.Selection of the best composite from developed composites by ANN.Tungsten fillers are a useful material for reinforcement. [ABSTRACT FROM AUTHOR]

The use of hybrid reinforcement in polymer composites has been getting attention due to its potential for weight and cost reduction while achieving improved design flexibility for mechanical and thermal properties. In this study, an interply hybridization of epoxy laminates was performed using layers of solid and hollow glass fibers. The structural and thermal performance of the resulting hybrid vascular composites was investigated. All composite parts were manufactured using vacuum‐assisted resin transfer molding (VARTM), following an interply hybridization plan for the stacking sequence of hollow and solid fiber layers. An expected decrease in flexural properties and thermal conductivity was observed for the laminates with completely hollow fibers. On the other hand, hybridization had a positive effect on the laminate properties. It was shown that hybrid vascular composites could be manufactured without a significant reduction in mechanical and thermal performance by a judicious hybridization plan. The optimum hybridization of the laminate achieved a 3.1% increase in the specific flexural strength and a 5.3% decrease in thermal conductivity while containing a vascular network that can be used for active thermal control. Highlights: A vascular interply composite structure consisting of hollow and solid fibers was manufactured and characterized for the first time.The I4 composite, vascularized through the middle layers of the laminate, has almost as much flexural strength as solid composite and much more specific flexural strength.The thermal conductivity of the I4 composite is almost as much as that of the solid composite.Functional composites for thermal management and smart applications can be manufactured using hollow fibers without sacrificing flexural strength and thermal conductivity with interply vascularization. [ABSTRACT FROM AUTHOR]

This study aims to analyze the effect of processing parameters, particularly the cooling rate, on the morphology and mechanical properties of reinforced glass fiber polypropylene (GF‐PP) films. To achieve the objective, a multi‐scale analysis was performed to study the different morphology of neat PP and reinforced PP films obtained by controlling the thermal condition during the fabrication process. Films of PP with a thickness of about 100 μm have been prepared to observe the crystalline microstructure's formation and follow its kinetics on the scale of the spherulites. The same procedure was followed using a single glass fiber to obtain the mono‐composite film of PP by controlling the interface/interphase between the fiber and the matrix. Moreover, the dependence of the damage mechanisms on the spherulite diameters and the mechanical test conditions was established. The deformation mechanisms (intra and inter‐spherulitic damage) were analyzed qualitatively and quantitatively according to the controlled morphologies produced for the polymer and the composite, especially at the level of the transcrystalline phase. The results confirm that the processing parameters affect not only the width of the transcrystalline phase but also the morphology of the fiber‐matrix interface. Furthermore, increasing the thickness of the transcrystalline phase exhibited remarkably higher interfacial shear strength, as demonstrated by the single fiber fragmentation test. Highlights: Impact of cooling rate on morphology and mechanical properties of glass fiber polypropylene (GF‐PP).Multi‐scale analysis to investigate the distinct morphologies of PP and GF‐PP.Deformation mechanism particularly intra and inter‐spherulitic damage.Attention to the impact on the transcrystalline phase and the fiber‐matrix interface.Influence of transcrystalline phase thickness on interfacial strength. [ABSTRACT FROM AUTHOR]

This research investigates the influence of kevlar and glass fiber reinforcements on the mechanical and thermal properties of epoxy/vinyl ester (hybrid resin) composite. The hybrid resin was synthesized by achieving an interpenetrating network between epoxy and vinyl ester. The composites were characterized using tensile, flexural, impact, and thermo‐gravimetric analysis (TGA). Scanning electron microscopy was employed to analyze surface morphology whereas Fourier‐Transformation Infrared Spectroscopy (FT‐IR) was used to investigate the possible interaction between the constituents of the composites. The findings have shown a notable improvement in the mechanical properties after the hybridization of the resin. For reference, the tensile strength of glass/hybrid resin and kevlar/hybrid resin composites were observed to increase by 8.33% and 23.65%, as compared to glass/epoxy and kevlar epoxy composites respectively, whereas, the bending strength of these composites was improved by 8.36% and 30.61%, respectively. TGA also showed an enhanced thermal stability of the hybrid resin‐based composites. Such improvements are noticed due to multi‐resin incorporation (the oxirane group of epoxy reacts with the hydroxyl group of vinyl ester), confirmed by the FTIR, TGA, and morphological analysis. This study signifies that the proposed hybrid composites are better in terms of strength and modulus relative to conventional metallic materials. Highlights: The paper presents the development of novel hybrid resin, reinforced with synthetic fibers.Hybrid resin is imparted positively and is highly favorable in improving the mechanical properties of composites.The tensile strength of novel composites is increased by 8.33% and 23.65% relative to their base specimens, and a similar trend is observed in flexural and impact analysis.Fractured analysis showed that composite laminates deteriorated more intensely due to cohesive matrix fracture; adhesion failure was not observed at all, as evidenced by the emergence of micro‐cracks in resin.Developed novel composites exhibited maximum thermal stability; residual char in glass/epoxy/vinyl‐ester composite attained 17.81% higher, whereas kevlar/epoxy/vinyl‐ester achieved 3.56% relative to glass/epoxy and kevlar/epoxy base samples. [ABSTRACT FROM AUTHOR]

The present work optimizes the geometric parameters of glass fiber reinforced polymer (GFRP) laminated pin joints under fatigue loading conditions using response surface methodology (RSM). RSM is utilized to construct polynomial functions that optimally capture the behavior of experimental data, intending to make statistical inferences. Key geometric parameters, that is the edge and width dimensions were studied in pursuit of enhanced performance under fatigue loading of pin joints. The study aimed to validate the effectiveness of the optimized parameters, particularly for attaining load‐bearing capacity, fatigue life, and failure mode using numerical and experimental approaches. Optimal configurations were achieved, that is edge and width equal to 16 mm at which the failure mode shifts to bearing mode. Another configuration with an edge of 20 mm and a width of 22 mm was achieved for optimized fatigue life. These findings underscore the practical implications of the optimization process, with the potential for substantial gains in fatigue life and strength of GFRP laminated pin joints in engineering applications. The identified optimal configurations exhibited a non‐catastrophic bearing failure mode, emphasizing a crucial characteristic that provides prior‐warning before the occurrence of final failure. The experimental results align well with the numerical outcomes regarding fatigue life and the mode of failure. Highlights: Parametric optimization of GFRP pin joint under cyclic loading.Optimization of GFRP pin joints via RSM for cyclic loading.Validation through numerical and experimental approaches.Comparison of fatigue life at optimum design points.Depiction of the failure modes using damage pattern under fatigue loading. [ABSTRACT FROM AUTHOR]

This study focused on the wear behavior of unidirectional, thick GF epoxy composites produced using the autoclave method. The thermal aging process was applied for 250 and 500 cycles to understand the wear behavior of the material as it ages over time. To evaluate the wear behavior of the samples, wear tests were carried out under three different loads (10, 20, and 30 N) and three different sliding distances (150, 300, and 450 m). Taguchi‐based regression analysis was used to analyze the experimental results. The results obtained were evaluated using ANOVA tables and main and contour graphs. When the test results are examined, it is surprisingly observed that the wear resistance of the composite material increases positively with the aging effect. With thermally aging while the coefficient of friction value of composite samples increases from approximately 0.12 to 0.3, the wear volume decreases from approximately 4 to 1.3 mm3. Taguchi based regression analysis showed that the relationship between wear and thermal cycle sliding distance and load can be established by reducing the number of experiments in wear studies. Highlights: Thermal aging effect on wear properties of thick GFRP was determined.Minimum wear volume and COF values were determined by applying ANOVA.It was determined that a load increment has the most impact on wear volume.Worn surface images supported the reduction in the wear rates of the thick GFRP.Empirical regression models developed for the mathematical prediction. [ABSTRACT FROM AUTHOR]

Drilling glass fiber reinforced polymer matrix (GFRP) composites typically causes burrs, splintering, and microcracks within the GFRP structure, as well as delamination, fiber pull‐out, and thermal degradation of the polymer matrix. Designing and manufacturing molded‐hole GFRP components, as opposed to drilling, has recently been proposed as a promising method for overcoming the issues associated with drilling, for which there is limited research. Specifically, the mechanical response of molded‐hole GFRP has not been fully addressed in the literature. In the present study, molded and drilled GFRP composites with epoxy matrix were fabricated by hand lay‐up, and then the samples were analyzed utilizing experimental and numerical analysis techniques. Stress and strain analyses of GFRP samples were performed in Ansys Transient Structural Analysis. Although the fiber orientations of the layer geometries [0°/90°] and 3D models were the same, an additional layer was defined in the direction of the fiber orientation [45°/−45°] of molded‐hole composites to simulate the fiber accumulation effect. Experimental findings revealed that the flexural strength of molded composites was 12% greater than that of drilled composites. According to the numerical analysis, 98.7% proximity was achieved between the experimental and numerical results. Thus, the present study has provided numerical modeling to understand the flexural strength of molded composites for the first time, which will contribute to the increased use of molded composites in numerous applications in the fields of aerospace, automotive, and marine. Highlights: Drilled‐ and molded‐hole GFRP composites were produced by hand lay‐up.Flexural properties of the composites were examined via 4P bending tests.Flexural strength of molded composites was higher than that of drilled ones.98.7% proximity was achieved between the experimental and FEM results.A unified FEM method is proposed for the molded‐hole composites. [ABSTRACT FROM AUTHOR]

In fiber‐reinforced composites, the interfacial bonding between fibers and the matrix is crucial for determining the material's performance. A vacuum‐assisted resin transfer molding (VARTM) process was utilized in this work to fabricate glass fiber fabric‐reinforced polyamide 6 (GFF/PA6) composites through in‐situ polymerization using caprolactam (CL) as the precursor. To enhance the fiber‐matrix interfacial bonding, polyethylene glycol (PEG) was incorporated into the polymerization system, improving the hydrogen bonding between the matrix and fibers. Morphological observations and interface layer analysis revealed that the introduction of PEG resulted in improved interfacial bonding and increased interface layer thickness. Molecular dynamics simulations indicated that the amino formate groups formed by the reaction with PEG exhibited more hydrogen bonds with the hydroxyl groups on the glass fiber surface, thereby promoting interfacial bonding between the matrix and fibers. When the PEG content was 10 wt%, the tensile strength and the elongation at break of the corresponding composite increased by 160% and 300% compared to GFF/PA6 composites without PEG. This study presents a promising strategy for enhancing the fiber‐matrix interfacial bonding by modifying the matrix, offering a prospective approach for developing high‐strength thermoplastic composites. Highlights: GFF/PA6 composites were fabricated via the VARTM method.The addition of PEG for matrix modification improved the interfacial bonding.The modification enhances the hydrogen bonding between the matrix and fibers.Good interfacial bonding can greatly promote the crystallization of the matrix.The composites exhibited a significant increase in strength and toughness. [ABSTRACT FROM AUTHOR]