复杂形状和边界条件下开口振声系统建模与声振特性研究

Sound radiation from open structures is a challenging topic in the field of sound radiation. For the open structure, the absence of considering not only the coupling between the structure and its surrounded acoustic fields on both sides but also the direct coupling between the finite cavity and the infinite exterior acoustic field at the opening restricts the further investigations on the characteristics of sound radiation. The attempt of this study aims at developing an analytical model which is suitable for handling the sound radiation from structure-acoustics coupling system with partial opening, complex shape and general boundary restraints. Based on this model, corresponding analytical investigations, numerical and experimental studies will be launched to shed a light on the vibroacoustic characteristics of, the transmission of vibroacoustic energy in and the mechanism of sound radiation from the coupled system. By developing the variational expressions of structural vibration of the structure and acoustic behaviors of the sound space, and variational expressions of particle velocity at the opening and at the surface of the structure influenced by the finite and infinite sound space, the characteristic equation of the partially opened structure-acoustics coupling system can be obtained by adopting Rayleigh-Ritz method. Further investigations on the influence of the opening on vibroacoustic characteristics of the system, the characteristics of sound energy transmission and the mechanism of sound radiation will be carried out, hoping to provide effective guidance for real-life problems.

带开口结构的声辐射问题是结构声辐射领域的一个研究难点。对开口结构而言，缺少同时考虑结构与两侧声场的耦合以及内部声场与外部声场经开口直接耦合的整体研究，制约了此类问题的进一步研究和实际应用。本课题旨在建立适用于复杂几何形状和任意边界约束条件下带有部分开口的结构声耦合系统声辐射问题研究的整体分析模型，基于对这类模型的理论分析、仿真和实验研究，进一步研究耦合系统的声振特性、振声能量传递和辐射机理。根据能量原理分别建立有限声场和弹性结构振动能量表达式基础上，结合在开口处和在结构内外表面分别建立的有限声场声压和无限声场声压对开口处和对结构内外表面质点振速影响的变分表达式，采用瑞利-利兹方法求解系统未知的局部坐标，从而得到系统的特性方程，并以此深入研究开口对系统声振特性的影响、声能量由开口和结构分别向外场传递的规律以及辐射的机理，以期为工程实际中的振声设计提供一种更接近真实情况的求解方法。

结构声耦合系统是舰船舱室的理论抽象模型，其振动噪声水平直接影响船员身心健康及舰船隐蔽性能。由于现实舱室系统中结构众多、边界约束复杂，属于复杂的声固耦合问题，很难通过简单规则的结构声耦合系统模型来描述。针对这一关键问题，本课题提出一种复杂形状和边界条件下的结构声耦合系统理论建模新方法，采用变分原理建立复杂结构系统动力学模型，依据提出的多声场耦合方法实现复杂结构声耦合系统建模及声振特性分析。旨在提出合理、有效的复杂形状和边界条件下结构声耦合系统动力学物理模型，建立复杂形状声场声学理论模型，实现复杂形状和边界条件下的结构声耦合系统声振特性研究，分析揭示系统能量传递及声辐射机理，相应方法通过实验验证。从而获得一种适用于复杂结构声耦合系统声振特性的理论建模方法，为舰船舱室系统振动噪声预测及后续的控制问题奠定理论基础。