声波在12重准周期声子晶体中的传播.docVIP

 Acoustic waves propagating through 12-fold quasi-periodic sonic crystals# 5 10 15 20 LU Minghui, LIU Xiaokang, NI Xu* (Department of Materials Science and Engineering, College of Applied Science and Engineering, National Laboratory of Solid-State Microstructures, Nanjing University, China) Abstract: Propagation of acoustic waves through 12-fold quasi-periodic sonic crystals (QSCs) has been studied by the multiple scattering method. Flat QSC lenses can focus acoustic waves at frequencies on both sides of the first gap of transmission spectrum. We have found this focusing imaging result from local multiple scattering in QSC, which means the modulation of density and modulus among short range plays a key role in controlling acoustic waves propagating in QSC. The focusing imaging was found to have the far-field-imaging and abaxial characteristics. In some case, there are two focusing imaging in the system due to the self-similarity of quasi-crystals. In addition, localized modes have been investigated in this paper. All the characteristics of acoustic wave propagating through QSCs stated above originate from the 12-fold symmetry of QSCs. Key words: acoustics; sonic crystal; quasi-periodic;quasi-crystal 0 Introduction In the past decade, growing efforts have been put on the study of sonic crystals (SCs), which are the analogues of photonic crystals (PCs). SCs control acoustic waves by the well-known Bragg scattering and could have some novel effects, such as acoustic band gaps and negative refraction. [1-7] These intriguing effects can be exploited to control and guide the propagation of acoustic waves and are anticipated for potential applications, such as sound shielding, highly directional 25 30 35 40 acoustic wave radiation and acoustic lenses. [4, 5] Recently, it has been found that quasi-periodic PCs (QPCs) and quasi-periodic SCs (QSCs) could also offer similar properties like their periodic counterparts, such as properties of the band gaps and non-near-