【作者】 朱石坚；

【导师】 于起峰；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2006， 博士

【摘要】 为了提高舰艇的战斗性能和生存能力，必须大大提高其水声隐身性能。常规减振方法只能降低辐射水声中特征线谱成分的幅值，而不能改变其特征，因此不能从根本上解决水声隐身问题。论文结合“十五”国防预研项目“潜艇有源振动控制技术研究”和海军武器装备科研项目“结构噪声线谱混沌控制技术研究”，以海军装备中实际使用的隔振系统为研究对象，将混沌动力学理论应用于非线性振动的理论分析中，解决了将离散的线谱转化为连续宽频谱的理论问题。通过计算和实验，对其效果进行了模拟和检验，从而初步确立了一套新的减振降噪、提高舰艇水声隐身性能的理论、设计、计算和实验方法。通过对实际型号和装备中具有不同刚度特性的隔振元件的静、动态力学性能研究及其在隔振系统中的应用研究，成功实现了隔振系统的混沌隔振，初步达到了降低或消除线谱的目的。论文的主要创新点：(1)独立提出了利用处于混沌振动状态的隔振系统来削弱或消除舰船特征线谱的理论和方法。(2)率先对非线性刚度的线性化问题作了理论研究，分析了静载荷对隔振系统实际性能的影响。(3)对具有非线性阻尼和非线性刚度的双层隔振系统的动力学特性进行了理论和仿真研究。研究发现，该系统具有丰富的动力学特性，包括周期运动、准周期运动和混沌运动。此外，根据激励频率选择合适的非线性阻尼和非线性刚度可以有效地减小系统的振幅。(4)提出了基于小波分析的混沌信号去噪方法。(5)从非线性隔振系统的原理出发提出了混沌隔振系统的隔振性能评估方法，即采用振级落差来评估隔振系统的整体性能，根据特征线谱处的能量衰减来评估隔振系统对特征线谱的隔离能力。(6)设计了混沌隔振实验装置，并进行了实验研究。实验结果表明，非线性隔振系统在混沌状态下具有良好的整体隔振性能，并能有效隔离线谱。更多还原

【Abstract】 In order to improve the combat performance and survivability of warships, the acoustic stealth must be advanced. Only the amplitude of line spectra not the spectrum configuration can be altered with the traditional vibration-isolation method. The problem of acoustic stealth, hence, cannot be resolved fundamentally. Combining with the "Tenth Five" national defense advanced research item "Research on the Active Vibration Isolation Technique in Submarine" and the naval weaponry and equipment research item "Study on the Application of Chaos Technique to Control the Line-spectra in the Structure-borne Noise", this paper studied the vibration-isolation system actually used in naval vessels, applied the chaotic dynamics to the nonlinear vibration analysis, and finally settled on a solution to the problem how the line spectra can be changed into the continuous spectrum. The effectiveness of the chaotic vibration-isolation method was verified through simulations and experiments. A new method for vibration-isolation was hence established and the acoustic stealth of marine vessels would be improved. The static and dynamic performances of isolators with different stiffness characteristics as well as the application of these isolators to the vibration-isolation system were studied. The chaotic vibration isolation was realized in vibration-isolation system and the line spectra were controlled or removed.The prime innovations of this paper are as follows:(1) A method using the chaotic motion state in the nonlinear vibration-isolation system to weaken or eliminate the line spectra in marine vessels was advanced.(2) The linearization of nonlinear stiffness was theoretically investigated, and the effect of static load to the performance of vibration-isolation system was analyzed.(3) The nonlinear dynamics of a two-degree-of-freedom vibration-isolation system with nonlinear damping and nonlinear spring was studied. Numerical simulations showed that the system exhibits periodic motions, quasiperiodic motions, and chaotic motions. It was also shown that the purposes of reducing the response amplitude of the system can be realized by adjusting properly the system parameters according to the exciting frequency. (4) A new method was proposed to eliminate the noise in chaotic signals on the basis of wavelet analysis.(5) A new performance index for evaluating the vibration-isolation effectiveness of the chaotic vibration-isolation system was presented, namely, the vibration-level difference was used to evaluate the whole vibration isolation performance and the energy attenuation at frequencies of the line spectra was used to evaluate the local isolation performance at the special dominant frequency.(6) The presented method was experimentally verified. Experiment results show that the reduction of the line spectra when the system is chaotic is much greater than that when the system is non-chaotic, and that the overall effectiveness of vibration-isolation in chaotic state is better than that in non-chaotic state.更多还原