Vibration damping with negative capacitance shunts: theory and experiment

Abstract

This paper analyzes in detail the enhancement of piezoelectric stack transducers bymeans of the well known ‘negative’ capacitive shunting. The stability is thoroughlystudied: starting from the electrical admittance curve of the transducer, a method isintroduced that quantifies the stability margins of the shunted structure. Two differentimplementations (series vs parallel) are investigated, and the lack of robustness of theparallel one is demonstrated.Next, this technique is experimentally applied on a truss structure. Its performances arecompared with those of passive shunt circuits and with those of an active control law, theso-called Integral Force Feedback or IFF. As expected, the damping introduced by thenegative capacitance shunt is larger than the damping obtained with the passive shunts; itremains, however, one order of magnitude smaller than that obtained with the IFF.