Study of Various Tensegrity Modules as Building Blocks for Slender Booms

Abstract

This study investigates the structural performance of long and slender tensegrity booms. Previous studies show that tensegrity structures are generally more flexible than conventional trusses or space frames. The aims here were (i) to quantify how much more flexible eleven different tensegrity booms are, when compared to state-of-the-art truss booms, (ii) to find a general explanation for this. The performance criterion used for the comparison was the first natural frequency of the boom. A finite element program with truss elements was used to compute the natural frequencies around the initial prestressed configurations. The results show that tensegrity booms have between one and three orders of magnitude lower natural frequencies than truss booms. It is concluded that for the best performing tensegrity booms, the bending stiffness is independent of the level of pre-stress and the number of infinitesimal mechanisms as the bending stiffness is given mainly by the material stiffness of the tension elements and not the geometric stiffness as the infinitesimal mechanisms are not activated by bending. Thus, whereas the level of pre-stress and the presence of infinitesimal mechanisms play major roles for the stiffness of some tensegrity structures, the axial stiffness and orientation of tension elements are most important for the studied slender booms.