Performance Comparison of Flattenable and Rollable Booms

This paper compares the deployed performance of several boom architectures that can be flattened and rolled. These booms are typically made from high strength metals or high strain composite materials and used as spacecraft deployable structures. Due to cross-section deformation, their structural behavior is highly nonlinear in the unrolled state. Complex local buckling and post-buckling behaviors are present, resulting in path dependent (following different loading and unloading paths) responses that are difficult to capture with closed form or implicit finite element integration schemes. Here, several flattenable boom architectures (slit-tube, living hinge boom, TRAC boom, and collapsible tubular mast variants) were analyzed for deployed loading, post-buckling, and unloading behavior. Boom analysis results and architectures are compared based on mass, stiffness, strength, and flattened width while all boom types are held to the same design rule of maximizing material thickness for a set flattened width of 10 cm and flattening strain of 1%. Representative post-buckled shapes and nonlinear load-deformation curves are shown for each boom style for bending and torsional loading. Results show that closed cross-section deployable booms can achieve stiffness performances comparable to non-deployable thin-walled tubes, with a moderate reduction in strength. Results also show that significant mass performance improvements can be achieved with trussed architectures.