Enabling electrical functionality of carbon fibre composites via tow steering during additive manufacturing

Tensile and flexural behaviors of additively manufactured continuous carbon fiber-reinforced polymer composites

Additive Manufacturing (AM) has revolutionized the production of three-dimensional objects by utilizing a layer-by-layer approach. Among the materials used, carbon fiber-reinforced polymer (CFRP) composites have gained significant attention. The integration of carbon fibers and a polymer matrix offers enhanced structural integrity, thermal stability, and corrosion resistance, making these composites appealing for aerospace, automotive, and a broad range of other engineering applications. AM of CFRP composites allows the precise alignment of carbon fibers during fabrication for the optimization of mechanical performance. Multiple AM methods have been developed for AM of CFRP, including fused deposition modeling (FDM), stereolithography (SLA), and continuous fiber printing. Challenges associated with the AM of CFRP include interfacial bonding, resin impregnation, printability and process control, and post-processing. This presentation reported an investigation of the printability, material property, and geometrical accuracy of CFRP composites using the FDM method. Short carbon fiber and polylactic acid (PLA) are selected and prepared as the filament for 3D printing. The 3D printing capability of short carbon fiber reinforced composites is investigated using different layer heights, printing speeds, and nozzle and build-bed temperatures to determine the optimal printing parameters. Critical mechanical properties of the 3D printed composites, including tensile and flexural moduli and strengths, are characterized following ASTM standards. The interlayer adhesion within composites is studied by scanning electron microscopy, optical microscopy, and porosity tests. The microstructures, particularly porous size and shape can be visualized using microscopy technologies. The average porosity of 3D printed composites can be calculated by comparing the design of 3D printed composites and the original filament. This study can lead to an improved understanding of AM-processed structural composites for broad aerospace, automotive, and mechanical applications.

Continuous carbon fiber reinforced polymer composites (CFRPCs) exhibiting superior mechanical properties have emerged as high‐performance engineering materials for various industrial applications. Additive manufacturing (AM) of CFRPCs enables production of customized structures with superior mechanical properties at a low cost and has gained tremendous popularity. In the present study, a novel AM technique namely laser‐assisted laminated object manufacturing (LA‐LOM) is proposed for producing CFRPCs using prepreg sheets with continuous carbon fiber reinforcement. The interfacial properties of the bonded prepreg sheets are critical for the performance of the additively manufactured CFRPCs. We further introduce graphene as a modifier between the prepreg sheets to improve the mechanical properties of the CFRPCs. It is shown that low porosity (0.38%), high concentrations of continuous carbon fibers (63 wt. %), and improved interfacial bonding strength contribute to excellent mechanical properties. For the composite structure ([0°]s fiber arrangements), in which 0.5 mg/ml graphene is introduced as interface modifier, the lap shear strength, tensile strength, and tensile modulus are 18 MPa, 2940 MPa, and 170 GPa, respectively, and the flexural strength and modulus are 1310 MPa and 140 GPa, respectively. The tensile strength and modulus outperform all AM‐produced structures reported in literature, including carbon fiber composites and metals and metal alloys. Meanwhile, the increases are observed in the lap shear strength by 25%, flexural strength by 10%, and flexural modulus by 27%, as well as tensile strength by 7% and modulus by 6%, compared to specimens without graphene reinforcement. This composite architecture design, involving laminated continuous carbon fiber reinforced prepreg sheets and graphene‐modified interfaces, provides a readily scalable manufacturing method toward excellent properties and this method can be further explored in industrial applications.

Additive manufacturing (AM) of carbon fibre reinforced thermoplastic composites can offer advantages over traditional carbon fibre manufacturing through improved design freedom and reduction in production time and cost. However, the carbon fibre composites produced using current state-of-the-art AM approaches generally possess high porosity (18–25 %) compared to those produced by conventional manufacturing (1 %). An approach known as composite fibre additive manufacturing (CFAM) is presented, involving selectively printing a binder and polymer powder onto discontinuous carbon fibre sheets, which are then compressed, heated and post-processed to form net shape components. The results demonstrate a correlation between compaction pressure applied and porosity/fibre volume fraction within components. Composite components were produced containing porosity of 1.5 % and fibre volume content of 15 % with 97 MPa tensile strength and 8.9 GPa elastic modulus, presenting a new approach for production of discontinuous carbon fibre reinforced polymer parts with mechanical properties exceeding those of state-of-the-art AM.

Using lightweight components to reduce vehicle mass is one of the tactics available to vehicle manufacturers to reduce CO2 emissions. Carbon fibre reinforced polymer composite with its high strength to density ratio is one of the potential materials to reduce component mass. The lessons learned from three research and development projects on automotive chassis structural components designed, manufactured and tested using carbon fibre composites provides insights into the opportunities for mass reduction and the cost, manufacturing and analysis challenges that combine to limit the applicability of carbon fibre composites in high volume automotive use. Projects investigated three structural cassis components, the Focus rear suspension tie blade knuckle, the F-150 front suspension lower control arm, and the Fusion (Mondeo) front subframe. All the projects developed, analysed, manufactured and tested carbon fibre composite replacement components that fit the package and met equivalent performance requirements to the production parts. Then the designs and manufacturing plans informed the cost estimates for these components at high automotive volumes. The tie blade knuckle chose thermoplastic resin while the front lower control arm and subframe investigated thermoset resin carbon fibre composites. Carbon fibre reinforced polymer composites offer the opportunity of approximately a 30% mass reduction compared to a steel component. This mass savings is less than anticipated. Due to the high constituent material costs of both the carbon fibre and the high performance resin, the complex manufacturing processes, and the final assembly processes the resultant "weight buy" exceeds an additional $35 USD of variable cost per kilogram of mass saved compared to the production steel component. All three of the components investigated require multi material solutions that include both random chopped and oriented continuous carbon fibre composites plus steel reinforcements at high point load areas such as the bolted connections. Also, the predictive CAE tools are not yet fully mature for carbon fibre composites leading to lower confidence initial designs.

Additive manufacturing technology brings new revolutionary potential for the development of carbon fiber reinforced polymer composites. Continuous carbon fiber reinforced composites developed using fused deposition modeling technology have the characteristics of high specific strength, high specific modulus, light weight, and flexible design, which is the solution direction for low-cost, rapid, and flexible application of advanced composite materials in the future. In this paper, the preparation of continuous carbon fiber reinforced polymer composites with continuous carbon fibers as reinforcement and thermoplastic/thermoset as matrix, surface modification and their mechanical properties are investigated, the interfacial characteristics and properties of continuous carbon fiber reinforced polymer composites under different pretreatment processes, auxiliary processes and post-treatment processes are studied, and the connection between the micro-morphology and the mechanical properties of this composite is further analyzed. The direction of defect resolution of continuous carbon fiber reinforced polymer composites fabricated by fused deposition technology is provided, and the future development direction is envisioned.

In recent years, additive manufacturing (AM), also known as 3D printing, has been developed as one of the major fabrication technologies for advanced composite materials. 3D printing offers a great way of producing composites with costefficiency, scalability, high productivity, and design flexibility. Among the numerous materials used in 3D printing, thermoplastic polymers with discontinuous reinforcement (i.e. powder, nanoparticles, short fibers) have been used successfully thanks to high processability. However, the thermoplastic/discontinuous fiber composites are often limited to extreme circumstances requiring high service temperature or mechanical properties due to the low glass transition temperature of the polymers or discontinuous reinforcement. Thermosetting polymer/continuous carbon fiber composites can be an alternative, but there has been no reported AM technique addressing the process of thermosetting polymers and continuous carbon fibers for direct 3D printing. A fundamental challenge of fabricating such composites is in controlling the irreversible viscosity change of thermosets. If a drastic increase of the polymer viscosity occurs before infusion, it is hard to infiltrate the polymers into the fiber bundle, whereas under-cured polymer cannot sustain a designed pattern during the process. Herein, we analyze dynamic capillary-driven flow generated by thermal gradient along carbon fibers based on the understanding of dynamic wicking and curing of epoxy resin in carbon fibers. It gives a significant breakthrough in overcoming these obstacles by controlling the viscosity and degree of cure of the thermosetting polymers. With numerical analysis, we prove that different liquid absorption capability along the fibers induces dynamic wicking of the resin. And in computational simulation, in-composite heating system (heating along carbon fibers) exhibits the abilities to heat the resin uniformly acting like internal heating and cure the composites with a high degree of curing. And we apply the dynamic capillarydriven flow to the 3D printing for manufacturing thermosetting/continuous carbon fiber composites. The great mechanical properties of the printed composites show that dynamic capillary-driven flow is applicable in fabrication of the composite.

Carbon fiber-reinforced polymer (CFRP) composite has extensive application in several industries, including the automotive and aerospace industries. Fabrication of micro-features in CFRP composite is an important process that is frequently performed for various applications including for micro-products and micro-components. The fabrication of precise micro-features in CFRP composite is difficult to achieve by conventional means, even by additive manufacturing (AM). Thus, in this study, the machinability characteristics of the CFRP composite were experimentally investigated. CFRP composite was fabricated by using the AM technique. The different process parameters of 3D printing (infill density and layer sequence) and micro-EDM (voltage, capacitance, and tool rotation) were considered to investigate their effect on the hole quality and productivity. The optimization of the different parameters chosen for the purpose of the investigation was also carried out. The important process parameters that have an impact on the process were identified and analyzed. The better machining performance of CFRP composite was noticed at higher infill density and alternative fiber arrangement. The capacitance was the most significant parameter among all the EDM parameters to produce good quality micro-holes in CFRP composite.

Study of the FFF additive manufacturing process of composite material based on L – polylactide (PLLA) with ultra-short carbon fibers. Tensile strength and elongation at break for all test specimens were determined according to ISO 527. Tensile modulus - ASTM D638-10, specimen density - PN-EN ISO 1183, microscopic examination - according to ASTM E2015 - 04 (2014). Charpy Shock Tests ISO 179 and ASTM D256. Bending test method ISO 178 and ASTM D 790. The rational modes of FFF additive manufacturing (AM) of carbon fiber composite based on PLLA was established. Properties of carbon fiber PLLA and unfilled PLLA was determinated for AM formed samples and injection molded samples. Carbon fiber composites have significantly higher flexural and tensile module us values compared to the original L-polylactide, which is due to the effect of polymer matrix reinforcement by the fibrous component. However, finished products obtained by AM PLLA carbon composite have a lower impact strength and tensile strength, which is likely to be due to the fact that the carbon fibers are short (50-60 mkm) and have a cavitations effect during injection molding and AM. Density of carbon fiber filled PLLLA was lower the theoretically calculated value for filament material as well for injection molded and AM formed samples. Density reduction probably the main cause of impact properties deterioration due to cavity forming around carbon fibers. Density and tensile properties of AM formed samples can be changed by AM slicing parameter – extrusion multiplier. Cavitation effect for carbon fiber composites observed for PLLA composite in form AM filament, injection molded parts and AM formed samples. Cavity forming was confirmed by optical microscopy and density measurement. Possible reason for cavity forming is orientation deformation of the fiber in polymer matrix during the formation of the filament. The effect of cavitation also persists in the AM of products from carbon composites due to the passage of the orientation at the exit of the printer nozzle. The possibility of regulating the density and physical and mechanical properties of carbon composite products obtained by the additive manufacturing method has been established. Selection of rational values of the extrusion multiplier and the direction of the layers in the additive molding allows you to create products with the desired complex of properties.

As the key strategic materials for national security, carbon fibers (CF) and CF reinforced composites must be independently guaranteed. Among them, the amount of carbon fiber reinforced polymer (CFRP) composite material accounts for more than 70% of carbon fiber composites. Resin matrix (content over 35 wt%) is one of the two basic materials of CF reinforced polymer composites, which directly determine the service performance and processing of the composites. The Advanced Composites Center (ACC) in Beijing University of Chemical Technology (BUCT) has carried out a series of fundamental and engineering research solve problems about how to prepare domestic high-performance resin matrix for carbon fiber with the aim of meeting the national strategic needs. ACC research team has made great progress in promoting domestic carbon fiber application and the innovation of high-performance domestic CF reinforced polymer composites. Since 2005, ACC research team have developed the resin matrix system and composites which are compatible with Toray T700/T800/T1000 carbon fibers and M40J, M55J high-modulus carbon fibers, and suitable for forming process with wide viscosity range. A series works have been conquered to promote the development of domestic carbon fibers from usable to easy-to-use. Research results have significantly improved the performance of domestic carbon fiber reinforced composites, optimized the preparation technology, and guaranteed the design and supporting capability of advanced weapons. In this paper, the research achievements and technical breakthroughs on CF reinforced polymer-based composites done by ACC research team in recent 10 years are summarized. The details include: (1) The cross-linking structure simulation of resin molecules used for CF. (2) Prediction of the relationship between molecular structure and properties of resins through molecule simulation method. (3) The new mechanism of double interface/double interphase and modulus transition layer for carbon fiber reinforced polymer composites. (4) The multiscale toughening and reinforcing methodologies of interfacial phases of carbon fiber reinforced polymer matrix composites. (5) In situ characterization of interface between carbon fiber and resin matrix composites through fluorescence matter. (6) Innovation of methodology for multi-stage/multi-scale toughening and strengthening of carbon fiber reinforced polymer composites. (7) Innovation in preparation technology of high performance resin materials used for carbon fiber. (8) Processing technology innovation and the related product engineering of CF reinforced polymer composites. The above-mentioned research works of BUCT have been supported by more than 30 projects, such as the National Military and Civilian Population Matching Project, the National Natural Fund Key Project and the National High Technology Research and Development Program (863) of China. And research results have been used in many key defense models of national defense industries, such as aerospace, weapons, nuclear industry, and aviation and so on. It has achieved considerable economic and social benefits and promoted the nationalization process of carbon fiber resin in the field of national defense. In the end, the development trend on high-performance CF reinforced polymer composites is generally prospected. And ACC research team will also tireless promote the whole life cycle usage of CFRP materials and contribute to the healthy and sustainable development of CFRP industry.

Large-scale additive manufacturing tooling for extrusion-compression molds

Fully recyclable, flame-retardant and high-performance carbon fiber composites based on vanillin-terminated cyclophosphazene polyimine thermosets

Experimental investigation of additively manufactured continuous fiber reinforced composite parts with optimized topology and fiber paths

Over the last few years, there has been a growing interest in the study of lightweight composite materials. Due to their tailorable properties and unique characteristics (high strength, flexibility and stiffness), glass (GFs) and carbon (CFs) fibers are widely used in the production of advanced polymer matrix composites. Glass Fiber-Reinforced Polymer (GFRP) and Carbon Fiber-Reinforced Polymer (CFRP) composites have been developed by different fabrication methods and are extensively used for diverse engineering applications. A considerable amount of research papers have been published on GFRP and CFRP composites, but most of them focused on particular aspects. Therefore, in this review paper, a detailed classification of the existing types of GFs and CFs, highlighting their basic properties, is presented. Further, the oldest to the newest manufacturing techniques of GFRP and CFRP composites have been collected and described in detail. Furthermore, advantages, limitations and future trends of manufacturing methodologies are emphasized. The main properties (mechanical, vibrational, environmental, tribological and thermal) of GFRP and CFRP composites were summarized and documented with results from the literature. Finally, applications and future research directions of FRP composites are addressed. The database presented herein enables a comprehensive understanding of the GFRP and CFRP composites’ behavior and it can serve as a basis for developing models for predicting their behavior.

Chitosan-doped carbon nanotubes encapsulating spread carbon fiber composites with superior mechanical, thermal, and electrical properties