Optical components for aerospace require high performance at low weight. The traditional route to achieving desired performance is to use exotic, expensive, and long-lead materials such as beryllium. An alternate approach is a highly efficient optimized design with a conventional alloy. A traditional and non-proprietary primary mirror and mount was designed to serve as a lightweight baseline. Topology optimization (TO) driven by different weighted combinations of service, mounting, and machining loads was performed on the mirror problem. Two types of design concepts were developed using advanced implicit geometry modeling workflows from the optimization results: 1) derived directly from the organic TO density field and 2) having field-driven feature parameters. Implicit modeling was enabled due to rapid design and analysis throughout as well as the ability to blend and grade material in 3D. High-fidelity finite element models and faceted surface files for printing were generated directly from the implicit geometry. The performance of the designs was promising. Specifically, the weight of the traditional lightweight mirror was matched, albeit with some sacrifice of performance; likewise, the performance was matched with an approximately 50% weight increase over baseline. Optimized designs were fabricated using laser powder bed fusion additive manufacturing, post-processed, machined (including diamond point turning) and experimentally tested for structural and optical performance. Fidelity of the as-built geometry to the nominal geometry was assessed by x-ray CT scanning. The printed parts all showed good integrity and confirmed the ability to design and build complex, stiff, lightweight, and optically effective designs.
- Employ design optimization and additive manufacturing to replace toxic, expensive and long lead materials.
- Optimize high-value components, including optical components, for size, weight, power and cost and achieve very aggressive lightweighting goals.
- Create an implicit geometry workflow stack to set up topology optimization, optimize a part for multiple load cases, generate lightweight field-driven designs, modify for additive manufacturability and prepare for printing.