Hierarchical Modular Structures and Their Mechanical Characteristics

Future structure systems need adapatability to various changes from the viewpoint of total cost for their missions. In order to introduce such adaptability into artificial structure systems, their future concepts with autonomous life cycles are discussed, which are typical features of things in nature. To realize such concepts hierarchical modular structures are proposed and studied. They consist of a number of basic modules, which are assembled with hierarchical assembly rules. A mathematical algorithm extended from the one for fractal formations is introduced, which keeps their basic property of geometrical symmetry. Some examples of hierarchical modular structures composed of basic modules with hexagonal shape are illustrated. Their mechanical characteristics such as characteristic frequencies and distributions of internal forces under some boundary conditions are also calculated. It is shown that the hierarchical modular structures are able to provide systematically various structures based on required mechanical properties and control strategies, which means they can easily construct various structure systems fitted to wide environments and their changes.