Stiffened star-shaped auxetic structure with tri-directional symmetry

A new auxetic structure was designed with rigid diamonds incorporated to enhance the strength of a star-shaped auxetic structure along with the symmetry in the present work. The new structure was fabricated through Multi-Jet Fusion process and subjected to quasi-static compression tests for static analysis. Finite element model was developed using ABAQUS and validated by experimental results in terms of deformation mode, nominal stress-strain curve, and Poisson's ratio of the auxetic structure. Theoretical model was also developed to predict the Poisson's ratio of a unit cell of the designed auxetic structure. The theoretically predicted Poisson's ratio is in tandem with that of obtained from a finite element model, which utilized periodic boundary conditions. Parametric study using the theoretical model revealed that the angle of the inclined members has shown a significant effect on the Poisson's ratio. The newly proposed structure exhibited 36% better specific plateau stress than a conventional 3D star-shaped auxetic structure of similar geometrical parameters.