Active Dense Tensegrity Structure: A Novel Concept for Shape Morphing Systems

The active dense tensegrity is desired to possess significant differences in bending stiffness (K) when considering the bending direction (up or down). Dense tensegrity structure was manufactured using tetrahedrashaped particles as the compression elements, and carbon fibers were used as the tensional cables such that an assembly in a dense planar array was obtained. Three types of polyhedral elements were considered: regular and homogeneous tetrahedra, truncated tetrahedra, and “Janus-type” tetrahedra made of part soft and hard solid material. For assemblies of regular tetrahedra, the tensegrity possessed the same stiffness in both bending directions (K, upward/K, downward = 1 due to symmetry), while for the tensegrity of the truncated tetrahedra (K, upward/K, downward = 25.2) and of the “Janus-type” tetrahedra (K, upward/K, downward = 4.7), significant bending stiffness asymmetries were realized, and a basic theory for the mechanical response of dense tensegrity structures was presented.