Scalable Closed-Form Modeling of Slender Lattice Columns Under Combined Loading

A comprehensive program of model development and validation by hardware testing was performed to achieve technology readiness level (TRL) 6 for lightweight graphite Coilable boom technology as part of the NASA New Millennium Space Technology 8 project. The testing performed for the current work has validated, with close correlation, new nonlinear coupled mechanics models, both numerical (finite element) and closed form, to predict the behavior of long, slender lattice columns subjected to combined axial and bending loads. These models were validated by hardware testing at various effective lengths and conditions, allowing application of the models across a wide range of scaling. These models account for both initial shape and loading (external loads and internal preloads). Despite their relative simplicity, the closed-form models were found to be extremely accurate (within a few percent) for calculating the slender truss behavior. Finally, these equations were reworked into dimensionless forms, generalizing and expanding the results of the TRL 6 test and correlation effort to apply well beyond the range of sizes, lengths, and strengths of trusses envisioned for future gossamer spacecraft systems.