Dynamic Characterization for Multi-Layer Membrane Space Altimeter

This paper presents an investigation into the dynamic properties of a deployable membrane structure for space altimeter applications. In particular, equations of motion are formulated which account for the viscous forces as well as the tensile ones which are normally addressed in a deployed membrane. Two commercially- available finite element codes, NASTRAN and ANSYS, are examined for their suitability in implementing the governing equations for three-dimensional membrane structures. In particular, the challenges of nonlinear governing equations and their implementation for a three-dimensional membrane structures are explored. The finite element formulation is used to evaluate the influence of membrane boundary shape and boundary tensile forces on the normal modes of the structure when atmospheric pressure is eliminated. The membrane under examination here is a prototype for the development of a possible on-orbit flight experiment in thin structure deployment, where such an experiment addresses necessary questions related to the use of this technology for membrane altimetry and synthetic aperture radar. The prototype includes multiple layers for signal radiation, grounding, and thermal protection, which must be kept parallel in the deployed configuration.