Design and fabrication of modular tensegrity-like lattices with auxetic properties

Tensegrity-like lattices have recently been found to feature a nonlinear mechanical response descending from that of the corresponding tensegrity structures. Here, a design procedure for additively manufactured tensegrity-like modular lattices with geometrically nonlinear behavior is proposed. A modular lattice based on the expanded octahedron unit was designed, fabricated, and tested, both numerically and experimentally, to investigate its effective mechanical behavior and to compare it with that of the parent tensegrity system. The tensegrity unit cell chosen for the lattice design compares favorably with other tensegrity units previously considered, as it features a triaxial shrinkage-expansion auxetic mechanism and has a low number of nodes and edges. Lattice samples composed of eight units arranged in a 2x2x2 array were fabricated by inverted stereolithography and subsequently tested in compression. The observed auxetic properties and nonlinear behavior are directly related to a soft mode of the lattice that is inherited from the mechanism of the parent tensegrity structure. The measured stiffening response of the lattice closely follows that of the implemented numerical model. The proposed design procedure can be extended to lattice metamaterials based on other tensegrity units and realized by different additive manufacturing techniques. • A design method for tensegrity-like lattices preserving nonlinear response of the unit is proposed. • Lattice cells are designed, fabricated by inverted SLA, and tested in compression. • Numerical model implements the actual stress-strain curve of the photopolymer resin. • The observed auxetic response of the supercell is evaluated numerically. • Measured stiffening response closely follows that of the implemented numerical model.