Nonlocal acoustic-mechanical metasurface for simultaneous and enhanced sound absorption and vibration reduction

Abstract

We propose an acoustic-mechanical metasurface with simultaneous sound absorption and vibration reduction functionalities. This acoustic-mechanical feature results from a nonlocal coupling effect in the designed composite meta-structure. A nonlocal meta-mesh is designed at the acoustic-mechanical interface and embedded in the metasurface array to connect adjacent unit cells, which can make a nonlocal coupling effect. This effect can improve the acoustic property, which strengthens sound absorption by 58.6 %, and the mechanical interface strengthens vibration acceleration reduction by 88.45 %. The resulting nonlocal acoustic-mechanical metasurface achieves an average absorption coefficient of higher than 0.9 within 267–638 Hz, and a vibration level difference of 18.75 dB within 490–920 Hz. The sample has an ultra-thin thickness of 8.5 cm (λ/14 for the lowest working frequency) and is lightweight (305.1 g), whose weight reduction reaches 42.8 % compared with conventional designs with similar functionalities. Our proposed design strategy will be enlightened for multi-functional acoustic-mechanical coupling meta-device.

Keywords

• Acoustic-mechanical metamaterial
• Acoustic-mechanical metasurface
• Nonlocal coupling effect
• Sound absorption and vibration reduction