Nonlinear Structural Analysis of an Icosahedron Under an Internal Vacuum

Abstract

The concept that a structure is capable of producing buoyancy using an internal vacuum rather than a gas dates back to the 1600s, but material technology has restricted the construction of such concepts for common geometries, such as the sphere. Different and often complex geometries compensate for the lack of light materials that provide the stiffness and strength needed. Therefore, this research looks at a lighter-than-air vehicle in the form of an icosahedral frame/skin configuration using nonlinear finite element analysis in order to determine the structural response of such a vehicle, its capacity to sustain a vacuum with both material technology that exists today and in the near future, and its buoyancy characteristics. The structural response is characterized with large displacements, where membrane behavior dominates the icosahedral skin response, generating geometric stiffening in the overall structure. It is shown that those displacements have minimal effect in the structure’s buoyancy, with no more than 4% reduction. Overall, the nonlinear analysis of the icosahedral structure provided tangible background on its behavior and the lighter-than-air vehicle applicability. It is feasibly possible to actually manufacture this type of vehicle in the very near future, depending upon newer materials with more advanced strength.