DESIGN OF CHIRAL AUXETIC METAMATERIALS FOR BETTER ENERGY ABSORPTION CAPACITY

Abstract

Unlike conventional materials, whose properties arise from their constituent atoms, the mechanical properties of metamaterials are intricately linked to their micro- and nano-scale structures. Auxetic metamaterials, in particular, exhibit exceptional mechanical properties due to their counter-intuitive deformation characteristics. In this research, firstly, hexagonal honeycomb and re-entrant honeycomb cellular solids were analyzed to investigate their Poisson’s ratio. The study examined how the re-entrant honeycomb cellular solid’s cell angle and wall thickness variations affect its Poisson’s ratio. Further, two different types of chiral auxetic metamaterial structures were compared in terms of their energy absorption capacity; one is a trichiral auxetic structure, and another one is an anti-trichiral auxetic structure while keeping the same relative density and same height, width, and extrude depth through the experimental and numerical analysis. Parameters of the 3D printer were optimized using Taguchi’s design of experiment methodology to fabricate 3D samples of these chiral auxetic structures. A uniaxial quasi-static compression test was conducted on both trichiral and antitrichiral structures, and the energy absorption capacity of the trichiral auxetic structure was approximately four times that of the anti-trichiral one. Also, both of these structures show negative Poisson’s ratio in both experimental and numerical analysis. Further, a parametric study was conducted on the trichiral auxetic structure by varying the radius of the cylinder and cell wall thickness of the trichiral auxetic structure. Results showed that both the cylinder’s radius and cell wall thickness significantly affect the energy absorption capacity of the trichiral auxetic structure.