Vibration Control Research On Intelligent Structures

Intelligent structures are being the focus in the study of vibration control because of it's advantages of fast reaction self-adapting self-diagnosing and self-recovery. The piezoelectric materials have strong electromechanical couple ability so that they are mostly used in intelligent structures especially for the problem of vibration control. In this thesis, we have the rectangular composite plate with piezoelectric sensors and actuators as ours study object. Methods of Riz and FEM are used to analyze the problem of the vibration control of the smart structures with the direct feedback gain. The study demonstrates piezoelectricity of the piezoelectric materials plays the important role in controlling the vibration of the smart structures. In this paper, using a new 12-degree-freedom quadrilateral plate bending rectangular element with one electrical degree of freedom on each node, the dynamic FEM formula and equation of vibration control of the piezoelectric composite plate are obtained on the basis of the constitutive equation and Hamilton's principle. By the programming language FORTRAN, FEM program has been written to solve the equation of vibration control and a cantilever plate with piezoelectric sensors and actuators is calculated to validate the FEM program. It has been testified that the result of vibration control of intelligent structures is satisfactory with reasonable feedback control method and proper feedback gain. In addition, active constrained layer damping (ACLD) has attracted scholar's interests because it has the advantages of passive control and active control. The mechanism of vibration control of ACLD and the models of how to deal with the viscid-electric material are introduced. The finite element model of ACLD with GHM model is established in this paper. Like the active control, ACLD has a lot to be studied because there are a lot of problems such as: the constitutive equation of smart materials is very complicated; the feedback control methods should be improved; it is very difficult to deploy and optimize the sensors and actuators; it is complicated to collect and feedback correctly the information of the structures without any time delay. But the smart structure must have a bright future and now it is being used in a great range of engineering.