Chopped Carbon Fiber Research Articles

Additive manufacturing of oriented chopped carbon fiber reinforced mullite refractory via extrusion-based technique- Effects of slurry rheological behavior and 3D printing parameters

Additive manufacturing of oriented chopped carbon fiber reinforced mullite refractory via extrusion-based technique- Effects of slurry rheological behavior and 3D printing parameters

Multiscale image-based modeling for failure prediction of sheet molding compound composite under uniaxial tension

Carbon fiber reinforced polymer (CFRP) composites are extensively utilized as primary load-bearing components in various engineering applications due to their superior strength-to-weight ratio and excellent mechanical properties. However, their intricate microstructural interactions within composite present a significant challenge for failure analysis of CFRP. Although finite element (FE) simulations have been proven feasible to conduct the failure analysis, the classical FE models are developed based on homogeneous fiber characteristics, ignoring the influence of internal structures on the damage evolution process. This paper presents a multiscale image-based modeling approach to predict the tensile failure procedure of chopped carbon fiber sheet molding compound (SMC) composite. To accurately reconstruct the representative volume element (RVE) model of the SMC composite, synchrotron micro-X-ray computed tomography (μXCT) was adapted to explore the SMC internal microstructure. Then microscale RVE models with different fiber volume fractions were constructed to predict the corresponding microcosmic mechanical properties, which were used as the inputs for mesoscale RVE models to determine the constitutive parameters of fiber chips having varied fiber volume and orientations. Finally, the YOLOv5_Seg algorithm was employed to extract the geometric feature parameters of the fiber chips for mesoscale RVE modeling and then the failure location and sequence under uniaxial tension were predicted. It is found that the final simulated failure behaviors were consistent with the experimental observations, confirming the feasibility of this approach for understanding the failure mechanisms of CFRP composites. Thus, once the internal microstructure is determined using experimental techniques or predicted by simulating the composite manufacturing process, this approach can also be utilized for design optimization and performance evaluation for CFRP composites.

Novel approach for strengthening of column by external wrapping with Carbon Fiber and Internally Embedded Damper System for resilient infrastructure

Abstract Columns as major structural components, lose strength due to sudden and accidental impacts. Such impacted columns can be restored by retrofitting, which increases their load-carrying capacity and lifespan, rather than reconstructing them. The common method of retrofitting involves externally wrapping the columns with fibre sheets. Numerous research studies have been conducted on enhancing the load-carrying capacity of a column by jacketing it with Fiber Reinforced Polymer (FRP). However, there is a lack of research on retrofitting columns internally to overcome vibrations produced due to impact loading. This paper addresses the retrofitting of a column both internally and externally. The external retrofitting is done by CFRP jacketing, and the internal retrofitting is achieved by developing a damper system to overcome damping forces. The experimental work aims to compare the load-carrying capacity of columns retrofitted internally with dampers and externally with CFRP jackets, with a plain concrete column. Dampers are evaluated based on energy absorption in comparison to plain cement mortar. It was found that energy absorption increased by 50% when the concrete was reinforced with 1mm chopped carbon fibers. Such reinforced concrete behaved as dampers, when placed inside the column to absorb the impact energy leading to a 9% increase in load-carrying capacity. The maximum load-carrying capacity was observed in columns wrapped with CFRP and damped with dampers, showing an increase of 25%. Finite Element Analysis is carried out to compare the experimental results and evaluate the damping property. Retrofitting a new column can enhance its initial load-carrying capacity, this helps in reducing the cross-section and percentage of steel usage in columns, contributing to sustainability. Retrofitting approaches to achieve 9th, 12th, and 13th sustainable goals, this leads to a significant contribution in the construction sector.

Fabrication and Evaluation of an Electromagnetic Shielding Material Made of Randomly Chopped Tape Carbon Fiber/Polyamide 6 Composites

Abstract Environmental pollution generated by electromagnetic wave radiation has significantly increased including in automotive applications. Thus, material technology, including polymer composite, has attracted a reduction of the negative effect of electromagnetic radiation. In this study, carbon fiber reinforced polyamide thermoplastic (PA-6/CF) made of carbon fiber with polyamide 6 tape, in the shape of a half-box, was produced using the hot compression method with different tape-length, and then the electrical conductivity and electromagnetic shielding performance were evaluated. The electrical conductivity was obtained from the resistivity measured by using a digital multimeter. Whilst the effectiveness of electromagnetic interference shielding (EMI-SE) was investigated using two methods, calculation, and actual measurement. The result shows that there is a different electrical conductivity between base and slope area of the PA-6/CF box composite. It also was observed that the actual EMI shielding performance shows a corresponding increase with the length of chopped carbon fiber tape and has a higher value compared to the calculated EMI-SE. Then, the highest value obtained for actual EMI-SE was 54 dB for the PA6/CF composite with 20-mm tape length, in the frequency range 0.3 – 1 GHz, and on horizontal antenna polarization. Whereas the composite with 10-mm and 15-mm tape length was the lowest EMI- SE (38 dB) on vertical antenna polarization, in the same frequency range. Furthermore, the microscopy analysis depicted that there are more voids exist in the slope area compared with the base area of the PA-6/CF composites. Finally, the molded PA-6/CF composites can be used as the battery enclosures of electrical vehicles in automobiles.

The effect of infill density on tensile properties of 3D printed chopped carbon fiber reinforced PLA composites materials

The effect of infill density on tensile properties of 3D printed chopped carbon fiber reinforced PLA composites materials

Energy absorption assessment of recovered shapes in 3D-printed star hourglass honeycombs: Experimental and numerical approaches

This study provides an experimental and numerical evaluation of the energy absorption performance of a 3D-printed star hourglass honeycomb structure with a novel design made from pure and reinforced PLA by chopped carbon fibers and continuous glass fiber. The study further investigates the energy absorption response of this structure after the shape recovery due to thermal stimuli under the quasi-static compressive loading. As an additive manufacturing process, Fused Deposition Modeling is used to produce the specimens with pure and reinforced PLA filament. The difference in the nonlinear response of PLA due to plasticity and damage in tension and compression loading directions, as a feature that helps the shape recovery, is considered in mechanical response analysis using the Finite Element approach. Then, in the obtained results distinguish constitutive laws in tension and compression mechanical properties are employed leading to a failure model using the appropriate algorithm consistent with the experiments. According to the obtained results which reveal good agreement regarding the experimental results, by designing appropriate auxetic configuration selecting suitable geometry parameters, and employing the proper material with diverse properties in tension and compression directions, it is possible to fabricate a lattice structure inherits the shape recovery after the compression deformation which exhibits acceptable energy absorption performance even the second shape recovery.

Carbon fibre detection in polymer composites reinforced by chopped carbon fibres through digital image processing and machine learning

Mechanical and thermodynamical properties and thus machinability of carbon fibre reinforced polymer composites significantly depend on the fibre orientation relative to the load direction. However, the orientations of the fibre groups in polymer composites reinforced by chopped carbon fibres are stochastic; therefore, the properties and machinability of such composites are challenging to plan, predict and optimise. We developed four different and novel approaches for fibre detection in polymer composites reinforced by chopped carbon fibres: (i) detecting the fibres through naked eye supported manual drawing, (ii) digital image processing of optical images, (iii) machine learning-based fibre detection, and (iv) rectangle fitting on the outputs of the automated processes using the Chaudhuri and Samal method. The applicability of the novel approaches was tested through optically captured images of polymer composites reinforced by chopped carbon fibres. The developed methods are each capable of detecting fibre groups at the top and bottom of the composite plate with certain limitations. The rectangle fitting approaches performed the best from the point of view of correctly identifying of fibre groups, followed by the machine learning-based and the conventional digital image processed, respectively. As a result of this study, the machining process planning and condition monitoring of polymer composites reinforced by chopped carbon fibres is more deeply supported.

Effect of v-notch on impact toughness of fibre reinforced laminates produced by fff method

The rapid development of additive technology necessitates identifying opportunities for practical application. For this reason, many experimental measurements have focused on tensile or bending tests, resulting in numerous publications. Previously, the authors evaluated Charpy impact test results to assess the effect of various printing parameters on absorbed energy, using specimens without the notch. However, other studies focused on Charpy impact testing used notched specimens, raising questions about suitability of notch usage for testing of fibre reinforced composites produced by extrusion methods. This paper aims do deal with this question and to evaluate the influence of V-notch on the impact toughness of specimens. For specimens reinforced with chopped carbon fibres, the notch markedly affects impact toughness irrespective of the direction of load orientation (flatwise or edgewise). Conversely, in the case of flatwise loading of specimens reinforced with long HSHT glass fibres, we observed that the notch does not impact the absorbed energy values. However, edgewise impact loading led to decrease of absorbed energy up to 50%. This decrease in absorbed energy can be attributed to the material arrangement in the lamina, as the filament follows the notch, resulting in the formation of inhomogeneities and stress concentrators. In the case of flatwise loading, the notches were created by the lamina layering, so the arrangement of the matrix and fibres in the layer was not affected.

Characterization of Chopped Carbon Fiber Reinforced Composites Produced Using Fused Deposition Modeling

Characterization of Chopped Carbon Fiber Reinforced Composites Produced Using Fused Deposition Modeling

Properties and transpiration cooling performance of Cf/SiC porous ceramic composite

Transpiration cooling have gradually become the lead candidate for thermal protection technology of hypersonic vehicle also due to its excellent cooling performance. The porous medium with exceptional properties can further improve thermal protection capability and reliability of transpiration cooling. This paper investigates the preparation and properties of Cf/SiC porous ceramic composite with low density and remarkable permeability, and probes the transpiration cooling performances of ceramic composites (mass ratio of silicon carbide particles and short chopped carbon fibers of 1:1) in the various heat flux conditions. The research results show that Cf/SiC porous ceramic composites prepared by adding short chopped carbon fibers have uniform pore size distributions (3～20 μm) and low densities (1.074 g/cm3 ～ 1.377 g/cm3), as well as outstanding wettability and permeability (6.07 × 10−8 mm2 ～ 12.22 × 10−8 mm2). Besides, The Cf/SiC porous ceramic composites (mass ratio of 1:1) display excellent transpiration cooling performance, meanwhile a new interesting phenomenon that the water pressure difference increases with the rising of heat flow is discovered. Such studies can provide an essential reference for developing porous medium in transpiration cooling technology.

The Effect of Chopped Carbon Fibers on the Mechanical Properties and Fracture Toughness of 3D-Printed PLA Parts: An Experimental and Simulation Study

The incorporation of fiber reinforcements into polymer matrices has emerged as an effective strategy to enhance the mechanical properties of composites. This study investigated the tensile and fracture behavior of 3D-printed polylactic acid (PLA) composites reinforced with chopped carbon fibers (CCFs) through experimental characterization and finite element analysis (FEA). Composite samples with varying CCF orientations (0°, 0°/90°, +45°/−45°, and 0°/+45°/−45°/90°) were fabricated via fused filament fabrication (FFF) and subjected to tensile and single-edge notched bend (SENB) tests. The experimental results revealed a significant improvement in tensile strength, elastic modulus, and fracture toughness compared to unreinforced PLA. The 0°/+45°/90° orientation exhibited a 3.6% increase in tensile strength, while the +45°/−45° orientation displayed a 29.9% enhancement in elastic modulus and a 29.9% improvement in fracture toughness (259.12 MPa) relative to neat PLA (199.34 MPa√m). An inverse correlation between tensile strength and fracture toughness was observed, attributed to mechanisms such as crack deflection, fiber bridging, and fiber pull-out facilitated by multi-directional fiber orientations. FEA simulations incorporating a transversely isotropic material model and the J-integral approach were conducted using Abaqus, accurately predicting fracture toughness trends with a maximum discrepancy of 8% compared to experimental data. Fractographic analysis elucidated the strengthening mechanisms, highlighting the potential of tailoring CCF orientation to optimize mechanical performance for structural applications.

Experimental investigation on energy absorption capability of 3D-printed lattice structures: Effect of strut orientation

This experimental study aimed to investigate the effect of strut orientation in various lattice structures that were created using 3D printers on the energy absorption capabilities of the structures. The experiment involved producing three different lattice structures, namely a cube lattice with vertical and horizontal struts, an octet structure with horizontal and 45˚ angled struts, and a body-centered-cubic (BCC) lattice structure with horizontal, vertical, and 45˚ angled struts using the FDM method. Nylon filament mixed with chopped carbon fiber was utilized as filament, and each lattice structure was designed to contain three units in the x and y directions and one and three units in the z-direction. The study conducted axial crushing tests on single-layer and three-layer lattices to determine the energy absorption capabilities of the various lattice structures. The octet lattice demonstrated the highest energy absorption in both single-layer and three-layer samples, making it the most efficient sample. In single-layer lattice samples, the cube and octet structures absorbed 77% and 94% more energy than the BCC structure, which absorbed only 12.8 J. However, the cube structure demonstrated the lowest energy absorption in three-layer samples. This was attributed to the buckling behavior seen in the strut of the lattice structure under axial load. The octet structure had the highest specific energy absorption value in both layers, making it the most energy-efficient sample.

Advanced acoustic design: 3D printed thermoplastic folded core sandwich structures with porous materials and microperforations for enhanced sound absorption

This study introduces a novel sound-absorbing sandwich structure with a folded core, created through 3D printing technology, to address the challenge of weak sound absorption in the low-frequency range in sound absorption materials (SAMs). The structure comprises chopped carbon fiber–dispersed thermoplastic polyamide (CF-PA), continuous carbon fiber (CCF) filaments, and polyurethane (PU) foam coated with graphene oxide (GO). Simulation studies revealed that optimized structural parameters and microperforation diameters resulted in enhanced sound absorption coefficient (SAC) of 99 % or more at 1250 Hz, within the low-frequency range (160–1600 Hz). The GO-coated PU foam SAMs demonstrated excellent sound absorption performance measured in the high-frequency range (1600–6000 Hz), achieving 99 % SAC at 2400 Hz. Furthermore, the manufactured folded core structure exhibited outstanding sound absorption performance, achieving SAC of 99 % at 732 Hz measured in the low-frequency (160–1600 Hz) band and 99 % at 600 Hz, showcasing broad absorption capabilities measured in the high-frequency band (160–6000 Hz). Additionally, a flatwise compression test on the structure filled with GO-coated PU foam demonstrated a 32 % improvement in compressive load, indicating the structure’s versatility for various applications.

Nondestructive Evaluation and Residual Property Assessment of Impacted Nylon/carbon-Fiber Additively Manufactured FFF Components Using Four-Point Bend and Ultrasonic Testing

ABSTRACT Fusion-based material extrusion additive manufacturing, commonly known as fused filament fabrication (FFF), is a layer-by-layer manufacturing process known for creating custom components, specializing in complex geometries, with applications in the aerospace, automotive, medical, as well as many other industries. Due to the critical nature of these industries, it is imperative to understand the relationship between the AM material in question, the nature of the resultant damage, and the impact of these two parameters on the future performance of the component. The purpose of this study is to investigate the relationship between low-velocity impact and the resultant damage in common functional FFF materials and to develop methods of visualizing that damage using ultrasonic nondestructive evaluation. Coupons of a nylon feedstock infused with and without 10% chopped carbon fiber were fabricated using an Essentium HSE printer and impacted at various energies. The extent of the damage was visualized using ultrasonic testing (UT), in which significant internal cracking was observed. Four-point bend testing was utilized to compare behavior of the material prior to impact at a lower impact energy (3J), and a higher impact energy causing visual fracture (7J). X-ray CT was also performed on two samples to validate UT findings.

The Impact of Internal Structure Changes on the Damping Properties of 3D-Printed Composite Material

This article investigates the impact of changes in the internal structure of composite materials on their dynamic properties. The present research focuses on 3D-printed specimens with different reinforcement fiber arrangements. The specimens are printed on a Markforged Mark Two 3D printer. The base material is nylon filled with chopped carbon fibers (Onyx) and the reinforcement is in the form of long carbon, glass and Kevlar fibers. The experiment is carried out by the impact method. The principle of this method is to expose the specimen to a short impulse of force while monitoring its frequency response. The obtained results determine the natural frequencies and internal damping of the individual structures. We found that the highest damping is achieved by specimens with glass and Kevlar fibers in 45°, 90° and ±45° configurations. On the other hand, the lowest damping is achieved by specimens with carbon fibers and 0° and 0°,90° configurations. Also, the specimens with circumferential reinforcement show lower damping coefficient values. The knowledge and results of this work can be used in the development of new components; for example, in the transport industry, where the low weight and sufficient strength of components are important factors. These components have to absorb vibrations from various sources, such as motors and external influences.

Experimental and numerical investigation of an additively manufactured sandwich composite bridge deck utilizing gyroid building blocks

This work investigates the integration of Additive Manufacturing (AM) techniques with cellular metamaterials integrated into composite sandwich beam systems. The study proposes an approach that combines composite materials for the face sheets with cellular structures using a Triply Periodic Minimal Surface (TPMS) Gyroid structure for the core to achieve maximum lightweight and load-bearing capabilities. The experimental and numerical campaigns were utilized for the material testing of 3D printing polymeric material reinforced with chopped carbon fibre (CF). To validate the composite sandwich structure, three bending experiments were conducted: (a) bending of the “core only” was performed to calibrate the material for the given print parameters; (b) bending of the “sandwich beam” composite with a periodic and homogenous Gyroid core bonded with glass fibre reinforced polymer (GFRP) face sheets; (c) the “arch beam” composite with the change in outer cross-section dimension with the same periodic and homogenous Gyroid core. The FEM analysis was combined with Digital Image Correlation (DIC) results to determine the bending stiffness of the sandwich beams and to detect the failure modes. It was discovered that integrating 3D printing into load-bearing structures through the composite “sandwich beam” system resulted in seven times increase in load-bearing capacity and four times increase in stiffness compared to results obtained with the “core only” structure.

Bending Strength of Continuous Fiber-Reinforced (CFR) Polyamide-Based Composite Additively Manufactured through Material Extrusion.

This paper shows the three-point bending strength analysis of a composite material consisting of polyamide doped with chopped carbon fiber and reinforced with continuous carbon fiber produced by means of the material extrusion (MEX) additive manufacturing technique. For a comparison, two types of specimens were produced: unreinforced and continuous fiber-reinforced (CFR) with the use of carbon fiber. The specimens were fabricated in two orientations that assure the highest strength properties. Strength analysis was supplemented by additional digital image correlation (DIC) analysis that allowed for the identification of regions with maximum strain within the specimens. The utilization of an optical microscope enabled a fractographic examination of the fracture surfaces of the specimens. The results of this study demonstrated a beneficial effect of continuous carbon fiber reinforcement on both the stiffness and strength of the material, with an increase in flexural strength from 77.34 MPa for the unreinforced composite to 147.03 MPa for the composite reinforced with continuous carbon fiber.

Additively Manufactured Carbon-Reinforced ABS Honeycomb Composite Structures and Property Prediction by Machine Learning.

The expansive utility of polymeric 3D-printing technologies and demand for high- performance lightweight structures has prompted the emergence of various carbon-reinforced polymer composite filaments. However, detailed characterization of the processing-microstructure-property relationships of these materials is still required to realize their full potential. In this study, acrylonitrile butadiene styrene (ABS) and two carbon-reinforced ABS variants, with either carbon nanotubes (CNT) or 5 wt.% chopped carbon fiber (CF), were designed in a bio-inspired honeycomb geometry. These structures were manufactured by fused filament fabrication (FFF) and investigated across a range of layer thicknesses and hexagonal (hex) sizes. Microscopy of material cross-sections was conducted to evaluate the relationship between print parameters and porosity. Analyses determined a trend of reduced porosity with lower print-layer heights and hex sizes compared to larger print-layer heights and hex sizes. Mechanical properties were evaluated through compression testing, with ABS specimens achieving higher compressive yield strength, while CNT-ABS achieved higher ultimate compressive strength due to the reduction in porosity and subsequent strengthening. A trend of decreasing strength with increasing hex size across all materials was supported by the negative correlation between porosity and increasing print-layer height and hex size. We elucidated the potential of honeycomb ABS, CNT-ABS, and ABS-5wt.% CF polymer composites for novel 3D-printed structures. These studies were supported by the development of a predictive classification and regression supervised machine learning model with 0.92 accuracy and a 0.96 coefficient of determination to help inform and guide design for targeted performance.

Experimental investigation on energy absorption capability of 3D printed onyx nested rings under lateral loading

This study presents a focused experimental exploration into the energy absorption characteristics and failure mechanisms of nested circular rings under lateral loading. The rings were 3D printed using the fuse deposition modeling method with an onyx material containing chopped carbon fiber. The dimensions of the rings were determined to be the same in width and thickness, while the diameter had four different values. The samples of nested rings consist of at least two and up to five individual rings. These samples were obtained by using individual rings in various different sequences and orders. Two different configurations for each nested sample type were also studied to observe the effect of the ring sequences and orders on the energy absorption capability. It is concluded from the results that even though the single ring with the smallest diameter has the highest force values, the highest energy absorption and specific energy absorption values were obtained in another single ring. The alignment of the single rings has a superior effect on the energy absorption capacity of the nested samples. Also, a gain in absorbed energy was observed in nested samples due to the interaction between the single rings. This interaction showed that the algebraic summation of the energy values of single rings used in a nested sample was lower than the energy value of the same nested sample. In the nested samples, the absorbed energy increased proportionally to the number of single rings. However, the crashworthiness parameters were affected quite differently from the energy absorption capacity. While the highest energy absorption values are obtained in nested samples with five single rings, other nested samples reached the highest values in terms of some of the crashworthiness parameters. The NR5-A sample absorbed 52% and 88% higher energy compared to the same combination of nested samples, which contain four and three single rings, respectively. Additionally, the specific energy absorption value of this sample is 32% and 47% higher than the same nested samples mentioned above. Considering these results, it can be expressed that the NR5-A sample is the best design in terms of an ideal energy absorption structure.

Enhanced thermal properties of tensile-aligned chopped carbon Fiber/HDPE composites for one-directional thermal ventilation

This study was aimed at enhancing the thermal properties of unidirectional chopped carbon fiber (CCF)/high-density polyethylene (HDPE) composites for applications requiring unidirectional heat dissipation. CCF/HDPE composite samples were fabricated using a special post-extrusion tension alignment method. The influence of different manufacturing variables, including fiber content, length, and draw ratio (DR, representing the tension), on the thermal conductivity was examined. Moreover, the response surface methodology (RSM) was used to investigate the influence of the manufacturing process variables. Results indicated that the thermal conductivity increased with increasing CCF wt.% and DR. The increase in DR promoted fiber alignment, contributing to enhanced thermal conductivity in the aligned direction. Additionally, the thermal conductivity increased with the increase in the CCF length. The proposed approach can facilitate efficient heat management in automotive and aerospace industries.