Influence of defect states on band gaps in the two-dimensional phononic crystal of 4340 steel in an epoxy

Abstract

The band structures of a new two-dimensional triangle-shaped array geometry of 4340 steel cylinders of square cross section in an epoxy resin were studied by the plane-wave expansion and supercell calculation method. The band gaps of this type of phononic crystals with different defects were calculated such as defect-free, 60 • crystal linear defect states, 120 • crystal linear defect states, and 180 • crystal linear defect states. It was found that the band gap will emerge in different linear defects of the phononic crystals and the bandwidth of linear defect states is larger than that of the free-defect crystal by about 2.14 times within the filling fraction F = 0.1-0.85. In addition, the influence of the filling fraction on the relative width of the minimum band gap is discussed.

Symmetry-controlled edge states in graphene-like topological sonic crystal*

“…In addition, it is noted that the filter is robust and topological protected, which is distinct from the ordinary defects. [55,56] Simulated results are given in Appendix B. This significant property to freely adjust the bandwidth of the edge states provides excellent ways for the design of adjustable topological acoustic materials.…”

Analysis on vibration characteristics of large-size rectangular piezoelectric composite plate based on quasi-periodic phononic crystal structure

“…[8][9][10] As a functional material with periodic structure, PC is also composed of two kinds of materials, and because of their band gap and passband characteristics, in recent years, many scholars have studied their applications in noise reduction and vibration reduction of acoustic transducers. [11][12][13][14] Kong et al [15] and Ahmed et al [16] have shown that the existence and width of a complete band gap can be adjusted by adding a defect state into the PC structure, thereby changing the filling rate of the scatterer, the temperature, etc. Based on their bandgap characteristics, the PCs have been widely used in vibration suppression.…”

Theoretical demonstration of the hybrid focusing points of sonic crystal flat lenses and possible applications

“…Metamaterials have been implemented by using artificial crystal structures for a wide range of wave spectra. Photonic crystals, [1][2][3][4][5][6][7][8][9][10][11][12] phononic crystals, [13][14][15][16][17][18][19][20][21][22][23] and sonic crystals [24][25][26][27][28] were developed for their technological potentials such as wave focusing, [24][25][26][27][28][29][30][31] wave isolation, [16][17][18]21] wave absorption, [10,22] and wave guiding. [2][3][4]32,33] The realization of flat lenses from crystal structures is one of the promising applications of metamaterials.…”