Characterization of Large Thin Film Membrane Dynamic Behavior with UAI-NASTRAN Finite Element Solver 1999-01-5518

The Next Generation Space Telescope (NGST) design calls for a large sunshield to passively cool the telescope and its detectors to temperatures in the 60 to 100 Kelvin range. The baseline design for the NGST sunshield consists of four struts supporting a large, four-layer, thin film Kapton® membrane. The behavior of large membrane systems must therefore be well understood in order to fully analyze the observatory’s behavior. A one-tenth-scale model of the NGST sunshield was analyzed using a network of rod elements to represent the wrinkle pattern due to pretension in the membrane. A stiffness matrix, updated from the geometric nonlinear static solution, was used to model the strain energy for dynamic responses of the sunshield. Both modal and frequency responses were analyzed. A test article mimicking the sunshield design was manufactured and tested in a vacuum chamber in order to recover the damping coefficient, natural frequencies and mode shapes for correlation with the model.