FoldableTensegrities.pdf

6 Foldable Tensegrities 6-1 Introduction Folding tensegrity systems has been one of our research topics for over a decade. This work began with some initial models [Ref 6-1] and now provides very interesting results so far as numerical models are developed; with introduction of folding processes the field of application of tensegrity systems has opened up considerably. Even the conquest of space can benefit from their characteristics. This is the reason why both practical work and theoretical developments are presented in this chapter. 6-2 Folding principle 6-2.1 Folding tensegrities: a new principle Folding is required to reduce the volume of objects in space. This operation allows for the transportation and storage of folded objects. Needless to say, the use of folding systems has greatly evolved since the nomadic lives led by primitive man, Nowadays, it covers a wide range of applications, from the simple fishermans chair to architectural projects and satellite components. This chapter deals with the folding of tensegrity systems. These systems have intrinsic properties that open up new ways to folding. On the basis of previously described properties of tensegrity systems, it appears that they can be folded and unfolded (and rigidified) by changing the element lengths. Length changes can be applied to both struts and cables. Many different possibilities can be explored, depending on the designers choice. This is quite different from the classical principle of scissors, or pantograph structures, which have mainly been developed for spatial structures. In this last case, finite mechanisms are dependent on the existence of many hinges in the structure, and to rigidify the structure one sometimes needs to i