由于人工声子晶体具有天然材料所不具备的异常物理性质,它能够调控弹性波或声波的传输.考虑复式晶格可以降低晶体结构的对称性,容易打开完全带隙,进而抑制波的传播.设计了单胞含6个“原子”的(3.4.6.4)晶格钢/水声子晶体,结合超声浸水透射技术,测试了第一布里渊区F-K和F-M方向带隙性质.结果表明:实验得到的宽频段8个完全带隙频率范围和有限元法计算值可以很好地吻合.还详细分析了完全带隙边界频率点本征模态和声波局域效应,这对于设计多带隙隔声材料具有重要参考意义.%Phononic crystals are man-made materials possessing unusual physical properties to regulate propagation of elastic waves or acoustic ones.Complex Bravais lattices may reduce lattice structures' symmetry to open easily their complete bandgaps and suppress transmission of waves.Here,a photonic crystal with 6-atom unit cells composed of (3.4.6.4) steel/water lattice arrays was designed.Based on the ultrasonic immersion transmission technique,the experimental transmission spectra of bandgaps were measured when acoustic waves propagated through the phononic crystal in F-K and F-M directions.The measured results showed that frequency ranges of eight complete bandgaps are well consistent with the computation ones using the finite element method;furthermore,eigen-modes of complete bandgaps' boundary frequency points and localized effects of acoustic waves are analyzed in detail.The experimental results provided a reference for designing sound isolation materials of multi-complete bandgaps.
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