Multifunctional mechanical metamaterials integrating energy absorption, vibration isolation and acoustic attenuation

Shock, vibration, and noise are typically coupled in engineering scenarios such as heavy machinery and aerospace. Traditional materials struggle to simultaneously meet the requirements for lightweight design and multi-field protection, while existing metamaterials often focus on a singular functionality. The integration of energy absorption, vibration isolation, and noise reduction into a single design remains largely unexplored. This study proposes a novel multifunctional mechanical metamaterial based on truncated conical shell units. Through a combination of theoretical modeling, numerical simulation, and experimental testing, its various performances were systematically characterized, and the governing laws of structural parameters on multifunctional synergy were elucidated. The results indicate that the metamaterial achieves repeatable and stable energy absorption by leveraging the negative stiffness effect. Furthermore, low-frequency and tunable vibration isolation is realized through parameter optimization, mass configuration, and pre-compression. Additionally, the closed cavities of the truncated conical shell facilitate a Helmholtz-like resonance effect, which, combined with structural-acoustic coupling and thermo-viscous dissipation, enables high-efficiency low-frequency sound absorption. This research provides a new strategy for the design of integrated multifunctional mechanical metamaterials, effectively enhancing their application potential in complex engineering environments.