Vibration damping and control using shunted piezoelectric materials

Research on shunted piezoelectric materials, conducted mainly over the past decade, provides new options to engineers who are responsible for solving structural vibration control problems. The general method is made possible by the relatively strong electromechanical coupling exhibited by modern piezoelectric materials. If a piezoelectric element is attached to a structure, it is strained as the structure deforms and converts a portion of the energy associated with vibration into electrical energy. The piezoelectric element (which behaves electrically as a capacitor), in combination with a network of electrical elements connected to it (a "shunt" network), comprises an electrical system that can be configured to accomplish vibration control through its treatment of electrical energy. Four basic kinds of shunt circuits are typically used: resistive, inductive, capacitive, and switched. Each of these kinds of shunts results in characteristically different dynamic behavior: a resistive shunt dissipates energy through Joule heating, which has the effect of structural damping. An inductive shunt results in a resonant LC circuit, the behavior of which is analogous to that of a mechanical vibration absorber (tuned mass damper). A capacitive shunt changes the effective stiffness of the piezoelectric element, which can be used to advantage in, for example, a tunable mechanical vibration absorber. A switched shunt offers the possibilities of controlling the energy transfer to reduce frequency-dependent behavior, or perhaps the conversion of energy to a usable form. This paper reviews recent research related to the use of shunted piezoelectric materials for vibration damping and control.