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 MultiJet 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 stressstrain 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.