For structures used in space communications (e.g., antennas) and structural support (e.g., booms and trusses for solar arrays), it is extremely important to have the ability to predict their deployed shape and structural behavior after they have been stowed for weeks or even months prior to launch. For the STTR proposal to NASA, L’Garde and the University of North Texas (UNT) will develop a design tool for the prediction of the material properties of tailorable composites used in space structural systems, as well as the accurate prediction of their structural and shape behavior, initially focusing on antennas made from membrane surfaces of revolution, e.g., membrane paraboloid with stiffening radial ribs and outer perimeter toroidal ring support. The design tool proposed will enable prediction of the materials properties from the percentage constituents of its elements.
For the Phase I STTR, L’Garde and UNT will collaborate in developing the framework of a design tool that will accurately predict the structural properties and resulting on-orbit surface shape of a “design reference” hybrid antenna that consists of shape memory alloy (SMA) or shape memory composite (SMC) material and membranous RF reflective surface. For a non-inflated antenna configuration, the radial antenna ribs made of SMA dictate the final surface shape accuracy and hence, it is very critical to have a design tool that can be used to determine the material stiffness, geometric and other structural characteristics – before and after stowage. The design tool developed will also be applicable to other hybrid geometries including space frames and hinge deployers for solar arrays. Both one-way and two-way SMAs will be investigated.
A design tool that can predict accurately the kinematic and structural performance of space structures will add to NASA’s analytical toolset. The proposed design tool will enable the prediction of the surface shape evolution of dish antennas to within 1mm surface accuracy and includes communication antennas between earth and space, space-to-space communications as well as assessment of the structural capabilities of deployable structural supports for solar panels and other gossamer systems like a very large solar sail.
Potential non-NASA applications include use of the design tool to be added to library of analytical codes to augment the suite of analyses in commercially available finite element codes for structural analysis. DoD, industry and academia will also find use for it especially for the prediction of hybrid structures incorporating elements that differ in stiffness by more than an order of magnitude.