Piezoelectric transducers have been used for semi-active vibration reduction in structures by altering the stiffness state and dissipating electrical energy. Common approaches include state switching, synchronized switch damping on a resistor (SSDS), and synchronized switch damping on an inductor (SSDI). Each of these methods requires four switches per vibration cycle, so any delay in the switch from the ideal moment could have a significant effect on the vibration reduction. An experimental investigation into the effect of switch delays on these techniques reveals that the abrupt change in piezoelectric voltage from the switch has the effect of a step input on the structure, which may excite higher order modes and increase the peak strain. This non-ideal switching of boundary conditions has implications towards the design and performance of these state switching techniques. Switching at the peak is classically considered the ideal switch time, but the influence of the switch on the local strain may actually result in a higher peak strain for the structure than with a delayed switch. This paper will examine switch times that lead and lag the ideal case for state switching, SSDS, and SSDI to quantify the level of vibration reduction achieved under non-ideal peak sensing.

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