Deployable Composite Toroid Holding a Circular Membrane

Deployable space structures that leverage high-strain composite shells have significant potential for applications requiring lighter and larger structures. However, due to the small thickness of coilable composite shells, often these structures are more compliant than desired. Thus, this paper investigates a novel approach using a curved tape-spring that forms a continuous ring perimeter structure. The double curvature of the composite ring increases its radial stiffness and the circular shape provides a high surface area-to-mass efficiency. The paper explains the deployment scheme for this structure and presents a detailed finite element analysis of the folding process. In addition, a prototype is built using an ultra-thin hybrid laminate and a Kapton membrane with an elastic spring attachment to prestress the structure. A folding and deployment test validates the presented scheme, which incorporates an origami fold pattern for the membrane.