Space Frames of Variable Geometry

Abstract

Space frames are generally studied as stable, rigid structures. However, the addition of transformation systems offers a new dimension in theoretical research. In this paper an approach to the transformation of polyhedral and spherical space frames is introduced, resulting in a uniform, rigid ‘impansion’, whereby all the edges are cut into three parts held together by two hinges. Geometrical description reveals a whole new family of such structures, presented here as being made transformable by the simple vertical motion of a central rod, going up and down, and ex/impanding the structure in a uniform symmetric and rigid way. Motorized scale models illustrate the process throughout the paper. Within this family two structures occur of particular interest, since they can be used as single space fillers: the cube and the rhombic dodecahedron. Used as impandable space frame elements, they can fill up a single- or multiple-layer grid, which is impandable and rigid.