Adaptive multi-mode resonant piezoelectric shunt damping

Multiple-modes of structural vibration can be suppressed through the connection of an electrical impedance to the terminals of a bonded piezoelectric transducer. The so-called resonant shunts, one commonly used class of shunt impedances, provide good nominal damping performance but they are highly sensitive to variations in transducer capacitance and structural resonance frequencies. This paper introduces a new technique for the online adaptation of multi-mode resonant shunts. By minimizing the relative phase difference between a vibration reference signal and the shunt current, circuit component values can be optimally tuned online. Experiments on a cantilever beam validate the proposed technique and demonstrate the simplicity of implementation. The adaptive law converges quickly and maintains optimal performance in the presence of environmental uncertainties.