Architectured and additively manufactured double-negative index metamaterials

Developing a new generation of multifunctional metamaterials with unusual thermoelastic properties enables a wide range of industrial applications, particularly in the aerospace industry. However, obtaining metamaterials with target properties by the systematic design of their microstructure and architecture remains a major challenge to this day. Topology Optimization (TO) is a powerful tool that can be used to develop the so-called anepectic metamaterials that combine both negative Poisson’s Ratio (NPR) and negative thermal expansion (NTE). Here, an overview of the existing contributions in the literature regarding such metamaterials is presented. A Finite Element (FE) model for an anepectic microstructure is presented here for the purpose of simulating in silico the experimental results obtained in previous works. It is noted that scarce contributions resort to TO to design such metamaterials and even fewer present experimental validation. The present work presents a state of the art of anepectic metamaterials and emphasizes thus the importance of the engineering-cycle completion, i.e., starting with the systematic and optimal design of metamaterials and ending up in prototype fabrication and its verification.