SUBJECT: Ph.D. Dissertation Defense
BY: Benjamin Beck
TIME: Friday, September 21, 2012, 3:30 p.m.
PLACE: Love Building, 109
TITLE: Negative Capacitance Shunting of Periodic Arrays for Vibration Control of Continuous Flexural Systems
COMMITTEE: Dr. Kenneth A. Cunefare, Chair (ME)
Dr. Massimo Ruzzene (AE/ME)
Dr. Alper Erturk (ME)
Dr. Krish K. Ahuja (AE/GTRI)
Dr. Manuel Collet (FEMTO-ST)


This thesis presents electromechanical and structural improvements for modeling and implementation of a negative capacitance shunt control system for vibration suppression. A shunt is considered any electrical network attached to a piezoelectric transducer that reduces the mechanical response of a system to which itís bonded. With regard to the many types of control shunts, the negative capacitance shunt has been shown to produce significant reduction in vibration over a broad frequency range yet is gain-limited by the parameters of the circuit. There are two aspects of a negative capacitance shunt system that are absent from the field and of interest here: determination of the electrical behavior of a negative capacitance shunt and assessment of wave attenuation using a periodic piezoelectric array. Three electromechanical aspects are developed: design for maximum suppression, more accurate stability prediction, and increased power-output efficiency. First, a method is developed that may be used to adaptively tune the magnitude of resistance and negative capacitance for maximum suppression. Second, with regard to stability, a method is developed to predict the circuit components at which the circuit will obtain a stable output. Third, through electrical modeling of the shunt-patch system, the components are chosen to increase the power output efficiency of the shunt circuit for a given impedance. The negative capacitance shunt is also combined with a periodic piezoelectric patch array to modify the propagating wave behavior of a vibrating structure. Analytical predictions are verified with experimental results for both a 1- and 2-D periodic array. Results show significant attenuation can be achieved with a negative capacitance shunt applied to a piezoelectric patch array.