J122012 宇宙エレベータの最適構造設計([J12201]解析・設計の高度化・最適化(1))

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In this paper, we discuss a shape design of tether in a space elevator system. The system consists of a long tether with flexibility and an elevator. The length of the tether is determined by considering a balance on centrifugal and gravitational forces. The cross-sectional area for long tethered structure is designed using the ideal area requirements for a constant stress tapered tether. The obtained shape of the tether has exponentially varying cross-section in axial direction. The cross-sectional area of tether at Earth-side end is determined by a specified allowable stress. A modal analysis is presented by using an FEM method for a uniform shape and for the obtained shape. We compared the eigen frequencies with the result of the reference literature, in which the tether is modeled by a long string which is fixed at the both end. We obtain the tether structure whose periods of the first and second modes are on the order of 20 hour and 10 hour.
2011-09-11