Temperature Dependent Frequency Response of a Constant Tension Membrane

Abstract

Membrane reflectors are attractive for use as space based optics and antennas. Membranes offer small stowed volume, yet when deployed have a large surface area. Once deployed in orbit the membrane will be exposed to the solar thermal cycle. The purpose of this study is to determine the frequency response of a constant tension membrane due to temperature changes. Understanding how the frequency response of the membrane changes with temperature is critical to both spacecraft control and the performance of the reflector. In this study a test apparatus is developed based on a membrane mounted in front of a pressure chamber. By varying the pressure using a small vacuum pump the shape and tension of the membrane can be varied. The test article is a 250mm diameter, 1 mil thick, Kapton membrane. Radiant heat was applied to the membrane and the frequency response was determined using a laser vibrometer. Results are presented for heated membranes that are allowed to expand while the chamber pressure is maintained constant, and for membranes where a constant tension was maintained throughout the heating. The test apparatus will be useful for validating computational models used to design future membrane optics and support structures.