The vibration of structures with engine, motor, or compressor transmits energy to surroundings and radiates unwanted noise. Hence it is necessary to reduce total vibratory power transmitted to the structure from the vibrating source for the reduction of radiated noise. Passive approach such as dynamic isolation method which requires negligible stiffness in the mount system is not suitable to support heavy dead weight of structures. In this cases, active method must be added to passive method to satisfy this trade-off.
In this paper, study on active vibration control of multi-point multi-stage mounting system on ships for the reduction of radiated noise is carried out. This system is modeled analytically considering the coupling between rigid and flexible modes. In order to determine efficient type, location and direction of sensors and actuators for isolation of transmitted vibratory power and control strategy, transmitted vibratory power with all the modal displacement information of various cases is compared with that of the case with the control strategy of minimizing totally transmitted power as the best possible control performance through simulations. The relation between the vibration of structures and the acoustic power radiated from structures is derived mathematically. Based on the obtained effective control strategy, a controller is designed in time domain based on the adaptive algorithm(Filtered X-LMS algorithm).
