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Proceedings Paper

Structural optimization of the outer ring of FAST Telescope
Author(s): Xin-yu Zhang; Hui Li; Shi-mo Yang
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Paper Abstract

The two-axis steering mechanism installed in the FAST focus cabin can be seen as a universal joint consisting of two ring beams and makes role in the process of real-time adjustment of the receiver orientation. The outer ring of the mechanism is a large-span curve beam with strict mass and rigidity requirements. The aim of this paper is to develop a simple and effective method for constructing a truss-shape structure for the outer ring under the upper-limit constraints of certain structural weight and mid-span deflection. Two truss configurations for weight minimization problems are presented. One assumes consistent beam height. The second design proposes varying heights along the ring. Analytical deflections are given based on the theory of thin-walled beam in combination of bending and torsion. In numerical optimization of the structure, some key geometrical parameters are selected to be optimized. The optimization is subsequently achieved by the steepest descent method, which is based on the sensitivity analysis of the variables (reduced to be dimensionless) in each iteration. Several sets of initial conditions for optimization have been generated randomly. Corresponding optimum results have small mutual deviations. Finally a comparison of the two designs considering stiffness-to-mass ratios is given in the numerical examples.

Paper Details

Date Published: 17 September 2012
PDF: 11 pages
Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 84445X (17 September 2012); doi: 10.1117/12.930994
Show Author Affiliations
Xin-yu Zhang, National Astronomical Observatories (China)
Graduate Univ. of Chinese Academy of Sciences (China)
Hui Li, National Astronomical Observatories (China)
Shi-mo Yang, National Astronomical Observatories (China)

Published in SPIE Proceedings Vol. 8444:
Ground-based and Airborne Telescopes IV
Larry M. Stepp; Roberto Gilmozzi; Helen J. Hall, Editor(s)

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