STRUCTURE AND CONTROL TECHNIQUES Structural and Dynamic Analysis of the SSPS Summary. — The purpose of this task was to perform structural and dynamic analyses of the SSPS structure for the purposes of: • Providing elastic characteristics (natural frequencies, generalized masses and mode shapes) of the structure for use in an analytical investigation of the elastic coupling between the SSPS attitude control system and the spacecraft's structural modes; • Determining deflections and internal member loads resulting from the various flight loading conditions to verify structural integrity; • Assessing desirable material characteristics; and • Identifying desirable technology developments. Results of this task will be applied to the design of structure and attitude control systems for very large-area, light-weight space structures represented by the SSPS. The SSPS will require the design of a structure that can not only support the solar cell blankets, concentrator mirrors, and transmission bus/structure for the various flight loadings, but also one that can be both assembled and controlled in space. To investigate the structural and dynamic aspects connected with controlling such a structure in space required: * The establishment of a baseline configuration, a structural math model, a dynamic math model, and flight loading conditions; • The input of flight and control system loadings into the structural model to determine internal loads and structural deflections; ® Assessment of the baseline configuration for internal loads and deflections, as well as candidate material characteristics; and • Identification of areas requiring future analysis and the analytical tools needed for analysis. Baseline Configuration.- The SSPS characteristics and the baseline configuration used in this task are shown in Figures 7, 8, and 9. The main structural framework for each solar array consists of a large-diameter coaxial mast transmission bus, four transverse DC power buses, and non-conductive struts. Shear loads are transmitted by tension-only wires. Structural continuity between the two solar arrays is supplied by the mast and by non-conductive structure running
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