Resumo em Inglês:

Abstract: Reinforced thermoplastic structural detail parts and assemblies are being developed to be included in current aeronautic programs. Thermoplastic composite technology intends to achieve improved properties and low cost processes. Welding of detail parts permits to obtain assemblies with weight reduction and cost saving. Currently, joining composite materials is a matter of intense research because traditional joining technologies are not directly transferable to composite structures. Fusion bonding and the use of thermoplastic as hot melt adhesives offer an alternative to mechanical fastening and thermosetting adhesive bonding. Fusion bonding technology, which originated from the thermoplastic polymer industry, has gained a new interest with the introduction of thermoplastic matrix composites, which are currently regarded as candidate for primary aircraft structures. This paper reviewed the state of the art of the welding technologies devised to aerospace industry, including the fields that Universidade Estadual Paulista Júlio de Mesquita Filho and Universidade de São Paulo are deeply involved.

Resumo em Inglês:

Abstract: This study had as main objective to show that the adequate combination of magnetic and dielectric particles can improve the radar absorbing materials performance. For this, formulations of polyurethane resin loaded with carbon black and NiZn ferrite, with general composition MFe2O4, where M = Ni, Zn or both elements, homogenized by conventional mechanical mixture, were prepared. Reflectivity measurements of different coating formulations applied on aluminum flat plates (l.0 ± 0.l mm-thickness) were performed using the Naval Research laboratory arch technique, in the X-band frequency range. X-ray diffraction and magnetic susceptibility evolution analyses of the tested ferrite showed that this magnetic additive presents different phases. Attenuation values of ~4 dB (~60% of the wave absorption) for the polyurethane/carbon black/ferrite formulation, 49/l/50 in wt.%, respectively, were found. This low attenuation values (~4 dB) is attributed to the presence of different phases in the NiZn ferrite, as shown by both the X-ray pattern and the magnetic susceptibility analyses, and also to the thickness and the additives concentration used. As main result, this study shows that the adequate combination of carbon black and NiZn ferrite improves the processed radar absorbing materials performance due to the adequate adjustment of the impedance matching, which favors the microwave absorber-electromagnetic wave interaction.

Resumo em Inglês:

Abstract: In order to aid the design of bonded joints, a computational tool named System of Analysis for Joints (SAJ) was developed. The software can analyze single and double lap bonded joint with composite-composite or metal-composite materials as adherent parts. Thus, SAJ can calculate the stress distribution, loads and displacements. Their results were compared to finite element software (ABAQUS™) and to specific composite analysis software (ESAComp™). After that, a study about the influence of joint design parameters on the mechanical behavior of the bonded joint was carried out. In regards to parametric study, SAJ leads to some conclusions, which can be used as a guide during the product design process. Therefore, aided by the computational tool, it is possible to perform a conceptual and preliminary design of bonded joints with more accuracy and varying many parameters (materials; fiber orientation and stacking sequence of the laminate; thickness; overlap length).

Resumo em Inglês:

Abstract: Following continually varying customer specific demands across the globe, aircraft design strategy is constantly changing. The manufacturers are focusing on finding ways to make the products more .fiexible thus meeting the several product variants with controlled manufacturing costs. Herein, the .fiexibility addresses the variety of needs with less product combinations through standardization/interchangeability while meeting all the requirements. Nowadays, the industry has also realized that the cost reduction has been one of the key driving factors to keep in the free-market competition. Therefore, it is imperative to find innovation methods across the manufacturing cycle of the aircraft keeping a close watch on cost control. The scope of innovation is extended to all areas of design encompassing its phases of all aircraft systems. The context of this paper is pertained to air conditioning and electrical systems, which are two areas where the routing of air ducts and electrical wires/cable bundles, respectively, need to be securely clamped to the structural elements. Brackets are extensively used for holding these ducts and cable bundles. It is found that, presently, several conventional clamping methods are used for holding the ducts and wire bundles individually. Hence, it is required to develop innovative brackets to hold combined both ducts and wire bundles wherever is possible. The new brackets impact potentially on weight and cost reduction in addition to substantial savings on assembly and maintenance time. The brackets thus designed have sufficient strength, low weight, and are easy to manufacture to be integrated with selected Air Transport Association systems. This paper aimed at describing the scope of the task, design requirements and best practices adopted while executing the pro}ect for an aerospace customer.

Resumo em Inglês:

Abstract: In this paper, a new anti-swing controller for helicopter slung load system near hover flight is proposed. This controller is based on time-delayed feedback of the load swing angles. The output from this controller is additional displacement that was added to the helicopter trajectory in the longitudinal and lateral directions. Hence, its implementation is simple and it only needs a small modification to the software of helicopter position controller. The parameters of the controllers are determined using the method of particle swarms by minimizing an index, which is a function of the load swing history. The simulation results show the effectiveness of the proposed controller in suppressing the swing of the suspended load and the stabilization of the helicopter.

Resumo em Inglês:

Abstract: An essencial requirement for a launcher with uncontrolled last stage is to compute the ignition time of that stage and its attitude, in order to obtain a proper orbit transfer from a nonpropelled trajectory to a desired orbit, since such stage it cannot change its velocity profile and its direction. This article presents an algorithm that allows achieving the proper conditions to inject a vehicle with uncontrolled last stage into a descent Keplerian trajectory, in order to permit its reentry through the Earth's atmosphere with strictly defined conditions of radius, velocity, andflight path angle at the entry interface. These specific conditions impose requirements to the configuration, performance, and trajectory of the launcher. This strategy considers that the total energy is applied instantlyfor the reentry orbit injection. Impulsive ignition time and necessary attitude for the last stage are obtained based on orbital parameters, having a match between the nonpropelled and reentry orbits, and boundary conditions at the initial state and at the entry interface. Impulsive ignition time was corrected for compensating the impulsive assumption and the calculated attitude related to an inertial frame. The obtained results show the efficiency of the algorithm involving reentry missions with uncontrolled last stage, as the Sharp Edge Flight Experiment (SHEFEX) program.

Resumo em Inglês:

Abstract: This paper has described a system design process, based on a multidisciplinary optimization technique, of a conceptual optimized hybrid propellant rocket motor. The proposed engine could be a technological option for the reentry maneuvering system of the Brazilian recoverable satellite (SARA), which was designed by the Brazilian Institute of Aeronautics and Space. The resulting optimized propulsion system must be viewed as a proof of concept allowing comparison to more conventional technologies, i.e., liquid and solid motors. Design effort was conducted for hybrid propellants engines based on a liquefying fuel (solid paraffin) and two different oxidizers, H2O2 (90% high-testperoxide) and self-pressurizing N2O. The multidisciplinary configuration optimization technique was supported on geometrical operating parameters of the motor, rather than on performance, in order to facilitate subsequent design and fabrication. Results from the code presented a hybrid motor, which was considered a competitive alternative for the deboost engine when compared to the traditional chemical systems, solid and liquid bipropellant, and monopropellant. The estimated mass of the reentry system, for the cases addressed in this study, varied from 22 to 29 kg, which is lower than either liquid bipropellant or solid engines formerly proposed.

Resumo em Inglês:

Abstract: In this work, the two-dimensional computational simulation of the ablative process in a composite used in rocket thermal protection systems via an interface tracking method was presented. The ablative model considers the presence of two simultaneous moving fronts, the pyrolysis and char fronts. The results were compared with some experimental data, showing better agreement than the one-front model. Such procedure will allow a more accurate dimensioning of rocket thermal protection systems, contributing for project optimization.

Resumo em Inglês:

Abstract: For geographic regions where significant power demand and highest electricity prices occur during the warm months, a gas turbine inlet air cooling technique is a useful option for increasing output. Inlet air cooling increases the power output by taking advantage of the gas turbine's feature of higher mass flow rate, due the compressor inlet temperature decays. Industrial gas turbines that opera te at constant speed are constant-volume-flow combustion machines. As the specific volume of air is directly proportional to the temperature, the increases of the air density results in a higher air mass flow rate, once the volumetric rate is constant. Consequently, the gas turbine power output enhances. Different methods are available for reducing compressor intake air temperature. There are I two basic systems currently available for inlet cooling. The first and most cost-effective system is the evaporative cooling. Evaporative coolers make use of the evaporation of water to reduce the gas turbine inlet air temperature. The second system employs two ways to cool the inlet air: mechanical compression and absorption. In this method, the cooling medium flows through a heat exchanger located in the inlet duct to remove heat from the inlet air. In the present study, a thermodynamic analysis of gas turbine performance is carried out to calculate heat rate, power output and thermal efficiency at different inlet air temperature and relative humidity conditions. The results obtained I with this model are compared with the values of the condition without cooling herein named of Base-Case. Then, the three cooling techniques are computationally implemented and solved for different inlet conditions (inlet temperature and relative humidity). In addition, the gas turbine was tested under different cooling methods for two Brazilian sites, and comparison between chiller systems (mechanical and absorption) showed that the absorption chiller provides the highest increment in annual energy generation with lower unit energy costs. On the other hand, evaporative cooler offered the lowest unit energy cost but associated with a limited cooling potential.

Resumo em Inglês:

Abstract: In the early 20th century, Aviation pioneers in North America and Europe experienced quite different working ambiences. The Europeans, except for those living in England, embodied the spirit of the French Revolution; the Ameri-cans incorporated the ideas from the Industrial Revolution or, according to many historians, the English Revolution. Due to this fact, Aviation in Europe and in the United States evolved quite differently. In order to justify the establishment of those connections, the present work has described the way aviation pioneers designed and built theirflying machines and the state of aviation in North America and in Europe in the early 20th century. A collaborative working atmosphere was present among the European pioneers thanks to the French Revolution ideas that found general acceptance in Europe. The European aviation pioneers frequently exchanged information regarding aeronautical experience or even whole designs. Contrary to this, in the United States aviation, its development suffered from lack of information from the people who were competing for the firstflight. Indeed, a fierce competition among the individuals was established. The knowledge coming from Europe, noticeably from the Germans Lilienthal brothers and George Cayley, was being retransmitted by open-minded people like Octave Chanute. That is the reason why America fell behind Europe in regard to airplane technology before the broke out of World War I and a patent war started in the United States among their aviation pioneers. In France, the Aéro-Club de France was created in the last years of the 19th century. Among its objectives, one was to attest the first person to perform a flight with a heavier-than-air machine. After the Brazilian Santos-Dumont's flight with his 14bis biplane in 1906, in Paris, Wilbur Wright went to Europe in 1907 and established a workshop to continue improving the Flyer concept. Wright's supporter, Octave Chanute, had warned him that the aviation world was catching up fast, especially in France. However, Wilbur was only able to get the Flyer airborne in August 1908 in France, with disappointing results. However, impressive flights took place in late 1908 and the Wright brothers' European Flyer was the basic airplane they were able to sell to the US armed forces for the first time in 1909. After Santos-Dumont's success in flying his 14bis airplane in 1906, many of his comrades established airplane factories. Those Dumont's friends were eager to sell planes to the French government, and a competitive atmosphere settled down in the old continent. In addition, the collaborative ambience ceased because the World War I was only a matter of time.

Resumo em Inglês:

Abstract: The increased complexity of organizational contexts in the end of the 20th centurv and beginning of the 21st century has resulted in the increment of the variables number to be considered during a performance evaluation. Therefore, many professionals began to search methods that would enable the simultaneous analvsis of multiple criteria. Thus, this paper has investigated the application of a multicriteria approach to evaluate the performance in the development of subsvstems during the development of complex products, by using the PROMETHEE GDSS and the GAIA methods. To achieve this objective, a study on the ITA-SAT satellite project wasperformed, in which a perception analvsis of the members of the project regarding the development of each subsvstem was carried out. Once these perceptions were captured, the proposed approach was used to identify subsvstems with less satisfactorvperformances. Finally, the results were analyzed and brought to discussion at a meeting with managers and project members with a feedback to the conclusions of this study.