Numerical modelling of bilayer tetra periodic metamaterials to predict the elastic response

Metamaterials that exhibit negative Poisson’s ratio are termed as auxetic materials. The chiral and achiral honeycombs comprising of an array of cylinders connected by ligaments are one class of auxetic metamaterials. These structures have been investigated for their in-plane linear elastic behavior in the past. In this paper, novel bilayer tetra periodic structures are proposed by combining chiral and/or achiral honeycombs along the out-of-plane direction. Finite element (FE) models are developed for estimation of in-plane linear Elastic modulus and Poisson’s ratio. In the first step, the present FE model is verified with the help of experimental data for single layer tetra-chiral and tetra-achiral structures available in the literature. Subsequently, following identical methodology, the linear elastic constants of bilayer structures are computed. A comparison of bilayer tetra periodic structures with the single-layer tetra chiral/achiral metamaterials is presented. Further, a parametric analysis (for varied geometries) was performed to find a correlation between the geometry and mechanical behavior.