Locally Resonant Phononic Crystals at Low frequencies Based on Porous SiC Multilayer

Abstract

In this work, a one-dimensional porous silicon carbide phononic crystal (1D-PSiC PnC) sandwiched between two rubber layers is introduced to obtain low frequency band gaps for the audible frequencies. The novelty of the proposed multilayer 1D-PnCs arises from the coupling between the soft rubber, unique mechanical properties of porous SiC materials and the local resonance phenomenon. The proposed structure could be considered as a 1D acoustic Metamaterial with a size smaller than the relevant 1D-PnC structures for the same frequencies. To the best of our knowledge, it is the first time to use PSiC materials in a 1D PnC structure for the problem of low frequency phononic band gaps. Also, the porosities and thicknesses of the PSiC layers were chosen to obtain the fundamental band gaps within the bandwidth of the acoustic transducers and sound suppression devices. The transmission spectrum of acoustic waves is calculated by using the transfer matrix method (TMM). The results revealed that surprising low band gaps appeared in the transmission spectra of the 1D-PSiC PnC at the audible range, which are lower than the expected ones by Bragg’s scattering theory. The frequency at the center of the first band gap was at the value 7957 Hz, which is 118 times smaller than the relevant frequency of other 1D structures with the same thickness. A comparison between the phononic band gaps of binary and ternary 1D-PSiC PnC structures sandwiched between two rubber layers at the micro-scale was performed and discussed. Also, the band gap frequency is controlled by varying the layers porosity, number and the thickness of each layer. The simulated results are promising in many applications such as low frequency band gaps, sound suppression devices, switches and filters.

Fano resonance based defected 1D phononic crystal for highly sensitive gas sensing applications

“…The damping rate is inversely proportional to the quality factor of our gas sensor as seen in Eq. (27). The 1D-DPC gas sensor has the lowest quality factor value towards CO 2 which equals 1050, but the CH 4 has the highest value equals 3040 among other gases.…”

“…If the interference was a constructive interference, it results in the formation of the stopped PC band gaps 64,65 . On the other side, when the interference is destructive, the resulted band is a transmission band 27,66 . The formula of the incident wave equation was written in Eq.…”

“…The defect layer will be filled with different gases that will be tested separately www.nature.com/scientificreports/ tion between the damping rate and the quality factor as seen in Eq. (27), this means that our gas sensor provides high quality factor measurements for CH 4 and O 2 gases at 30 °C and 40 °C. On the other hand, for the CO 2 and NH 3 gases it shows high quality factor at 40 °C and 80 °C.…”

“…There are several techniques have been developed to investigate the propagation of acoustics waves through the PC including the TMM, plane wave expansion(PWE) method, the finite difference time domain (FDTD) method [56][57][58] . However, of these techniques, only the TMM method is a suitable method for calculating the transmission of incident acoustic waves through the multilayer structure 27,45,52 .…”

Acoustic Metamaterials for Noise Reduction: A Review

“…designed a 1D porous silicon‐carbide phononic‐crystal sandwiched between two rubber layers. [ 19 ] This structure solved the problem of a low‐frequency phonon bandgap. These studies used a pipe or cavity to obtain the negative equivalent parameters.…”