A lightweight metastructure for simultaneous low-frequency broadband sound absorption and vibration isolation

Area of Science:

• Materials Science
• Acoustics
• Mechanical Engineering

Background:

• Low-frequency noise and vibration are persistent challenges in lightweight structures.
• Existing solutions often lack multi-functionality or broad-spectrum performance.
• Metamaterials offer tunable properties for advanced acoustic and mechanical applications.

Purpose of the Study:

• To develop and validate a lightweight metastructure for simultaneous broadband low-frequency vibration and noise reduction.
• To investigate the acoustic and mechanical properties of a novel face-centered cubic sandwich structure.
• To explore the use of reinforcement learning for optimizing metastructure performance.

Main Methods:

• Theoretical modeling using bottom-up acoustic impedance theory for unit cells.
• Numerical simulations and experimental validation of a 3x3 supercell for sound absorption.
• One-dimensional supercell analysis for flexural wave bandgap validation for vibration isolation.

Main Results:

• A multifunctional metastructure featuring spiral slits and micro-perforations was designed.
• Broadband low-frequency sound absorption was achieved through reinforcement learning optimization.
• A wide hybridized bandgap for flexural waves was demonstrated, confirming vibration isolation capabilities.

Conclusions:

• The proposed metastructure effectively reduces both vibration and noise across a broad low-frequency range.
• The integration of spiral slits and micro-perforations in a sandwich structure is a promising approach.
• This work offers a new pathway for designing lightweight, high-performance structures for aerospace and transportation.