Abstract
The thickness-shear modes in a circular cylindrical piezoelectric transformer considering the effect of an epoxy-bonded layer are analyzed, and an exact solution is obtained from the equations of the linear theory of piezoelectricity. Systematic parametric studies are subsequently carried out to quantify the effects of the epoxy-bonded layer upon the transformer performance, including its thickness, elastic coefficient and mass density. It is demonstrated that whilst the thickness and elastic coefficient of the layer affect significantly the resonance frequencies, transforming ratio, power density, admittance and efficiency, and its mass density has negligible influence. On condition that the thickness of the epoxy layer is vanishingly small so that it degenerates into the solution by the classical shear-lag model. Upon comparing with the predictions obtained by employing the traditional shear-lag model, it is found that the interface viscous damping is absolutely due to the elastic coefficient of the epoxy layer, and the present structure model is found to be more accurate especially when the thickness of the epoxy layer can not be neglected.