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... torate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. This project was aimed at developing analytical approaches to improving and better understanding the dimensional stability of composite space structures under thermal environments and changing material behavior due to microscopic damage. A comprehensive review of the literature on damage modeling of polymer matrix composite laminates was conducted. Damage due to matrix cracking was characterized using micromechanics. Aspects of predicting and utilizing degraded properties at the fiber and matrix level were studied. A computational approach to optimization of structure dimensional stability by introduction of "antidistortion appliqués" was developed for minimizing thermally induced instability. The concept involves adding material to offset and eliminate measured instabilities. The concept was demonstrated but the approach is limited by the current lack of precision measurement systems for large structures.