The chiral structures and their mechanical properties of auxetic metamaterials. (a) Normalized buckling stress of chiral and hexagonal honeycombs with respect to relative density [77]. (b) Finite element prediction of E as a function of the number of ligaments [78]. (c) finite element prediction of E as a function of β [78]. (d) finite element prediction of E as a function of α [78]. (e) finite element prediction of ν as a function of α [78]. (f) schematic illustrations of double-arrow [79] and re-entrant hexachiral [80] structures. (g) schematic of a disordered hexachiral system. (h) mean Poisson's ratio and Young's modulus of chiral structures with different degrees of disorder, together with standard deviations of the results. (i) structural parameters of hexachiral structures and Poisson's ratio variation of irregular hexachiral structures. (j) clockwise and counterclockwise chiralisation of a hexagon with triangular rotational symmetry [83].