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Lightweight cellular materials for shape adaptable satellite antennas
This thesis aims to demonstrate the limits of mechanical performance of fiber reinforced composite metamaterials undergoing extreme deformations using FE and experimental methods. Application to engineering structures is shown through a demonstrator of a reconfigurable satellite antenna.
**Background**
Periodic mechanical metamaterial structures show tre-mendous potential for shape adaption, with global dimension changes of as much as 90%. These are composed of repeating unit cells which can achieve large deformation through geometry via to a soft actuation mode (ex. Rotating square configuration in figure above). Conventional mechanical metamaterials lever-age multi-material 3D printing to realize complex polymer structures. However, application of these to aerospace structures remains elusive, as these structures are burdened by the tradeoff between high deformability and high stiffness. Realizing mechanical metamaterials from fiber reinforced polymer (FRP) composites presents an attractive, yet labor intensive, option to improve mechanical performance.
As such, a technique for integral fabrication of a metamaterial consisting of 3D printed hubs and FRP composite reinforcement and connecting ligaments is under development at CMASLab. The 3D printed hubs function as both tooling for the autoclave cure of the composites and as functional surfaces. A promising application of such structures is reconfigurable antennas for satellites, where the 3D printed hubs can be coated with conductive layers. Other applications include deployable space structures where high surface area is a required, including solar sails and optical telescopes.
**Motivation**
FRP structures manufactured using this method have been able to withstand up to 60% global strain until failure, outperforming many polymer designs. In addition, finite element simulations indicate the extreme tunability of such metamaterials. For example, they open the possibility to achieve engineering properties not found in natural materials. However, the limits of mechanical performance are unexplored and have to be demonstrated experimentally.
**Background** Periodic mechanical metamaterial structures show tre-mendous potential for shape adaption, with global dimension changes of as much as 90%. These are composed of repeating unit cells which can achieve large deformation through geometry via to a soft actuation mode (ex. Rotating square configuration in figure above). Conventional mechanical metamaterials lever-age multi-material 3D printing to realize complex polymer structures. However, application of these to aerospace structures remains elusive, as these structures are burdened by the tradeoff between high deformability and high stiffness. Realizing mechanical metamaterials from fiber reinforced polymer (FRP) composites presents an attractive, yet labor intensive, option to improve mechanical performance.
As such, a technique for integral fabrication of a metamaterial consisting of 3D printed hubs and FRP composite reinforcement and connecting ligaments is under development at CMASLab. The 3D printed hubs function as both tooling for the autoclave cure of the composites and as functional surfaces. A promising application of such structures is reconfigurable antennas for satellites, where the 3D printed hubs can be coated with conductive layers. Other applications include deployable space structures where high surface area is a required, including solar sails and optical telescopes.
**Motivation** FRP structures manufactured using this method have been able to withstand up to 60% global strain until failure, outperforming many polymer designs. In addition, finite element simulations indicate the extreme tunability of such metamaterials. For example, they open the possibility to achieve engineering properties not found in natural materials. However, the limits of mechanical performance are unexplored and have to be demonstrated experimentally.
The goal of the thesis is to examine the achievable mechanical performance of these structures as well as to demonstrate achievable extreme properties experimentally. In addition, the thesis would focus on showing the applicability of the metamaterials to engineering structures. In particular, the development and functionality of a reconfigurable satellite antenna would be demonstrated.
The goal of the thesis is to examine the achievable mechanical performance of these structures as well as to demonstrate achievable extreme properties experimentally. In addition, the thesis would focus on showing the applicability of the metamaterials to engineering structures. In particular, the development and functionality of a reconfigurable satellite antenna would be demonstrated.
Dr. Maria Sakovsky (msakovsky@ethz.ch)
ETH Zürich
LEE O 204
Leonhardstrasse 21
8092 Zürich
Phone: +41 44 633 61 49
www.structures.ethz.ch
Dr. Maria Sakovsky (msakovsky@ethz.ch)
ETH Zürich LEE O 204 Leonhardstrasse 21 8092 Zürich