Date of Completion

8-24-2011

Embargo Period

9-6-2011

Advisors

Michael Accorsi; Jeong-Ho Kim

Field of Study

Civil Engineering

Degree

Master of Science

Open Access

Open Access

Abstract

Due to their lightweight, ease of construction, and sturdy design, three-dimensional frame-membrane structures have often been used as semi-permanent structures by the military and disaster relief agencies. The membrane provides a fully enclosed space for the people or equipment inhabiting the structure, while the frame adds extra structural support for any harsh loading such as impact, blast, or heavy wind loads. Because of their success on Earth, frame-membrane structures have also been proposed as possible lunar habitat. However, for any proposed lunar habitat, including frame-membrane structures, to be successful, it must be able to withstand the harsh lunar environment including, but not limited to, lack of atmosphere/hard vacuum, extreme temperature (daytime temperature = +123°C; nighttime temperature = -233°C), radiation, and space debris impact.

This research presents the structural response of an internally pressurized and regolith covered frame-membrane design. The structure is subjected to impact and thermal loading and incorporates the effects of the added mass due to the regolith cover and the stress stiffening from the internal pressurization. The impact loading was analytically determined considering a moving projectile, for example space debris, hitting the midpoint of a frame member at the crest of the structure. Results from the static, frequency, and dynamic nonlinear (large deformation) finite element analyses are presented.

Results from this research show that frequency is affected by the external temperature, internal pressurization, and added regolith mass. The increasing the external temperature increases the natural frequencies and conversely decreasing the temperature decreases the frequencies. The addition of internal pressure is seen to increase the frequencies slightly, whereas the addition of the mass from the regolith cover drastically reduces the frequency. The static analysis shows that the external temperature and the internal pressurization have a significant effect on the static displacements and stresses. The dynamic results due to impact load shows that the application of the extreme lunar temperatures reduces the dynamic amplitude (compared to cases where the outside temperature is the same as the inside temperature). The internal pressurization is seen to have little effect on the dynamic amplitude and oscillation. The added mass due to the regolith is seen to reduce the oscillation amplitude and increase the period.

Major Advisor

Ramesh B. Malla

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