粘弹性多层复合结构吸声特性研究

【作者】 刘志宏；

【导师】 盛美萍；

【作者基本信息】 西北工业大学 ， 环境工程， 2005， 硕士

【摘要】 海洋环境噪声是海洋环境污染的一个突出问题。水下航行器产生的噪声是目前急待解决的一个重要的海洋环境污染问题。 吸声覆盖层技术是水下结构声隐身技术的关键,本文分别采用平面声波入射下吸声覆盖层的一维与二维近似模型展开理论研究,该研究有助于更好地了解吸声覆盖层的声学特性,对吸声覆盖层声学结构的设计及吸声橡胶材料的选用具有一定的指导意义。 在线性粘弹性假设条件下,通过引入复弹性模量,使粘弹性波动方程具有和弹性波动方程类似的形式。同时,为了简化分析在研究中将吸声覆盖层的复合结构看成平面多层结构。采用传递矩阵方法研究水下结构吸声覆盖层模型的声吸收特性;研究带有空腔结构的非均匀复合吸声覆盖层结构的声吸收特性;对比了非均匀层中变截面空腔与打圆柱形空腔在吸声特性方面的差异;研究了不同声学结构的形状尺寸、材料参数对吸声性能的影响;并初步研究了斜入射条件下均匀复合结构的声学特性。本文通过对水下结构吸声覆盖层的研究得出了一些有意义的结论: 1.不同的吸声材料参数对结构的吸声特性影响显著; 2.复合多层结构的声吸收特性优于单层结构的声吸收特性; 3.带空腔结构的声吸收特性优于均匀复合多层结构的声吸收特性,尤其是低频的吸声特性得到了显著的改善。 4.不同的空腔形状对水下吸声结构吸声特性的影响有明显不同。所得到的上述结论有助于对吸声机理的进一步了解;所进行的理论推导可以方便地对不同结构、不同材料的吸声覆盖层进行吸声系数的计算,对于吸声覆盖层设计具有一定的理论指导意义和工程实际意义。更多还原

【Abstract】 Noise produced by underwater aircraft is an increasingly very important ocean environmental pollution.The technique of anechoic coating is crucial to underwater structure stealth technology. In this thesis, one-dimensional and two-dimensional approximate theoretical model of an incidence plane wave on anechoic coating are established and studied theoretically. Theoretical research is helpful to understand the acoustical characteristics of anechoic coating, and has important guiding significance for the design of anechoic coating and the choice of rubber material.Introducing the complex visco-elastic modulus, visco-elastic wave equation has the similar form with elastic wave equation for harmonic wave motion, in case of linear visco-elastic. The anechoic coating is assumed to be planar multi-layered system in the theoretical analysis. Simultaneously, absorption characteristic of anechoic coating on underwater structure is studied. Various cavity size, cavity shape, perforation ratio and material parameter concerns are analyzed. And the absorption performance of oblique plane wave on multi-layered structure is studied elementarily.Some very useful results are obtained through the analysis of anechoic coating of underwater structure. Material parameter, various cavity size, cavity shape etc are greatly contribute to absorption characteristic.As can be seen from the above conclusions , which are helpful to comprehend the mechanism of sound absorption better. The theoretical compute about absorption coefficient have good adaptability to various structures and different function of the sound-absorbing material and can provide greater theoretical guidance and engineering guidance for the design of the anechoic coating.更多还原