Key Laboratory of Modern Acoustics, MOE, and Institute of Acoustics, Nanjing University, Nanjing 210093, China.
Ultrasonics. 2010 May;50(6):577-82. doi: 10.1016/j.ultras.2009.12.002. Epub 2009 Dec 16.
The effective velocity of elastic waves for two-dimensional (2D) phononic crystals with rectangular lattice in the long-wavelength limit is studied by numerical simulations. It is demonstrated that, for all three propagating modes, not only the modes polarized in-plane (L wave and SV wave), but also the mode polarized out-plane (SH wave), the effective velocities are distinctly anisotropic and the slowness curves exhibit twofold symmetry. The anisotropy increases as the filling fraction increases or as the width to length ratio of the lattice decreases, and high anisotropy can be obtained in phononic crystals with large contrast between material parameters, which is much higher in rectangular lattice than in square lattice with the same material parameters. Owing to these dependences, the effective velocity can be controlled in engineering.
通过数值模拟研究了在长波极限下具有矩形晶格的二维（2D）声子晶体中弹性波的有效速度。结果表明，对于所有三种传播模式，不仅平面内极化模式（L 波和 SV 波），而且平面外极化模式（SH 波），有效速度都是明显各向异性的，慢度曲线呈现出二倍对称。各向异性随填充率的增加或晶格的宽长比的减小而增大，在材料参数差异较大的声子晶体中可以获得较高的各向异性，而在具有相同材料参数的矩形晶格中则要高得多。由于这些依赖性，有效速度可以在工程中进行控制。
