Theoretical analysis by Mindlin theory and experimental measurements of the piezoceramic circular bimorphs in resonance

This paper investigates the free vibration characteristics for piezoceramic bimorphs in series connections by using theoretical analysis, numerical calculation, and experimental measurement. Series- and parallel-type piezoceramic bimorphs under fully-clamped boundary conditions are analyzed in this study. The theoretical solutions are derived base on the Mindlin's plate theory to explore the coupled out-of-plane (transverse) and in-plane (planar) resonant vibration characteristics; the numerical calculations based upon finite-element method are also performed and agree very well with the theoretical results for resonant frequency and corresponding mode shape. Two optical techniques, amplitude- fluctuation electronic speckle pattern interferometry (AF-ESPI) and laser Doppler vibrometer (LDV), and an impedance analysis are used to validate the theoretical and numerical results. It is shown that there is no difference between theoretical and numerical results regarding vibration characteristics of series- and parallel-type piezoceramic bimorphs. However, the experimental findings obtained by impedance analysis reveal that the boundary condition plays an important role for the excited vibration modes of parallel-type piezoceramic bimorphs. The imperfect clamped-circumference simulation in experimental procedure will result in some unexpected vibration modes arising, which can be distinguished between out-of-plane and in-plane modes by AF-ESPI measurement. ? 2021