Deployable Composite Boom

Just like a kid's slap bracelet, the Bi-CTM design includes a secondary stable low-energy state aside from the rigid deployed state. The result is that the Bi-CTM is not under high-spring stress when coiled up which simplifies the stowage process as well as enabling a more controllable extension of the boom. The simplified stowage process enables reduced size, mass and complexity of the storage and deployment mechanism system. Compared to the majority of deployable thin-shell booms, which have at best a semi-open cross section, this true closed-cross-section boom is stronger, while keeping the compact nature of rollable booms, and is able to overcome both bend and twist buckling related limitations. Using omega-shaped cross sections with optionally circular, parabolic or ellipsoidal segments, where each half of these thin-shell composite booms can use equal (symmetric boom) or different (asymmetric boom) cross section geometry and/or composite laminates, offers a great deal of boom customization in terms of stable coiled diameter and structural properties. Bi-CTM boom design optimization provides for maximized area moments of inertia and torsional constant, which related to the boom stiffness and the loading capacity, while remaining a bistable design. A sister to SHEARLESS booms, the Bistable Collapsible Tubular Mast (Bi-CTM) boom, offers compact storage on a cylindrical drum that deploys a composite material boom with a closed tubular cross section that has unmatched bending and torsional stiffness for the mass of the thin-shell structure. The Bi-CTM is also scalable for long booms given the load carrying capacity. The Bi-CTM's two omega-shaped composite thin-shells form a bonded closed section which can spool onto a relatively compact drum for compact launch packaging and provide unparalleled stiffness to mass ratio when deployed. When using the booms as beam-column structures with a primarily compressive load component, this ratio determines the structural mass efficiency of the components, making the Bi-CTM exceptional for lightweight deployable structural rigging with higher load demands. The improved dimensional and thermal stability offered by the closed-section shape and low coefficient of thermal expansion materials of the Bi-CTM, enables the use of the boom technology in precision applications that require high stability in harsh environments.