Wyniki wyszukiwania - Biblioteka Nauki

1

Test section design for measuring the drag coefficient of a suborbital rocket model at Ma 2.45

100%

Wasilczuk F. , Kurowski M. , Flaszyński P.

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tom Nr 3 (276)

86--100

EN

This study investigates the drag coefficient of three models of suborbital rockets with different nosecones. A test section allowing for force measurement of a 1:50 scale rocket model was designed with the aid of numerical simulations. The velocity obtained in the wind tunnel corresponds with a Mach number of 2.45. RANS simulations were used in verifying operating parameters, as well as testing the support configurations for connecting the model with the bottom wall of the tunnel section. Pressure distribution measurements on the top and bottom walls of the wind tunnel matched simulation results well. The shock structure in the test section was visualized using the schlieren technique, revealing that the measured angle of the main shock generated at the tip of the rocket matched the simulation data. Finally, the measured forces were compared with simulations for one of the nosecone configurations. Despite very good agreement for pressure distribution on the wind tunnel walls and shock structure, a significant mismatch in the forces measured was nevertheless observed: the simulated CD (0.57) being four times larger than that obtained in measurements (0.138). Further analysis of the test section is required to pinpoint the source of discrepancies and redesign the force measurement system to achieve improved force results.

2

Using Sandblasting and Sol Gel Techniques for the Preparation of a Metal Surface and Their Effects on the Durability of Epoxy-Bonded Joints

100%

Sałaciński M. , Zabłocka M. , Synaszko P.

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tom Iss. 4

94--99

EN

The epoxy-bonded joints are widely employed in aerospace in the Composite Patch Bonded Repair (CPBR) method used for repair metallic and composite structures. The properties of epoxy usually meet the mechanical and environmental requirements, but the durability of bonded joints depends also on the surface preparation. The most common techniques used for the surface preparation are Forest Product Laboratory’s (FPL) technique and Phosphoric Acid Anodizing (PAA). Both methods ensure very good adhesion but they have some disadvantages. They require the application of toxic and aggressive acids, dangerous for the operator. Also, the use of acids for cleaning the surfaces can cause corrosion. The sandblasting treatment of metal surfaces ensures quite good adhesion. This technique requires neither specialist equipment nor the use of toxic substances. Recommended by the Royal Australian Air Force (RAAF) the technique is also used by the Air Force Institute of Technology. Sol Gel is a new product developed for the treatment of metal surfaces before bonding. It is not hazardous for the operator and it does not cause corrosion due to its specific chemical composition. The article describes the behavior of bonded joints between two metal surfaces prepared using sandblasting and Sol Gel. The investigations were carried out in various environment conditions according to the ASTM Standards.

3

An Analysis of the Spanish Aerospace Sector: the Case of the Start-Up Ecosystem in Madrid

100%

Morillas-Guerrero J. J.

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tom Nr 4 (269)

37--47

EN

After launching the First Survey on the Spanish aerospace industry, important results were obtained, which helped to delve into the roots of the digital transformation (DT) of this sector, focussing on the Madrid region (Spain). From this type of study, which had not been carried out until now at the regional level, extremely interesting data have emerged that allow us to define the situation of Madrid companies in the aerospace sector. We have characterised and quantified the influence of what we have called ‘transformative enablers’. We have also analysed their relationships with the general characteristics of the companies, such as location, number of employees, legal form or type of company. We also obtained interesting conclusions about the role of respondents within organisations to discover the ‘capillarity’ of their situations and thus understand the degree of DT in terms of whether they achieve the so-called Industry 4.0 (Fourth Industrial Revolution) specifications. Finally, we have carried out a monographic study of the disruptive innovations within the start-up ecosystem to understand its definition and scope in the aerospace industry as a precursor of the latter’s DT.

4

Leading-edge polymer/carbonaceous nano-reinforcement nanocomposites — opportunities for space sector

58%

Kausar A. , Ahmad I.

Advances in Materials Science

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2023

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tom Vol. 23, nr 4(78)

99--122

EN

Carbonaceous or nanocarbon nano-reinforcement nanocomposites have been found as emergent candidates for aerospace industry. Consequently, the multifunctional nanocomposites have been fabricated using marvelous nanocarbon nanostructures like graphene, carbon nanotube, fullerene, carbon black, etc. Manufacturing techniques have also been engrossed for the formation of high performance engineering nanocomposites having fine strength, heat stability, flame resistance, and other space desired features. These practices include solution, in situ, and melt procedures, on top of specific space structural design techniques, for the formation of aerospace structures. The aerospace related material property enhancements using various carbonaceous nano-reinforcements depends upon the type of nanocarbon, dimensionality, as well as inherent features of these nanostructures (in addition to the choice of manufacturing methods). Furthermore, carbon nano-reinforcements have been filled, besides carbon fibers, in the epoxy matrices. Nanocarbon coated carbon fibers have been filled in epoxy resins to form the high performance nanomaterials for space structures. The engineering features of these materials have been experiential appropriate for the aerospace structures. Further research on these nanomaterials may be a key towards future opportunities in the aero systems. Additionally, the explorations on structure-property relationships of the carbonaceous nanocomposites have been found indispensable for the development of advanced aerospace structures.

5

Nanocomposites of nanocarbon functionalized carbon fibers — manufacturing to methodological applications

58%

Kausar A. , Ahmad I.

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tom Vol. 24, nr 1(79)

46--71

EN

Carbon fibers have been technically applied in high performance materials and industrial scale applications. Importantly, carbon fiber reinforced composite materials have found applications in aerospace industries. These properties of carbon fiber reinforced composites depend upon the carbon fiber features such as length, orientation, surface properties, adhesion with matrices, etc. To improve the surface properties of carbon fibers and adhesion and interactions with polymers, fiber modification has been suggested as an efficient approach. Carbon nanoparticle or nanocarbon functionalized carbon fibers have been manufactured using various facile physical and chemical approaches such as electrospraying, electrophoretic deposition, chemical vapor deposition, etc. Consequently, the modified carbon fibers have nanocarbon nanoparticles such as graphene, carbon nanotube, nanodiamond, fullerene, and other nanocarbons deposited on the fiber surface. These nanocarbon nanoparticles have fine capability to improve interfacial linking of carbon fibers with the polymer matrices. The chemical vapor deposition has been adopted for uniform deposition of nanocarbon on carbon fibers and chemical methods involving physical or chemical modification have also been frequently used. The resulting advanced epoxy/carbon fiber/nanocarbon composites revealed improved tensile and physical profiles. This review basically aims manufacturing and technical aspects of polymer/fiber/nanofiller nanocomposites toward the development of high performance structures. The resulting morphology, strength, modulus, toughness, thermal stability, and other physical features of the nanocarbon functionalized carbon fibers have been enhanced. In addition, the fabricated polymer/fiber/nanofiller nanocomposites have fine interfacial adhesion, matrix-nanofiller-filler compatibility, and other characteristics. The application areas of these nanomaterials have been found wide ranging including the strengthened engineering structures, supercapacitors, shape memory materials, and several others.