Overall Design And Optimization Of FAST Back-Structure

In order to make further progress in astronomy, improve our ability in deep space detection and take part in international competition and cooperation, a new radio telescope will be constructed in Guizhou province in china, which is the largest one in the world—Five-hundred-meter Aperture Spherical radio Telescope (FAST), and preliminary study is started since 1994. The innovation of FAST is the active reflecting surface, which means that the reflector can be transformed from original sphere to different required working paraboloids.As a so large telescope, the research of the supporting structure for the reflecting surface is very important to make sure that FAST can be implemented successfully. At press time the cable-net structure has been adopted. As an connective part between cable net and panel, back-structure is an important part of the cable-net structure, its performance directly effects the costs and the precision of the FAST. So a detailed study about back-structure must be carried out to find out the best form. the back-structure should have a detailed analysis and the construction program.First, a shape-keeping method for the design of sub-structures is presented, according to the high accuracy requirement (RMS less than 2 mm), and we analysised two kinds of back-structure with the shape-keeping method, contrast to the unshape-keeping method.Secondly, researching and optimizing sevrial kinds of back-structure, we have suggested three kinds of back-structure, Spatial grids structure, Cable supporting structure and Cable-net hybrid structure, and analysised them to get the informations of different kinds of them for Structural Tests.Lastly, we designed the Full-scale model experimentation of back=structure for the reference of then actual back-structure, included the back-structure test-bed, the back structure (Double-layer grids structures and Local double-layer grids structures), special nodes and so on.