Continuous Glass Fiber Research Articles

Mechanical behavior of polymer-based composites using fused filament fabrication under monotonic and fatigue loadings

The use of additive manufacturing has been widely developed in the industry due to its ability to make complex shapes. The use of reinforcing fibers has provided a wider design capability in this field. Due to the effect of the number of fibers reinforced used on the mechanical properties, the study of the obtained mechanical properties is of great importance. This paper presents the experimental findings of tensile loading and three points bending fatigue tests performed on polymer-based composites (Onyx (which is CF-PA6) and reinforced Onyx with continuous glass fiber (CF-PA6 + GF) using Fused Filament Fabrication. Tensile properties of various types of printing conditions (Solid, Triangular, Rectangular, and Hexagonal fill patterns) have been compared. The coupled frequency amplitude affects the nature of the overall fatigue response which can be controlled by the damage mechanisms accumulation and/or by the self-heating. For fatigue loading, self-heating has been observed and yielded a temperature rise to about 60°C which is more than the glass transition temperature of the polymer. Multi-scale damage analysis of the sample in fatigue showed that the first observed damage phenomenon corresponds to the debonding of the filaments which leads to the propagation of transverse cracks.

3D printing of multidirectional composite materials reinforced with continuous fibres: impact damage behaviour

3D printing is a promising additive manufacturing technology capable of producing functional parts of continuous fibre reinforced thermoplastic composites (CFRTPCs). Thus recyclable parts having complex geometries are obtained in a simple manner [1]. In addition, the use of thermoplastic polymers significantly reduces the manufacturing costs because, unlike thermoset polymers, autoclave is not required for curing purposes. This is one of the greatest opportunities for 3D printing as an alternative to conventional manufacturing processes [2, 3]. Pieces obtained from both, conventional manufacturing methods and 3D printing technology, consists on a sequence of stacked sheets. Although greater automation and the possibility to optimize the design of each sheet are advantages of 3D printing, the adhesion between the matrix and the reinforcement fibres is insufficient and consequently, parts with inferior mechanical properties are obtained. Some studies have been interested in the effect of different process parameters on the mechanical performance of the printed parts, however, further research is required. A fundamental challenge is to get good consolidation between the fibres and the polymer matrix, with control of the fibre orientation and low cost [4, 5]. The aim of this work was to evaluate the mechanical properties of multidirectional 3D printed continuous carbon, glass and Kevlar fibre reinforced nylon composites, manufactured by FDM technique. Special attention was paid to the impact damage resistance and tolerance. [1] L. Nickels, Strengthening the 3D printing composites field, Reinforced Plastics, 62 (2018) 298-301 [2] L.G. Blok, M. L. Longana, H. Yu and B. K. S. Woods, An investigation into 3D printing of fibre reinforced Thermoplastic composites, Additive Manufacturing, 22 (2018) 176-186 [3] T. Liu, X. Tian, M. Zhang, D. Abliz, D. Li and G. Ziegmann, Interfacial performance and fracture patterns of 3D printed continuous carbon fibre with sizing reinforced PA6 composites, Composites Part A: Applied Science and Manufacturing, 114 (2018) 368-376 [4] R. Velu, F. Raspall and S. Singamneni, 3D printing technologies and composite materials for structural applications, Green Composites for Automotive Applications, chapter 8 (2019) 171-196 [5] Q. Hu, Y. Duan, H. Zhang, D. Liu, B. Yan and F. Peng, Manufacturing and 3D printing of continuous carbon fiber prepreg filament, 53 (2018) 1887-1989

Determination of the compressive and tendile moduli of the pultruited bars by bending tests

Corrosion of the steel bars is the first cause of degradation of the reinforced concrete structures. This is the reason why in recent years non-corrosive materials are using to increase the useful life of these structures. Glass fiber reinforced polymer (GFRP) bars are an alternative to traditional steel bars. These bars are manufactured from continuous glass fiber embedded in a polymeric resin by the pultrusión process. Due to the great variability in the mechanical properties provided by manufacturers, it may be useful to define a test procedure to characterize the material in a simple manner. This work shows a procedure to determine the compression, tensile and flexural moduli of a GFRP bar by means of bending tests.

Influence of fibre alignments on the mechanical properties of novel Spirograph based non-woven mat composites

Fibre architecture of glass fibre (GF) reinforced polymer composites has a major impact on the mechanical properties for structural applications. In this study, a novel continuous glass fibre non-woven GF mat based on Spirograph art pattern is laid using a customized mechanical system. Spirograph-based continuous glass fibre non-woven (SNW) mat of different patterns was prepared and GF laminate epoxy composites were fabricated with the aim of achieving quasi-isotropic mechanical properties. The samples were cut to dimensions of test specimens from various identical locations symmetrically from a circular-shaped SNW composite laminates which were subjected to flexural, impact, shear and modified compression with anti-buckling tests. One particular SNW pattern composite laminate exhibited 40.82% better impact and 49.01% better shear resistance than commercial 0°/90° woven roving mat composite. The developed SNW laminate composite had quasi-isotropic fibre orientation and better mechanical properties without any stitching and interlacing as in case of woven fibre laminate composite.

Effect of boundary condition and variable shell thickness on the vibration behavior of grid-stiffened composite conical shells

In this research, it is aimed to investigate the effect of boundary condition and variable shell thickness on the vibration behavior of grid-stiffened composite conical shells. In order to fabricate the stiffeners and shell for the experimental study, continuous and woven glass fibers have been used during a filament winding process, respectively. Due to the non-uniform distribution of the stiffeners in a stiffened conical shell, the equivalent thickness varies along the longitudinal axis. The stiffener and shell structures have been reduced into an equivalent shell using smeared method. The governing equations have been solved in order to evaluate the natural frequencies of the grid-stiffened conical shell by the use of first-shear deformation theory (FSDT) along with the power series method. In order to validate the analytical solutions, an experimental modal analysis have been carried out on a real grid-stiffened composite conical shell with uniform shell thickness. In addition, the finite element solution has been provided for further validations. Furthermore, the effects of various geometric parameters, variable shell thickness and boundary conditions have been discussed.

Mechanical and FEA-Assisted Characterization of 3D Printed Continuous Glass Fiber Reinforced Nylon Cellular Structures

The main objective of this study was to investigate the mechanical behavior of 3D printed fiberglass-reinforced nylon honeycomb structures. A Continuous Fiber Fabrication (CFF) 3D printer was used since it makes it possible to lay continuous strands of fibers inside the 3D printed geometries at selected locations across the width in order to optimize the bending behavior. Nylon and nylon/fiberglass honeycomb structures were tested under a three-point bending regime. The microstructure of the filaments and the 3D printed fractured surfaces following bending tests were examined with Scanning Electron Microscopy (SEM). The modulus of the materials was also evaluated using the nanoindentation technique. The behavior of the 3D printed structures was simulated with a Finite Element Model (FEM). The experimental and simulation results demonstrated that 3D printed continuous fiberglass reinforcement is possible to selectively adjust the bending strength of the honeycombs. When glass fibers are located near the top and bottom faces of honeycombs, the bending strength is maximized.

The influence of preheating temperature on the mechanical properties of injection-overmolded hybrid glass fiber reinforced thermoplastic composites

Thermoplastic overmolding technique is an advanced integrated manufacturing technology to fabricate hybrid fiber reinforced thermoplastic composites (hybrid composites) components in which short fiber reinforced thermoplastics are injected onto the surface of thermoformed continuous fiber reinforced thermoplastic (CFRT) laminate (organosheet). To further clarify the bonding mechanism between the heterogeneous interface of short and continuous glass fiber reinforced thermoplastic composites, a series of experimental tests and molecular dynamic (MD) simulations were conducted to investigate the preheating temperature of organosheet on mechanical properties of hybrid composites. The experimental results reveal that the surface roughness of organosheet is increased with raising the preheating temperature, resulting in the enhancement of mechanical interlock at the bonding interface. The interface region in SEM observation is gradually disappeared due to molecule diffusion. Simulation results show that both diffusion coefficient and interfacial bonding energy are clearly improved with preheating temperature. Compared with the non-preheating condition, the flexural strength of the hybrid composite is increased by more than three times when the preheating temperature is set as 220 °C by IR heater. Moreover, the fracture mode of hybrid composites has been proven to change with the preheating temperature.

Preparation of Continuous Glass Fiber Reinforced Polylactic Acid by Means of a Melt Impregnation Method and Application as a 3D Printing Consumable

Abstract3D printing of continuous fiber reinforced composites (CFRC) has become a trend. However, the continuous glass fiber reinforced filament (CFRF) is mainly CFRF/PA for 3D printing. there are few studies on CFRF/PLA with PLA as matrix and continuous fiber as reinforcement. In this paper, continuous glass fiber reinforced filament/PLA (CGFRF/PLA) which can be used in 3D printing are prepared by molten impregnation process with PLA as matrix material and continuous glass fiber as reinforcement. Orthogonal experiment method was used to study the process parameters of CGFRF/PLA. The results show that when CGFRF/PLA is prepared, the parameters are set as the cavity die temperature 215 °C, the outlet die temperature 212 °C, the sizing die temperature 202 °C. And the winding speed of the composite material is 7r/min. The diameter of the composite wire we get is 0.45 mm with the roundness error is 0.01 mm. The roughness is 18um, and the bending degree is 25.8 %. At the same time, this study can provide ideas for the preparation of more multiple CFRF.

Impregnation modeling and preparation optimization of continuous glass fiber reinforced polylactic acid filament for 3D printing

AbstractContinuous glass fiber reinforced polylactic acid (CGF/PLA) composites were prepared by 3D printing technology in this study. The multi‐roll melt impregnation mold was manufactured according to the melt impregnation model. CGF/PLA filament was prepared by a melt impregnation device, and then used to prepare CGF/PLA composite materials by the self‐modified 3D printer device. The full impregnation of the fibers was achieved by the action of the coverage angle of the tension roller in the impregnation mold. The effects of the total coverage angle, traction speed, fiber content, and impregnation temperature on the fiber impregnation effect and 3D printed product performance were studied. The bending strength, tensile strength, impact strength, and interlayer shear strength of the printed sample reached 312, 220, 154, and 14 MPa, respectively. The strategy in this study can effectively improve the impregnation effect of PLA resin on CGFs and promote the development and application of 3D printing technology in the field of high‐performance composite manufacturing.

Fabrication and axial compression test of thermoplastic composite cylindrical sandwich structures with hierarchical honeycomb core

A hierarchical thermoplastic composite honeycomb sandwich cylindrical structure consisting of continuous glass fiber reinforced thermoplastic (GFRTP) composite skins and hierarchical honeycomb core was designed and fabricated by the means of filament winding and interlocking method. Axial compression tests were conducted to evaluate the load bearing capacity and reveal the failure modes. The results show that local buckling and face crushing were the primary failure modes for sandwich cylindrical structures. The mechanical properties including the specific energy absorption (SEA) and the ultimate loading capacity of sandwich cylindrical structure are 5.45 and 15.24 times greater than that of the hierarchical core. Besides, the hierarchical thermoplastic composite honeycomb sandwich cylindrical structures also perform better on loading-capacity efficiency when compared with structures as referenced.

Annealing of chopped and continuous fibre reinforced polyamide 6 produced by fused filament fabrication

Fused filament fabrication allows for the additive manufacturing of complex geometries without requiring moulds. The cooldown during the printing process causes the bonding between the layers to be weak. As a result, the mechanical properties are behind those of parts manufactured using conventional techniques. This study investigates the influence of an annealing process on the mechanical performance of continuous and chopped fibre reinforced polyamide 6 in the build-up direction. A correlation between the annealing temperature and the mechanical performance was found. The Young's modulus increased by a factor of three, while the ultimate tensile strength (UTS) increased by 50% for the chopped carbon fibre reinforced material and by 186% for the continuous glass fibre reinforced material. A temperature dependent transition from the gamma to the alpha phase was observed while the crystallinity only slightly changed. Air voids within the parts were found to be the main cause of embrittlement.

ОЦЕНКА ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ ЗОЛЫ РЕФТИНСКОЙ ГРЭС В ПРОИЗВОДСТВЕ НЕПРЕРЫВНОГО СТЕКЛОВОЛОКНА

The article presents the results of the evaluation of the study of the possibility of using ash and slag waste (ash) of Reftinskaya GRES as a component of the charge used in the production of continuous glass fiber of high-modulus (type E), dielectric resistant (type S) and high-strength, chemically stable basalt (type B) compositions. Since the chemical composition of ash is multicomponent and significantly differs from the compositions of raw materials traditionally used in the production of glass fiber, in order to establish the technological features of its use as a component of the charge, experimental compositions of glasses were designed to achieve their specified physical and mechanical properties, with the maximum possible content of ash in the composition of glass charges. A priori assessment showed that acceptable properties of glass for glass fiber compositions E, S and B can be obtained at the content of 36%, 68% and 64% ash in the charges, respectively, for the listed types of glass. The determination of the glass transition temperature intervals of the experimental charge compositions showed that an increase in the ash content in them increases the temperature that ensures the production of a high-quality melt. Studies of the tendency of experimental glass compositions to crystallization, which prevents the effective process of fiber formation, allowed us to determine that almost all compositions have a reduced tendency to crystallization, therefore, they can be used in the production of glass fibers of types S, E and B.

Hygrothermal aging effects on the mechanical properties of 3D printed composites with different stacking sequence of continuous glass fiber layers

The present work studied the effects of hygrothermal aging on the flexure behaviors of 3D printed composites reinforced with continuous glass fibers. Composites filled with different stacking sequence of continuous glass fiber layers were prepared. Printed laminated composites were subjected to the hygrothermal environment for up to 30 days. Moisture absorption processes and the corresponded microstructure changes were monitored along with the flexural responses of specimens. Multi-scale morphological investigation was applied to reveal the underlying deformation and failure mechanisms of the specimens under flexion with the consideration of different staking sequence of continuous glass fiber layers. The results showed that the evolution of mechanical properties induced by hygrothermal aging was influenced by the competition of different mechanisms. Polyamide matrix crystallization and the elimination of partial residual stress provided the strengthening effect, while the loss of intralayer and interlayer bonding as well as breakage of glass fiber and matrix weakened the mechanical properties of printed composites. The flexural behaviors of composites with separated distribution of continuous glass fiber layers exhibited higher hygrothermal stability in the early stage of aging. However, this advantage weakened with increasing aging time due to gradual delamination between glass fiber layer and matrix layer.

Preparation and Performance Index Test of Continuous Glass Fiber Reinforced Filament- Polylactic Acid for 3D Printer

The “independent extrusion” 3D printer of Continuous Fiber Reinforced Thermoplastic Composites (CFRTPC) is gradually recognized by the market, but it cannot be widely used due to the limitations of printing materials. This paper focuses on the development of Continuous Glass Fiber Reinforced Filament- Polylactic Acid (CGFRF-PLA) for “independent extrusion” printing. The preparation device of Continuous Fiber Reinforced Filament (CFRF) was designed, and the effects of preparation process parameters such as temperature, speed and coupling agent on the performance index of CGFRF-PLA were studied by experiments, the best preparation process parameters were determined.

Braiding Thermoplastic and Glass Fibers in Composite Dental Post Improves Their Mechanical Compatibility, In Vitro Experiment.

Mechanical compatibility with the human dentin is a considerable issue when fabricating dental fiber posts. To this purpose, this study introduces a new method of fabricating compatible dental posts using braiding techniques of thermoplastic fibers (matrix) with glass fibers (reinforcement). Fifty fiber-reinforced composite (FRC) posts of thermoplastic yarns polypropylene (PP) braided with continuous filaments glass fibers (GFs) for reinforcement, varying in fiber volume fraction (FVF), and core types are fabricated and tested. Posts are performed using a braiding machine, and braids are placed in an aluminum mold. The filled mold is playced inside an oven at the melting temperature of the polypropylene to produce the final post’s shape. An ultrasonic test is conducted to measure the shear modulus and Young’s modulus of FRC post specimens by measuring the velocities of both the P-wave and S-wave. In order to ensure the accuracy of the measurements, each sample is measured three times, and then the means and standard deviations of each sample are calculated before analyzing the test results using the means of two steps, namely, clustering and comparing the P and R² values of each cluster, which revealed that FVF, fiber mass, and core type of the specimen had a significant effect on the resulted Young’s and shear modulus. The results indicate that the proposed method can fabricate competitive dental posts with regard to different fabricating variables. The samples show Young’s modulus ranges of from 10.08 GPa to 31.83 GPa. The following tested hypothesis is supported: the braiding technique of thermoplastic fibers with glass fibers will improve the mechanical compatibility of the resulting posts (ex vivo).

Optimization of printing parameters of 3D-printed continuous glass fiber reinforced polylactic acid composites

A novel 3D printing strategy for continuous glass fiber reinforced polylactic acid (CGF/PLA) composites was proposed. CGF/PLA filament was prepared by a melting impregnation device, and then CGF/PLA filament was directly supplied to the self-modified 3D printing device. The impregnation process was optimized systematically, and the fiber content reached up to 45 wt%. A specific compatibilizer was used and the amount of compatibilizer was optimized to enhance the interfacial bonding between fiber and polymer. The effects of printing parameters such as nozzle diameter, edge width, layer thickness, printing speed and temperature on the mechanical properties and microstructure of the final printed products were studied. The flexural strength and flexural modulus of the printed products reached 312 MPa and 21.5 GPa, respectively. The fabrication strategies proposed in this study can provide a low-cost and high-strength method for the industrial application of 3D printed continuous fiber reinforced thermoplastic composites.

Quasi-static and dynamic crush behaviour of 3D printed thin-walled profiles reinforced with continuous carbon and glass fibres

The present paper investigates the suitability of cFF printed material and technologies for crashworthiness applications. To this end, the quasi-static and dynamic crush behaviour of 3D printed thin-walled hollow profiles reinforced with continuous carbon (cCF/PA) and glass fibres (cGF/PA), in axial and radial loading were analysed. Despite the specific microstrutural differences generated during 3D printing, the nature of the constituents (fibre and matrix) controlled the differences between the crush behaviour of both profiles. Although a stable collapse mode was observed for each profile under quasi-static and impact loading, a ductile response was only reported for the cGF/PA profiles. Under radial quasi-static conditions the cCF/PA profiles showed SEA values greater than the cGF/PAs. Nevertheless, the radial impact performance of the cGF/PA profile was greater as the material presented a strain-rate dependency. The radial SEA values obtained for steered glass fibres were lower than those values obtained for axial loading. However these SEA values are promising, in that they were at least 2–3 times higher than any values found in the literature. The results therefore indicate that concentrically printed cGF/PA reinforcements could be exploited for impact loaded hollow profile applications.

Graphene Deposition on Glass Fibers by Triboelectrification

In this work, a novel nanomaterial deposition technique involving the triboelectrification (TE) of glass fibers (GF) to create attractive charges on their surface was investigated. Through TE, continuous GF were positively charged thus, attracting negatively charged graphene oxide (GO) nanoparticles dispersed in a solution. The electrical charges on the glass fibers surface increased with the intensity of the TE process. The deposited GO coating was then chemically treated to obtain reduced graphene oxide (rGO) on the surface of GFs. The amount of coating obtained increased with the GO solution concentration used during the deposition process, as revealed by FESEM analysis. However, the same increment could not be noticed as a function of the intensity of the process. Both uncoated and coated GF were used to obtain single fiber microcomposites by using a bicomponent epoxy matrix. The fiber/matrix interfacial shear strength was evaluated through micro debonding tests, which revealed an increment of fiber/matrix adhesion up to 45% for rGO coated GF in comparison to the uncoated ones. A slight improvement in the electrical conductivity of rGO coated fibers through TE compared to conventional dip coating was also observed in terms of volumetric resistivity by a four-point probe setup.

Impacts of thermoplastics content on mechanical properties of continuous fiber-reinforced thermoplastic composites

Continuous fiber reinforcements are widely used to enhance mechanical properties of composite materials, but the impregnation of continuous fiber reinforcements with thermoplastics is a challenge due to high melt viscosity of the thermoplastic matrix. One of promising routes to improve the impregnation is to prepare commingled yarns with continuous matrix filaments and reinforcement fibers. In this study, we investigate mechanical properties of commingled yarns comprising different ratios of continuous glass fibers and polypropylene filaments, and of the composite plates made up of fabrics woven by the commingled yarns with a different polypropylene content. We found that undistributed or bunched glass fibers occur at high PP contents (>50 wt%), inducing an inhomogeneous mixing of the continuous reinforcement fibers and polypropylene filaments, which resultantly leads to abrupt changes in mechanical properties of both commingled yarns and resulting composites. Notably, the inhomogeneous distribution of continuous glass fibers in the commingled yarn at high PP contents gives rise to unexpected viscoelastic characteristics of resulting composites although impregnation of continuous glass fibers with polypropylene matrix is enhanced as the absolute amount of the polymer matrix increases.

Process parameters and mechanical properties of continuous glass fiber reinforced composites-polylactic acid by fused deposition modeling

This article focuses on 3D printing of continuous glass fiber reinforced composites-polylactic acid by fused deposition modeling. An innovative continuous fiber reinforced composite 3D printer and self-made continuous glass fiber reinforced filament-polylactic acid are applied to study the influences of process parameters including printing temperature, speed, layer height, and fiber volume fraction on mechanical properties of continuous glass fiber reinforced composites-polylactic acid printing samples. Tensile and three-point bending tests are carried out to explore the mechanical responses of printed samples. Experimental results show that the mechanical properties of continuous glass fiber reinforced composites-polylactic acid printing samples are better than those of polylactic acid samples. The tensile and flexural strengths of the specimens are increased by 400% and 204% when the fiber volume fractions are about 5.21% and 6.24%, respectively. The microscopic observations of the fracture surfaces of the tensile samples are also conducted to analyze the influences of layer heights on tensile strength and failure mechanism.