Design and mechanical characterization of discretely assembled mechanical metamaterials for macroscale applications

Manufacturing large-scale mechanical metamaterials (MMs) is extremely challenging owing to the limitations of machining technology and equipment. This study proposes a family of discretely assembled MMs to address this issue. In this work, six types of MM unit cells are divided into several face blocks, which can be mass-produced by traditional low-cost manufacturing processes. The discrete face blocks are then assembled using connectors and fasteners to form a unit cell. These assembled unit cells can be further discretely assembled for modular constructions and reconfigurable MM structure systems. The results show that the discretely assembled MMs exhibit excellent mechanical properties such as high stiffness, compression resistance, and auxetic and chiral behaviors. In addition, two typical application scenarios and an example show that the discrete assembly strategy provides accessibility for the heterogeneous and multi-material assemblies of MMs. The discrete assembly strategy, benefiting from the incremental assembly feature, is proven to be a low-cost and highly repeatable forming process. It provides scalability and functionality that are not achievable with traditional manufacturing techniques. Combined with advanced design methods and automated assembly processes, discretely assembled MMs will be significant in future intelligent structures, soft robotics, and aerospace.