On the connection of circular nodes with three and four tangentially attached struts and their influence on mechanical properties

Structures with chiral, antichiral, or metachiral configurations are prominent examples of mechanical metamaterials. Different methods have been introduced to increase the tunability of such structures. However, they are usually limited in the range of achievable mechanical properties. Herein, we present a method to expand the achievable properties significantly by exploring various node-strut connection configurations. Advancing from conventional chiral-based metamaterials, all possible combinations of strut connections to circular nodes with three and four tangentially attached struts were generated and analyzed. Additionally, each structure was investigated with four different node diameters. In this way, a wide range of Young's moduli, shear moduli and Poisson's ratios can be achieved. Overall, 294,912 unique unit cell geometries were created. All structures were analyzed by means of numerical homogenization simulations to obtain the full stiffness tensor of each geometry. In this study, we particularly focus on the relationship between the Young's modulus and its corresponding Poisson's ratio of orthotropic structures. Selected full-size geometries were also created and simulated with a displacement-controlled extension load case to visualize the deformation behavior.