“…These included the double-V re-entrant system [100] and another motif [101], later referred to as the "anti-tetrachiral" motif [102][103][104] (Figure 1c). Nowadays, much more developed commercially available software such as ANSYS (Ansys Inc., Houston, TX, USA), MSC Marc (Hexagon AB, Newport Beach, CA, USA) and ABAQUS (Dassault Systèmes Simulia Corp., Johnston, RI, USA) combined with high computational power are essential tools when conducting research in the mechanical properties of materials and has, thus, been utilized by several research groups, as noted in Appendix A, in the study of auxetic metamaterials [63,[105][106][107][108][109][110][111][112][113]. It is also most useful that various textbooks have been written to guide researchers through the background theory and application of FEA [70,71,114].…”