Date of Award
Master of Science in Aeronautical Engineering
Department of Aeronautics and Astronautics
Richard G. Cobb, PhD.
The future of large aperture telescopes relies heavily on the development of segmented array designs. Today's monolithic mirror technology has reached a barrier, particularly for space-based telescopes. These large diameter, dense mirrors allow stable high-resolution imaging but are incompatible with optimized space launch. Segmented mirror telescopes are designed to balance lightweight with compact stowage. The structure necessary to support the flexible mirror array often combines isogrid geometry and complex actuation hardware. High-fidelity finite element models are commonly used to economically predict how the optics will perform under different environmental conditions. The research detailed herein integrates superelement partitioning and complexity simplifying techniques, resulting in a 92% size reduction of a nodally dense (1x106 degrees of freedom) model to allow efficient tuning and validation. Measured vibration data of a segmented mirror telescope was collected to allow system characterization and preliminary tuning. A single frequency comparison tuning iteration decreased the model's error in predicting system dynamics, up to 500 Hz, by 4% on average. Results demonstrate it is possible to drastically reduce a model size while preserving analytical accuracy. The methodologies presented, applied to similar models with complex isogrid structures, would allow efficient model validation using standard equipped US Air Force desktop computers.
DTIC Accession Number
Dras, Luke C., "Model Uncertainty and Test of a Segmented Mirror Telescope" (2014). Theses and Dissertations. 743.