【作者】 张妍；

【导师】 姚熊亮；

【作者基本信息】 哈尔滨工程大学 ， 船舶与海洋结构物设计制造， 2008， 硕士

【摘要】 水下航行体的声隐身历来是人们所关心的问题,在其壳体表面敷设各种声学覆盖层是应用最广泛也是非常有效的一种提高其隐身性的方法。本文基于有限元原理研究了具有空腔结构的吸声覆盖层在声波任意角度入射情况下的反射、透射及吸声特性;运用非均匀波导理论对隔声去耦瓦的隔声性能进行了研究。基于三维有限元基本理论研究了吸声覆盖层的声特性,自编程序数值模拟了不同背衬条件下的反射系数、透射系数及吸声系数频响曲线。将粘弹性材料作为具有一定内损耗的弹性介质来考虑,计及粘弹性材料的切形变,将吸声材料的弹性模量表示成复数形式。取吸声覆盖层的一个空腔单元进行分析,并运用Bloch—Floquet周期关系研究了材料后面的边界条件、空腔的形状以及声波入射方向对谐振吸声结构的影响。采用非均匀波导理论研究了敷设于耐压壳体外表面的隔声去耦瓦的隔声特性。将多层结构的传递矩阵求逆,利用声能的反向传输关系,对隔声去耦瓦进行空腔形状和材料参数设计,提出了优化方案,得到了使隔声去耦瓦低频隔声性能较佳的腔型。研究表明:材料杨氏模量对隔声去耦瓦隔声量的影响大于密度和损耗因子对其的影响;隔声层采用倒置腔型可以明显改善现有隔声去耦瓦的低频隔声性能。更多还原

【Abstract】 The stealth performance of submarines is usually concerned by people. Acoustic covering layers are usually applied to the surface of the shells that is very effective to improve the stealth performance of underwater moving bodies. In this paper, the finite element method is applied to analyze the sound reflection、transmission and absorption characteristics of layered acoustic structures when the incident plane wave impinges at normal and oblique incidence. Then, the sound insulation of sound-isolating and decoupled tile is studied based on the theory of non-uniform wave guide.Sound character of anechoic coating is studied by the finite element approach, .’ and the solution is obtained by the program.The frequency response curves of reflection coefficients、transmission coefficients and absorption coefficients are numerical simulated on different cases of backing conditions .The viscoelastic material is considered as the elastic medium with the certain internal losses, including the shear deformation of the viscoelastic material, and the Young’s modulus are expressed as complex numbers. A unit cell is analyzed, and the influences of boundary condition、shape of the cavities and the direction of incident wave to harmonic properties are studied with the help of Bloch—Floquet periodic relations.Sound insulation of sound-isolating and decoupled tiles covered on the outside surface of pressure hull is studied based on the theory of non-uniform wave guide. Shapes of cavities and material parameters are designed by inversion of transfer matrixes and the sound energy relation of inverse transmission. In the end, the shape of cavities of sound-isolating and decoupled tiles which have better sound insulation is obtained. The researches show that the impact of Young’s modulus on sound transmission loss is more than density and loss ratio; invertion cavities can improve the low frequency sound insulation character of present sound-isolating and decoupled tiles apparently.更多还原