Papers by Keyword: Carbon Fiber (CF)

Abstract: The effect of recovered carbon fiber (rCF) to the burning property of polyurethane composites was investigated. The carbon fiber reinforced polymer (CFRP) in mat form was first glycolysed at 190-200 oC and characterized by FTIR, TGA, DSC and SEM analyses. The rCF was added at 0, 0.5, 1.0 and 1.5% (w/w). The polyurethane filled with recovered carbon fiber composites (PU-rCF) have also undergone burning test. The TGA analysis of PU-rCF indicated the percentage of weight loss decreased from 95.6% to 91.4% as rCF content increased. The DSC showed the glass transition temperature, T_g of PU-rCF increased with increasing addition of rCF from 56.7 to 63.0oC. The burning rate of the PU-rCF decreased from 6.1 mm∙s^-1 to 2.8 mm∙s^-1 with increasing rCF. The FTIR analysis confirmed that there was no chemical interaction between the rCF and PU. The addition of rCF to PU has improved the burning property of the composite.

Abstract: This paper explicitly highlights the modal analysis of thin walled multi-cell multi-tapered composite beams in cantilever configurations, using MSC Patran / Nastran finite element package. Initially, the verification of the model was done with the analytical results in order to ensure the model accuracy. All the multi-tapered beams under examination are composed of closed section and three cell configuration. There is a vivid description of all the effects of composite material and stacking sequence on the modal frequencies. It also suggests the ways to shift the natural frequencies of the multi-tapered beams. This paper verifies the effects of different geometrical configurations of beams (tapered angles, lengths and point of variation of tapered angles) on the modal frequencies. This research is also useful in aerospace industry while designing the aircraft wing, which would experience the vibrations due to wind gust and engine cycles.

Abstract: PO/CB (Polyolefin/Carbon Black) PTC (Positive Temperature Coefficient) composite with easy processing, low cost characteristics has been applied widely. But it suffered from a relatively short lifespan because of its NTC (Negative Temperature Coefficient) effect and low PTC intensity. In order to overcome this shortcoming, the CF was calcination-treated to prepare LDPE/CF (Low Density Polyethylene/Carbon Fiber) PTC composite. Influence of length, content and treatment method of CF on PTC properties of composites was investigated. Results showed that 0.5mm length CF in composites had higher PTC intensity than that of 2mm length CF. PTC intensity of the composites was enhanced more effectively by calcination treated CF compared to the untreated CF. The maximum PTC intensity was 8.1 when CF’s content was at 8wt%.

Abstract: The characteristics, structure and applications of polyetheretherketone (PEEK) composites are introduced briefly. The research progress of friction and wear resistance properties of PEEK composites, modified by carbon fiber, other nanometer and micro-particles, are summarized. Suggestions for further research are put forward.

Abstract: Phenomenological constitutive equations are applied successfully to predict stress-strain relationship for semi-crystalline polymers at high strain rates encountered in mechanical tests. The parameters of mechanical behaviour law for polymer composites with nanoscopic additives and carbon fibres can be identified by applying a known law over a lot of data obtained from compressive tests. The objective of this study is to investigate the applicability of the model G'Sell - Jonas in the case of poly (ether-ether-ketone) composites with carbon nanotubes and carbon fibres.

Abstract: This paper presents a study of the wearing behaviour of polymeric composite materials reinforced with short carbon fibres. Reinforces carbon fiber materials are more effective if refer to specific properties per unit volume compared to conventional isotropic materials. The composite materials used in this research work are obtained combining epoxy with short carbon fibres with titanium carbide and tantalum carbide in order to investigate the wearing intensity of the obtained composites. Varying the percent of epoxy from 29,35% to 43,92% and the percent of short carbon fibres from 35,43% to 53,70%, two different composite materials are obtained and tested. Wearing intensity tests are carried out, at room temperature, in dry conditions, on a pin-on-disc machine. The friction coefficient was measured maintaining constant the rotational speed (14 m/s) and time (120s) and varying the pin-on-disc pressing force: 4, 8 and 12 daN. The pressing load had different effects on the wearing behaviour of the composite coating in dry friction condition. With low percent of epoxy and high percent of carbon fibers the wearing intensity is touching the highest value and gradually decreases with the increasing load, while in low percent of carbon fibers the wearing intensity became larger gradually along with the load increasing.

Abstract: The first results of an experimental campaign are reported that evaluates the efficiency of anchored CFRP reinforcements on brick masonry. Near End Supported Single Shear Tests were carried out on masonry pillars made according two different patterns, in order to detect the influence of both bed and perpend joints. The results are compared with results obtained from previous experimental campaign in which CFRP reinforcements were applied on “only brick” surfaces.

Abstract: The surface modification of carbon nanotubes (CNTs) has been recently observed to influence the distribution of CNTs in epoxy resin and the mechanical properties and electrical conductivities of these CNTs. Accordingly, the treatment of CNTs to with organic acids to oxidize them generates functional groups on the surface of CNTs. This investigation studies the consequent enhancement of the mechanical properties and electrical conductivities of CNTs. The influence of adding various proportions of CNTs to the epoxy resin on the mechanical properties and electrical conductivities of the composites thus formed is investigated, and the strength of the material is tested at different temperatures.The test results also indicate that mechanical strength and electrical conductivity increase with the amount of CNTs added to the composites. Different coefficients of expansion of the matrix, fiber and CNTs, are such that overexpansion of the matrix at high temperature results in cracking in it.Moreover, the creep behaviors of carbon fiber (CF) /epoxy resin thermosetting composites and CNTs/CF/ epoxy resin composites were tested and analyzed at different stresses, orientations of fiber, temperatures and humidities. The creep exhibits only two stages-primary creep and steady-state creep. The effects of creep stress, creep time, and humidity on the creep of composites that contain various proportion of CNTs were investigated at various temperatures.Additionally, increasing the number of cycles in cyclic creep tests at room temperature resulted in a decrease in creep strain even at a high temperature of 55°C. Possible room temperature creep mechanisms have been proposed and discussed. With increasing number of creep tests, the creep strain decreased due to strain hardening which occurred during creep. Creep strain is believed to increase with applied stress, creep time, humidity, temperature and degree of the angle θ between the orientation of fiber and the direction of the applied stress.Finally, the test results of creep strain of CF/epoxy resin composites and CNTs/CF/epoxy resin composites tested under various conditions can be smoothly fitted by the fitting curves of Findley power law.

Abstract: Experimental observations and data are employed to elucidate the effect of indenter size on the deformation and energy absorption of composite sandwich beams. Unlike metal face sheets that yield and plastically deform to create an intact indentation zone; composite face sheets tend to fail in a brittle manner resulting in fibre breakage that leads to widespread fracture. This mode of failure can dictate how the load is transferred throughout the structure and directly affect the energy absorption character of the composite sandwich beam. Quasi-static and low velocity impact (LVI) three-point bending experiments with various indenter diameters were conducted to observe the interaction between indenter and face sheet and the energy absorption properties. The results are compared with existing analytical expressions.

Abstract: The paper have described the vibration and damping analysis of carbon fiber wind turbine blade with viscoelastic damping treatment using commercial ANSYS program. The wind turbine system including a carbon fiber layer and a viscoelastic damping layer was attached on inside of carbon layer. Firstly, the natural frequencies and mode shape of pure carbon fiber turbine blade were compared with viscoelastic damping treated turbine blade using modal analysis. There were 1mm, 2mm, 3mm thickness damping layer finite element model to be constructed. The results show the little changes in lower first mode but getting smaller with higher modes. Finally, the frequency response functions of damped and undamped turbine blade were calculated for investigating the damping effect of viscoelastic damping layer. As shown in the results, the viscoelastic damping layer has good damping effect for vibration control of carbon fiber wind turbine blade.