Modified spiral folding pattern for deployable membranes

Abstract

Solar sails which provide propellant free propulsion are quite effective for missions that utilize small spacecrafts. These structures require a larger surface area compared to launch vehicles, hence require adopting deployable concepts. Neglecting geometric effects of membrane thickness can result in plastic deformations and wrinkling of membranes. As the issues arise in the stored configuration, they can be overcome by certain modifications to the fold-line arrangement in the pattern. We have developed a modified fold-line arrangement for modules which utilizes the spiral folding pattern using the arrangement of nodes in the folded state. We provided an offset to the nodes along the vertices of the hubs to the folded configuration to let the folding pattern accommodate the thickness. The proposed modification rearranges thenodes in the folding pattern which overcomes the adverse effects caused by the membrane thickness while achieving a compact folding state. Modified folding pattern was verified using paper models for different thicknesses and different levels of complexity.