Frequency Analysis of a Frame-Membrane Lunar Habitat Considering Extreme Temperatures and Internal Pressure

Abstract

The ambient environmental factors present on the lunar surface pose the most difficult challenges for long term human settlement of the Moon. Aside from the dangerous radiation levels and the lack of atmosphere, the temperature on the surface can range from very cold during the night (-233°C) to very hot during the daytime (134°C) posing a variety of complications including the alteration of the structural response of the habitat due to thermal expansion and contraction. This paper presents the study of the membrane attachment and variation of both surface temperature and internal pressure and their effects on the frequency response of a lunar habitat made of an aluminum frame with a Kevlar membrane attached to contain the internal air pressurization. The frame-membrane structure was considered pinned at bottom periphery of the structure. For the frame alone without the membrane attached, the hot external temperatures increased deflections and decreased frequencies slightly while the cold temperatures had the opposite effect of increasing the natural frequency of vibration by a small amount. When the membrane was attached, the initial modes were dominated by local membrane vibrations with lower frequencies when no internal pressure was applied. The internal pressure and high daytime external temperatures were observed to increase the frequency of the structure further when considering global vibrations and the low nighttime temperature was found to enhance local membrane vibrations and decrease the natural frequency of vibration throughout all of the first twenty-five modes.