Improved evaluation of Poisson’s ratio in 3D-printed auxetic metamaterials using finite element and experimental methods

This study presents an investigation into the Poisson’s ratio behavior of 3D-printed auxetic lattice structures with varied unit cell sizes, strut lengths, and inclination angles. Auxetic lattice structures with various unit cell sizes (3 × 3, 4 × 4, and 5 × 5 mm3), strut lengths (1.25 and 1.9 mm), and inclination angles (60° and 70°) were designed and simulated using SOLIDWORKS CAD software and ABAQUS Simulation Packages and fabricated via stereolithography using a photopolymer resin. Compressive mechanical performance was assessed experimentally, while finite element analyses incorporating both linear elastic and nonlinear Neo-Hookean material models were conducted in ABAQUS. Poisson’s ratio values were systematically calculated from lateral and longitudinal deformations measured experimentally through image analysis and extracted from finite element simulations. The nonlinear material model demonstrated superior correlation with experimental data especially for larger unit cell configurations highlighting the importance of accounting for complex deformation mechanisms in auxetic materials. These findings have predominant control of structural parameters on auxetic behavior, with larger configurations undergoing more uniform deformation and showing better simulation-experiment correlation. This illustrates the benefit of nonlinear models in being able to better predict the response of auxetic structures and the model’s use in customizing the auxetic structure for a specific application.