高维准零刚度浮筏系统的混沌化频谱重构

Based on the idea of reducing the line spectra characteristics of the submarine by chaotification when it sails stealthily, some achievement on chaotification of vibration isolation system has been acquired. But effect of these chaotification approaches on line spectra reduction is not remarkable so far. Moreover, the intensity of chaotic spectra is quite high. The mechanism of the chaos is not clear and the performance of chaotification is not assessed from the practical engineering technique aspect. All these issues limit its engineering application. Therefore, the quasi-zero stiffness isolator and nonlinear time delay control will be adopted in this research. The dynamic equation of high dimensional quasi-zero stiffness floating raft system will be established and the vibration characteristics and passive vibration isolation performance will be studied by numerical simulation. Then the nonlinear time delay feedback controller will be derived in line with nonlinear control theory. Appropriate performance index able to evaluate the significance of the line spectra will be constructed. Local optimization will be conducted by adjusting the nonlinear time delay control parameters in order to achieve concealment of line spectra feature by spectra reconstruction. Finally, experiments on dynamics control will be carried out to assess the accuracy and feasibility of the theoretical methods and verify the spectra reconstruction performance of the high dimensional quasi-zero stiffness floating raft system. Research of this project will enrich and develop nonlinear dynamic theory and approaches, accelerate the development of research on vibration and control of complicated systems, and provide theoretical foundation and technique support for control of line spectra features of submarine.

针对通过混沌隔振来降低潜艇隐秘航行时的线谱特征，以提高其声隐身性能这一理念，目前隔振系统的混沌化研究已取得一些成果，但其对削弱线谱特征效果不大，并且混沌谱强度较高，混沌机理尚不明确，混沌化效果未从工程实际技术层面加以评估，诸多问题严重限制了其工程应用。为此，本项目拟结合准零刚度隔振器与非线性时延控制以达到混沌化与降谱的双重目的。首先，建立高维准零刚度浮筏系统的动力学方程，分析其振动特性与被动隔振效果；其次，采用非线性控制理论推导时延控制器并求得其混沌参数域；然后，构造能评估线谱特征的量化指标，通过调节控制参数进行局部优化，以达到频谱重构与掩盖线谱特征的目的；最后，通过开展动力学控制实验研究，来评估理论方法的准确性与可行性，并验证高维准零刚度浮筏系统的频谱重构功效。本项目的研究将丰富与发展非线性动力学理论与方法，推动复杂系统的振动与控制研究发展，为控制潜艇线谱特征提供理论基础与技术支持。

针对通过混沌隔振来降低潜艇隐秘航行时的线谱特征，以提高其声隐身性能这一理念，本项目结合准零刚度隔振器与非线性时延控制以达到混沌化与降谱的双重目的。首先，建立高维准零刚度浮筏系统的动力学方程，分析其振动特性与被动隔振效果；其次，采用非线性控制理论推导时延控制器并求得其混沌参数域；然后，构造能评估线谱特征的量化指标，通过调节控制参数进行局部优化，以达到频谱重构与掩盖线谱特征的目的；最后，通过开展动力学控制实验研究，来评估理论方法的准确性与可行性。数值结果表明，通过将控制参数设置在不稳定区域，可以有效实现混沌化，验证了稳定性分析对混沌化设计的指导作用。通过准零刚度隔振器与时延控制的独特组合可以有效地改变频谱结构，尤其对于高频区域。准零-准零刚度隔振系统具有很低的力传递率，并且能够实现低频隔振，可以有效地适用与低频隔振，对于高维系统同样适用。讨论了阻尼与激励幅值对力传递率特性的影响。相对于单自由度线性隔振系统，准零-准零刚度隔振系统向低频扩展了80% 。在隔振区间，准零-准零刚度隔振系统的力传递率比相应线性系统低4倍。在x，y，z方向的传递力幅值分别为原激励的9.8%, 9.8%, 0.4% 。本项目的研究将丰富与发展非线性动力学理论与方法，推动复杂系统的振动与控制研究发展，为控制潜艇线谱特征提供理论基础与技术支持。