流固混合声子晶体中负折射与导波特性研究

Negative refraction and guided waves in fluid-solid phononic crystals

针对声子晶体中负折射现象产生的原因以及调控波导的方法,本文研究了工字型钢在空气中正方形排布所形成流固混合型声子晶体的波动特性。数值计算是通过有限元方法进行的。根据等频率曲线确定声子晶体产生负折射的频率,并进行模拟验证。通过引入线性缺陷,设计直线和折线型波导,调控波的传播。并通过引入耦合共振缺陷,研究结构中耦合共振波导的波动特性。结果表明:在?=0°的声子晶体中,5255 Hz时波仅沿y方向传播。在?=45°的声子晶体中,3045 Hz时波的传播会出现负折射现象。只有在特定的频率范围内,波在Z型线性波导中能够较好地传播。在不同的频率范围内,波在2种直线型耦合共振波导中均能够较好地传播。相关结果为流固混合型声学器件的设计提供一定的数值基础。

In this paper,negative refraction and guided waves in fluid-solid phononic crystals formed by I-shaped steel arranged in air in the square lattice are studied.Numerical calculations are conducted by using the finite element method.According to the equifrequency contour,the frequency where negative refraction appears is determined and verified by simulation.Linear and bent waveguides are designed to control wave propagation by introducing linear defects.And wave propagation in coupled-resonantor waveguides are studied by introducing linear chains of defects.The results show that in phononic crystal for?=0°,the wave propagates only along the y direction at 5255 Hz.The negative refraction occurs when wave propagation at 3045 Hz in phononic crystal for?=45°.Only in a specific frequency range can waves propagate in a Z type linear waveguide.In different frequency ranges,waves can propagate in the two straight coupled-resonantor waveguides respectively.The results are relevant for the design of acoustic devices based on fluid-solid phononic crystals.