Experimental calibration of digital piezoelectric shunts: practical considerations, parameter estimation and dielectric losses

Piezoelectric shunts have been studied extensively over the past decades for vibration mitigation of flexible structures. The admittance of the electrical circuit in a piezoelectric shunt can be synthesized by a digital control unit, commonly referred to as a digital piezoelectric shunt. While the digital control unit requires power (and is therefore semi-active), it allows for a straightforward implementation and adaptation of, in theory, any electrical circuit, making it effective for prototyping. Furthermore, the hardware of the digital shunt allows for a direct measurement of the dynamic capacitance of the piezoelectric transducer by applying a known current and measuring the resulting voltage. All required parameters for calibration of a shunt
targeting a single vibration mode can be obtained directly from such capacitance measurements, eliminating the need for additional sensors in the shunt calibration. This study considers practical issues for experimental implementation of digital shunts from capacitance measurements, such as the influence of delay introduced by the digital control unit on the performance of the shunt. Furthermore, it is demonstrated how the performance of a resonant digital shunt is affected by the parallel resistance in the used digital shunt hardware and dielectric losses in the
piezoelectric transducer. Corrections for these effects are introduced by modification of the implemented transfer function and their effectiveness is evaluated experimentally for a composite
blade.