Thermally Induced Vibrations of a Solar Wing with Bowed STEM
Hagler, Shawn 1983-
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Storable Tubular Extendible Members (STEMs) are often used for deploying spacecraft subsystems such as flexible solar cell blankets, like those used on Hubble Telescope. Systems using long flexible appendages such as the STEMs used on Hubble often undergo thermal excitations due to a thermal gradient through the cross-section when entering and exiting solar eclipse. These vibrations can greatly reduce pointing accuracy and lead to mission failure. Boeing obtained a patent in 2006 for the High Power Thin Film Solar Array (HPSA) which could provide 130kW of power to a spacecraft. The deployed structure relies on bowed STEMs and a tether system to keep the solar panels taut and in alignment with the sun. The system is predicted to minimize the effects of thermal excitation. This thesis proves that the HPSA design can outperform its straight STEM counterparts with respect to thermal-structural stability under unidirectional solar radiant heating through the use of finite element models created in ANSYS. In comparison to Hubble, a HPSA wing configuration is capable of providing a 44.5 percent increase in the first modal frequency, a 98.8 percent reduction in steady state tip deflection, and 96.9 percent reduction in tip vibration amplitude.