Active Vibration Control Of Basic Hull Structures Using Macro Fiber Composite

In the modern naval battle, enhancing submarine's hidden ability is becoming more and more important, because of the anti-detection technique developping fastly. However, in view of the worse control effect at low-frequency and weak adjustability to external influence, conventional passive vibration control can't satisfy the modern naval rigorous demands. Fortunately, active vibration control technology not only monitors the structure's real-time vibration, but also has more remarkable control effect and superior suitability. At the present time, it has a primary application in the vibration damping of ship engineering. In addition, due to functional materials rapidly developping, especially, with the coming of piezoelectric composite materials, the advanced active control technique has more applicability, lager damp amplitude and wider applied field, which basing on the piezoelectric-effect and inverse- piezoelectric-effect of piezoelectric materials.In the end of nineties, NASA had successfully manufactured the excellent macro fiber composite (MFC), which assembles actuating and sensing abilities. Comparing with the conventional piezoelectric ceramic materials, it provides the required durability, excellent flexibility, higher electromechanical coupling factors and stronger longitudinal actuating force by using interdigital electrodes. On the basis of the application of submarine structures'active vibration control by using MFC actuators, this paper ,starting with the mechanical characteristics of MFC actuators and sensors, investigates finite element models, vibration-control simulation system and physical experimental test of the submarine structures equipping with MFC. The main research contents of this thesis are as follows:Firstly, the strain and stress distribution of composite structure are analyzed basing on the simplified piezoelectric equations. Then, MFC's actuating equations working as actuators and sensing equations using as sensors are derived. Whereafter, sensing and actuating abilities are discussed in details.Secondly, the finite element technique using the commerical package ANSYS11.0 is applied to investigate four kinds of MFC's piezoelectric characteristics. And then, the naval structures'modal analysis is used to determine the positions of MFC. Subsequently, two-dimensional optimal piezoelectric equations, including piezoelectric-actuating-moment equation, voltage equation and piezoelectric-control proportional divisor, are renewedly derived. Numerical simulation results display two composite structures'deflection curves based on vibration controlling-on and controlling-off. Lastly, in order to validate the theoretical analysis method, the vibration control experiment of cantilever beam and honeycomb aluminous panel are built and tested with different activating force. The experimental results verify that MFC used in submarine structures'active vibration control are feasible and effective.