水下结构去耦覆盖层的动力吸振器效应研究

Dynamic absorber characteristics of decoupling coating covering underwater structure

去耦覆盖层的低频减振降噪是水下结构声辐射的一个难点问题。采用模态分解法和粘弹性阻尼流体传递矩阵模型,建立了敷设去耦覆盖层的四端简支撑矩形板水下振动和声辐射模型。分析了去耦覆盖层的减振降噪特性,研究了去耦覆盖层的物理参数(如杨氏模量、损耗因子、密度等)对板的均方振速和辐射声功率的影响规律。研究结果表明:对于板的单个振动模态,板-去耦覆盖层-流体系统可看作是一个两自由度系统,它具有两个共振频率和一个反共振频率,去耦覆盖层会引入类似动力吸振器的效应;针对具体结构,通过合理调整去耦覆盖层的参数,能够充分利用动力吸振器效应,有效降低水下结构低频振动与声辐射。

Noise reduction by means of applying decoupling coating on underwater structures is commonly used in the marine field. Assuming decoupling coating as viscoelastic fluid, a vibration and acoustics model of a simply supported rectangular plate covered by decoupling coating is presented. The model simulates the vibration and acoustic response of the structure which is water-loaded on one side and air backed on the other. The characteristics of vibration and acoustics reduction by the decoupling coating are analyzed, and the influences of the physical parameters of decoupling coating to vibration velocity of base plate and sound radiation power are researched. The results show that： for single flexural mode of plate, ＇ plate-decoupling coating-water layer＇ is similar to two-freedom degree system, which has two resonant frequencies and an anti-resonant frequency, and dy- namic absorber characteristics are introduced by decoupling coating. Dynamic absorber characteristics could be used to reduce the low-frequency vibration and underwater radiation noise by selecting suitable parameters of decoupling coating.