Piezoelectric vibration damping by a hybrid analog-digital shunt

Vibration mitigation using piezoelectric shunt damping is effectively performed using a digital shunt that consists of a voltage-controlled current source and a digital control unit. Compared to fully passive circuits, the digital shunt can be retuned by updating its control transfer function; however, it loses all damping performance during an outage. The present study introduces a hybrid configuration that combines a digital shunt and a passive resonant shunt with analog components. The passive shunt can be designed to secure a certain minimum performance at power loss, while the digital shunt is used to retain optimal damping. Tuning expressions are derived for a digital unit that synthesizes an additional resonant circuit, resulting in a 2×RL hybrid shunt with two series RL-elements in parallel. The proposed hybrid analog-digital shunt thereby acts as a sensorless two-terminal device, suitable for practical engineering applications that require fail-safe behavior. The effectiveness and stability of the hybrid shunt are derived for an equivalent single-degree-of-freedom structure, and subsequently validated experimentally for a composite blade.