Method for discrete assembly of Cuboctahedron Lattice Materials

The novel technology is a method for the design, manufacture, and assembly of modular lattice structure based mechanical metamaterials composed of cuboctahedron unit cells. The main parameters for determining the behavior of an architected lattice material are 1. Lattice geometry: base unit cell topology defines joint connectivity and informs general lattice behavior (e.g. bending or stretch dominated), which can then be used for performance prediction relative to constituent material and density. Cell size (edge length) and edge thickness (cross section) can be used to calculate relative density; 2. Base constituent material: solid properties (mechanical, thermal, electrical, etc.) are used to calculate effective properties of resulting lattice, as well as to inform manufacturing processes. The invention relates particularly to a cuboctahedral lattice geometry, which can be decomposed into face connected cuboctahedrons. The material used is determined by the manufacturing process, such as injection molding. This offers a range of high-performance options such as glass fiber and carbon fiber reinforced polymer (GFRP, CFRP) composites. The size of the lattice can vary based on the application. Molded individual faces (bottom left figure) are then assembled into the cuboctahedron voxel building block (bottom right figure). This assembly can be achieved with a number of methods, including permanent methods such as welding or gluing, or reversible methods such as bolting or riveting. Aeronautical and aerospace applications require strong and stiff lightweight materials and structures. The invention relates to a construction system for mechanical metamaterials based on discrete assembly of a finite set of types of parts, which can be assembled in varying orders to produce spatial variation in a range of properties such as rigidity, and auxetic behavior. This system achieves desired material properties through design of the parts such that global behavior is governed by local mechanisms. The invention describes the design methodology, production process, modeling, and experimental characterization of metamaterial behaviors. This approach benefits from incremental assembly that eliminates system deployment scale limitations, best-practice manufacturing of components for reliable, low-cost production, and interchangeability through the use of a consistent assembly process across part types.