Embodiment of parallelizable mechanical logic utilizing multimodal higher-order topological states

Abstract

The dramatic advancement of autonomous engineering systems has fueled a surge of research interest in materials and structures embodying intelligence within the mechanical domain. Fundamental to achieving this mechanical intelligence is the ability to process information using the mechanics and dynamic characteristics of structures, such as wave propagation. While utilizing elastic waves for information processing and computing is a promising concept, a critical issue for current platforms is the lack of robust wave transmission that is insensitive to material or structural imperfections. The goal of this research is to overcome this obstacle by leveraging the extraordinary elastic wave control capabilities of higher-order topological metamaterials. More specifically, this work uncovers a novel approach that harnesses multimodal higher-order topological states to achieve robust and frequency-selective mechanical logic. Multimodal resonance is engineered into a 2D higher-order topological metamaterial to create 0D corner states that emerge in eight distinct frequency bands and have a rich collection of displacement field characteristics. A new phase-engineering strategy is synthesized that encodes binary information within the corner states to achieve eight fundamental mechanical logic gates. Crucially, this approach produces an easily detectable mechanical signal due to the temporal and spatial confinement of the higher-order topological states. The multifaceted frequency-dependent features of the corner states are innovatively employed to provide the logic gates with frequency-selective functionality and parallelize unique logic operations across multiple frequency channels. The mechanical logic uncovered in this study will pave the way for future intelligent structures that are much more resilient to cyberattacks and harsh environments, as compared to current systems that are built solely on electronics-based logic.