Dynamic Performance of Post-buckled Precompressed Piezoelectric Actuator Elements

Post-buckled precompressed (PBP) piezoelectric elements have recently been used to enable a new class of actuators that are able to provide far higher deflections compared to the traditional bimorph piezoelectric actuators while maintaining full force and moment generating capabilities. Past research has proven that PBP actuators are capable of generating deflections three times higher than conventional bimorph actuators. In this paper, this work has been extended to the dynamic response realm and the performance of PBP actuators is investigated under various axial loads, at various actuation frequencies. Both analytical and finite element models have been developed in order to evaluate the performance of the actuator regarding the natural frequency shift under increased axial loads. Experimental verification has shown that the overall damping ratio of the structure is a function of the axial forces. Values derived from experiments have been used in the Finite Element model to predict the displacement output, phase angle shifting and end rotation. Numerical and analytical results correlate very well with the experiments and thus give credit to the formulation presented in this work.