Session: 01-12-02: Spacecraft Structures 2

Paper Number: 161651

161651 - Snap-Through Shaping of Thin-Shell Deployable Structures 

Large space structures have the potential to dramatically improve life on Earth in an era of global warming. For instance, ultra-lightweight, large space structures can enable the creation of large microwave reflectors, antennas, and sunlight collectors for continuous climate monitoring and in-space power generation. The challenges in designing large space structures include maintaining a high surface accuracy and the limited volume capacity of existing launch system fairings. A recent study highlighted that even with the largest rockets currently being envisioned today, tightly-packaged mesh reflectors would exceed packaging constraints for diameters above a hundred meter [6]. One recommended solution to pushing the limits of aperture size is in-space manufacturing and assembly (ISAM). ISAM has been employed as a solution for manufacturing parts in space and for assembling antennas and lenses in NASA’s On-orbit Servicing, Assembly, and Manufacturing (OSAM-1 and OSAM-2) projects [8]. ISAM processes could overcome size constraints imposed by rocket fairings by directly manufacturing antennas in space from tightly packaged feedstock. However, today’s ISAM concepts suffer from severe limitations that prevent their use at large scales. In-space manufacturing concepts feature a high power consumption, which dramatically reduces their build rates, and large masses, which make structures hard to control once manufactured [9]. On the other hand, in-space assembly often requires multiple robots interacting with flexible structures [10], which presents risks and operational challenges that remain unresolved. An innovative concept proposed to overcome the limitations of designing and creating large space structures is in-space deformation processing, where a structure is processed into a desired shape through plastic deformations. While this process requires less energy compared to in-space manufacturing and can accelerate the on-orbit creation of structures, it also features its own set of limitations. Deformation processing relies on high density ductile materials, which reduces the structure’s mass efficiency. Additionally, controlling such a heavy structure during manufacturing and mission operations presents considerable challenges caused by large changes in inertial properties during the building process and low natural frequencies once deployed. To address these issues, this research presents a hybrid approach combining in-space manufacturing and in-space assembly. It integrates recent advances in deformation processing with proven deployable structure technology to circumvent conventional ISAM power and mass limitations. This new process utilizes lightweight composite deployable booms, whose shape can be programmed during deployment through elastic buckling. This new deformation processing paradigm effectively replaces plastic deformations by structural instabilities as shaping mechanism, which enables the very low-power forming of ultra-lightweight brittle fiber composites. In particular, we employ a deployable feedstock made of a periodic bistable cell arrangement. Snap-through buckling can be induced in selected cells during deployement, which in turns generates global curvature in the deployed boom. In addition, multiple booms can be woven together by two deployment mechanisms located on the spacecraft, before being pinched to form large doubly-curved structures such as paraboloids. An algorithm takes as input the reflector shape and returns a set of cells to collapse during deployment. This presentation introduces the new snap-through shaping concept, presents finite element parametric studies on the bistable behavior of a single unit cell, as a building block of a cellular structure, and the multistability of the full feedstock meta-structure. Plans for an experimental validation campaign will also be presented.

Presenting Author: Fabien Royer Cornell University

Presenting Author Biography: Fabien is an assistant professor in the Sibley School of Mechanical and Aerospace Engineering at Cornell University. Prior to that he was a Postdoctoral Associate in the Department of Aeronautics and Astronautics at the Massachusetts Institute of Technology. Fabien obtained his MSc and PhD in Space Engineering from Caltech, as well as his Diplôme d’Ingénieur from ISAE-SUPAERO (French national institute for Aeronautics and Space). At Caltech, Fabien worked in Prof. Pellegrino's Space Structures Laboratory where his research focused on ultra-lightweight shell structures, their instabilities, and their application to very large space solar power spacecraft. He also worked on the AAReST (Autonomous Assembly of a Reconfigurable Space Telescope) small satellite mission for which he led part of the spacecraft software and hardware development. In addition to his research, Fabien co-chaired the Caltech Space Challenge 2019, an international student space mission design competition. Fabien was awarded the William F. Ballhaus Prize for outstanding doctoral dissertation by the Caltech Aerospace Department (GALCIT), as well as the Ernest E. Sechler Memorial Award for most significant contribution to the department’s teaching and research effort. In addition, he received the Shirley Thomas Academic Scholarship from the Aerospace Historical Society, and he is a Fellow of the Keck Institute for Space Studies.