复杂弹性圆柱壳低频声振特性与有源控制机理研究

The low-frequency line spectrum noise is an important component of self-noise in underwater vehicles, and may be effective features for enemy’s underwater acoustic detecing system, which can result in a significant impact on the safety and attack ability for underwater vehicles. In this project, the underwater vehicle is simplified as a finite stiffened cylindrical shell, the active control of noise radiated from such a structure is investigated based on the analysis of the low frequency vibro-acoustic characteristics. The main work is summarized as follows.(1)The vibro-acoustic theoretical model will be established using Flügge’s thin shell theory and the low-frequency vibro-acoustic characteristics of the stiffened shells in different fluids are analyzed.(2) Active control of sound radiated from a submerged finite cylindrical shell equipped with piezoelectric sensor and actuators based on the Hamilton’s principle and the state space equations is investigated, optimizing the location and number of the secondary actuator, and the control mechanisms are analyzed.(3) The error sensing Strategy for active control of sound radiated from a submerged finite stiffened cylindrical shell based on modal sensing are proposed. (4)The experimental study on active control of sound radiation from a submerged finite cylindrical shell is carried out. This project is the improvement, in-depth and development of the existing research, its characteristic and innovation in theory is to establish the vibration and acoustic model of smart complex cylindrical shell, and improve the theory system of active structure acoustic control for the cylindrical shell in the range of low frequency; In application，control technology is put forward to reduce low frequency acoustic radiation for the cylindrical shells.

水下航行器航行时存在很多低频强线谱噪声，成为敌方水声探测设备的捕捉特征，对水下航行器的安全和攻击能力产生很大影响。本项目将水下航行器简化为有限长加筋圆柱壳体结构，在分析其低频声-振特性的基础上，开展结构振动声辐射有源控制研究，主要内容有：（1）基于Flügge薄壳理论建立弹性加筋圆柱壳受激振动的理论模型，研究加筋圆柱壳在不同流体中的低频声振特性；（2）建立加筋圆柱壳体和作动/传感器系统的声振模型和有源控制模型，优化作动/传感器位置和数目，分析有源控制机理。（3）构建基于模态传感的误差传感技术，优化误差传感器的数目和位置。（4）完成水下有限长圆柱壳结构声辐射有源控制实验研究。本项目是申请者已有研究的完善、深入和发展，其特色和创新之处在于理论上建立复杂弹性圆柱壳的振动与声学模型和有源控制模型，完善低频范围内圆柱壳结构声有源控制研究的理论体系；在应用上提出降低加筋圆柱壳低频声辐射的控制技术。

圆柱壳作为飞机机身、压力舱、潜艇及小型水下航行器等工程结构的简化，其振动和辐射噪声及振动噪声控制方面受到越来越多的关注。本项目通过分析有限长圆柱壳结构低频声-振特性，开展结构振动声辐射有源控制研究，可为解决圆柱壳结构声低频声辐射控制问题提供理论基础。首先，开展了不同形状筋条结构振动的数值仿真和实验研究，基于薄壳理论建立弹性圆柱壳受激振动理论模型，分析低频范围内不同流体中圆柱壳振动模态和声辐射模态的对应关系，利用有限元软件分析加筋和附加质量对板壳结构振动特性的影响；建立了有限长圆柱壳体有源控制模型，首次利用结构辐射模态分析了有限长圆柱壳有源控制，从模态角度理解控制前后的物理机理。开展了基于单元辐射器法的圆柱壳辐射声压的振动传感策略研究，利用PVDF单元检测辐射模态幅度，构建了基于结构模态传感的误差传感策略；最后，通过搭建实验平台开展圆柱壳振动模态和受激振动后的声振模态特性分析。另外，本项目还提出了一种基于激光扫描的圆柱壳模态振动声辐射测试装置，能够利用激光测振仪等装置测量任意边界条件下圆柱壳振动的模态振型、固有频率和阻尼等特性参数，通过测得壳体振速间接计算圆柱壳振动产生的声压（近场或远场）或声功率。本项目取得的研究成果为复杂圆柱壳结构声辐射控制提供了一种新途径。