Membranes and Thin Shells for Space Reflectors

When the diameter of a space antenna reflector exceeds the launcher shroud dimensions, a large deployable reflector technology must be applied. For deployable reflector concepts different approaches are available ranging between shells, rod-cables and rod-membrane systems. For the latest ones having dimensionally stable thin membranes with high in plane stiffness and/or finite bending stiffness facilitating for the stowablity is significant. Using such membranes, highly accurate double curved large reflector surfaces, so called flexible thin shell-membranes can be built. New types of flexible shell-membranes based on fibre reinforced silicone technology being developed at the Institute of Lightweight Structures (LLB) are discussed and an evaluation of thermo-mechanical properties is given in the paper. Evaluation is performed via mechanical tests and FEM nonlinear analyses. Large deployable reflector SMART is presented next, which uses the mentioned shell-membrane. The design principles and building blocks of SMART as well as results of thermo-elastic and dynamic analysis using a fully parametric FE model are addressed. The feasibility of creation of the flexible shell-membrane reflecting surface for LDRs using triax carbon fibre reinforced silicone (CFRS) technology is proved. SMART reflector with CFRS surface has demonstrated the credibility of RF and mechanical concepts up to 10–12 GHz. Reflector demonstrator is being built.