A unit cell structure with tunable Poisson ' s ratio from positive to negative

A novel unit cell structure with re-entrant hollow skeleton is designed and its Poisson's ratio has been studied using the finite element method (FEM) as a function of the geometric variables and the parent material Poisson's ratio. The simulation results showed that the Poisson's ratio of the unit cell structure is tunable over the full range of Poisson’s ratio (-1 to +0.5) by varying the geometric variables and parent material Poisson's ratio. Three types of samples with identical geometric variables were fabricated via 3D printing using three different materials, and their Poisson's ratios were measured and compared with the ones from FE simulation, and excellent agreement was found between the experimental results and FE simulation.