Air Force Institute of Technology, WPAFB, OH 45433 Cyclic structures, such as antenna arrays, multi-bay trusses and compressor blades, are significantly impacted by slight changes to system periodicity. Manufacturing errors of 5% or less can result in drastic changes to a structures modal behavior. This change in modal behavior is significant since it may result in focusing of modal energy to individual substructures of the system. Poor modal identification can result in poorly designed control systems, resulting in shape control and pointing issues for space antennae. Additionally, modal energy focusing may damage individual system components due to unanticipated levels of cyclic loading, leading to high cycle fatigue. In this study, the effects of varying the levels of system mistuning on the mode localization is investigated. A test article representative of a space antenna has been constructed and its~modal properties determined for various levels of both mistuning and inter-structure coupling. The objective is to determine the probability and severity of system localization from information on the system substructure imperfections. Additionally, reduction of mode localization through the addition of passive control to the system by way of piezoceramic materials is investigated.
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