Emergence of bilayer-locked states and synthesis of elastic wave networks in a programmable 3D topological metamaterial

Abstract

Recently, concepts from topological physics have been used to achieve exceptional elastic wave transport phenomena in 3D mechanical systems. Although interesting, the previously studied 3D topological elastic structures are fixed after fabrication and thus cannot adapt to changes in the external environment or operating conditions. This lack of reconfigurability limits potential performance and functionality. In this Letter, we advance the state of the art by proposing a programmable 3D topological metamaterial that can be tuned adaptively via carefully designed metastability. A metastable switching methodology is developed that enables the synthesis of multiple unique topological states in a 3D mechanical structure. By taking advantage of the adaptivity of the proposed metamaterial, the path of 2D topological surface states is on-demand controlled, a bilayer-locked topological state is discovered, and 3D elastic wave networks with advanced filtering and splitting capabilities are realized. The findings presented in this Letter offer insight into how topology can be used to control the flow of energy in 3D elastic structures. Furthermore, the advanced functionalities of the proposed metamaterial could be harnessed to create intelligent and robust devices for various purposes, such as mechanologic, vibration mitigation, energy harvesting, and remote sensing.