Design and finite element analysis of a novel auxetic structure

In this study, a novel auxetic structure, namely RDN, is presented in two- and three-dimensions. The unit cells are created by modifying the conventional re-entrant structure and the 2D and 3D structures are formed by multiplying these unit cells. Finite element analyses are conducted to study the deformation mechanism of these structures under uniaxial tension, and the mechanical properties of the structures are obtained. Also, a 3D unit cell is modelled with different strut thickness values to examine the effect of the strut thickness on mechanical properties. Numerical models are developed using ANSYS/Static Structural software and linear elastic analyses are performed by applying small displacements to the structures. It is found that the 2D and 3D RDN structures possess a high negative Poisson’s ratio but relatively small stiffness compared to the other auxetics. The analyses of the 3D unit cells showed that increasing the strut thickness led to higher stiffness values but reduced auxetic behaviour of the structure.