Research On Active Vibration Control Of Piezoelectric Smart Structures

Smart structures are being the focus in the study of vibration control due to its advantages of fast reaction, self-adapting, self-diagnosing and so on. The piezoelectric materials have strong electromechanical couple ability so that they are studied by most scholars.In this thesis, a beam with bonded piezoelectric sensors and actuators is studied. Analytic method and FEM are used to analyze the problems of the vibration control of the smart structures. Constant-gain negative velocity feedback, as well as a linear quadratic regulator (LQR) approach has been used for active vibration control with the structures subjected to initial position, impact and harmonic excitations. These are simulated with Matlab. For the first method, the vibration control of a piezoelectric cantilever beam with LQR is researched under the changes of weighting coefficient Q, R. Because of the disadvantage of the analytic method, a FEM approach is presented. The dynamics FEM formula and equation of vibration control of the piezoelectric cantilever beam are induced on the basis of the Hamilton's principle. The comparisons of the control laws are also studied.The analysis of the dynamics characteristics is significant in the dynamics of the structures. Due to the distribution and length of the piezoelectric elements, the changes of the natural frequency, modal shape and nodal point of a piezoelectric cantilever is studied.Piezoelectric elements can be used as sensors and induced strain actuators in active vibration control systems. Since the distribution of the piezoelectric elements can affect control performance greatly, it has to be carefully determined. The theoretical analysis is made on the optimal positioning of piezoelectric elements for the active vibration control applications.