A MODAL STRAIN-ENERGY APPROACH TO THE PREDICTION OF RESISTIVELY SHUNTED PIEZOCERAMIC DAMPING

The use of piezoceramic materials with resistive shunting circuits has previously been shown to increase passive structural vibration damping. The ability to tailor the frequency dependence of damping is especially attractive when active linear time-invariant control of uncertain structures is to be attempted. A method for predicting the damping performance of resistively shunted piezoceramics based on a variation of the modal strain energy approach has recently been developed. Using this approach, the damping for a structural mode of vibration may be found as the product of the effective fraction of modal strain energy stored in the piezoceramic material, an effective piezoceramic material loss factor and a frequency shaping factor. A finite element model may be used to accurately determine the effective modal strain energy fraction; the effective material loss factor is closely related to the piezoceramic electromechanical coupling coefficient; and the frequency shaping factor results from the dynamics of the shunting circuit. Design concerns include the effect of stiff piezoceramic material on mode shapes, the frequency dependence of piezoceramic elastic properties, and the effect of adhesive on load transfer from the structure to the piezoceramic. Analytical and experimental results are presented for a uniform cantilevered beam with two pairs of resistively shunted piezoceramic plates. The results show good agreement between predicted and measured added damping.