The elastic properties of an actively controlled piezoelectric transducer: Measurement, analysis and tuning

We report on the development of a method for the measurement of the effective stiffness of a piezoelectric transducer which is bonded to a vibration control system and operated using an approach known as active elasticity control (AEC). Using high-accuracy measurement techniques it is shown that the effective stiffness of the transducer can reach negative values in a certain frequency range, when a suitable active shunt circuit is connected to its electrodes. Extensive analysis proves the consistency of mechanical and electrical measurements of the dynamically loaded piezoelectric transducer compared with the AEC model. A method which allows the computation of adjustments to the active shunt circuit based on the vibration control device's measured mechanical transfer function is developed. The applicability of the method to a real vibration control system is also demonstrated.