Multi-line spectra reduction of vibration isolation system based on chaotification method

Line spectra in the radiated noise of marine vessels are the most visible signals,which can be detected,tracked and identified by passive sonar of the enemy,and hence it is of great significance to reduce the line spectra for improving the acoustic stealth of marine vessels.The technology of chaos spectra reduction was used to reduce line spectra in the radiated noise of submarines based on the fact that response spectrum of a nonlinear system under harmonic excitation is a continuous one when chaos occurs.The feedback chaotification of the single-degree-of-freedom vibration system and multi-degree-of-freedom vibration systems subjected to harmonic excitation were analyzed,and the chaotification method of the multi-degree-of-freedom vibration system subjected to multi-frequency excitation was proposed.The study discovered the condition and approach that the vibration system enters the chaos state subjected controller effect,and overcome the difficulties that how to maintain the chaotic motion when the operation condition and the environment change.The experimental platform of the two-degreeoffreedom VIS for discretization and chaotification was designed,and the dynamics of the system with different feedback plus was experimentally studied.The results confirmed the effectiveness of this method,and can provide the theoretical and experimental bases of design for chaos VIS.