Papers by Keyword: Short Carbon Fiber

Abstract: It is a serious problem that short carbon fiber reinforced polyamide 66 (SCFRPA66) cannot be easily shaped by 3D-printing for practical usages. In order to improve on the brittleness, homogeneous low potential electron beam irradiation (HLEBI) to both sides of 3D-SCFRPA66 samples was found to increase strain at tensile strength (εts), corresponding to homogeneous deformation and fracture strain (εf), as well as resistant energy of homogeneous deformation (Ehd), whereas the HLEBI decreased the tensile strength (σts). This improvement in ductility can be explained by lone pair electrons, dangling bond generation, shortening and relaxation of the polymeric chains by the HLEBI.

Abstract: The research was conducted on incorporating short carbon fiber and multi-layer graphene into ultra-high performance concrete (UHPC) to improve the dynamic mechanical performance and electromagnetic shielding effectiveness (SE). In the electromagnetic shielding effectiveness testing, the results shown that UHPC with uniformly distributed conductive fibers exhibited superior shielding effectiveness at high frequencies. In comparison to normal concrete, the UHPC demonstrated the capability to withstand higher impact energy. Simultaneously enhancing both electromagnetic shielding characteristics and dynamic mechanical performance of cementitious materials can be challenging. In this study, employing a composite structure was effective solution to overcome this issue. In accordance with the experimental results, a scaled testing protective facility has been constructed, and the research results could provide the reference for the design and construction of protective structures.

Abstract: Among all additive manufacturing techniques, fused deposition modeling (FDM) has been used the most extensively to fabricate continuous fiber reinforced polymers. Onyx, a short carbon fiber reinforced PA6 composite material developed by Markforged, has received widespread attention, and been employed as matrix in FDM-fabricated composites. This study investigates the tensile properties of continuous glass fiber (GF) reinforced Onyx (CGFRO) composites under quasi-static loading. CGFRO contains three different components, which are short carbon fiber in micrometer scale, continuous glass fiber and polyamide-d thermoplastic. The synergistic reinforcing behavior of these three components was evaluated experimentally by testing Onyx material, and CGFRO with different volume fractions of fibers (Vf). It was found that the failure mode of Onyx was different from that of GF/Onyx and the deformation modes of GF/Onyx varied with the volume fraction of glass fiber. The tensile properties of CGFRO increased with glass fiber volume fractions, where 42% Vf specimens exhibited the highest tensile modulus and strength of 10 GPa and 383 MPa, respectively, which are approximately nine times higher than that of Onyx parent material.

Abstract: Generally, thermoplastic polymers due to their viscoelastic behavior tend to appear creep deformation at low temperature compared to metals; this continuous creep deformation caused irregular shapes with time and resultant unstable dimensional parts. Therefore, the investigation of creep behavior in thermoplastic polymers must be considered as an essential requirement in the design process. This work exanimated the creep rupture behavior for Polyamide 6.6 and their composites which content of 1%MWCNT_S or 30 short carbon fibers under variant applied stresses and temperatures, as well as, to create analytical model to the obtained results Findley power law model was employed for this purpose with a comprehensive verification to their compatibility to the experimental results. The results appeared that the addition of reinforced materials and decreasing applied stresses and temperatures will cause an enhancement in creep resistance by increasing rupture time and decreasing the minimum creep rate values. On the other hand, using of Findley power law model gives a good agreement to the obtained experimental results.

Abstract: Carbon fiber reinforced polymer is mostly used to improve the performance of polymer-based component. Nevertheless, composite material properties depend on many factors such as fiber direction, length of fiber, matrix material and manufacturing process. This work aims to study the effect of fiber length and orientation on material stress-strain relationship. Short carbon fiber length (0.2 and 0.5 mm) reinforced with phenolic resin and long carbon fiber reinforced with commercial matrix material were studied. Long carbon fiber showed higher tensile strength than short carbon fiber with longitudinal direction, whereas slightly difference was observed for transverse direction. The printing path significantly affects failure location as area with lower fiber density exhibit lower local strength. Finite element simulation of the tensile test was carried out with the homogeneous material model which suggested that it could accurately predict the load capacity of printed composite. The bending strength was then computationally predicted. It was found that 0 degree offered higher bending load capacity than 90 degree orientation for all carbon fiber length with smaller difference with shorter fiber. Almost insignificant effect of fiber orientation was observed for 0.2 mm. fiber length.

Abstract: The properties of composite materials do not depend only on the properties of raw materials but also other parameters such as volume fraction, geometry, dimension and material distribution etc. Carbon fiber reinforced polymer is one of the top choices of composite material because carbon fiber has light weigh with high tensile strength. For fiber-based composite such as carbon fiber composite, directions of carbon fiber with respect to loading direction could also affect to the strength of composite material under load. In this work, the properties of short carbon fiber-resin composite were investigated (fiber length of 0.2 mm.) with two different fiber orientations, i.e. 0 and 90 degrees to applied load. The 3D printing technique was employed in order to control carbon fiber direction and minimize material loss leading to material cost reduction. It was found that 3D printing technique could control direction of fiber in most case. However, at area with high curvature, the unexpected fiber direction was observed due to post hot process during which material flow was expected. It should also be noted that fiber path during 3D printing process may be very crucial as it could result in low strength local area due to low fiber density. This area could promote stress concentration leading to final fracture.

Abstract: This paper investigated the fracture behavior of the unavoidable breakage of carbon fibers and fiber orientation of short carbon fiber reinforced polycarbonate composite in injection process. In this experiment, short carbon fiber mixed compound of 1mm, 3mm, 5mm, 7mm length with 10wt.%, 15wt.%, 20wt.% in polycarbonate for injection molding were produced through the extruder. The dumbbell specimens for tensile evaluation were made by injection molding. The parent specimens were made by double gate method, the weld specimens were made by single gate method which was controlled by inserting a stopper through the runner of the mold cavity. Short carbon fiber reinforced PC composite was evaluated by micro-CT with regard to the particle size of short fiber with a diversified quantitative analysis through entire process of the injection process in composite. The quantitative distribution of fiber orientation was also examined by micro-CT with regard to normal direction or anisotropy. Weld line of short carbon fibers reinforced PC composite weaken the bonding strength by 50% compared to parent materials because the weld line is composed with concentrated anisotropy orientation of short carbon fiber in weld line. Evaluation of the mechanical properties of the injection specimens group was utilized by universal tensile strength tester. In addition, fracture surface of parent and weld materials was investigated by a SEM.

Abstract: Using screw injecting molding method to prepare the short fiber strengthening thermo plastic resin composite material, using short carbon fiber as strengthening material and polytene resin as matrix. Study different influence of carbon fiber content to the hardness of short fiber strengthening thermo plastic resin composite material. The result shows that the hardness of short carbon fiber strengthening thermo resin composite material increase as increasing the short carbon fiber content.

Abstract: The effect of different factors, such as carbon fiber content, temperature, electrifying time and frequency, power density on the electrothermal properties of the composite papers with different carbon fiber content was researched. The results show that the resistivity of the composite papers decreases with the increasing of carbon fibers. The current-voltage relationship is in good conformity with the Ohm's law. The negative temperature coefficient and good reversibility are shown during the heated and cooled process of the papers. The resistance of the papers decreases gradually with electrifying time and trends to stable after several hours. On-off electrifying times on its resistance have little effect in the long term. The curve of power density and surface temperature shows a good linear behavior.

Abstract: Short carbon fiber is used to reinforce phenol formaldehyde (PF) resin/graphite composite. With carbon fiber by thick nitric acid liquid-phase oxidative surface treatment (TNALPOST) and its content 3.wt%~ 4.wt%, the composite flexural strength is increased highly and electrical conductivity is also increased on some degree. To PF resin/graphite matrix material without carbon fiber added, if PF resin content is 15.wt%, its flexural strength is 49.0MPa and electrical conductivity is 111S/cm. But with adding carbon fiber by TNALPOST and the same PF resin content , the composite flexural strength and electrical conductivity approach 68MPa、122S/cm respectively, both mechanical property and electrical property satisfy the requirement of USA Department of Energy on carbon filler/polymer composite bipolar plate. The PF resin/graphite composite without carbon fiber added presents brittle fracture mode, but with carbon fiber added, it presents ductile fracture mode. According to the fracture morphology by scanning electron microscopy, carbon fiber and matrix is on relatively weak boundary bonding state accompanied by fiber de-bounding、sliding、pulling-out and bridge-making to crack, they are main factors contributed to improving composite toughness.