Anisotropic Metallic Microlattice Structures for Underwater Operations. Issue 6 (22nd November 2022) - Shen, Chen
Abstract : Metamaterials have offered unprecedented potentials for wave manipulations. However, their applications in underwater acoustic wave control have remained largely unexplored. This is because of the limited material choices and the lack of reliable fabrication techniques for the complicated structures. Herein, a metamaterial with microlattice structures as the building blocks is proposed for underwater operations. By designing the building blocks of the metamaterial and assembling them in a layered fashion, anisotropy is embedded in the structure, which results along different effective sound speeds in orthogonal directions. The designed metamaterial is fabricated by metal additive manufacturing using aluminum and steel. Experiments are performed using a resonator tube to evaluate its performance in water. An anisotropy ratio of around 2 is achieved, which is in good agreement with numerical simulations. The proposed metamaterial provides an effective means for underwater sound control with reduced fabrication difficulties and increased service life. Abstract : An underwater metamaterial with octet truss microlattice structure is designed and fabricated by metal 3D printing. By using a layered arrangement of the lattice structure with steel plates, a large anisotropic ratio of acoustic properties is achieved. The developed microlattice metamaterial is mechanically robust and long durable in harsh environments, and broadens the applicability of underwater metastructures.