IMPEDANCE-BASED MODELING OF ACTUATORS BONDED TO SHELL STRUCTURES

When discrete piezoelectric actuator patches bonded on structures are used for active shape, vibration, and acoustic control, the desired de formation field in the structure is obtained through the application o f localized line forces and moments generated by expanding or contract ing bonded piezoelectric actuators. An impedance-based model to predic t the dynamic response of cylindrical shells subjected to excitation f rom surface-bonded induced strain actuators is presented. The essence of the impedance approach is to match the actuator impedance with the structural impedance at the ends of the actuators, which will retain t he dynamic characteristics of the actuators. A detailed derivation of the actuator and structural impedance is included. It is found that th e actuator's output dynamic force in the axial and tangential directio n are not equal. Various case studies of a cylindrical thin shell are performed to illustrate the capabilities of the developed impedance mo del. Out-of-phase actuation is shown to be the most efficient in excit ing the lower order bending modes of shell structures. The paper is co ncluded with a finite element analysis verification of the derived imp edance model.