CHAPTER 4 EVOLUTION

CHAPTER 4 EVOLUTION

As previously mentioned, tensegrity structure still required more advanced study especially in the field of architecture. After the concept of tensegrity was invented, Snelson, Fuller and Emmerich directed their investigation differently.

Snelson took more sculptural approach, thought he was the one who began to study about principles of tensegrities, he avoided very deep mathematical and physical approaches, it was due to his background of artist and he also analysed that the application of tensegrity system is complicated. This process provided him the facility to develop very different configurations, asymmetrical and non-conventional, applying his intuitive knowledge and achieving impressive sculptures. On the other hand, Fuller and Emmerich took a distinct approach, by studying different achievable classification of tensegrity system. They did it by making models and practical experiments as their main tools and in contradiction to Snelson, they look for feasible applications in architecture and engineering.

In 1961 Fuller started to develop a series of tensegrity structure with vertical faces of three, four, five and six each. He also discovered the “six-islanded-strut icosahedron Tensegrity” (expanded octahedron). He been searching for new designs, method and application of tensegrities for construction. He made a variety of experiments to design geodesic tensegrity domes which is a hemispherical thin -shell structure (lattice -shell) based on geodesic polyhedron, although they lacked of stability due to the absence of triangulation.

Rene Motro, most likely one of the primary specialists in tensegrity at present, started to publish his studies on the subject in 1973: topolgie deestructures discretes (topology of discrete structures). Incidence sur leur comportement mecanique (impact on their mechanical behaviour). Autotendent icosaedrique (self-tending icosahedron). It was an internal note about the mechanical behaviour of this kind of structure. From this time forth, Civil Engineering of the University of Montpelier (France) laboratory and engineer became a reference in terms of tensegrity research. Couple year later, in 1976, Anthony Pugh and Hugh Kenner continued this work with different approach. On the one hand, Pugh wrote the “Introduction to Tensegrity” which is fascinating for the various of models that it outlines and his strict classification and typology. On the other hand, Kenner developed the useful “geodesic math (curve representing in some sense the shortest oath between two points in a surface) and how to use it” which shows how to calculate “to any degree of accuracy”. The suitable details of geometry (length and angles of the framing systems), and explores their potentials.

During the 1980s, some authors tried to develop the field opened for them previously. Robert Burkhardt started complete analysis and maintain similarity with Fuller (1982) in order to acquire more details about the geometry and mathematics of tensegrity. The final output, 20 years later, is very complete, useful, and continuously revised Practical Guide to Design Tensegrity. Other important researches have been Ariel Hanaor, who explain the main bidimensional assemblies of elementary self-equilibrated cell and Nestorovic with his presentation of metallic integrally tensioned cupola (a small dome on the top of a roof). In the following year, Connelly and Back have aimed to find a proper three- dimensional generalization for tensegrities. Using the mathematical tools of group theory and representation theory and the capabilities of computers, they have drawn up a complete catalogue of tensegrities with detailed prescribed types of stability and symmetry, including some that have never been seen before.

A lot of other authors such as, S. Pellegrino, A.G. Tibert, A.M. Watt, W.O. Willams, D. Willamson, R.E. Skelton, Y. Kono, Passera, M. Pedretti, etc. have also studied the physics, mathematics (from geometrical, topological and algebraical point of view) and mechanics of tensegrity structure.