【作者】 黄茜；

【导师】 沈火明；

【作者基本信息】 西南交通大学 ， 一般力学与力学基础， 2007， 硕士

【摘要】 随着社会经济的不断发展，噪声作为重要的环境问题之一，得到了广泛的关注。几十年来，有源噪声控制技术(ANC)作为一门新兴的学科得到了迅速发展，人们试图利用它来弥补传统被动噪声控制在低频段的不足。基于辐射模态的结构声有源控制(ASAC)避免了振动模态中复杂的耦合项，使得计算和控制更加简便。既有的研究成果均来源于四边简支矩形薄板，而对边简支对边自由的板的辐射模态控制还未见报道。本文的主要工作有：(1)基于振型叠加法，从理论上推导了对边简支对对边自由矩形板在简谐激励下的位移、速度关系式，并采用有限元模拟和MATLAB编程计算印证了理论推导的结果。进而利用速度分布式得到板周围空间声压分布的近似解。这些结论为进一步研究对边简支对边自由板的声辐射问题提供理论基础。(2)利用辐射模态理论，获得了板的各阶辐射模态、辐射效率随频率的变化趋势，并研究了辐射模态与结构振动模态的对应关系。(3)针对辐射模态的特性，提出了抵消前N阶声辐射模态伴随系数和声功率最小化两种控制策略，并对两种方法的控制效果进行了比较。初步研究了激振力与控制力位置对控制的影响。研究结果表明：在低频段，基于辐射模态的声控制方法可以让对边简支对边自由板的声辐射得到明显的控制，而合理的控制力布放位置会使控制大大改善。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 simply supported 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 simply supported 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 simply supported 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 k 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 simply supported and other two free sharply. And reasonable controlling forces locations will greatly improve the control effect.更多还原