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ABSTRACT
The barrel unimorph is a specific type of sensing elements consisting of metal barrel shell and piezoelectric wafer attached to the inner bottom of the metal shell. The frequency equations of the barrel unimorph are deduced from Rayleigh-Ritz energy equation and elastic boundary conditions, from which the resonant frequency and effective electromechanical coupling coefficients are obtained. The flexural vibration of unimporh is studied by using numerical calculation and finite element analysis (FEA). The result indicates that the experimental trend of changes with resonance frequency in response to changes in structure parameters of unimorph is matched to the trend simulated by FEA. The effective electromechanical coupling coefficient is optimum when thickness ratio(α) of barrel to bottom (whole of wafer and barrel) is in the range of 0.3∼0.6 and radius ratio(β) of piezoelectric wafer to metal barrel is in the range of 0.6∼0.8. Furthermore, there is a sharp decline in electromechanical properties if α or β is outside of the above range. The conclusions will help to design and manufacture barrel unimorph sensors.
Funding
This work has been supported by the Natural Science Foundation of Liaoning (No. 2015020643, 2015020082).