A theoretical framework for physically-realizable kagome metamaterials and its implications on dualities and topological edge modes

Abstract: Since the discovery of topological modes in idealized ball-and-spring kagome lattices, significant efforts have been devoted to realizing mechanical analogues of these ideal lattices via practical fabrication techniques. While numerical and experimental characterizations of these mechanical analogues have been reported, theoretical modeling that accounts for realistic structural effects (e.g., the bending behavior of thin ligaments-a departure from ideal hinges allowing free rotation) has been lacking. Here we propose a theoretical framework to investigate the dynamic properties of physically-realizable kagome metamaterials consisting of solid triangles and ligaments, in which triangles and ligaments are modeled as rigid bodies and elastic springs, respectively. By applying the framework, validated through finite element analysis, to twisted and deformed kagome metamaterials, we theoretically show the required conditions for achieving certain unique dynamic properties, including dispersion dualities and topological edge modes. The presented study unequivocally reveals the effects of structural components on these properties, which could enable new design strategies for wave propagation manipulation in kagome-based metamaterials.