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 dampin g. The ability to tailor the frequency dependence of damping is especi ally attractive when active linear time-invariant control of uncertain structures is to be attempted. A method for predicting the damping pe rformance of resistively shunted piezoceramics based on a variation of the modal strain energy approach has recently been developed. Using t his approach, the damping for a structural mode of vibration may be fo und as the product of the effective fraction of modal strain energy st ored 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 fra ction; the effective material loss factor is closely related to the pi ezoceramic electromechanical coupling coefficient; and the frequency s haping factor results from the dynamics of the shunting circuit. Desig n concerns include the effect of stiff piezoceramic material on mode s hapes, the frequency dependence of piezoceramic elastic properties, an d the effect of adhesive on load transfer from the structure to the pi ezoceramic. Analytical and experimental results are presented for a un iform cantilevered beam with two pairs of resistively shunted piezocer amic plates. The results show good agreement between predicted and mea sured added damping.