Papers by Keyword: Carbon Fiber

Abstract: Achieving a strong bond between carbon fiber (CF) and recyclable thermoplastic polymer (TP) has always been highly sought after. So far, applying electron beam (EB) irradiation with optimal dose and cathode potential (V_c) has shown success in increasing mechanical properties of interlayered CFRTPs. However, with concern for durability and safety, higher strength is desired. Therefore, EB setting applying electron beam (EB) irradiation with cathode potential (V_c) to 170, 210, 225 or 250 kV was applied to CFRTPA (carbon fiber reinforced thermoplastic polyamide) articles just before shipping. Specimens were 9 CF plies alternating between 10 PA (polyamide) sheets, designated [TPA]₁₀[CF]₉. When optimal EB dose of 43.2 kGy is applied to both finished specimen surfaces after fabrication, experimental results show higher V_c setting of 250 kV can increase impact strength of the [TPA]₁₀[CF]₉ over that at 170 kV. In summary, the 250 kV-EB (250 kV) strengthens [TPA]₁₀[CF]₉ significantly, about 25 to 27% larger than that of 170 kV and zero (untreated). Based on Christenhusz and Reimer equation to calculate penetration depth, D_th of EBI into polymers, increasing V_c to 250 kV increased D_th to more than 2 times that at 170 kV.

Abstract: This article focuses on the production of tensile test (ASTM D638-03) specimens using fused deposition modelling technique as preliminary study for preparation of 3D-printed SUAV wings. Carbon-PLA (nylon 6/66 copolymer adding with 20% of carbon fiber) was used as 3D filament. There were 7 printing orientations: 0^o, 15^o, 30^o, 45^o, 60^o, 75^o, and 90^o based on tensile axis with 3 specimens for each direction (21 specimens in total). Printing parameters were set using open-source slicing application CURA. It was found delamination and fracture outside the gauge length causing high deviation of the mechanical properties value. So, the result of the testing test seems like do not comply with theoretical aspect of relationship between fiber orientation and tensile properties of composite materials. Taking care of printing parameters and increasing the number of specimens has an opportunity to achieve high precision results since precise data is crucial as a starting point for the development of SUAV wings.

Abstract: Friction stir spot welding as a solid state processing technique is used to join dissimilar and similar metals, composites and polymers. This study illustrates the implementation of friction stir spot welding (FSSW) on additive manufactured nylon-based composites with chopped carbon fibre reinforcements. The purpose of this study is to employ FSSW technique for joining additive manufactured carbon fibre composites. The utilization of pinless tool serves a crucial function in the formation of sound welded joints. The joining process consists of two mechanisms: the piercing and melting of the sheets and the adhesive bonding during the re-solidification. As a result of the FSSW process, the joints indicate a decent mechanical performance with a lap shear failure force (LSFF) of about 250N.

Abstract: For the purpose of environmental protection, the solution to the excessive release of carbon dioxide in the atmosphere has become the focus of current research. The electrochemical reduction of carbon dioxide, which enables the capture and storage of carbon dioxide and its conversion into new compounds, has shown its effectiveness. By studying various methods of preparing CO2 absorption electrodes, Carbon fiber material is considered as a promising electrode material due to its good electrical conductivity and availability. In this paper, Ag/PTFE composites (Silver as catalyst, PTFE as hydrophobic agent), combined with carbon fibers, are used as Gas diffusion electrodes (GDE) materials. After verifying its hydrophobicity by contact angle measurement, the performance of electrode is tested. The results show that the new electrodes synthesised are suitable for use as Gas diffusion electrodes materials (GDE) and that Ag catalysts combined with carbon nanofibers can be used for the electrochemical reduction of CO₂.

Abstract: The use of a carbon fiber composite material to make external prostheses in the form of a femoral socket was the subject of this laboratory study. According to the prior bibliographical studies, this material adapts well to this type of prosthesis. The objective of this research is to study its microscopic structure, in order to verify the good wetting of the fibers by the resin, the good cohesion and molding by infusion. The morphological study of the facies of the parallelepiped-shaped specimens was carried out after cuts perpendicular to the axis of the fiber strands, parallel according to the width and thickness of the specimen. This study was carried out using a scanning electron microscope (SEM), in order to determine, thanks to the typical microstructure of the composite, the various degradations, which appear as a result of the effect of static tension. The laminate used is based on three layers of carbon taffeta fabric and an orthocrylic resin. Tensile tests have been carried out at a speed of 1mm/min with a Zwick/Roell machine with a load cell of 50 kN. This speed was chosen to allow a comparative study with glass fiber specimens, which have been used previously for the production of prostheses, before those made of carbon. The microscopic study allowed to identify the four types of degradation; Matrix fracture, which manifested itself as fault lines, in preferred directions of different sizes. This contributed to interlaminar delamination. The decohesion that contributes to delamination in a different way from that of matrix breakage is visible at different levels. Interlaminar delamination results from the combined effect of matrix breakdown and decohesion and manifests itself as uneven strata. Fiber breakage was manifested by shearing. This study allowed to observing a degradation of the material imposed by static traction. As for the material used in orthopaedics, it has retained good cohesion and meets the requirements of prostheses, despite the defects detected by the microscopic study.

Abstract: Reliable composite forming experiments are required to characterize composite formability, to aid material development, and to validate process simulations models. Due to practical reasons, however, typically a limited amount of forming configurations is studied. The objective of this study is, therefore, to develop a methodology for obtaining controlled forming results in a wide range of configurations. Press forming experiments using a dome geometry were used to explore the formability of two commercial unidirectional thermoplastic composite materials. A variety of forming configurations was employed by changing the blank dimensions and layup. The observation of wrinkling defects was simplified by leaving an additional 3 mm tool gap. Blank width and layup had the most influence on the wrinkling severity, followed by blank thickness and length. Quasi-isotropic layups were found to produce wrinkles in nearly all cases, confirming a difficulty in general to form double curved parts. The size and number of wrinkles in these layups were found to change with the stacking sequence. Cross-ply layups showed better formability, but significant wrinkles were still observed depending on the orientation of the blank relative to the layup. The formability experiments using a dome geometry provided a reliable methodology for controlled forming results in many configurations using a generic toolset. Additionally, a comprehensive comparison of formability for two commercial thermoplastic UD materials in a variety of scenarios was provided.

Abstract: Carbon fibre (CF) is widely used in CF reinforced plastic (CFRP) components. However, waste CF, CFRP and the end-of-life (EOL) CFRP structures will cause an even bigger problem in the next years because of strict environmental regulations. Currently, recycling is carried out almost entirely by the use of pyrolysis to regain CF as a valuable resource. This high temperature process is very energy consuming and the resulting fibres are brittle. Hence, not suitable for textile processing into yarns or fabrics. To enable a grave to cradle circle, a new approach based on a solvolytic recovery of CF and the subsequent spinning process to obtain a hybrid yarn suitable for weft knitting processing is the focus of the international research project IGF/CORNET 256EBR “3D-r-CFRP”.

Abstract: A significant strategy to reduce the demand for natural resources and the associated environmental impact is enhanced material efficiency in the design process for new building structures. Innovative concepts for designing, modelling, constructing, producing and utilising sustainable resource-efficient concrete-based building components will be the foundation for future-oriented constructions. For this reason, the ability to process biologically inspired 3D textile reinforcement structures is crucial to fully exploit the potential of carbon concrete. This research project provides a fundamentally realigned, CAE-supported approach so that optimization algorithms, numerical models for the generation of robot placement paths and bionically induced yarn positioning can be taken into account. The evolved intelligent and modular yarn placement system forms the basis to overcome current challenges involved in the placing and stabilizing of spatial and highly branched reinforcement topologies during the manufacturing process. Hence, the novel tool-independent, geometrically highly variable, robot-supported fibre placement technology is supposed to be capable of manufacturing biologically inspired load adapted 3D textile topologies with reinforcement in z-direction.

Abstract: In this study, it was possible to evidence the efficiency of the use of carbon fiber coating in concrete structures and its application to promote the protection and maintenance of these materials, seeking to prolong the useful life of this type of structure. From mechanical tests, such as compressive strength, it was possible to observe an increase of 37% in the breaking load, as well as an increase of about 40% in compressive strength, when compared to tests with pure concrete. Therefore, the results pointed to the optimization of the mechanical properties of the structure, coated with carbon fiber and cured with epoxy resin. In other words, the use of this external load combined with epoxy resin was an important element in concrete reconstruction and reinforcement. Another interesting point was the issue of the high fiber rigidity observed in the AFM, allowing an excellent interaction with the resin in the coating of the specimen. The study showed that this type of coating can be used for the recovery of structures, as well as a reinforcement element, since many projects have difficulties with the high maintenance cost, as well as the daily monitoring of concrete structures.

Abstract: Carbon fibers have been TiO₂ coated. Previously, the carbon fiber surface has been heat-treated to remove the sizing. The TiO₂ layer has been formed on the fiber surface using the sol-gel technique by immersion in a solution. After coating, the samples have been dried at room temperature and annealed at 500 °C in air for 30 minutes. The phase composition of the coating obtained has been studied using X-ray diffraction. X-ray diffraction analysis of the coating and sol has shown that the rutile phase and the average size of TiO₂ crystallites grow with an increase in the annealing temperature. The results of studying TiO₂ coating antioxidative properties within 500-800 °C are given. Studying the morphology of the TiO₂ coating on the fiber surface and the burnout rate (weight change) have shown that the coating exhibits good oxidation resistance up to 600 °C.