Short Fiber Research Articles

Experimental and theoretical studies on 3D printed short and continuous carbon fiber hybrid reinforced composites

3D-printed carbon fiber composites hold significant potential in aerospace applications because of their lightweight, high strength and complex structure fabrication capabilities. However, additive manufacturing characteristics such as high porosity, anisotropy and continuous fiber content significantly affect the mechanical properties of printed parts. The aim of this study is to investigate the influence of hybrid printing of short and continuous carbon fibers on the mechanical properties and failure mechanisms of composites and to develop a model to predict elastic properties considering porosity. First, mechanical testing and characterization of short and continuous fiber reinforced polyamide (nylon) print filaments are performed. The results indicate that the elastic modulus and ultimate strength of continuous carbon fiber filaments reach 60 GPa and 1500 MPa, respectively, while the strength and elastic modulus of short carbon fiber filaments reach 60 MPa and 1 GPa, respectively. Then tensile specimens with different continuous fiber orientations and different continuous fiber placement sequences are printed and tested using a multi-material 3D printing technique. The specimens are characterized before and after testing using scanning electron microscopy and microscopy to assess the porosity and failure mechanisms of specimens with different configurations. The results show that the mechanical properties of the printed parts are much lower than those of the print filaments, which proves the serious negative impact of the material extrusion process on the mechanical properties of the printed structural parts. Finally, an analytical method for predicting the elastic behavior of printed composites is developed by introducing the porosity factor in the volume-averaged stiffness model. For continuous and short fiber filled composites with different fiber contents and printing orientations, the predicted results are in agreement with the experiments, and the prediction error is greatly reduced from 30 % to <5 %.

Silver with tribo-chemistry facilitation synergized with graphite particles for enhancing the tribo-performance of PEEK composites

The proactive design of tribo-chemistry at friction interface is an effective way to improve the quality of transfer film. Herein, silver served as an assistant in tribo-chemistry, along with graphite incorporated into the short carbon fiber (SCF)/ polytetrafluoroethylene (PTFE)/poly ether ether ketone (PEEK) composite. The lowest wear rate of 3.5 × 10-7 mm3/Nm was achieved for the composite at a graphite content of 5 wt% and a silver content of 5 wt% (Gr5Ag5) under dry friction condition, primarily benefiting from the synergistic interaction of silver and graphite. The transfer of silver and graphite to the friction interface endowed the transfer film with lubricity and load-bearing ability. Crucially, the oxides generated by silver enhanced the strength of the transfer film, and the tribo-chemical reaction involving Ag could increase the bonding of the transfer film to the metal.

Shear Behavior and Modeling of Short Glass Fiber- and Talc-Filled Recycled Polypropylene Composites at Different Operating Temperatures

The present paper aims to broaden the field of application of the phenomenological model proposed by the authors in a previous study (ICP model) and to assess the shear properties of a recycled 30 wt.% talc-filled polypropylene (TFPP) and a recycled 30 wt.% short glass fiber-reinforced polypropylene (SGFPP), used in the automotive industry. The materials were produced by injection molding employing post-industrial mechanical shredding of recycled materials. In particular, Iosipescu shear tests adopting the American Standard for Testing Materials (ASTM D5379) at three different operating temperatures (−40, 23 and 85 °C) were performed. The strain was acquired using a Digital Image Correlation (DIC) system to determine the map of the strain in the area of interest before failure. Lower operating temperatures led to higher shear chord moduli and higher strengths. Recycled SGFPP material showed higher mechanical properties and smaller strains at failure with respect to recycled TFPP. Finally, the ICP model also proved to be suitable and accurate for the prediction of the shear behavior of 30 wt.% SGFPP and 30 wt.% TFPP across different operating temperatures.

Tensile and Impact Properties of Woven Glass Fibers/Epoxy Composites Filled with Short Glass Fibers

Glass fiber/polymer composites are widely utilized in many structural applications because of their high specific strength and stiffness-to-weight ratios. In this study, woven glass fiber/epoxy was hybridized with short glass fibers of different lengths (2, 4, 6, 2+4, 2+6, and 4+6 mm) and contents (3, 6, 9, and 12 wt%) to produce hybrid woven SGF/epoxy composites. Variations in the thickness, fiber volume fraction, density, and void content of the prepared composites were determined. Mechanical tests such as tensile and Charpy impact tests were conducted. Compared to the woven fabric composites without short glass fibers (control samples), the tensile strength increased by approximately 13% at an optimum weight fraction of 3 wt% using short glass fiber lengths of 4 mm. Meanwhile, the incorporation of short glass fibers into the woven glass composites decreased the tensile modulus for all lengths. The maximum enhancement in the impact strength (approximately 14%) was achieved by the hybrid composite samples reinforced with 4 mm of short glass fibers at 3 wt%. This hybrid composite offers 18% and 20% improvements in the specific tensile and impact strengths, respectively. In summary, filling the woven fabric composites with specified short fiber contents and lengths can increase their mechanical performance when resin-rich regions are reinforced with short fibers without forming relatively thick interleaves between the woven fabric plies

Influential reinforcement parameters, elemental mapping, topological analysis and mechanical performance of lignocellulosic date palm/epoxy composites for improved sustainable materials

The value of biomaterials for green products has begun to develop more ecofriendly and renewable sustainable materials for a better circular economy and to reduce carbon footprints. This work presents integrated investigations of the lignocellulosic date palm/epoxy composites at various reinforcement condition parameters for sustainable structural materials where elemental mapping, topological analysis, and mechanical performance have been performed. Mapping energy dispersive X-ray spectroscopy was utilized to assess the composite composition properly. Elemental mapping and a scanning electron microscope were employed to evaluate the chemical composition of the composites. The mechanical performance of the produced composites was also explored in terms of ultimate tensile strength, tensile modulus, elongation at break, and impact energy properties. The effects of fiber loading, fiber length, and fiber width (as long fiber, short fiber, and long-thin fiber) were investigated for the date palm fiber/epoxy composites. Results have revealed that the composite behavior was affected by several influential reinforcement parameters. The energy dispersive X-ray spectroscopy maps by C–K, O–K, Si–K, K-K, and Ca-K demonstrated that the composites contain mainly carbon, silicon, and oxygen. It was evident that the modulus of elasticity property of short fiber composites exhibits an increasing trend with higher fiber content, even at 35 wt%. Moreover, the enhancement of tensile strength for the short fiber size composites reached 72.5 %. However, such tensile strength of thin fiber size/epoxy composites achieved 135.7 % at 25 wt% indicating superior development of this mechanical property. The long date palm fiber composites demonstrated the best value of modulus of elasticity and the maximum impact energy of 15.3 kJ/m2 attained at 25 wt%, which is about 112.5 % enhancement. Scan electron microscope was capable of confirming that broken fibers were not separated from the matrix indicating the good adhesion between the fiber and the matrix that supports their good mechanical performance.

Tailoring the additional content of short carbon fiber in the reduced graphene oxide-Cu self-lubricating composites for enhanced mechanical and tribological performance

The reduced graphene oxide-Cu self-lubricating composites with short carbon fiber fillers were fabricated by powders wet-mixing combined with hot-pressed sintering process. The impacts of short carbon fiber content on microstructure, mechanical and tribological performance of reduced graphene oxide-Cu composites were characterized. The reduced graphene oxide/carbon fiber hybrid fillers were randomly distributed in the sintered bulk compacts. The hybrid filled composites achieved enhancement in mechanical and tribological properties. With increasing carbon fiber content, hardness and compressive yield strength of the prepared composites were increased, and both friction coefficient and wear rate showed a constant decrease trend under different loads. Owing to the synergy effect of reduced graphene oxide/carbon fiber hybrid lubricant fillers during sliding together with the greatly enhanced hardness and yield strength, up to 0.6 wt% carbon fiber incorporation resulted a lowest friction coefficient and decreased wear rate. Randomly distributed reduced graphene oxide/carbon fiber hybrid fillers provided the lubrication to reduce friction and wear for Cu matrix.

Thermal and mechanical behaviour of recycled short milled carbon fibre reinforced polypropylene and recycled polypropylene composites: A comparative study

Environmental and economic factors have driven research into the recycling and applications of recycled carbon fibres (rCF). This paper presents a comparative study characterizing and comparing the mechanical and thermal performance of recycled short milled carbon fibre (rSMCF) on virgin and recycled polypropylene composites. The effects of rSMCF on VPP and RPP on mechanical performance were analysed and compared. At 5 wt% rSMCF, recycled polypropylene achieved 52.3% and 47.3% improvement on tensile and flexural modulus, while at the same rSMCF loading, virgin polypropylene only improved 37.7% and 17.5%, respectively. The un-notched impact strength of RPP-based composites reduced from 83.2 kJ/m2 to 60.1 kJ/m2 when rSMCF content increased from 1 wt% to 5 wt%, indicating future work should enhance the fibre/polymer interface performance. Crystal contents (χ0) of the PP/rSMCF composites were investigated by differential scanning calorimetry (DSC), and the results were analysed and mapped to the mechanical performance. The results of this study propose a novel scalable method for the production of high-performance VPP/RPP composite materials using rSMCF.

Constructing flexible fiber bridging claws of micro/nano short aramid fiber at interlayer of basalt fiber reinforced polymer for improving compressive strength with and without impact

The high-performance Basalt Fiber Reinforced Polymer (BFRP) composites have been prepared by guiding Micro/Nano Short Aramid Fiber (MNSAF) into the interlayer to improve the resin-rich region and the interfacial transition region, and the flexible fiber bridging claws of MNSAF were constructed to grasp the adjacent layers for stronger interlaminar bond. The low-velocity impact results show that the MNSAF could improve the impact resistance of BFRP composites. The compression test results demonstrate that the compressive strength and the residual compressive strength after impact of MNSAF-reinforced BFRP composites were greater than those of unreinforced one, exhibiting the greatest 56.2% and 73.3% increments respectively for BFRP composites improved by 4 wt% MNSAF. X-ray micro-computed tomography scanning results indicate that the “fiber bridging claws” contributed to better mechanical interlocking to inhibit the crack generation and propagation under impact and compression load, and the original delamination-dominated failure of unreinforced BFRP composites was altered into shear-dominated failure of MNSAF-reinforced BFRP composites. Overall, the MNSAF interleaving might be an effective method in manufacturing high-performance laminated fiber in industrial production.

Improvements in the Characteristics of Plant Fiber Reinforced Concrete

Plant Fiber is lightweight, has a high specific strength, and the ultimate elongation is high and can improve the shortcoming of concrete. Concrete is easy to crack and break, and its tensile strength and other mechanical properties are not high. The chemical composition and mechanical properties of some plant Fibers that are often used are analyzed first. The modification of plant Fiber will also be discussed. Firstly, the chemical composition and mechanical properties of some plant Fibers are analyzed, and the modification methods of plant Fibers are also discussed; then, the mechanical properties of plant Fiber-reinforced concrete, hydration properties, heat preservation properties, durability, and other properties of plant Fiber-reinforced concrete are analyzed and summarized in detail. The conclusions are as follows. When the strength of concrete is increased by plant Fiber, the long Fiber is the best tensile strength method, the short Fiber is the most practical, and the length and content of the Fiber. The influence of factors such as water-cement ratio; plant Fiber can delay the release of the heat of hydration of cement by changing the hydration characteristics of cement, thereby improving the anti-cracking ability of mass concrete; concrete plant Fiber can improve the thermal stability and durability, and the lyotropic effect of plant Fiber on concrete Affect the flowability of paste. Plant Fibers can improve the thermal insulation and durability of concrete and reduce the thermal cracking of concrete. The plant Fiber is used as a reinforcement in the concrete of the railway foundation, which can enhance its tensile strength, impact strength, and flexural strength. The optimal loading range is 0.6-0.9%, and the long Fiber lay-flat method is the best. In the mixed method, these five physical reverse effects can be prepared in the range of 1.2-2.0%. The single tensile squeezing capacity of 30 plants using the mixed method is up to 3.69 MPa, which is the only chemical evaluation capacity of 46.5%.

Effect of the Glass Fiber Orientation on Mechanical Performance of Epoxy based Composites

Composites are one of the most advanced and adaptable engineering materials. The strength of any composite depends upon volume/weight fraction of reinforcement, orientation angle and other factors. The present work focuses on the determination of the mechanical properties of pure epoxy and unidirectional glass fiber reinforced epoxy. Nowadays, glass fibers are being used in several engineering applications like electronics, aviation, automobile, sport industry etc. Glass fibers are having excellent properties like high strength, flexibility, stiffness, and resistance to chemical attack. With an increase in the content of unidirectional glass fiber volume the properties of unidirectional glass Fiber Reinforcement Polymer (GFRP) composite were improved. It may be used in different forms like chopped, woven mat, short fibers and long fibers etc. Each type of glass fiber has unique properties and is used for different applications. The mechanical and thermal properties of various polymer composites reinforced with glass fibers when subjected to mechanical loading have been studied and reported.

Clinical Performance of Short Fibre-reinforced Glass Ionomer Cement Restorations in Cervical Carious Lesions: 12-Month Randomized Clinical Trial.

The aim was to assess the clinical performance of experimental short fiber-reinforced glass-ionomer cement (FR-GIC) in the treatment of cervical caries lesions. A total of 45 patients were randomly enrolled in this trial according to the split-mouth design. The FR-GIC was prepared by adding short glass fibers at a mass ratio of 20% into the powder portion of Fuji II LC. The cervical lesions in the intervention group were restored with FR-GIC, while unmodified Fuji II LC was applied as the control. Clinical evaluation was performed by two blinded operators at baseline, at 6, and 12 months using modified USPHS criteria. The data were analyzed using Friedman's test, followed by the Nemenyi post hoc test with a significance level of α = 0.05. After 1 year, all restorations were fully retained. There was no statistically significant difference (p⟩0.05) between the two materials based on the evaluated criteria. Both groups had 4 (10%) cases with Bravo scores for cavos-surface marginal discoloration. Regarding marginal integrity, Bravo scores were observed in 5 (12.5%) cases in the intervention group and 4 (10%) cases in the control group. Both materials in the treatment of cervical caries lesions demonstrated satisfactory clinical outcome throughout the 12-month follow-up.

Genome-wide association study of fiber quality traits in US upland cotton (Gossypium hirsutum L.).

A GWAS in an elite diversity panel, evaluated across 10 environments, identified genomic regions regulating six fiber quality traits, facilitating genomics-assisted breeding and gene discovery in upland cotton. In this study, an elite diversity panel of 348 upland cotton accessions was evaluated in 10 environments across the US Cotton Belt and genotyped with the cottonSNP63K array, for a genome-wide association study of six fiber quality traits. All fiber quality traits, upper half mean length (UHML: mm), fiber strength (FS: gtex-1), fiber uniformity (FU: %), fiber elongation (FE: %), micronaire (MIC) and short fiber content (SFC: %), showed high broad-sense heritability (> 60%). All traits except FE showed high genomic heritability. UHML, FS and FU were all positively correlated with each other and negatively correlated with FE, MIC and SFC. GWAS of these six traits identified 380 significant marker-trait associations (MTAs) including 143 MTAs on 30 genomic regions. These 30 genomic regions included MTAs identified in at least three environments, and 23 of them were novel associations. Phenotypic variation explained for the MTAs in these 30 genomic regions ranged from 6.68 to 11.42%. Most of the fiber quality-associated genomic regions were mapped in the D-subgenome. Further, this study confirmed the pleiotropic region on chromosome D11 (UHML, FS and FU) and identified novel co-localized regions on D04 (FU, SFC), D05 (UHML, FU, and D06 UHML, FU). Marker haplotype analysis identified superior combinations of fiber quality-associated genomic regions with high trait values (UHML = 32.34mm; FS = 32.73gtex-1; FE = 6.75%). Genomic analyses of traits, haplotype combinations and candidate gene information described in the current study could help leverage genetic diversity for targeted genetic improvement and gene discovery for fiber quality traits in cotton.

Experimental Investigation into the Mechanical and Piezoresistive Sensing Properties of Recycled Carbon-Fiber-Reinforced Polymer Composites for Self-Sensing Applications.

This study investigates the mechanical and piezoresistive sensing properties of recycled carbon-fiber-reinforced polymer composites (rCFRPs) for self-sensing applications, which were prepared from recycled carbon fibers (rCFs) with fiber lengths of 6, 12, 18, and 24 mm using a vacuum infusion method. Mechanical properties of the rCFRPs were examined using uniaxial tensile tests, while sensing characteristics were examined by monitoring the in situ electrical resistance under cyclic and low fatigue loads. Longer fibers (24 mm) showed the superior tensile strength (92.6 MPa) and modulus (8.4 GPa), with improvements of 962.1% and 1061.1%, respectively. Shorter fibers (6 mm) demonstrated enhanced sensing capabilities with the highest sensitivity under low fatigue testing (1000 cycles at 10 MPa), showing an average maximum electrical resistance change rate of 0.7315% and a gauge factor of 4.5876. All the composites displayed a stable electrical response under cyclic and low fatigue loadings. These results provide insights into optimizing rCF incorporation, balancing structural integrity with self-sensing capabilities and contributing to the development of sustainable multifunctional materials.

Synergy performance of hybrid fiber-reinforced ultra-high-performance cementitious composites with low fiber contents

This study aims to assess the synergistic tensile performance resulting from the hybridization of long and short fibers. Three types of long steel,fibers, i.e., twisted, hooked, and smooth fibers, along with two types of short fibers, i.e., smooth and polyamide fibers, were incorporated into ultra-high-performance concrete (UHPC) at a total volume content of 1.5%. To predict the tensile resistance of the hybridizations, various machine learning models, including artificial neural network (ANN), decision tree (DT), random forest (RF), and support vector machine (SVM), were applied by utilizing a significant number of collected experimental results. Experimental findings demonstrated that the hybridization of long and short fibers effectively enhanced tensile resistance compared to mono fibers. These hybridizations exhibited negative synergy factors in post-cracking strength but positive synergy factors in both strain capacity and specific work to fracture. Predictions using machine learning models revealed that the RF model exhibited outstanding performance in predicting the tensile resistance of the hybridizations. Furthermore, the compressive strength of the matrix was found to be the most important factor affecting post-cracking strength, whereas fiber length had the most substantial impact on the strain capacity.

Enhancing interlaminar fracture toughness and shear strength of carbon fiber composite laminates via orientation of nickel-plated short carbon fibers in a magnetic field

This study aimed to enhance the interlaminar mechanical properties of carbon fiber composites by incorporating nickel-plated short carbon fibers (Ni@SCFs) between adjacent layers in a magnetic field. Herein, non-flocked composites, flocked composites with unoriented Ni@SCFs, and flocked composites with oriented Ni@SCFs using a magnetic field were fabricated to investigate the impact of fiber orientation on the mode I interlaminar fracture toughness (GIC) and interlaminar shear strength (ILSS) of the composite laminates. It was observed that Ni@SCFs were distributed at varying vertical angles between adjacent layers under the influence of the magnetic field. The areal density of oriented Ni@SCFs was systematically increased, resulting in notable enhancements in both initiation and propagation of GIC for flocked composites. At a flocking density of 6 g/m2, maximum values reached 533 J/m2 and 769 J/m2 respectively, representing a substantial increase of 52 % and 63 % compared to non-flocked composites. Additionally, the ILSS of flocked composites with oriented Ni@SCFs significantly improved to 55.83 MPa at a flocking density of 2 g/m2, indicating an increase of 27 % over non-flocked composites. The oriented Ni@SCFs played a crucial role in inhibiting crack propagation through the fiber bridging effect.

Enhancing the Fire Resistance of Ablative Materials: Role of the Polymeric Matrix and Silicon Carbide Reinforcement.

The primary characteristic of ablative materials is their fire resistance. This study explored the development of cost-effective ablative materials formed into application-specific shapes by using a polymer matrix reinforced with ceramic powder. A thermoplastic (polypropylene; PP) and a thermoset (polyester; UPE) matrix were used to manufacture ablative materials with 50 wt% silicon carbide (SiC) particles. The reference composites (50 wt% SiC) were compared to those with 1 and 3 wt% short glass fibers (0.5 mm length) and to composites using a 1 and 3 wt% glass fiber mesh. Fire resistance was tested using a butane flame (900 °C) and by measuring the transmitted heat with a thermocouple. Results showed that the type of polymer matrix (PP or UPE) did not influence fire resistance. Composites with short glass fibers had a fire-resistance time of 100 s, while those with glass fiber mesh tripled this resistance time. The novelty of this work lies in the exploration of a specific type of material with unique percentages of SiC not previously studied. The aim is to develop a low-cost coating for industrial warehouses that has improved fire-protective properties, maintains lower temperatures, and enhances the wear and impact resistance.

Wear and Friction Behavior on Extrusion-Based 3D Printed Short Carbon Fiber Reinforced PETG Composites with Annealing and Laser Treated Effects

Wear and Friction Behavior on Extrusion-Based 3D Printed Short Carbon Fiber Reinforced PETG Composites with Annealing and Laser Treated Effects

Analysis of Short Fiber Measurements Calculated from the Length Distribution from an HVI Fibrogram

ABSTRACT Cotton fiber length is one of the most important fiber quality attributes, as it has a direct impact on the quality of spun yarn. Of particular interest is information regarding the shorter fibers in the sample, as research has shown that shorter fibers adversely affect yarn quality. In a previous work, some authors proposed a method whereby a complete fiber length distribution can be calculated from the fibrogram produced by the USTER High Volume Instrument (HVI). In this paper, we perform an exploratory analysis on a large set of over 5,000 samples, focusing on short fiber measurements provided by the new method of reconstructing the fiber length distribution from the HVI fibrogram. Overall, the results demonstrate that the short fiber measurements based on the reconstructed distributions of HVI fibrograms reveal structure in the data not present in other short fiber measurements from the HVI or the USTER Advanced Fiber Information System (AFIS). Additionally, we show that the new fibrogram-based measurements can detect fiber breakage that occurs as a result of AFIS testing. In short, the results indicate that the length measurements based on the new method offer an improvement over the existing measurement techniques.

Characterization of thermomechanical properties and damage mechanisms using acoustic emission of Lygeum spartum PLA 3D-printed biocomposite with fused deposition modelling

This study examines the morphological, physicochemical, mechanical, and thermal properties of 3D-printed biocomposite fabricated using fused deposition modeling (FDM) with short Lygeum spartum fibers and PLA. Scanning electron microscopy (SEM) was used to analyze fracture surfaces and fiber dispersion within the PLA matrix after mechanical testing. Chemical and thermal properties were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Mechanical performance was assessed through tensile and flexural testing, supplemented by digital image correlation (DIC) and acoustic emission techniques. The incorporation of 10% short natural fibers mitigated the brittle behavior of 3D-printed PLA, resulting in a more ductile biocomposite. These materials exhibited improved mechanical and thermal properties, including increased flexural modulus, higher elongation at break, and enhanced thermal stability compared to neat PLA. These findings underscore the potential of these biocomposites as biodegradable and eco-friendly materials for various applications.

Dependence of the mechanical properties of nylon-carbon fiber composite on the FDM printing parameters

Nylon-based polymer reinforced with short carbon fibers (PA-CFs), fabricated using the Fused Deposition Modeling (FDM) 3D printing process, has been proposed for various applications. However, the mechanical performance of these materials as a function of printing parameters, including wall thickness at infill contents < 100 %, has yet to be reported in the literature. This paper focuses on the effects of infill percentage, nozzle temperature, and wall thickness on the porosity content, microstructure, and mechanical properties of PA-CF specimens. Employing a Taguchi (L9 − 3^3) design of experiments, tensile and flexural testing were conducted to assess their mechanical response. The printing temperature induces microstructural changes, promoting interlayer debonding due to voids and pores at wall- and skin-core interfaces. Wall thickness significantly impacts tensile strength and can be maintained between 0.8 and 1.35 mm for maximum flexural strength, while maximal tensile strength can only be achieved with a wall thickness between 1.15 and 1.5 mm.