Resumo em Inglês:

Abstract: Alcântara Space Center (ASC) is the Brazilian gate to the space where rockets of different sizes are launched. At ASC there is a relative topographical variation, coastal cliff, which modifies the atmospheric boundary layer characteristics and can cause interference for operations of rockets. In the present work, a simplified model (mock-up) was studied in a wind tunnel. A scale factor of 1:1000 was used and the atmospheric flow was measured using the hot wire anemometer (HWA) and particle image velocimetry (PIV) techniques. Using of HWA it was possible to calculate values of average wind speed and fluctuations in a set of points of the section of tests that representing the region of the ASC. Through these measures, other meteorological parameters that represent the atmospheric flow, such as the friction velocity (u*), the roughness length (z0) from the logarithmic profile and the alpha exponent (a) of the power law were calculated. With the use of the PIV´s technique, the streamlines and the vorticity fields were obtained and it was noticed that the vorticity generated downwind of the coastal cliff has a strong turbulence (vorticities around 2000 s-1). A rectangular building (simulating the mobile integration tower) was inserted at the mock-up and the downwind turbulence was similar to the one generated by the coastal cliff.

Resumo em Inglês:

Abstract: Aircraft crews are subjected to radiation doses of cosmic origin in the regular exercise of their functions. The present paper gives an estimate of typical doses received by crews of the Flight Test Special Group of DCTA (GEEV) from July 2007 to November 2009. The dose estimates were performed using the CARI-6 and PCAIRE codes and were compared with each other and with values obtained by other authors in other regions of the globe, being analyzed from the standpoint of estimating radiobiological risk.

Resumo em Inglês:

Abstract: Thrust and drag components must be defined and properly accounted in order to estimate aircraft performance, and this hard task is particularty essential for propulsion system where drag components are functions of engine operating conditions. The present work describes a numerical method used to calculate the drag in different nacelles, long and short ducted. Two- and three-dimensional calculations were performed, solving the Reynolds Averaged Navier-Stokes (RANS) equations with a commercial Computational Fluid Dynamics (CFD) code. It is then possible to obtain four drag components: wave, induced, viscous and spurious drag using a far-field formulation. An expression in terms of entropy variations was shown and drag for different nacelle geometries was estimated.

Resumo em Inglês:

Abstract: The poly (aryl ether ketones) are used as matrices in advanced composites with high performance due to its high thermal stability, excellent environmental performance and superior mechanical properties. Most of the physical, mechanical and thermodynamic properties of semi-crystalline polymers depend on the degree of crystallinity and morphology of the crystalline regions. Thus, a study on the crystallization process promotes a good prediction of how the manufacturing parameters affect the developed structure, and the properties of the final product. The objective of this work was to evaluate the thermoplastics polymers PEKK e PEEK by DSC, aiming to obtain the relationship between kinetics, content, nucleation and geometry of the crystalline phases, according to the parameters of the Avrami and Kissinger models. The analysis of the Avrami exponents obtained for the studied polymers indicates that both showed the formation of crystalline phases with heterogeneous nucleation and growth geometry of the type sticks or discs, depending on the cooling conditions. It was also found that the PEEK has a higher crystallinity than PEKK.

Resumo em Inglês:

Abstract: Thermal aging of hydroxy-terminated polybutadiene (HTPB) stabilized with 2,6-di(tert-butyl)hydroxytoluene (BHT) was carried out at 60ºC from 1 to 11 weeks. Samples of 200 mL were stored in sealed 500-mL Erlenmeyer flasks under atmospheric pressure or vacuum and periodically withdrawn for physical and chemical analysis, infrared spectroscopy characterization and measurement of HTPB/IPDI (isophorone diisocyanate) reactivity, expressed as pot life. Mechanical properties of the cured polyurethane, prepared from aged HTPB, were assayed by uniaxial tension tests. Despite the unchanged chemical structure, an increase in HTPB/IPDI binder reactivity was observed, being correlated with BHT depletion measured as color change (yellowing). Aging of HTPB showed no interference on mechanical properties of the cured polyurethane.

Resumo em Inglês:

Abstract: Phenolic resin has long been used as matrix for composites mainly because of its flame retardant behavior and high char yield after pyrolysis, which results in a self supporting structure. The addition of ceramic powders, such as SiC and B4C, as fillers to the phenolic resin, results in better thermo-oxidative stability, but as drawbacks, it has poor homogeneity, adhesion and processing difficulties during molding of the composites. The addition of single elements, such as boron, silicon and phosphorus in the main backbone of the thermo-set resin is a new strategy to obtain special high performance resins, which results in higher mechanical properties, avoiding the drawbacks of simply adding fillers, which results in enhanced thermo-oxidative stability compared to conventional phenol-formaldehyde resins. Therefore, the product can have several applications, including the use as ablative thermal protection for thermo-structural composites. This work describes the preparation of a boron-modified phenolic resin (BPR) using salicyl alcohol and boric acid. The reaction was performed in refluxing toluene for a period of four hours, which produced a very high viscosity amber resin in 90% yield.The final structure of the compound, the boric acid double, substituted at the hydroxyl group of the aromatic ring, was determined with the help of the Infrared Spectroscopy, 1H-NMR, TGA-DSC and boron elemental analysis. The absorption band of the group B-O at 1349 cm-1 can be visualized at the FT-IR spectrum. 1H-NMR spectra showed peaks at 4.97-5.04 ppm and 3.60-3.90 ppm assigned to belong to CH2OH groups from the alcohol. The elemental analysis was also performed for boron determination.The product has also been tested in carbon and silicon fibers composite for the use in thermal structure. The results of the tests showed composites with superior mechanical properties when compared with the conventional phenolic resin.

Resumo em Inglês:

Abstract: Advanced carbon fiber hybrid carbon-ceramic matrix composites are realizing their potential in many thermostructural components for aerospace vehicles. This work presents ab-initio predictions of elastic constants and thermal properties for 2.5D carbon fiber reinforced carbon-silicon carbide hybrid matrix composites, by using the homogenization technique. The homogenization technique takes properties of individual components of the composites (fiber and matrix) and characteristics of the geometrical architecture of the preform to perform calculations. Ab-initio modeling of mechanical and thermal properties is very attractive, especially during the material development stage, when larger samples may be prohibitively expensive or impossible to fabricate. Modeling is also useful when bigger samples would be prohibitively expensive or impractical. Thermostructural composites made of 2.5D preforms are easy to manufacture in relation to 3D preforms. Besides, 2.5D preforms are also resistant to thermo cycling and have high resistance to crack propagation in relation to ply stacked composites such as unidirectional (1D) and bidirectional (2D) structures. The calculations were performed by setting an overall carbon fiber volume fraction at 40, 45 and 50 for a 2D stacked composite, and volume fraction in Z-direction of 2, 4 and 6.

Resumo em Inglês:

Abstract: The most usual ceramic material for coating turbine blades is yttria doped zirconia. Addition of niobia, as a co-dopant in the Y2O3-ZrO2 system, can reduce the thermal conductivity and improve mechanical properties of the coating. The purpose of this work was to evaluate the influence of the addition of niobia on the microstructure and thermal properties of the ceramic coatings. SEM on coatings fractured cross-section shows a columnar structure and the results of XRD show only zirconia tetragonal phase in the ceramic coating for the chemical composition range studied. As the difference NbO2,5-YO1,5 mol percent increases, the tetragonality increases. A significant reduction of the thermal conductivity, measured by laser flash technique in the zirconia coating co-doped with yttria and niobia when compared with zirconia-yttria coating was observed.

Resumo em Inglês:

Abstract: The present work describes details of the several steps of the technology involved for the orbital Gas Tungsten Arc Welding (GTAW) process of pure commercially titanium tubes. These pieces will be used to connect the several components of the propulsion system of the China-Brazilian Satellite CBERS, and is part of the Brazilian aerospace industry development. The implantation involved the steps of environment control; cut and facing of the base metal; cleaning procedures; piece alignment; choice of the type, geometry and installation of the tungsten electrode; system for the pressure of the purge gas; manual tack welding; choice of the welding parameters; and, finally, the qualification of welding procedures. Three distinct welding programs were studied, using pulsed current with increasing speed, continuous current and pulsed current with decreasing amperage levels. The results showed that the high quality criteria required to the aerospace segment is such that usual welding operations must be carefully designed and executed. The three welding developed programs generated welds free of defects and with adequate morphology, allowing to select the condition that better fits the Brazilian aerospace segment, and to be implanted in the welding of the CBERS Satellite Propulsion System.

Resumo em Inglês:

Abstract: In this work, three welding programs for orbital gas tungsten arc welding (GTAW), previously developed, were used, using pulsed current and increasing speed (#A), constant current (#B) and pulsed current and decreasing current (#C). One of these should be used for the propulsion system of the Satellite CBERS (China - Brazil Earth Resources Satellite). Welded joints using tubes of commercially pure titanium were obtained with these procedures, which were characterized by means of mechanical and metallographic tests. The obtained results showed that the three welding procedures produce welded joints free of defects and with adequate shape. Although small differences on mechanical properties and on microstructure have been observed, the three welding programs attained compatible results with international standards used in the aerospace segment. The welding program #B, due to the reduced heat input used, was considered to obtain slightly advantage over the others.

Resumo em Inglês:

Abstract: Recognizing the need to consolidate the research and development (R&D) activities in microelectronics fields in a strategic manner, the Plasma Processes Laboratory of the Technological Institute of Aeronautics (LPP-ITA) has established a technology roadmap to serve as a guide for activities related to development of sensors based on silicon carbide (SiC) thin films. These sensors have also potential interest to the aerospace field due to their ability to operate in harsh environment such as high temperatures and intense radiation. In the present paper, this roadmap is described and presented in four main sections: i) introduction, ii) what we have already done in the past, iii) what we are doing in this moment, and iv) our targets up to 2015. The critical technological issues were evaluated for different categories: SiC deposition techniques, SiC processing techniques for sensors fabrication and sensors characterization. This roadmap also presents a shared vision of how R&D activities in microelectronics should develop over the next five years in our laboratory.

Resumo em Inglês:

Abstract: The inherent risk in high-tech activity requires the construction of technological strategies that serve global strategy of the company. The present study aimed to characterize the technological position of small and medium technology-based companies of the aeronautical sector located in the Vale do Paraíba, and to examine whether these companies have a technological strategy formalized and disseminated. The adopted methodology was a descriptive exploratory research, carried out through in-depth individual interviews conducted with the small e medium company's owners of the cities of Caçapava, São José dos Campos and Taubaté, Brazil. The authors concluded that it is necessary that companies, especially small and medium-sized, adopt a technological innovation strategy integrated with the company's overall strategy. This will help keeping them competitive within their specificities, and not only in the domestic market, but also in international markets.

Resumo em Português:

Resumo: O Departamento de Ciência e Tecnologia Aeroespacial (DCTA) tem função relevante na satisfação das necessidades da Força Aérea e no incremento da capacidade tecnológica global do país. Assumir um papel pró-ativo na gestão da inovação é fundamental para o cumprimento dos objetivos estratégicos e deve ser encarado como uma condição necessária para a constituição de um ambiente propício à disseminação do conhecimento produzido às empresas do parque industrial brasileiro. Este trabalho fundamentou-se em duas abordagens: a de que a inovação tecnológica é um processo cumulativo - o qual é estabelecido por meio da interação entre o governo, empresas e instituições de P&D, além do mercado - e a abordagem technological foresight, no sentido de que a gestão estratégica da inovação tecnológica implica negociar demandas e campos promissores de investigação e também em atuar nas condições do ambiente no qual estão inseridos os atores, promovendo uma macrocoordenação. Este artigo apresenta considerações sobre a indústria aeroespacial brasileira e sobre o contexto da inovação tecnológica no Ministério da Defesa e no Comando da Aeronáutica, especificamente no DCTA; o objetivo foi enfatizar a necessidade de uma atuação estratégica pró-ativa para a geração de inovação tecnológica e propor um método de gestão dessa inovação para o DCTA.

Resumo em Inglês:

Abstract: The Aerospace Science and Technology Department (DCTA, acronym in Portuguese) has a relevant role. of attending the air force necessities and of incrementing the Brazilian's global technological capacity. Taking over to a pro-active role in the innovation management is a fundamental step to achieve the strategic goals and it must be faced as a necessary condition for the formation of a favorable environment to disseminate knowledge to the Brazilian industrial sector. This work is based on two approaches: the technological innovation is a cumulative process - which is established by means of the interaction among government, enterprises and R&D institutions, besides the market - and the technological foresight approach, in which the strategic management of the technological innovation implies negotiating demands and promising investigation fields, besides influencing on conditions of the environment in which the actors are inserted, promoting a macro-coordination. This paper presents considerations about the Brazilian aerospace industry and about the technological innovation context at the Defense Ministry and at the Aeronautic Command, specifically at DCTA. The object was to emphasize the necessity of a pro-active strategic action in order to generate technological innovation, and to propose a method of management of this technology for DCTA