Eliminating Shear in Flattenable and Rollable Booms

Abstract Flattenable and rollable booms are used in applications where a long beam-like structure must be transformed into a compact package and later deployed or unfurled. The rolling approach is known for achieving high linear compaction ratios wherein a boom can be packaged to a small fraction of its deployed length. However, the process induces large material strains from the combination of flattening and rolling. Specifically, large shear stresses build in the lateral flattening hinges when the booms are rolled. This paper explores the design and performance of these booms through a combination of design, manufacturing, and rolling tests. A hybrid design approach that uses inflation pressure to achieve boom hoop stiffness and uses interleaved high strain composite materials to achieve boom axial stiffness is found to greatly reduce hinge shear stress.