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Deployment Dynamics of Thin-Shell Space Structures


Pedivellano, Antonio (2021) Deployment Dynamics of Thin-Shell Space Structures. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/4zbq-g037.


Thin-shell structures provide a lightweight solution for deployable structure applications. Despite being only few tens of microns thick, these structures provide excellent bending stiffness, thanks to their curved cross-section. Their thinness also allows them to be elastically packaged into small volumes to fit into a launch vehicle; once in space, they can be self-deployed by releasing their stored elastic energy.

Most space applications use thin-shell structures to deploy and tension thin membranes, such as solar sails, drag sails, and solar arrays. Recently, a novel space solar power architecture has been developed at Caltech, and it relies on distributed thin-shell components, connected in a space frame, to create large-area deployable structures. Thanks to the unique properties of thin shells, these structure provide superior stiffness-to-mass ratio and self-deployment capabilities. However, to demonstrate their reliability and enable their use on space missions, their deployment dynamics must be understood and predicted.

Ground testing is the established approach to verify a structure throughout its design and qualification process. However, replicating the space environment in a laboratory setting is generally not possible, especially for lightweight structures, which are very sensitive to the effects of gravity and air. Numerical models are therefore the only tool to predict the behavior of a structure in space. However, validation with ground experiments is necessary to build confidence in the models, which must be able to capture the complexity of the interaction with air, gravity, and the suspension system that supports the weight of the structure.

The goal of this thesis is to develop high-fidelity models for large space structures, where multiple thin-shell components are folded together and deploy by releasing their strain energy. This overall objective is achieved in 3 steps. First, a ladder-type rectangular strip is introduced, as a building block for more complex architectures. The strip is composed by two thin-shell longerons, symmetrically folded at two locations. The deployment dynamics of this structure is investigated through experiments on 1 m-scale prototypes, both in air and in vacuum. A detailed analysis of its elastic folds is performed using full-field displacement measurements from Digital Image Correlation. A finite element model of this strip is presented, and it is shown to accurately capture the dynamics of the strip for all tested conditions. Then, the implementation of the packaging and deployment scheme of a space solar power spacecraft, composed of multiple strips, is discussed. A kinematic model of the structure is proposed as a design tool to achieve systematic folding. A novel concept of a deployment mechanism to coil the structure in a robust and reliable way is proposed. Also, a staged deployment scheme is demonstrated, to reduce the uncertainty of strain-energy deployment for large space structures. Finally, the deployment dynamics of a 2 m-scale space structural prototype, based on the space solar power architecture, is investigated. A full-scale finite element model of the structure is implemented to replicate its complex folding scheme and capture the deployment process, including the interaction with the deployment mechanism and the suspension system. The simulations predict well the behavior of the structure observed in experiments through motion capture techniques.

The work presented in this thesis advances previous studies on the deployment dynamics of simple thin-shell components, and demonstrates that even complex thin-shell architectures can be packaged and deployed in a controlled and predictable way. The solutions proposed in this thesis have guided the packaging process and the design of the deployment mechanism for DOLCE, an upcoming flight demonstration of the space solar power architecture described in this work. However, this research has much broader implications, as the experimental and numerical framework presented herein can be generalized to different shell-based architectures, and contributes to enabling a new generation of lightweight deployable structures for future space applications.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Deployment dynamics, Thin shells, Space solar power, Deployment mechanism
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Space Engineering
Awards:Hans G. Hornung Prize, 2021.
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Pellegrino, Sergio
Thesis Committee:
  • Daraio, Chiara
  • Lapusta, Nadia
  • Pellegrino, Sergio
  • Ravichandran, Guruswami (chair)
Defense Date:28 May 2021
Non-Caltech Author Email:apedivel (AT)
Funding AgencyGrant Number
Caltech Space Solar Power ProjectUNSPECIFIED
Record Number:CaltechTHESIS:06012021-002457442
Persistent URL:
Related URLs:
URLURL TypeDescription conference paper 2021 - Strip deployment conference paper 2020 - Staged deployment conference paper 2020 - DOLCE prototype mechanism patent application 2020
Pedivellano, Antonio0000-0003-2321-7301
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14213
Deposited By: Antonio Pedivellano
Deposited On:07 Jun 2021 15:37
Last Modified:08 Nov 2023 18:53

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