Elastic Shape Morphing of Ultra-Light Structures by Programmable Assembly
Aerospace
Elastic Shape Morphing of Ultra-Light Structures by Programmable Assembly (TOP2-329)
Mission Adaptive Digital Composite Aerostructure Technologies
Overview
Aerostructure parts made from ultra-light materials, such as a lattice covered by a skin, present an opportunity to dramatically increase the efficiency of load bearing aerostructures. NASA Ames Research Center has been developing lighter-than-air vehicle and structure concepts using octahedral unit cells called voxels that are the building blocks for creating larger aerostructures. This novel addition to the family of technologies introduces interface parts to connect a skin to a voxel substructure. The skin is designed to transfer aerodynamic pressure loads directly to the substructure through the interface parts. The parts can be tuned to achieve aerodynamic efficiency gains through substructure programmability. The substructure can be morphed by aeroelastic tuning to increase aerodynamic efficiency. Tuning the substructure’s torsional stiffness response can also program the anisotropic substructure stiffness to promote tip twist under aerodynamic loads.
The Technology
The technology uses a base set of the substructure, interface, and skin building blocks to design an aerostructure that maximize the aerodynamic loading of the aero structure while maintaining the appropriate safety factor. The main substructure building blocks used are octahedral unit cells, which, when connected at their nodes, produce a cuboctahedral lattice structure. The interface building block set connects the vertices of the substructure building blocks to the skin components and the root and tip plates. The skin is a collection of flat and curved plates that are designed to overlap one-another and to transfer aerodynamic pressure loads directly to the substructure through the interface parts. Panels are not interconnected and thus do not behave as a structural stressed skin. Neighboring panels overlap by 10.2mm to ensure a continuous surface for airflow while still allowing panels to slide past one another during aeroelastic shape change. The structure was developed with adherence to the following guidelines: (i) All second voxel type groupings are limited to linear string shapes; (ii) No second voxel type grouping string can be longer than three blocks long; (iii) Second voxel type grouping strings can not be placed within two unit spaces of each other; (iv) Second voxel type grouping strings placed spanwise will reduce bending and torsional stiffness; (v) Second voxel type grouping strings placed chordwise decreases airfoil shape stability; (vii) Second voxel type grouping strings reduce the total length of building block extrusion.
Benefits
- Seeks to incorporate manufacturing at scale and offers extensibility across designs and applications, enabling cost-effective production and broad adaptability
- The basic building blocks are 3-dimensional parts such as octahedral unit cells. The interface parts are molded parts that connect the unit cells together to form a cubooctahedral lattice
- The addition of an actuation system creates an active structural mechanism, enhancing roll control during flight in addition to passive shape change
- Utilizes a building-block based design and ultra-light structure, offering improved efficiency and reduced weight for enhanced performance
- Design flexibility extends the application space for a single building block set, allowing for versatile use across various scenarios
- Adaptive structures are finding an increasing number of applications due to their ability to respond to changing environments and use-cases
Applications
- Aerospace industry
- Manufacturing industry
- Architectural applications - building construction, and infrastructure maintenance
- Autonomous robotic assembly industries
- Design, manufacture, and assembly of modular lattice structures composed of cuboctahedron unit cells
- Morphing aerostructures at various scales
- Reconfigurable large-scale infrastructure
- High-performance on-orbit assembled infrastructure
- Commercial air vehicle application, including UAVs
- Automotive industry (including autonomous vehicles)
Technology Details
Aerospace
TOP2-329
ARC-18393-1
https://pubmed.ncbi.nlm.nih.gov/33479558/
https://www.researchgate.net/publication/331664560_Elastic_shape_morphing_of_ultralight_structures_by_programmable_assembly
https://bej.pages.cba.mit.edu/home/Gregg_et_al-2018-Advanced_Engineering_Materials__1_.pdf
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