Numerical Analysis of a Two‐Dimensional Open Cell Topology with Tunable Poisson's Ratio from Positive to Negative

A two‐dimensional (2D) open cell topology with eight‐sided star perforations is proposed. Its mechanical properties (including Poisson's ratio and energy absorption capacity) and deformation behaviors are studied using finite element method (FEM) as a function of the geometric parameters. Simulation results showed that the Poisson's ratio of the structure is tunable from positive to negative by varying the geometric parameters that define the shape of the perforation. A minimum Poisson's ratio of −0.68 is achieved when the geometric parameter α, which determines the inner corner sharpness of the star perforation, is equal to 0.1. The highest energy absorption capacity is observed in the model which exhibits the minimum Poisson's ratio. The star perforation cells shrink when the lattice structure is being compressed due to the negative Poisson's ratio effect. Compressive samples are fabricated by 3D printing from Tango Black Plus, and their Poisson's ratios are measured and compared with numerical results. Excellent agreement is found between measurements and simulation.