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基于等效参数反演的敷设声学覆盖层的水下圆柱壳体声散射研究
引用本文:金国梁,尹剑飞,温激鸿,温熙森.基于等效参数反演的敷设声学覆盖层的水下圆柱壳体声散射研究[J].物理学报,2016,65(1):14305-014305.
作者姓名:金国梁  尹剑飞  温激鸿  温熙森
作者单位:国防科学技术大学机电工程与自动化学院, 装备综合保障技术重点实验室, 长沙 410073
基金项目:国家自然科学基金(批准号: 51275519)资助的课题.
摘    要:应用了一种等效方法计算敷设声学覆盖层无限长圆柱壳体水下声散射特性.等效方法的核心是忽略复杂声学覆盖层内部的声学结构,将其作为具有等效材料参数的均匀阻尼层进行建模,该均匀阻尼层具有和原覆盖层相同的复反射系数.进而,应用COMSOL Multiphysics软件建立敷设均匀阻尼层圆柱壳体的有限元模型并求解其声散射特性.等效方法的关键是等效材料参数的获取.采用充水阻抗管实验和有限元数值实验两种方法获取声学覆盖层贴敷在与壳体具有相同厚度、相同材料背衬条件下的复反射系数,在此基础上,基于遗传算法反演材料的等效参数.研究表明,等效参数具有频变特性,且尽管等效杨氏模量和等效泊松比在频率范围内存在较大波动,但是等效前后复反射系数仍保持一致.为了验证等效方法求解壳体声散射特性的准确性,同时建立了敷设声学覆盖层壳体的完整有限元模型,将覆盖层内部声学结构进行精细建模,并求其声散射特性.结果表明,两种方法求得的形态函数符合得较好,在整个频率范围内平均误差大约为1 d B.

关 键 词:声散射  声学覆盖层  等效参数  有限元方法
收稿时间:2015-06-19

Investigation of underwater sound scattering on a cylindrical shell coated with anechoic coatings by the finite element metho d based on an equivalent parameter inversion
Jin Guo-Liang,Yin Jian-Fei,Wen Ji-Hong,Wen Xi-Sen.Investigation of underwater sound scattering on a cylindrical shell coated with anechoic coatings by the finite element metho d based on an equivalent parameter inversion[J].Acta Physica Sinica,2016,65(1):14305-014305.
Authors:Jin Guo-Liang  Yin Jian-Fei  Wen Ji-Hong  Wen Xi-Sen
Institution:Science and Technology on Integrated Logistics Support Laboratory, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China
Abstract:Anechoic coating attached to the surface of an underwater object is used for absorbing sound wave thereby reducing the reflection. The anechoic coating is often made of viscoelastic materials embedded with designed acoustic substructures, such as air cavities. The prediction of sound scattering on underwater object coated with such materials can be challenging due to the complex geometry of the anechoic coating, and it has been a research subject of interest in underwater acoustics. In this paper, we study the sound scattering on an infinite cylindrical shell coated with anechoic coating. Two types of coatings are considered: one is a layer of homogeneous isotropic material, and the other is a layer of homogeneous isotropic material with periodically embedded cylindrical air cavities. We use an equivalent method, in which the anechoic coating with air-filled cavities is regarded as a homogeneous isotropic material with equivalent material properties. The key point of the equivalent method is to ignore the internal structure of the anechoic coating, and the anechoic coating is considered as a homogeneous isotropic layer with the same complex reflection coefficient. These equivalent material properties are acquired based on the data of complex reflection coefficient obtained from either the physical experiment using water-filled impedance tube or the numerical experiment using the finite element method with COMSOL Mutiphysics software. Then a genetic algorithm is developed to inversely calculate the equivalent Young's modulus, Poisson's ratio, and damping loss factor of the coating which has the same reflection coefficient as the original coating. The results of the equivalent material properties show that 1) the three properties are all frequency dependent; 2) in general, equivalent Young's modulus increases with the increase of frequency, meanwhile the equivalent damping loss factor tends to decrease; 3) there is a wide variation in the results of equivalent Poisson's ratio. Despite that, the reflection coefficient of the equivalent homogeneous isotropic coating accords well with that of the original coating.Based on the above, the sound scattering on the infinite cylindrical shell coated with the equivalent coating is calculated by using the finite element method based on COMSOL Mutiphysics software. In order to verify the accuracy of the equivalent model, we use COMSOL Mutiphysics software to build up the full geometrical model of the coated shell to calculate the sound scattering. This can be considered as the benchmark. The results of morphic function show that the scattering calculated using equivalent material properties accords well with that obtained from the full finite element model with a mean error of about 1 dB in all frequency spectrum range.
Keywords:sound scattering  acoustic coating  equivalent parameter  finite element method
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