【作者】 石炜；

【导师】 沈火明；

【作者基本信息】 西南交通大学 ， 工程力学， 2010， 硕士

【摘要】 近年来,噪声成了一个重要的环境问题,引起了众多专家学者的广泛关注,也是目前的一个研究重点。作为一门新兴的学科,有源噪声控制技术在最近的几十年时间里发展很快,由于传统的被动噪声控制在低频段存在缺陷,因此可以利用它来弥补不足。结构声有源控制基于辐射模态的理论,它避免了振动模态中复杂的耦合项,简化了计算。本文以对边固定对边自由矩形板为研究对象,在对其进行振动分析的基础上,对其声辐射模态控制进行了研究。论文主要研究内容有：(1)应用振型叠加法,推导了对边固定对边自由矩形薄板在简谐激励下的位移、速度关系式,分别利用MATLAB编程计算和有限元模拟证明了理论推导的结果。并由速度分布式得出了板周围空间声压分布的近似解。(2)基于声辐射模态理论,分析对边固定对边自由矩形板的各阶辐射模态以及辐射效率随频率的变化趋势,并研究了该种情况下声辐射模态和振动模态的对应关系。(3)根据辐射模态的特性,提出了抵消前N阶声辐射模态伴随系数法和声功率最小化法两种控制方法,并比较了两种方法的控制效果。最后讨论了激振力与控制力位置对控制效果的影响。更多还原

【Abstract】 With the development of social economy, noise has been obtained widespread provenance as one of the significant environmental issues. In the past decades, the active noise control has been developed rapidly as a newly arisen discipline, which are expected to overcome the disadvantages of traditional passive noise control techniques in low-frequency stage. Based on the radiation modes, method of active structural acoustic control can avoid the complicated coupling of vibration modal and simplify the calculation and control burden. However, all the existing research production of radiation modes originate from rectangular plates with all four sides simply supported, while noise control about plates with one pair of opposite sides fixed and other two opposite sides free has not been reported yet.The current study is summarized as follows:(1)Based on the modal superposition method, the displacement and velocity formula of plate with two opposite edges fixed and other two free under excitation are deduced by theoretical analysis. Meanwhile, the finite element simulating and MATLAB programming and calculation are also used to confirm the results. Further, approximate solution for sound pressure distribution around the plate is obtained by velocity distribution. All conclusions above can provide a theoretical basis for a further study on sound radiation of plate with two opposite edges fixed and other two free.(2) By the theory of radiation mode, the changing trend about radiation modal、radiation efficiency of each step versus frequency is established. In addition, the correspondence relationship between radiation mode and structure vibration mode are analyzed systemically.(3) Aiming at radiation modal characteristics, two control methods of canceling acoustic radiation coefficient of the first N steps and minimizing acoustic power are presented and then compared for controlling effect. The influence of control effect with different position of exciting force and controlling force is also analyzed preliminarily.The research results show that in low-frequency sound control method based on the radiation mode can reduce the acoustic power of plates with two opposite edges fixed and other two free sharply. And reasonable controlling forces locations will greatly improve the control effect.更多还原