Lightweighting design optimisation for additively manufactured mirrors

Carolyn Atkins; William Brzozowski; Naomi Dobson; Maria Milanova; Stephen Todd; David Pearson; Cyril Bourgenot; David Brooks; Robert Snell; Wenjuan Sun; Peter Cooper; Simon G. Alcock; Ioana-Theodora Nistea

doi:10.1117/12.2528105

9 September 2019 Lightweighting design optimisation for additively manufactured mirrors

Carolyn Atkins, William Brzozowski, Naomi Dobson, Maria Milanova, Stephen Todd, David Pearson, Cyril Bourgenot, David Brooks, Robert Snell, Wenjuan Sun, Peter Cooper, Simon G. Alcock, Ioana-Theodora Nistea

Author Affiliations +

Proceedings Volume 11116, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems II; 1111617 (2019) https://doi.org/10.1117/12.2528105
Event: SPIE Optical Engineering + Applications, 2019, San Diego, California, United States

Abstract

Design for additive manufacture (AM; 3D printing) is significantly different than design for subtractive machining. Although there are some limitations on the designs that can be printed, the increase in the AM design-space removes some of the existing challenges faced by the traditional lightweight mirror designs; for example, sandwich mirrors are just as easy to fabricate as open-back mirrors via AM, and they provide an improvement in structural rigidity. However, the ability to print a sandwich mirror as a single component does come with extra considerations; such as orientation upon the build plate and access to remove any temporary support material. This paper describes the iterations in optimisation applied to the lightweighting of a small, 84mm diameter by 20mm height, spherical concave mirror intended for CubeSat applications. The initial design, which was fabricated, is discussed in terms of the internal lightweighting design and the design constraints that were imposed by printing and post-processing. Iterations on the initial design are presented; these include the use of topology optimisation to minimise the total internal strain energy during mirror polishing and the use of lattices combined with thickness variation i.e. having a thicker lattice in strategic support locations. To assess the suitability of each design, finite element analysis is presented to quantify the print-through of the lightweighting upon the optical surface for a given mass reduction.

Conference Presentation

Citation Download Citation

Carolyn Atkins, William Brzozowski, Naomi Dobson, Maria Milanova, Stephen Todd, David Pearson, Cyril Bourgenot, David Brooks, Robert Snell, Wenjuan Sun, Peter Cooper, Simon G. Alcock, and Ioana-Theodora Nistea "Lightweighting design optimisation for additively manufactured mirrors", Proc. SPIE 11116, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems II, 1111617 (9 September 2019); https://doi.org/10.1117/12.2528105

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