Journal of Aerospace Engineering

How do we begin to expand our civilization to the Moon? What are the technical issues that infrastructural engineers, in particular, must address? This paper has the goal of introducing this fascinating area of structural mechanics, design, and construction. Published work of the past several decades about lunar bases is summarized. Additional emphasis is placed on issues related to regolith mechanics and robotic construction. Although many hundreds of papers have been written on these subjects, and only a few tens of these have been referred to here, it is believed that a representative view has been created. This summary includes environmental issues, a classification of structural types being considered for the Moon, and some possible usage of in situ resources for lunar construction. An appendix provides, in tabular form, an overview of structural types and their lunar applications and technology drivers.

The initial buckling behavior of thick laminated composite curved panels with random material properties subjected to various in-plane edge loads has been investigated. For this purpose, an approach is presented to obtain the governing equation and the buckling load statistics with the help of an accurate $C^0$ finite element in conjunction with first-order perturbation technique. A higher order shear deformation theory has been used for the laminate. The laminate material properties, subjected to inherent variations about the mean value, have been modeled as random variables. Results for second-order statistics of buckling load have been presented for laminated spherical panels and validated with available results in literature and Monte Carlo simulation. The influence of curvature-to-side ratio, side-to-thickness ratios and edge support conditions on buckling load statistics has been studied. The sensitivity of buckling load statistics for spherical panels to variations in material properties has been compared with that of cylindrical panels.

Nonlinear finite-element models that predict the load-elongation behavior of single- and dual-bolted conical-head bolted lap joints are developed, and the load-elongation predictions are compared with experimental test data. The study is conducted for several panel thicknesses with a 4.8 mm size fastener and 2024-T3 clad aluminum alloy panels. The model load-elongation predictions are in excellent agreement with experimental test data. The results show that (1) dual-bolted lap joint test results underpredict the strength of single-bolted lap joints; and (2) numerical models may reliably predict the load-elongation behavior of mechanically fastened lap joints at a fraction of the cost and time of experimental testing.

By adopting the energy method, a method of calculating the stability of the rotational composite shell is presented that takes into account the influence of nonlinear prebuckling deformations and stresses on the buckling of the shell. The relationships between the prebuckling deformations and strains are calculated by nonlinear Karman equations. The numerical method is used to calculate the energy of the whole system. The nonlinear equation is solved by combining the gradient method and the amended Newton iterative method. A computer program is also developed. Examples are given to demonstrate the accuracy of the method presented in this paper.