两自由度非线性隔振系统线谱混沌化控制技术研究

线谱混沌化是提高潜艇声隐身性能的主要手段,但难以实现小振幅下的持续混沌化;同时,非线性隔振系统由于多个吸引子共存,混沌化品质依赖于初始条件和系统参数。为此,利用开环加非线性闭环方法研究两自由度非线性隔振系统的吸引子迁移和线谱混沌化。建立两自由度非线性隔振系统的动力学方程并分析其全局性态,得到系统的全局分岔特性及吸引子共存规律;通过开环加非线性闭环方法实现不同吸引子之间的迁移控制,使系统在不同初始条件下始终运行于基础振动最小的混沌吸引子上;利用开环加非线性闭环耦合方法实现驱动系统和响应系统之间的广义混沌同步,使系统在不同参数下始终处于小振幅持续混沌运动。仿真结果表明该方法具有可行性和稳定性,能实现隐匿线谱信息和保持隔振性能的双重功能。

Line spectra chaotification of a 2DOF nonlinear vibration isolation system

Line spectra chaotification is the main method to improve the acoustic stealth of submarine, but it is difficult to achieve chaos under the variable working conditions and small amplitudes.At the same time, due to the coexistence of multi-stable attractors in the nonlinear vibration isolation system, the quality of chaos depends on initial conditions and systematic parameters.In this paper, the attractor migration control and the line spectra chaotification of two-degree-of- freedom (2DOF) nonlinear vibration isolation system have been studied by using the open-plus-nonlinear-closed-loop (OPNCL) method.Firstly, the dynamic equation of the 2DOF nonlinear vibration isolation system was established and its exhaustive bifurcation characteristics were analyzed.The regulations of global characteristics and coexistent attractors were obtained.Secondly, the OPNCL control was used to realize the migrations in different attractors, which could ensure that the system always working in the lowest line spectra intensity and the best overall vibration isolation performance.Finally, an OPNCL coupling method was used to achieve generalized chaotic synchronization between the drive system and the response system, which effectively obtained sustainable chaos even under the variable working conditions and small amplitudes.Simulation results show that the feasibility and validity of the OPNCL method, which achieves the dual goals of hiding line spectrum information and maintaining vibration isolation performance.