变厚度薄膜型声学超材料单胞的隔声性能数值研究

The numerical study of sound Insulation performance of membrane acoustic metamaterial cell with variable thickness

在船舶舱室中,结构振动引起的噪声有着低频、宽带的特点。常规的低频噪声,其隔声控制受到质量定律的约束,需要更为质密宽厚的材料。而基于一定设计的薄膜型声学超材料是一种单胞在几何尺寸上远小于声波波长的周期性材料,可以在某些低频频段下实现完全隔声。以往研究多讨论了等厚度的薄膜,对表面形状也呈周期性变化的变厚度薄膜研究甚少。本文利用商用有限元软件Ansys和Virtual. Lab Acoustic数值计算变厚度薄膜型声学超材料单胞的工作频率,并模拟单胞的驻波管实验。研究了变厚度薄膜型声学超材料单胞隔声性能随结构参数(包括质量块质量、薄膜厚度以及薄膜张力)的变化规律,为薄膜型声学超材料在船舶降噪方面的设计与应用提供参考依据。

In the ships cabin, the noise due to the structural vibration is low-frequency and broadband. The sound insulation performance of conventional materials follows the sound insulation mass law, which means a higher density material should be used for a great sound insulation performance in low-frequency. The designed membrane acoustic metamaterial is a periodical material that can insulate sound totally at some low frequencies, and the geometric size of its cell is much smaller than the wavelength of sound. But the past investigation mainly concentrated on the membrane with constant thickness,based on simulation with Ansys and Virtual.Lab Acoustics, a standing wave tube test of the membrane acoustic metameterial cell with variable thickness is established, and its working frequency is also studied. By the numerical calculation, a few vital factors influencing the sound insulation performance are studied, including the mass of the mass block, the thickness of the membrane and the tension of the membrane, which will provide some references for the design and application of the membrane acoustic metamaterial in ship’s sound attenuation.