Papers by Keyword: Space Application

Abstract: Generally, commercial motors are produced as the lineup of series of outer diameter. The output power is changed with their length. However, the production number of space motor or power assist leg motor is small, while the power ratio versus motor weight is very important factor. The geometric study is proposed in this paper; especially, such problems of outer rotor versus inner rotor motor, outer diameter versus length. The motor characteristics are assumed with the FEM simulation. These constants depend on the motor pole number and driving amplifiers. Hence the exact geometrical dimensions should be determined with the careful simulation. Before simulation rough geometrical size can be determined, then the exact simulation will be carried out to determine the motor dimension and estimate the produced motor characteristics. The results are planned to compare with some of the experimental results.

Abstract: In this work, the sol-gel technology is used to produce silica based xerogels and aerogels suitable for insulation applications in Space. The properties of the obtained materials are tailored varying the precursor – Methyltrimethoxysilane (MTMS) or Methyltriethoxysilane (MTES), and the solvent – methanol or ethanol. A two-step acid-base catalyzed synthesis is used, being the obtained gels dried at atmospheric pressure, in the case of xerogels, and in supercritical conditions, for aerogels. Density and thermal conductivity must be made as low as possible for the sought application and only highly porous materials can fulfill this requirement. The obtained xerogels and aerogels, either with MTMS or MTES, show very promising properties for thermal insulation in Space, when methanol is used as solvent. The more suitable materials are obtained with MTMS and exhibit very low density (80-100 kg/m3), very high surface area (~ 400 m2/g) and small pore size (~ 30-40 Å). They also show moderate flexibility and a remarkable hydrophobic character (~ 150º).

Abstract: In this study, thermal responses of advanced fiber/epoxy matrix composite materials are considered for spacecraft thermal design. These thermal responses are important, because the localized thermal behavior from applied heat loads can induce thermal stresses, which can lead to functional failure of the spacecraft system. Since most of polymer matrices exhibit relatively poor thermal conductivity, the composite materials have been widely considered only for structural application and little for thermal application. However, recently pitch-based high performance carbon fiber becomes available and this fiber shows high thermal conductivity. Because of this combination of low CTE and high thermal conductivity, continuous carbon fiber composites make them suitable for thermal management of spacecraft. The advanced composite material is composed of a continuous high modulus pitch based fiber (YS90A) and DGEBA epoxy resin(RS3232). It was demonstrated that advanced composite material satisfied thermal requirement for a lightweight thermal radiator for heat rejection of communication satellite.