Brito C.A.R.,University |
Pardini L.C.,IAE |
Alves N.P.,Quimlab Cientifica Ltda
Polimeros | Year: 2013
This paper summarizes the conventional spinning processes used to obtain polyacrylonitrile (PAN). A brief history of the development of PAN fiber is presented. The employability of PAN fibers is attributed mainly to the textile sector and aviation (as main precursor for carbon fibers). Currently, the wet spinning process became the only means of industrial production of PAN fibers, which employs DMF (dimethylformamide) as the main solvent for this technique of spinning. We describe a new method of spinning of PAN with no need of using highly toxic solvents. This innovative technology enables spinning by melting PAN using glycerin (from biodiesel production) as the primary plasticizer.
Cioffi M.O.H.,Sao Paulo State University |
Voorwald H.J.C.,Sao Paulo State University |
Procedia Engineering | Year: 2010
Fiber reinforced polymer composites have been widely applied in the aeronautical field. However, composite processing, which uses unlocked molds, should be avoided in view of the tight requirements and also due to possible environmental contamination. To produce high performance structural frames meeting aeronautical reproducibility and low cost criteria, the Brazilian industry has shown interest to investigate the resin transfer molding process (RTM) considering being a closed-mold pressure injection system which allows faster gel and cure times. Due to the fibrous composite anisotropic and non homogeneity characteristics, the fatigue behavior is a complex phenomenon quite different from to metals materials crucial to be investigated considering the aeronautical application. Fatigue sub-scale specimens of intermediate modulus carbon fiber non-crimp multi-axial reinforcement and epoxy mono-component system composite were produced according to the ASTM 3039 D. Axial fatigue tests were carried out according to ASTM D 3479. A sinusoidal load of 10 Hz frequency and load ratio R=0.1. It was observed a high fatigue interval obtained for NCF/RTM6 composites. Weibull statistical analysis was applied to describe the failure probability of materials under cyclic loads and fractures pattern was observed by scanning electron microscopy. © 2010 Published by Elsevier Ltd.
Schichi O.C.,University of Sao Paulo |
Henriques V.A.R.,IAE |
De Oliveira J.L.,IAE |
SAE Technical Papers | Year: 2012
Titanium alloys have been widely used in manufacturing of fans, compressor disks, and blades of advanced aircraft engines. However, titanium alloys are very sensitive to fretting fatigue damage, which may affect the safe reliability of the aircraft engine compressor. The multilayer coatings seem to be the most promising coating concept due to many requirements (e.g. multifunctional character, moderate residual stresses, good adherence to metallic substrates, proper hardness to toughness ratio and low friction coefficients) for titanium alloys exposed to complex wear conditions. This work aims the development of techniques for production of Ti/TiN multilayer coatings by Electron Beam Physical Vapor Deposition (EB-PVD) in order to define the influence of the number and thickness of the layers in the surface hardness of Ti-13Nb-13Zr alloy produced by powder metallurgy (P/M) from elemental hydrides. The samples were characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and Vickers indentation. The multilayers presented a continuous and columnar structure, large thickness and high adhesion to the substrates. It was possible to establish a relation involving the number and the thickness of the layers with the final surface hardness. Copyright © 2012 SAE International.
Costa A.P.,Sao Paulo State University |
Botelho E.C.,Sao Paulo State University |
Polimeros | Year: 2011
Advanced thermoplastic composites are an alternative to thermoset composites in many aeronautical applications owing to their superior properties. Among the thermoplastic matrix, PPS (poly phenylene sulfide) stands out due to its structural characteristics. The objective of this study is to evaluate the influence of environmental conditioning on the shear behavior of PPS/carbon fiber composites. Samples of this material have been conditioned in saline water solution, in hygrothermal conditioning and under UV radiation. After conditionings the specimens were evaluated by interlaminar shear strength (ILSS) and Iosipescu shear test methods. The environmental conditioning reduced the interlaminar shear stress (ILSS) of conditioned composites in comparison with non-conditioned composites tested with the same method (58.4 ± 1.9 MPa). The ILSS decreased by ca. 14 and 3%, respectively, after hygrothermal conditioning and saline water solution. Moreover, the values of interlaminar shear stress under UV radiation decreased by 2, 11 and 9% after exposure times of 300, 600 and 900 hours, respectively. The non-conditioned composites tested with the Iosipescu method (109.2 ± 0.4 MPa ) also had ILSS decreasing with environmental conditioning: the values decreased 6% after hygrothermal conditioning and 12% after saline water solution. The UV radiation exposure led to a decrease of 6, 10 and 14% following exposures during 300, 600 and 900 hours, respectively.
Smrcek L.,University of Glasgow |
Klein S.,Academy of Fine Art and Design |
27th Congress of the International Council of the Aeronautical Sciences 2010, ICAS 2010 | Year: 2010
This paper is primarily concerned with the design and manufacture of a flying car and problem of traffic management in the world today. A possible solution to this problem would be to design a flying or hovering car which will take the problem away from the overcrowded roads. Given technological advances in aircraft construction, navigation and operation; flying cars or personal aircraft is not only a possibility but a necessity for the future. The feasibility and viability of such a concept was investigated in terms of producing a conceptual design for a two-person carrying flying vehicle, manufacturing prototype, ground and in-flight testing. Flying cars have featured heavily in science fiction writing and films for many years, however the idea, of actually building such a vehicle only came into fruition at the start of the twentieth century. The design was somewhat unsuccessful and therefore research was discontinued. Production of other flying cars in US has been reported over the next three decades until recently. Traffic congestion on roads all over the world is becoming an overwhelming problem. Larger roads and motorways are especially overused which causes the average speed of vehicles at peak times to be reduced to around 35 miles per hour in some countries. This, in turn, means that extra fuel is wasted and the exhaust emissions in the atmosphere increase rapidly.One solution to the problem would be to merely build more roads, however this is a very expensive process and is not very viable in large built up areas. An alternative to expanding current traffic networks would be to develop a new system of highways in the sky for a future flying cars. Much like the cars of today flying cars will require similar rules as used by automobiles at present, and this is where the development of virtual "highways in the sky" present themselves. These skyways would be a network of predetermined routes controlled by the flying cars air traffic control and management. The computer system will also maintain the flying cars motion in terms of speed and direction so that they all remain suitably spaced in the air. The systems could be made up of a series of computer networks which can control all of the flying cars in the area it covers, instead of one world-wide system. Rules and legislations will have to be developed. This paper also is intended to summarize the literature review carried out in the context of flying car design. It outlines the main features and work done in this field in order to gain a relevant and comprehensive background. The final aim of the project is to create a flying car design concept and flying prototype and system for transport infrastructure. Therefore, all the information contained in the project has the purpose of setting the initial design requirements as well as looking at the feasibility of the production of such a vehicle. © 2010 by the International Council of Aeronautical Sciences - ICAS.