A CIRCULAR TOTAL-REFLECTION ELASTIC METASURFACE FOR REDUCING SOUND RADIATION OF THIN PLATE

In this paper, we propose a circular elastic metasurface (CEM) composed of subunits with different thicknesses to realize the total reflection of flexural waves in broadband, and further to achieve the broadband sound radiation of a thin plate, referred to as a CEM plate. Results demonstrate that the sound power and sound radiation efficiency of the CEM plate within the vibration isolation band are both significantly reduced compared with the corresponding uniform plate, which is attributed to the vibration isolation caused by the total reflection of flexural waves. The analyses on the wavenumber spectra of vibration velocity and supersonic intensity patterns of the CEM plate further reveal the reduction mechanism of sound radiation, which is that most of the vibration energies present as subsonic components with a weak sound-vibration coupling and a poor sound radiation ability. Our design achieves sound radiation reduction by weakening the sound-vibration coupling degree through vibration redistribution, rather than vibration reduction, providing a lossless and lightweight design method for noise reduction in engineering.