Carbon Fiber Filament Research Articles

Delamination observation occurred during the flexural bending in additively manufactured PLA-short carbon fiber filament reinforced with continuous carbon fiber composite

Additive manufacturing (AM) or 3D printing is process of fabricating polymer, ceramics, metallic and composite parts with complex geometries by means of optimized printing parameters. Fused deposition modeling (FDM) is an extrusion based 3D printing technology most commonly used for printing thermoplastic and fiber reinforced thermoplastic composite materials. This technique is extensively used due to its simplicity in usage, materials alteration and low cost and has the ability to fabricate parts with both short and continuous fibers. Continuous carbon fiber (CCF) are extremely lightweight, stiff and durable and when utilized as reinforcement material, they have a wide range of engineering applications. In this study, we are aiming to combine short carbon thermoplastic material with CCF to form continuous carbon fiber reinforced thermoplastic composite (CCFRTC) material using FDM 3D printing technique. After the fabrication process, the additively manufactured composite specimen undertakes flexural bending test. During the flexural test, delamination occurred. This such caused was studied, discussed and explored by examining the fracture interface study using microscope's micrographs. At last, further study, recommendations and enhancement in the development were also presented.

Prediction of the Seebeck coefficient of thermoelectric unidirectional fibre-reinforced composites

In this work, new analytical equations are derived to precisely assess the longitudinal and transverse Seebeck coefficient values of a unidirectional (UD) carbon fibre reinforced polymer (CFRP) composite lamina, as a function of the properties of the constituents and the fibre volume fraction. Accurate Finite Element (FE) analyses were also carried out on fibre-matrix unit cells, and the results were compared to those obtained with the analytical methods showing a very satisfactory agreement.Experimental measurements were carried out on single carbon fibre (CF) filament level, as well as on a CF/epoxy UD lamina that corroborated the proposed equations with the experimental results.

Investigation of mechanical and fracture behavior of pure and carbon fiber reinforced ABS samples processed by fused filament fabrication process

Purpose Acrylonitrile butadiene styrene (ABS), as a light and high strength thermoplastic polymer, has found extensive applications in different industries. Fused filament fabrication, known as three-dimensional (3D) printing technique is considered a rapid prototyping technique that is frequently applied for production of samples of ABS material. Therefore, the purpose of this study is to investigate the mechanical and fracture behavior of such materials and the techniques to improve such properties. Design/methodology/approach Experimental and numerical analyses have been conducted to investigate the effects of internal architecture and chopped carbon fiber (CF) fillers on the mechanical properties and mixed mode fracture behavior of the ABS samples made by 3D printing technique. Four different filling types at 70% filling ratios have been used to produce tensile and special fracture test samples with pure and CF filled ABS filaments (CF-ABS) using 3D process. A special fixture has been developed to apply mixed mode loading on fracture samples, and finite element analyses have been conducted to determine the geometric function of such samples at different loading angles. Findings It has been determined that the printing pattern has a significant effect on the mechanical properties of the sample. The addition of 15% CF to pure ABS resulted in a significant increase in tensile strength of 46.02% for line filling type and 15.04% for hexagon filling type. It has been determined that as the loading angle increases from 0° to 90°, the KIC value decreases. The addition of 15% CF increased the KIC values for hexagonal and line filling type by 64.14% and 12.5%, respectively. Originality/value The damage that will occur in ABS samples produced in 3D printers depends on the type, amount, filling speed, filling type, filling ratio, filling direction and mechanical properties of the additives. All these features are clearly dependent on the production method. Even if the same additive is used, the production method difference shows different microstructural parameters, especially different mechanical properties.

Longitudinal compression failure of 3D printed continuous carbon fiber reinforced composites: An experimental and computational study

Fused filament fabrication (FFF) with continuous carbon fiber filaments has proven to be a promising manufacturing technique in engineering applications. To provide guidance in the design of 3D printed carbon fiber reinforced polymer (CFPR) components, the longitudinal compression failure of continuous CFPR composites using the FFF technique is investigated systematically. First, longitudinal compression tests are performed for 3D printed continuous CFRP composites with and without designed waved filaments. The degradation of the failure strength is remarkable when the waved filaments are introduced. Nevertheless, further degradation is limited when more waved filaments are adopted. Next, the fracture morphologies are analyzed, and in-plane and out-of-plane kink-bands are observed in the microscopic images. For the specimens with waved filaments, fracture occurs at the cross-section with the contact region of the waved and regular filaments, as well as the cross-section with the maximum misalignment angle. Correspondingly, a computational framework for 3D printed continuous CFPR composites is established to explore the longitudinal compression failure mechanisms. The meso-scale computational models are reconstructed according to the geometric features of the deposited continuous CFRP filaments and the actual void volume fraction. The elastic properties of the filament are calculated by a micro-scale representative volume element (RVE) model, which is based on the fiber random distribution algorithm. The plastic deformation and failure is described by a filament constitutive model which is established by the Liu-Huang-Stout yield criterion and a simplified Tsai-Wu failure criterion. The experimental validation demonstrates the feasibility of the computational models to predict the stress-strain curves of 3D printed materials, and also capture the realistic longitudinal compression failure behavior.

Design and Manufacturing of New Low (Weight and Cost) 3D Printed Pylon Prosthesis for Amputee

The standard traditional prosthetic pylon is manufactured from stainless steel, titanium, Aluminium alloys due to their lightweights. Despite the low weight of pylon made of these alloys, the pylon is characterized by its high costs. In this study, a new prosthetic pylon is designed and manufactured from PLA carbon fiber material to produce a pylon characteristic with a lighter weight and cheaper than the standard pylon with its ability to bear the patient’s weight without any mechanical failure. The mechanical properties (yield stress, ultimate stress, and endurance stress) of the PLA carbon fiber filament were measured. The finite element method analysis of the pylon was done by using the ANSYS-14.5 program. The experimental and numerical results showed that the weight of the new prosthetic pylon is less than the weights of Stainless steel, Titanium, and Aluminium pylon by 60%,42%, and 50%, respectively, and the cost of the new prosthetic pylon is cheaper than the Stainless steel, Titanium, and Aluminium pylon by 97.5%,98%, and 96%, respectively. The mechanical properties of printed pylon material are the modulus of elasticity equal to 1.38GPa, the yield stress is 33.5MPa, the ultimate stress is 49.14 MPa, and the endurance stress is 19.16 MPa. The results also showed that the pylon’s buckling stress is higher than the yield stress and von mises stress is less than the yield stress; this proves the successful design of the pylon. The new design is cheaper, lighter, and can withstand higher patient weights.

Improving the structural properties of composite T-joints by z-weaving of continuous metallic filaments

An experimental investigation is presented into improving the maximum load limit and other structural properties of T-shaped laminate joints by through-thickness weaving of thin metal filaments. Preforms of carbon fibre T-joints are first woven using continuous metallic or fibrous filaments made of copper, steel or carbon fibre yarns and then infused with epoxy. Stiffener pull-off tests performed on the cured T-joints show that the stainless steel z-filaments yield greater improvements to the strength and absorbed energy capacity than fibrous carbon fibre filaments by up to 80% and 30%, respectively, while copper filaments yield a smaller improvement than carbon fibre filaments. The levels of strengthening by the z-filaments depend on their volume fraction and material type, with stainless steel being more effective than copper or carbon. This study demonstrates that through-thickness weaving of continuous metallic filaments are highly effective at strengthening and toughening T-joints made of laminated composites.

Fabrication and characterization of asbestos free epoxy based brake pads using carbon fiber as reinforcement

In the fabrication of automotive vehicle brake linings, the usages of asbestos create an adverse reaction on humankind and the surroundings. Hence it led to the evolution of organic-based brake lining without using asbestos material. The various types of asbestos-free brake lining materials are developed to create new lining compositions providing effective performance. In our work, the effect of carbon fiber reinforced in brake linings are studied, and their friction performances are examined. The composition of carbon fiber contents are varied by 0%, 5%, 7.5%, and 10% by volume in the total weight of the mixture of brake composites and corresponding brake pads are fabricated. The various physical, mechanical and tribological analyses are performed. The experimental work results revealed that the sample with 10% of carbon content has high tensile strength, flexural strength, Rockwell hardness, and friction co-efficient. Also, the wear test showed a low value for the sample containing 10% of carbon content. The microstructural analysis revealed that the sample having 10% of carbon content has closure packing, which causes the strong bond formation of a matrix with carbon fiber filament.

Application of FBG Technology in Additive Manufacturing: Monitoring Real-Time Internal Temperature of Products

This study presents an investigation of the influence of infill density on inner temperature change of Polylactic Acid (PLA) and carbon fiber filaments. Five groups of different infill densities (20%, 40%, 60%, 80%, and 100%) were considered for testing and analysis in additive manufacturing. Fiber Bragg grating (FBG) sensors were used to monitor the internal temperature change of all prototypes during additive manufacturing process. Monitoring tests indicate that relationships of temperature against printing time are characterized by three typical parameters including the first peak temperature (FPT), minimum temperature (MT), and completion temperature (CT). All FPT, MT, and CT values increase substantially as the increase of infill density values. MT values generally present at relatively lows infill density values but coincide with CT values at high infill density values. At low infill density levels (infill density is no higher than 60%), fabrication of the upper surface of prototypes leads to substantial temperature rise, and this rise appears to be limited at infill density values of 80% and 100%. This study can be used to reveal printing quality of 3D printed products arise from non-uniform distribution of temperature change.

Fibre misalignment and breakage in 3D printing of continuous carbon fibre reinforced thermoplastic composites

This paper investigates the formation of manufacturing induced fibre misalignment and breakage during fused filament fabrication (FFF) 3D printing of 1 K continuous carbon fibre filament. Single stripes at various turning angles and curvatures are printed by a desktop printer Prusa i3 using a specific brass nozzle and characterised using X-ray computed micro-tomography (µCT) and optical microscopy. A finite element (FE) model of the printing process is also established to support the experimental measurement. It has been found that high porosity and fibre misalignment in the printed straight stripe result from the weak fibre/matrix interface and the uneven pressure executed by the nozzle. Increase of turning angle and/or reducing of curvature radius leads to more aggravated printing defects, including shape inaccuracy, fibre twisting, folding and misalignment, due to the excessive force from the nozzle, debonding with the print bed and the unmatched geometry of nozzle outlet and fibre filament. Severe fibre breakage and significant change of thickness can be seen in the samples with turning angles larger than 120° or curvature radius smaller than 5 mm, while the wrinkles of the stripe in the inner periphery appear more frequently as the curvature radius decreases.

A novel use of twisted continuous carbon fibers in additive manufacturing of composites

3D printing of composites is one of the trending topics in the field of additive manufacturing. Several research papers on carbon fiber reinforced composites, used carbon fiber tows directly or sized carbon fibers as reinforcement for the composite, which is time consuming and not reliable as frequent clogging occurs. This paper presents a simple method by introducing the novel use of twisted carbon fiber filament and analyze its effect on the additive manufactured composites. The matrix material used is PLA. The commercially available 3D printers for printing continuous fibers, use double nozzle setups for printing the matrix and reinforcement separately in a layer by layer manner. However, there are no reports on the use of twisted continuous carbon fiber as filament and its effect on the printed parts. This paper uses twisted carbon fibers with single nozzle setup such that the material coming out of the nozzle will be ready to use CCF-PLA composite. Thus, the need of separate stacking of each layer of the matrix and fiber can be avoided. A separate path process planning has been done for printing the twisted carbon fibers in consideration of its continuity and the anisotropy. Standard mechanical tests are conducted, and the morphological study of the composite is done.

Damage properties of pre-embedded connection of carbon fiber wound composite tubes

In this study, a new connection technology of composite tubes is proposed: carbon fiber (T700/TDE86) filament winding composite tubes with pre-embedded titanium alloy joints, which realize the application of light-weighting heavy load pod for a stratospheric airship. The axial tensile behavior of specimens was determined through experimental tests and by using finite element method. In comparison with the conventional bonding connection joints, the maximum failure load of specimens is higher than 105 kN, indicating the excellent mechanical properties of the novel connecting structure. Damage in the adhesive layer is caused by the opposite movement trend between the embedded titanium and the composite tube, and the main failure mode refers to the fiber tear damage. The ±30° layer near the ends of the titanium joint is subjected to a larger tensile load and is completely damaged because of the failure of the adhesive layer. Subsequently, the inter-layer reaches the ultimate failure strength, delamination takes place, and then the structure loses its loading capacity. Numerical simulation results of the progressive damage process and failure load are in good agreement with the experimental results. Stress analysis indicates that the failure of the adhesive layer is not the dominant factor that causes the structure to lose its load-bearing capacity. Moreover, structural strength is dominated by the tensile strength of the ±30° layers and the interlaminar shear strength between 90° layer and 30° layer. The circumferentially tightened 90° yarns in the grooves are also critical to the load-bearing effect of the structure.

Experimental investigations on mechanical behavior of the carbon fiber tube reinforced polyurethane foam

The paper proposes a carbon fiber tube reinforced polyurethane foam material (CPM). Mechanical behavior of the CPM is investigated by quasi static crushing experiment. The results show that the carbon fiber tube reinforced design can obviously improve the energy absorption and load carrying capacity of the polyurethane (PU) foam. Parameter studies show that the density of the PU foam, the number and the diameter of the thin carbon fiber tube have significant effect on mechanical performance of the CPM. Moreover, the CPM filled thin walled columns (aluminum column or carbon fiber column) are further developed and their crushing behaviors are investigated under axial crushing conditions. The results show that the CPM filled design can effectively improve the crashworthiness of the aluminum column or the carbon fiber column. The interaction behavior between the CPM and the thin-walled column presents a significant contribution to energy absorption of the CPM filled columns. Moreover, the CPM filled carbon fiber column has greater potential to improve the crashworthiness than the CPM filled aluminum column. The research findings of this paper provide a new method for designing the lightweight protective structure.

Lubricants and Coupling Agents in the Processes of the Liquid-Phase Modification of the Surface of Carbon and Glass Fiber Fillers in the Production of Structural Materials: A Review

This review considers the major approaches used in the application of coupling agents and lubricants onto fiber. It is shown that the use of lubricants and coupling agents in the matrix–filler system of carbon and glass fiber-reinforced plastics (GFRPs and CFRPs) provides the required level of interfacial interaction. For polymer composite materials, the maximum positive effect is achieved by controlling the ratio of the functional groups on the surface of the fiber. It has been found that nitrogen-containing modifiers should be used for the formation of the optimum composition of the surface of a fiber with the predominance of amino and hydroxyl groups. The considered methods of modification of the surface of the fiber will make it possible to improve the quality of the polymer composite materials being developed due to the increase in the adhesive interaction of their components.

High strength expansive concrete-encased-steel filled carbon fiber reinforced polymer tubes under axial monotonic and cyclic load

High-strength concrete-encased-steel filled CFRP (carbon fiber reinforced polymer) tube (HCSFC) takes advantages of high strength of concrete, steel and confinement of FRP, resulting in enhanced structural load carrying capacity and deformability. In this study, expansive high-strength concrete is filled between CFRP tube and sectional steel to study the mechanical properties of high-strength expansive concrete-encased-steel filled CFRP tube (HECSFC) under monotonic and cyclic axial compression. Twenty-four specimens were fabricated in this study. The variables included the number of CFRP layers (0, 1, 2 layers), cross-sectional shape (circular and square), self-stress level (with or without self-stress) and loading mode (monotonic and cyclic). Test results show that the peak load of HCSFC specimen is greater than their nominal load-carrying capacity, which indicates that CFRP plays a confinement role on the internal core concrete-encased-steel. As the number of layers increases, both the normalized peak load and the ultimate axial strain increase. For specimens under the same number of layers, cross sectional shape and loading mode, the ultimate axial strain and strain reduction factor of self-stressing specimens are higher than those of nonprestressed specimens. At the same time, it is found that the confinement efficiency of CFRP on circular specimen is higher than that of square specimen. Analytical results show that the modified existing stress-strain models of CFRP confined concrete predict well with the experimental results.

Nanocarbon and macrocarbonaceous filler–reinforced epoxy/polyamide: A review

Epoxy is a thermosetting polymer and an engineering material for structural and composite applications. However, pure epoxy has disadvantages of stiffness and low toughness properties, so limiting its practical uses. Polyamide is an important thermoplastic polymer for commercial uses. Epoxy has been blended with polyamide (thermoplastic polymer) to enhance the toughness and mechanical properties. Consequently, epoxy/polyamide blend matrix has been developed for composite applications. Incorporation of carbonaceous nanoparticles in epoxy/polyamide blend has been used to improve the morphological and physical properties of these materials. This review describes scientific development in the field of epoxy/polyamide-based nanocomposite and composites. Epoxy/polyamide materials have been reinforced with micro- and macroscale carbonaceous fillers such as graphene, carbon nanotube, nanodiamond, carbon black, carbon fiber, and hybrid fillers. The strength, modulus, toughness, electrical, conductivity, thermal conductivity, and thermal stability properties of epoxy/polyamide have been influenced through the incorporation of nanofillers. The fundamentals and applications (coatings, adhesives, electronics, radiation shielding, automotive/aerospace) of these materials have been discussed. Toward the end, applications, future, and challenges of epoxy/polyamide-based nanocomposites have been comprehended.

A study on sliding wear behaviour of carbon fiber reinforced IPN composites

Carbon fiber usage is keep on increased in most of the industrial applications due to its light weight, high weight to stiffness ratio, high tensile strength, chemical resistance, low thermal expansion, high – temperature tolerance and low weight. Their uses mostly evidenced in nearly all of the applications like aerospace, military, motorsports, civil engineering applications. In this present study, carbon fiber is loaded with different proportions of alumina (0%, 10%, 15% and 20%) as filler in the presence of interpenetrating polymer networks (IPN – vinylester/polyurethane), as matrix material. The physical properties of the carbon fiber loaded interpenetrating polymer networks (IPNs) with alumina filler (particulate) have been thoroughly investigated as per ASTM standards. Besides that to completely know about the influence of coating of nickel on carbon fiber and loading of alumina filler on wear characteristics, through the pin-on disc the wear analysis were carried out. It is evidenced that the alumina filled carbon fiber (uncoated) reinforced IPN composite has shown noteworthy raise in wear resistance. Similarly the nickel coated carbon fiber, alumina loaded IPN composites as well have shown the very good wear resistance characteristics.

Vertical Fibrous Morphology and Structure-Function Relationship in Natural and Biomimetic Suction-Based Adhesion Discs

Summary Recent years have seen rapid development in bio-inspired materials for adhesion. However, it remains challenging to realize robust adhesion on rough aquatic surfaces. An inspiring natural model is the remora fish, which has evolved to retain powerful adhesion to hosts using a dorsal suction disc. We find that the remora suction disc has a unique fibrous architecture of vertically oriented collagen fibers that enable anisotropic mechanical properties and enhanced adhesion performance. In the engineered prototype, vertically oriented nylon fibers are embedded into the soft silicone matrix using electrostatic flocking. The anisotropic mechanical properties are validated in both natural and biomimetic suction discs. Furthermore, the biomimetic suction disc demonstrates an enhanced adhesion function with a maximum 62.5% increase in pull-off force and a 340% increase in attachment time compared with the silicone control. This work can shed light on natural adhesion mechanisms and inspire novel designs for aquatic soft adhesives and actuators.

Investigation of the thermal characteristics of a heating element based on aluminum with nanoporous alumina

In this work, we studied the thermal characteristics of flat heaters made of aluminum with a strip heating element in the form of carbon fiber. In order to provide the necessary insulation of the heating element from the metal base, a layer of porous anodic aluminum oxide with a thickness of 20 μm was formed on the aluminum surface. The ends of the carbon fiber filament were metallized with a layer of copper for subsequent soldering during the assembly of the electric heater. The carbon fiber filament of electric heater had an electrical resistance of 60 Ohms. Studies of the propagation of heat fluxes in the volume of a board made of aluminum with nanoporous aluminum oxide were carried out using thermal imaging measurements. The paper presents the dependence of temperature changes on the surface of the lid of a heating element made of aluminum and on the opposite side — heat transfer side with heating time. The results showed that the heat generated by a linear heating element of carbon fiber, quickly distributed throughout the entire volume of the aluminum plate of the heating element. This indicates a high thermal conductivity of the aluminum base of the heater, the parameters of which allow to achieve the required thermal characteristics of the heater.

Studies on dynamic mechanical and thermal properties of boron carbide filled carbon fiber/epoxy composites

This study aims at studying the dynamic mechanical and thermogravimetric properties of boron carbide (B4C) filled carbon fiber (CF)/epoxy composites (BC-CF/Ep composites) using the wet lay-up process assisted by vacuum bagging technique. The B4C fillers were used in varying filler weight percentages (1%, 3% and 5%) in the different CF/Ep composites and are uniformly mixed in epoxy system through ultrasonification process and was used as the matrix. The Toray make bidirectional twill (2 × 2) woven T800CF was used as the reinforcing material. The Dynamic Mechanical Analyzer (DMA) and Thermogravimetric Analysis (TGA) tests are conducted to study the dynamic capacity and thermal degradation behavior respectively. In the DMA, the storage modulus (E1), loss modulus (E11), damping behavior (Tanδ) and glass transition temperature (Tg) of CF/Ep composite specimens are studied with increasing temperature from (25–173)°C. The BC1% composites showed better storage modulus, loss modulus and damping factor, while unfilled CF/Ep and BC3% composites showed better Tg than other CF/Ep composites. As far as TGA is concerned, the BC1% composites exhibited better thermal stability than all other composites. The dynamic tests resulted in the trend of BC1% > unfilled CF/Ep > BC3% > BC5% composites. The TGA tests also followed the trend of BC1% > unfilled CF/Ep > BC3% > BC5% CF/Ep composites.

Dispersion of electrically conductive carbon fibres in self-compacting concrete using chemical and mechanical dispersing techniques

In this study, the influence of the mechanical de-agglomeration of carbon fibres in the mixing water blended with methylcellulose and sodium dodecyl benzene sulfonic acid salt (SDBS) for dispersion of carbon fibres in self-compacting concrete (SCC) was studied. The mechanical energy needed for de-agglomeration was provided by churning the carbon fibres in the treated water using mechanical churner at varying speed of 1440RPM to 23000RPM. The degree of dispersion was evaluated by investigating the variations in rheological, electro-mechanical and microstructure properties of carbon-fibre reinforced SCC. It was observed that the mechanical churner at lower speed (1440RPM to 11000RPM) in the surfactant blended water successfully deagglomerated the carbon fibre filament threads without disturbing their individual morphology that resulted in better distribution of fibres in the concrete. Microstructure images further confirmed the role of mechanical mixing in improving the dispersion of fibres.