Dynamic Response of a Pressurized Frame-Membrane Lunar Structure with Regolith Cover Subjected to Impact Load

Abstract

A three-dimensional internally pressurized frame-membrane structure covered with regolith shielding has been proposed as a possible lunar habitat. This paper presents results from the static, frequency, and dynamic impact analysis of the structure using a nonlinear (large deformation) finite-element technique. The results are presented, taking into account the effects of the added mass of the regolith and stress stiffening because of the applied internal pressurization load. The impact loading is analytically derived by considering the impact of a moving object/debris/projectile hitting the midpoint of one of the frame members at the crest of the structure. For the frequency analysis, the results show that both pressurization and added regolith mass affect the frequency and mode-shape characteristics, where the effects of the added mass of the regolith are observed to be substantially larger than the effects of pressurization. For the static and dynamic analyses, the midspan impact results show that both pressurization and added regolith mass affect the displacement and stress of the structure. The internal pressurization (prestressing) causes the structure to statically expand and stresses it, but has little effect on the dynamic amplitude of the oscillation of the displacement and stress. The added mass of the regolith also influences the static displacement and stress by slightly contracting and stressing the structure. However, it has a much larger impact on the transient analysis, reducing the oscillation amplitude and increasing the period.