Thermally induced vibrations in inflatable space structures: theory and experiment

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One of the main obstacles to placing spacecrafts in orbits is their high price for launch. Therefore, weight has always been a major design concern for space industry. Inflatable technology is a promising solution for placing large metrology systems in space to meet their launch volume and mass goals. This emerging technology offers lightweight, stowable and deployable satellite systems that can be compressed into folded stacks of a few inches thickness during launch and can be inflated and deployed over hundreds of feet in space. Because these structures are stowed during launch and deployed only upon reaching the destination orbit, the critical loads and disturbances in space are of particular importance. This is in contrast with older satellites for which most critical loads are met during launch. One of the most important sources of environmental disturbance is the rapid temperature change encountered on passing through the Earth's shadow. Such disturbances can induce bending moments and torques in the structure which result in thermal oscillations that can corrupt the pointing accuracy and precision of the satellite system and can last anytime from a few hours to a year. Therefore, a major objective of the proposed research is to develop novel analytical and experimental techniques for investigation and characterization of thermal loads on some of the major components of inflatable structures such as rigidized booms and Mylar membranes. This study will investigate the dynamic response of these materials to rapid temperature changes. The experimental techniques along with complementary modeling methods for inflatable structures represent novel aspects of this work and will make a significant contribution to our understanding of the thermal dynamic behaviour of the inflatable structures. The results will be used to develop control techniques to minimize the susceptibility of such systems to thermal disturbances. The proposed research program is intended to train the next generation HQP in structural vibration and control, with experimental applications which are in demand by industrial companies such as COM DEV International Ltd., MDA and the Canadian Space program.