Scaling Analyses for Large-Scale Space-Based Membrane Optics

To meet future requirements, space telescopes are envisioned to require primary mirrors that will be on the scale of >= 10 m in diameter. Packaging restrictions of current and foreseeable launch vehicles prohibit the use of a single rigid monolithic mirror of that size. Membrane-optics research seeks to create large-diameter apertures out of thin flexible filmlike reflective material. In this analysis, structures with embedded in-plane-actuated piezoelectric elements for active surface shape control were examined. By analyzing the nondimensional form of the governing differential equation, relative effects of linear and nonlinear terms are apparent. Then, through a series of MSC Nastran finite element models, scalahility issues are explored to include the effects of nonlinear terms, existing membrane pretension, and unimorph-versus-bimorph actuation. Results show that although small-scale (existing) test articles may respond in accordance with linear models, they may mask the nonlinear characteristics that dominate large full-scale membrane optics in the proposed applications.