Truncated regular octahedral tensegrity-based mechanical metamaterial with tunable and programmable Poisson's ratio

Tensegrities consisting of axially loaded strings and bars have various technologically important applications. In this paper, we design a mechanical metamaterial with tunable and programmable Poisson's ratio on the basis of truncated regular octahedral tensegrity (TROT). A theoretical model for evaluating the deformation behaviors of TROT is established by involving the principle of virtual work. Our experimental data obtained from the tests of 3D printed TROT sculptures agree well with theoretical predictions. By systemically investigating the mechanical properties of the TROT metamaterial, it is found that the Poisson's ratio can be programmed to a desired value in a wide positive/negative range through the structural prestress, initial twist angle, and the stiffnesses of strings/bars. This mechanical metamaterial can be utilized not only as elementary cells to assemble other larger scale of metamaterials, and also as prototypes with tunable properties in designing advanced machineries for applications such as robotics and aerospace engineering.