Performance characteristics of active constrained-layer damping

Theoretical and experimental performance characteristics of the new class of actively controlled constrained layer damping (ACLD) treatment are presented. The ACLD under consideration consists of a visco-elastic damping layer which is sandwiched between two piezo-electric layers. The three-layer composite ACLD when bonded to a vibrating structure acts as a SMART constraining layer damping treatment with built-in sensing and actuation capabilities. Particular emphasis is placed on studying the performance of ACLD treatments that are provided with sensing layers of different spatial distributions. The effect of the modal weighting characteristics of these sensing layers on the broad band attenuation of the vibration of beams that are fully treated with the ACLD is presented theoretically and experimentally. The equations governing the operation of ACLD treatments with modally shaped sensors are presented. The theoretical predictions of the model are compared with the experimental performance of a computer-controlled beam treated with Dyad 606 visco-elastic layer sandwiched between two layers of polyvinylidene fluoride (PVDF) piezo-electric films. Comparisons with the performance of conventional passive constrained layer damping are also presented.