【作者】 刘杨；

【导师】 杜敬涛； 沈建平；

【作者基本信息】 哈尔滨工程大学 ， 动力工程（专业学位）， 2016， 硕士

【摘要】 弹性板结构广泛应用于船舶工业、航空航天、建筑工程等各个工程领域,在外部的激励作用下弹性板结构振动声辐射是一种重要的噪声来源,对于具有低频传播特性的结构声辐射,需要采用有源控制技术以达到满意的抑制效果。在很多场合下,弹性板与背腔存在明显耦合,针对此种情况下弹性板结构声辐射研究尚不充分,限制了此类声辐射有源控制系统的优化设计。本文以存在背腔情况下弹性板结构声辐射特性分析及有源控制建模开展了如下工作:首先对复杂边界条件下板结构的固有振动特性以及声辐射特性进行理论分析,通过二维改进傅里叶余弦级数来表达弹性约束边界条件下板的振动位移,再利用能量法以及Rayleigh-Ritz方程求解所有未知傅里叶系数。然后利用近场瑞利积分求解板结构辐射声功率以及辐射阻抗,并通过仿真分析,对模型特性进行分析和验证。针对含弹性壁面封闭空间的理论模型,引入背腔Lagrangian函数,并考虑声腔-弹性板耦合面声压的相互作用效应,利用MATLAB语言进程编程仿真。然后设计板-腔耦合系统动力学特性实验,对比仿真结果,证明本文方法的正确性以及程序编写的准确性。考虑有声腔耦合作用的板结构声辐射问题,求解板-腔耦合系统振动特征矩阵方程,利用板结构耦合系数向量,求解结构辐射声功率以及辐射效率。对比耦合声腔前后板结构模态辐射效率以及辐射声功率的变化,考虑声腔深度、边界弹簧约束刚度对耦合效应的影响。最后采用二次最优控制原理,以板结构辐射声功率为目标函数,求解最优次级控制力,建立有源噪声控制预报模型,分析弹性板边界约束条件,次级控制力的物理位置,声源激励位置以及声腔深度对有源系统控制效果的影响。更多还原

【Abstract】 The flexible panel is reasonable representation of many engineering occasions, such as the shipbuilding, aerospace, architectural engineering and other fields. The sound radiated by the flexible panel under external excitation is considered as the main noise source. Active noise control shows the satisfied effect of the attenuation for the low frequency sound radiation. In some circumstance, the panel is backed by acoustical cavity, and the radiation from flexible panel backed by acoustical cavity should be taken into account. It can be found that most of the current studies are limited to the sound radiation from single plate structure, and the optimal design for the active noise control is limited. Surrounding the structural-acoustic system, sound radiation and its modeling problem of active noise control, the following research work has been carried out in this thesis:Firstly, the natural vibration and sound radiation characteristics of the plate are investigated with elastic boundary condition. The displacement of the plate is constructed in the form of standard two-dimensional improved Fourier cosine series, and the unknown expansion coefficients are determined using the energy method and Rayleigh-Ritz procedure, the plate sound radiated power and radiation resistance subsequently determined from the near-field Rayleigh integral with the known vibration velocity distribution of the plate. The accuracy and effectiveness of proposed method are demonstrated through numerical examples.The interaction between the structural vibration and sound field is established through increasing the Lagrangian procedure of the sound cavity, which includes the sound pressure acting on the structural-acoustic interface. Some simulation is performed through MATLAB programming language. In the meanwhile, some relevant experimental setups are designed and built up to validate the accuracy of proposed method.The sound power radiated from a rectangular plate backed by cavity is determined from the vibro-acoustic governing matrix equation and the vibration coupling coefficient vector. Some comparisons are presented to show the difference between the coupling and uncoupling circumstances. The effect of the cavity depth and the boundary restraining stiffness on the radiation behavior of planar sources is also studied.Finally,the sound power radiated is chosen as the performance function using the linear quadratic optimal control theory to search for the optimal secondary force. The active structure acoustic control system model is established, and the effect of boundary restraining stiffness, cavity depth, the secondary force position and the excitation source position on the sound attenuation of the controlling system are investigated in much details.更多还原