Advanced control systems that include built-in smart-material elastic-deformation structural actuators have been proposed for deployable thin-shell structures that are required to be maintained in precise shapes once deployed. This approach to structural shape control was conceived to enable the development of lightweight telescope mirrors, radar reflectors, and the like that could be stowed compactly for launching and transport, then deployed in outer space to required precise shapes at much larger dimensions (of the order of 10 m). The concept may also be applicable to similar, but probably smaller structures for terrestrial use.
A typical shell structure according to the proposal (see figure) would include (1) a flexible single- or multiple-layer face sheet that would include a reflective mirror surface; (2) structural supports in the form of stiffeners made of shape-memory alloys; and (3) bimorph-type piezoelectric actuators, possibly of a variety of sizes and shapes. The actuators, together with an electronic control subsystem, would implement a concept of hierarchical distributed control: The shape-memory actuators would be used for global shape control and would generate the large deformations needed for the deployment process. The piezoelectric actuators would generate smaller deformations and would be used primarily to effect fine local adjustments of the shape of the mirror.
Because of the geometric and material nonlinearities of shell structures, this work considers the essential nonlinearity of the large deformations needed for stowage and deployment, and the further complexity and nonlinearity that obtains in structures that include flexible membranes. This research and development effort will serve as a foundation for designing and building such structures integrated with hierarchical distributed control systems. The proposed work will take advantage of recent advances in mathematical modeling, dynamics, and distributed sensing and control of structures that exhibit nonlinear responses and undergo large deformations.
This work was done by Gregory Hickey and Shyh-Shiuh Lih of Caltech and Horn-Sen Tzou of the University of Kentucky for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Physical Sciences category.
NPO-21138
This Brief includes a Technical Support Package (TSP).
Deployable Shell Structures with Shape-Control Actuators
(reference NPO-21138) is currently available for download from the TSP library.
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Overview
The document presents a NASA Technical Support Package focused on innovative deployable shell structures that incorporate shape-control actuators. These structures are designed for applications in aerospace, particularly for components such as telescope mirrors and radar reflectors that need to maintain precise shapes once deployed in space.
The core concept revolves around the use of smart-material actuators, which enable the structures to adapt and control their shapes dynamically. This capability is crucial for ensuring optimal performance in the harsh conditions of outer space, where traditional rigid structures may not suffice. The document outlines the design principles and potential applications of these deployable structures, emphasizing their lightweight and compact nature, which allows for easy transportation and deployment.
The proposed designs leverage advanced control systems that can respond to environmental changes and operational requirements, ensuring that the deployed structures can achieve and maintain their intended configurations. This adaptability is particularly important for missions that require high precision and reliability, such as astronomical observations or satellite communications.
Additionally, the document highlights the collaborative efforts of the Jet Propulsion Laboratory (JPL) and the California Institute of Technology, underlining the rigorous research and development processes involved in creating these innovative solutions. It also includes a disclaimer regarding the mention of specific commercial products or services, clarifying that such references do not imply endorsement by the U.S. Government or JPL.
Overall, the document serves as a comprehensive overview of the advancements in deployable shell structures, showcasing the potential of smart-material technology in enhancing the functionality and efficiency of aerospace systems. By integrating shape-control actuators, these structures represent a significant step forward in the design and deployment of aerospace components, promising to revolutionize how we approach challenges in space exploration and satellite technology.
