Continuous Carbon Fiber Research Articles

Parametric analysis of 3D printing parameters on stiffness and hysteresis characteristics of pediatric prosthetic foot coupon samples

Background: This research paper presents a comprehensive parametric study that investigates the influence of various 3D printing parameters on the mechanical properties of a pediatric prosthetic keel using coupon samples. Objective: To analyze how 3D printing parameters impact upon on 2 crucial mechanical properties: stiffness and hysteresis. Methods: Key 3D printing parameters including the amount of continuous carbon fiber layers, fiber distribution, and matrix fill pattern, are systematically varied, and mechanically tested through compression to analyze the results. Results: The results demonstrate the substantial impact that printing parameters have on the mechanical characteristics of 3D-printed pediatric prosthetic feet. Notably, the selection of these parameters for the prosthetic keel plays a pivotal role in shaping the overall performance and functionality of the prosthetic foot, emphasizing the need for precise parameter optimization in pediatric prosthetic design, if 3D printing is the manufacturing process. Conclusions: The findings of this study contribute to a better understanding of the manufacturing process for pediatric prosthetic feet via 3D printing and offer valuable insights for optimizing their design. By identifying the ideal combination of 3D printing parameters that yield the desired stiffness and minimize hysteresis, we aim to enhance the performance and comfort of pediatric prosthetic devices, ultimately improving the quality of life for young users.

Effects of Absorption on the Tribological Properties of Carbon Fiber Reinforced Polyamide-6 Composites Manufactured by Fused Deposition Modeling

Abstract The present work studied the water absorption behavior of polymeric composite materials fabricated using 3D printing technology, as well as its effect on their tribological properties. Polyamide-6 was selected as the base matrix material. Short and continuous carbon fibers are used as the reinforced material. The results showed that the moisture absorption would impair the mechanical properties of polymer matrix and interface bonding between the fiber and the matrix. As a result, the tensile strength of the fiber reinforced polymer composites (FRPCs) decreases with water absorption. Nevertheless, the effects of moisture absorption on the wear properties of FRPCs are more complicated, which are depending on the fiber length and sliding conditions. With the short fiber reinforcements, moisture absorption deteriorated the wear resistance under all the testing conditions. With the increase of moisture level, more severe fiber damage/removal was observed, associated with the higher wear loss. With a relative high volume fracture of continuous carbon fiber (∼35 vol%), however, the wear resistance of the FRPC increased with moisture level, especially under a relatively low load. Based on microscopic observations, it was proposed that water inside FRPC specimens is able to provide the lubricating and cleaning effects, which contribute to a lower friction and smooth worn surfaces. The work provides new insights into designing and selecting printed polymer materials, subjected to different loading conditions.

Advancing composite 3D printing: deep learning-optimized rheology-modified polymers with continuous carbon fiber reinforcement

Advancing composite 3D printing: deep learning-optimized rheology-modified polymers with continuous carbon fiber reinforcement

Dynamic Analysis and Vibration Control of Additively Manufactured Thin-Walled Polylactic Acid Polymer (PLAP) and PLAP Composite Beam Structures: Numerical Investigation and Experimental Validation

This study primarily presents a numerical investigation of the dynamic behavior and vibration control in thin-walled, additively manufactured (AM) beam structures, validated through experimental results. Vibration control in thin-walled structures has gained significant attention recently because vibrations can severely affect structural integrity. Therefore, it is necessary to minimize these vibrations or keep them within acceptable limits to ensure the structure’s integrity. In this study, the AM beam structures were made of polylactic acid polymer (PLAP), short carbon fiber reinforced in PLAP (SCFR|PLAP), and continuous carbon fiber reinforced in PLAP (CCFR|PLAP), with 0°|0° layer orientations. The finite element modeling (FEM) of the AM beam structures integrated with macro fiber composite (MFC) was carried out in Abaqus. The initial four modal frequencies of bending modes (BMs) and their respective modal shapes were acquired through numerical simulation. It is crucial to highlight the numerical findings that reveal discrepancies in the 1st modal frequencies of the beams, ranging up to 1.5% compared to their respective experimental values. For the 2nd, 3rd, and 4th modal frequencies, the discrepancies are within 10%. Subsequently, frequency response analysis (FRA) was carried out to observe the frequency-dependent vibration amplitude spectrum at the initial four BM frequencies. Despite discrepancy in the amplitude values between the numerical and experimental datasets, there was consistency in the overall amplitude behavior as frequency varied. THz spectroscopy was performed to identify voids or misalignment errors in the actual beam models. Finally, vibration amplitude control using MFC (M8507-P2) was examined in each kinematically excited numerical beam structure. After applying a counterforce with the MFC, the controlled vibration amplitudes for the PLAP, SCFR|PLAP, and CCFR|PLAP configurations were approximately ±19 µm, ±16 µm, and ±13 µm, respectively. The trend in the controlled amplitudes observed in the numerical findings was consistent with the experimental results. The numerical findings of the study reveal valuable insights for estimating trends related to vibration control in AM beam structures.

High-throughput in-situ mechanical evaluation and parameter optimization for 3D printing of continuous carbon fiber composites

The mechanical properties of carbon fiber reinforced thermoplastic (CFRTP) molded parts produced by thermal fusion lamination 3D printing vary with printing conditions. This study assesses the influence of the 3D printing parameters on the mechanical properties of resulting CFRTP products through parameter evaluation testing. An in-situ three-point bending test mechanism was developed to enhance the efficiency of these tests, allowing the same 3D printer to handle all processes from printing multiple CFRTP specimens simultaneously to conducting a bending test, reducing manual handling time to about one minute. Using this modified 3D printer, 700 specimens with varying printing conditions were produced, and their flexural strength was measured semi-automatically. Results revealed that the flexural strength of the 3D-printed CFRTP object varied with nozzle temperature, printing pitch, and stacking pitch, but not with printing speed. Machine learning was then employed to predict the maximum flexural strength and determine optimal printing parameters using the collected data as training data.

Highly protective and functional strengthening strategies for 3D printed continuous carbon fiber reinforced polymer composites: manufacturing and properties

Carbon fiber-reinforced polymer (CFRP) composites have gradually emerged as a crucial material in the aerospace industry. However, inadequate impact resistance and thermal stability limit survival in extreme environments. Inspired by the specific functions of multiple layers of tissue, from bird feathers to the musculoskeletal system. We propose low-cost composite strengthening strategies and efficient novel three-dimensional graphene aerogel manufacturing methods. A novel graphene aerogel/carbon fiber reinforced polymer (GAC) composite prepared by in-situ laser-induced graphene (LIG) layers on the surface of 3D-printed CFRP. GAC composites enhance CFRP's impact protection, thermal insulation, and electromagnetic shielding capabilities. For protection, GAC composites reduce low-velocity impact damage by 26.2%. The graphene layer can increase the thermal buffering capacity of the material four times, and the long-term service temperature can be increased by 40% compared to traditional CFRP. For functionality, the composites enable electromagnetic interference (EMI) shielding effectiveness of up to 50.2 dB. Furthermore, it can achieve surface heating above 400 °C and rapid de-icing through electrothermal effects. The simple and efficient processing method of GAC composites and tunable functionalities holds promise for the development of highly protective and intelligent aircraft skins.

The effect of ultrasonic treatment of a cured monolayer formed by three-dimensional printing from a prepreg reinforced with continuous carbon fiber on the resistance to the flow of solid particles

—The effect of ultrasonic processing at resonant frequencies of 22 and 44 kHz of a monolayer formed by three-dimensional printing from prepregs reinforced with continuous carbon fiber on the resistance to the flow of solid particles by imitating it by jet-abrasive treatment is investigated. The increment of the weight of both control and experimental samples in comparison with the initial state was established. It is shown that the force effect of ultrasound in rational modes contributes to a decrease in weight gain by 31.4% when processed at a frequency of 22 kHz and by 9% when processed at a frequency of 44 kHz. The decrease in weight increment is determined by an increase in the density of the monolayer structure after ultrasonic exposure, which leads to an increase in surface hardness in units of Schor-D by 13.5% at a frequency of 22 kHz and by 10% at a frequency of 44 kHz.

High strength C/Si‒Ni‒C composites fabricated by reaction melt infiltration with Si‒Ni alloy at lower temperature

AbstractSilicon‒nickel alloy (Si‒Ni) was first used for fabricating continuous carbon fiber reinforced ceramic matrix composites by reaction melt infiltration process. Based on Si‒Ni phase diagram, 66.7 at.% Si‒Ni was chosen, which has a lower liquidus temperature of 1115°C. The C/Si‒Ni‒C composites were infiltrated at temperature of 1270°C‒1390°C, and the prepared composite consists of C, SiC, NiSi, and NiSi2 phases. The density of the composite is higher than 2.29 g/cm3 and their open porosity is below 3%, indicating the composite was infiltrated completely by the Si‒Ni alloy. The C/Si‒Ni‒C composite exhibits significantly higher flexural strength and fracture toughness compared to the C/C‒SiC composite infiltrated with pure silicon at 1500°C. Specifically, the flexural strength and fracture toughness of the C/Si‒Ni‒C composite infiltrated at 1390°C increase by 140% and 300%, respectively. The improvement of mechanical properties contributed to the low reactivity between silicon‒nickel with carbon fibers, and the lower infiltration temperature, which can reduce degradation of carbon fiber as reinforcement. Moreover, the NiSi2 and NiSi alloy phases in the C/Si‒Ni‒C composite replace the brittle silicon phase in the C/C‒SiC composite, which can obviously enhance the fracture toughness.

Adjustment of Mechanical Properties of 3D Printed Continuous Carbon Fiber-Reinforced Thermoset Composites by Print Parameter Adjustments.

Reinforcing thermoset polymers with continuous carbon fiber (CF) tow has emerged as a promising avenue to overcome the thermal and mechanical performance limitations of 3D printed polymeric structures for load-bearing applications. Unlike traditional methods, manufacturing continuous fiber-reinforced composites by 3D printing has the unique capability of locally varying the mechanical properties of the composites. In this study, continuous CF thermoset composite specimens were printed with varying line spacing, resin flow rate, and nozzle sizes. The resin flow rates for different line spacings and nozzle sizes were optimized by topographic analysis. Printed composite mechanical properties were evaluated, and their trends were correlated with the trend of print parameter changes. Results showed that tensile strength and modulus could be altered and improved by ~50% by adjusting the printing process parameters. Higher composite strength and modulus were obtained by shortening the line spacing and nozzle diameter.

Additive manufacturing of continuous carbon fiber reinforced polymer composites using materials extrusion process. Mechanical properties, process parameters, fracture analysis, challenges, and future prospect. A review

Additive manufacturing of continuous carbon fiber reinforced polymer composites using materials extrusion process. Mechanical properties, process parameters, fracture analysis, challenges, and future prospect. A review

Self-Repairable Carbon Fiber-Reinforced Epoxy Vitrimer Actuator with Multistimulus Responses and Programmable Morphing.

Smart shape-changing structures in aerospace applications are vulnerable to damage in harsh environments. Balancing high mechanical performance with self-repair capabilities poses a challenge due to inherent trade-offs between strength and flexibility. To address this challenge, an asymmetric bilayer-structured actuator was fabricated using commercially available continuous carbon fiber tows (CFs) as the passive layer and a dynamic cross-linked epoxy vitrimer as the active layer. The construction of the vitrimer-CF actuator involves a simple and scalable hot-pressing process, resulting in a tensile strength of 234 MPa and an interfacial bonding strength of 405 N·m-1. This actuator exhibits remarkable deformation capability (210°/7 s) and an efficient self-repair ability under various stimuli, including thermal (60-160 °C), light (0.4-1.0 W·cm-2), electric (2-4 V), and solvent (acetone). By adjustment of the orientation angle of CFs, complex left-handed and right-handed curling structures can be achieved. Leveraging the insights from photothermal/electrothermal actuation mechanisms, a quadruped crawling robot is developed capable of crawling 4 cm with a single light illumination. The actuator can lift objects 45 times its weight when subjected to light stimuli. Additionally, a flap actuator is constructed to achieve an angle change of 63° within 10 s under an electric stimulus, enabling remote control over the aircraft flight angle. These results demonstrate the potential of the vitrimer-CF actuator for advanced applications in intelligent aerospace structures.

Experimental and numerical investigation of the damage propagation in regularly arrayed short fiber reinforced composite laminates under low‐velocity impact

AbstractThe outstanding mechanical performance and flowability of unidirectionally arrayed chopped strands (UACSs) give them an advantage in the manufacture of engineering structures with complex geometry. For the application of practical structures, the impact responses and damage evolution of material under low‐velocity impact must be investigated in advance. In this study, UACS laminates and continuous carbon fiber laminates with a stacking sequence of [0/90]4s and a thickness of 2 mm were fabricated for low‐velocity impact tests at 7, 11, 15, and 20 J. The impact responses and postimpact intralaminar damage area were analyzed according to the experimental results, including impact load responses and ultrasound C‐scan inspections. Moreover, to predict the damage evolution of the internal structure, the 3D finite element models were constructed in ABAQUS using a progressive damage model (PDM) through a user‐material subroutine VUMAT. Compared with continuous carbon fiber laminates, the dissipated energy of UACS laminates increases by approximately 10.64% and 57.37% for the 15 and 20 J, respectively. However, the intralaminar damage area of UACS laminates decreased by 29.96% and 28.16% at 15 and 20 J, respectively, since the discontinuous slits in UACS laminates can guide damage paths and suppress damage propagation.Highlights The regularly arrayed short fiber reinforced composite was studied. Revealed the low‐velocity impact responses and predicted the damage evolution. UACS and CFRP laminates have comparable impact performance. Illustrated the slits design can suppress the damage to a relatively small area.

A Comparative Study of Non-Destructive Testing Techniques: Active Thermography versus Shearography for 3D-Printed Thermoplastic Composites Reinforced with Continuous Carbon Fiber

This study investigates the feasibility and effectiveness of two non-destructive testing methods, active thermography and shearography, on 3D-printed thermoplastic (TP) composites reinforced with continuous carbon fiber. Artificial defects were introduced into the composite plate to benchmark the detection capabilities of these non-destructive testing techniques (NDT). Active thermography produced a thermogram that highlighted defects through variations in surface temperature. Although effective for identifying defects ranging from 3 to 10 mm in size at four different depths, specifically 1 mm, 1.25 mm, 1.5 mm, and 1.75 mm, through the thickness of a 2.8 mm plate, the method encountered some limitations. It faced challenges in detecting deeper defects and accurately determining their shapes. Shearography, which utilizes fringe pattern distortions to detect surface displacement anomalies, successfully identified near-surface defects within the same size range. However, it required more expertise for accurate interpretation and struggled with detecting smaller and deeper defects. The complementary strengths and limitations of these methods suggest that employing both could offer a more comprehensive solution for defect detection in 3D-printed TP composites.

Experimental investigation of high-velocity impact response and compression after impact behavior of continuous carbon fiber thermoplastic composites

In order to meet the urgent needs for the application of thermoplastic composite structures in aircraft manufacturing and other fields, the impact resistance and damage tolerance of continuous carbon fiber reinforced thermoplastic composite laminates (CCFRTP) are investigated by high-velocity impact (HVI) and compression after impact (CAI) experiments in this paper. The impact experiment results show that the ballistic response of laminates under small-angle conventional impact is similar, and the impact resistance of laminates under large-angle oblique impact is significantly improved. The failure mechanism of laminates under high-velocity impact is revealed by analyzing the impact process of the projectile, the energy absorption level, the failure morphology and internal damage degree of laminates comprehensively. It is clear that the impact angle and velocity of the projectile will significantly affect the coupling form of the failure mechanism and lead to differentiated results. The results of in-plane compression experiment of laminates with impact damage show that the bearing capacity of laminates is significantly weakened by high velocity impact damage, and the residual strength of laminates is directly determined by the mode and degree of impact damage. In particular, through the analysis of the energy absorption mechanism, a trend prediction model of ballistic limit value with impact angle is established, and the influence of high-velocity impact damage on the residual strength of laminates is revealed. This study provides a better understanding of the mechanical response of thermoplastic composite structures to high-velocity impact loads.

Preparation of continuous carbon fiber reinforced PA6 prepreg filaments with high fiber volume fraction

High-performance continuous carbon fiber prepreg filaments have been a research hotspot in the field of additive manufacturing in recent years, and are considered to be an effective option for improving the mechanical strength of thermoplastic composite parts. However, the effect of fiber volume fraction on the microstructure and tensile properties of 3D printed prepreg filaments remains miss. Therefore, this study selected suitable impregnation processes and materials to prepare prepreg filaments with different fiber volume fraction and investigated their mechanical properties and microscopic morphologies. The results show that the increase of fiber volume fraction effectively promoted the interface bonding between fiber and resin, and increased capacity for load transfer. When the fiber volume fraction was 54.0 %, the tensile strength of the prepreg filaments and specimens reached 1977 MPa and 334 MPa, respectively. This study can provide a process optimization strategy for the preparation of more types of continuous fiber prepreg filaments with high fiber volume fraction, as well as a data reference for the preparation of high-performance 3D-printed thermoplastic composites.

Bioinspired 4D Printed Tubular/Helicoidal Shape Changing Metacomposites for Programmable Structural Morphing

AbstractBiological structures combine passive shape‐changing with force generation through intricate composite architectures. Natural fibers, with their tubular‐like structures and responsive components, have inspired the design of pneumatic tubular soft composite actuators. However, no development of passive structural actuation is available despite the recent rise of 4D printing. In this study, a biomimicry approach is proposed with inspiration from natural fiber architecture to create a novel concept of thermally active 4D printed tubular metacomposites. These metacomposites exhibit high mechanical performance and 3D‐to‐3D shape‐changing ability triggered by changes in temperature. A rotative printer is proposed for winding a continuous carbon fibers reinforced PolyAmide 6.I composite on a PolyAmide 6.6 polymer mandrel in a similar manner to the structure of cellulose microfibrils within the polysaccharide matrix of natural fiber cell‐walls. The resulting 4D printed tubular metacomposites exhibit programmable rotation and torque in response to thermal variations thanks to the control of their mesostructure and the overall geometry. Energy density values representing a trade‐off between the rotation and the torque are comparable to shape memory alloys when normalized by stiffness. Finally, a proof of concept for an autonomous solar tracker is presented, showcasing its potential for designing autonomous assemblies for structure morphing.

Rate-dependent mechanical and self-monitoring behaviors of 3D printed continuous carbon fiber composites

3D printed continuous carbon fiber reinforced polymer (CFRP) composites offer great advantages in structural health monitoring (SHM) owing to their flexibility in complex structure fabrication. Considering the many prospective aerospace applications, tensile experiments were designed to study their mechanical and self-sensing behaviors under a wide range of strain rates. The turning points in the resistance vs strain curves reveal the damage evolution of the specimens and divide the deformations into linear straining and damage evolution regions. Fiber elongation and fiber contact reduction dominate the resistance increase in the linear straining region and the resistance curve behaves linearly. But fiber breakage is the predominant factor in the damage evolution region, yielding a concave resistance curve. Strength, fracture strain, and resistance variation are found to display significant strain rate dependencies that increase with increasing strain rate. Numerous microcracks are formed and evolved into secondary cracks under dynamic loading. This process absorbs more strain energy and produces more carbon fiber breaks, sustaining a higher fracture strain and resistance variations. A model is developed to describe the strain- and strain rate- dependent resistance behaviors, and the predicted results agree well with experimental data. The outcomes of this work contribute to the application of 3D printed continuous CFRP composites in SHM.

STUDY OF THE USE OF THERMAL DRILLING IN MECHANICAL JOINING OF MG SHEET AND GFRP/CFRP COMPOSITES WITH THERMOSOFTENING MATRIX

The paper discusses the joining of magnesium based metallic sheet and composites with thermosoftening polypropylene matrix reinforced with bi-directional continuous glass and carbon fibers by thermal drilling technology. The bushing formation has been investigated by separately drilling AZ91 Mg alloy sheet at two rotational speeds and feed rates to find out the parameters at which a bushing with optimum length and thickness, suitable for joining with the composite, is formed. Under these conditions, the joining of the metal sheet and composite was then carried out by simple thermal drilling. During simple drilling, delamination of the composite occurred in the vicinity of the hole, which was resolved by flanging the bushing with a penetration of the tool from the opposite side. When AZ91 was joined to carbon fibers reinfirced composite, there was a lack of bushing formation due to the higher resistance of the carbon fibers, which are present in the composite in greater numbers compared to the glass fibers. This problem was solved by sequential drilling, which means that a flowdrill tool was used to create a hole in the composite itself, then overlaid with Mg sheet and again drilled, forming the bushing and flanging the bushing from the opposite side. The sequential drilling resulted in joints with a load capacity of 0.8 - 1.4 kN, which exhibit the characteristics of a hybrid - mechanical and adhesive joint.

Mechanical Properties and Economic Analysis of Fused Filament Fabrication Continuous Carbon Fiber Reinforced Composites.

Additive manufacturing of composites offers advantages over metals since composites are lightweight, fatigue and corrosion-resistant, and show high strength and stiffness. This work investigates the tensile and flexural performance of continuous carbon-fiber reinforced (CCF) composites with different guide angles and number of layers. The cost and printing time analyses were also conducted. Tensile specimens with a contour-only specimen and one CCF layer with a 0° guide angle exhibited nearly comparable strength values. Increasing the number of CCF layers enhances the tensile properties. For the identical cost and reinforcement amount, 0°/0° provides a higher tensile strength and elastic modulus compared with 15°/-15°. The same phenomenon was observed for 15°/0°/-15° and 0°/0°/0°. The samples with one and two reinforcement layers had similar stiffness and maximum load values for flexural tests. For the samples with four layers, there was a considerable improvement in stiffness but a minor decrease in the maximum load.

Coaxial direct writing of ultra-strong supercapacitors with braided continuous carbon fiber based electrodes

Supercapacitors produced based on 3D printing technology greatly expand the range of materials and geometric complexity. However, the production of fiber-based supercapacitors typicallyrequires subsequent steps. For the first time, we report a coaxial direct writing technique that enables the one-step fabrication of braided flexible solid-state supercapacitors. Continuous carbon fiber is used as a flexible substrate. α-manganese dioxide nanowires and activated carbon are used as active materials. The entire electrode assembly is coated with solid-state electrolyte and then braided. Through coaxial direct writing technology, the braided electrodes and sealings can be extruded by a coaxial nozzle to continuously print free-form ultra-strong supercapacitors with a tensile strength of the braided electrodes up to 636 MPa. Electrochemical measurement results show that the printed capacitor exhibits an excellent specific capacitance, and it still maintains a capacitance retention of 90.1% after 1000 cycles. The supercapacitor exhibits nearly identical electrochemical capacitive characteristics at various bent angles. This work paves the way for integrating enhanced durability and adaptability into next-generation wearable and portable electronic systems.