Combining acoustic black hole and phononic crystal to attenuate structural vibrations

Resumo

In the last decades, phononic crystals (PCs) have been investigated extensively and proposed for noise and vibration attenuation, due to the bandgap generated by a destructive wave propagation interference. However, PCs are limited by the characteristic of anisotropy and the periodic cell size that must be of the same order of magnitude as the wavelength in the direction of wave propagation, which are determinants for the band gap width and attenuation. The Acoustic Black Hole (ABH) effect has also been used to attenuate structural vibrations by slowing the waves in a thin-walled structure with a power-law thickness variation. The aim of this paper is to establish reliable numerical approaches for designing and modeling an effective passive structural device combining periodicity and ABH effects to attenuate vibrations efficiently. This structural PC-ABH device is modeled by the Spectral Element (SE) method and verified by the Wave Spectral Element (WSE) method. Simulated examples are performed and the results are compared between the methods and their efficiency to extended band gap widths and to attenuate the structural vibrations are evaluated.