Analysis, experiments and application of an antiprismatic deployable space truss system characterized by snap-back behaviour

The specific cylindrical system, namely the deployable antiprismatic lattice structure, derived from the yoshimura origami pattern and proposed by Hegedűs, is characterized by its pop-up deployment due to the energy accumulated from lengthening some bars during packing. Zero deployment-load corresponds both to the fully deployed and the compact configuration, the latter being an unstable equilibrium state corresponding to the maximal internal energy. The packing behavior of the antiprismatic deployable structure will be shown through a simplified 2D structure possessing similar packing properties to that of the chosen specific system. The equilibrium paths of packing and the concerning difficulties (bifurcation of the path, snap-back phenomenon, singular configurations etc.) as well as the packing sequences will be revealed through analytical and numerical research.

A different system, slightly deviating from the original one will be also presented. The original system is constructed from identical double antiprisms with an elastic middle polygon and rigid polygons in the boundaries. The modified model eliminates the rigid internal polygons; the pop-up column is constructed from continuously rotating elastic polygons with two rigid polygons on the top and on the bottom. When the non-stiffened structure is only controlled by the displacement of the top facet, the packing patterns show a quite interesting chaotic, but not completely stochastic system. The simulation developed proved that in the case of certain geometrical parameters, there are certain number of possible patterns, among which the numerical errors (or in reality the imperfections) choose.

An attempt is given to provide ideas for application of antiprismatic structures by combining the ideas and characteristics of the available systems and the topology of the antiprismatic structure. If the restriction of symmetrical behavior is relieved the asymmetrical structural forms can be used for adaptive architectural designs, for structures that could change morphological properties due to different external excitations. Some small physical models built for experimenting will be presented, some sketches for possible applications and control systems will be shown.