Influence of elastic characteristics of the polymer/resin in lateral resonances of piezocomposites(1-3)

The excellent electromechanical coupling characteristics and small mechanical impedance of 1-3piezocomposite materials has resulted in their widespread acceptance for use in clinical diagnosis. However, one of the most important problem to drive 1-3 piezocomposites in thickness vibration mode may be the appearing of lateral vibration modes. These modes are related to the ratio between the periodicity of the ceramic rod array and the thickness mode wavelength. In earlier works, studying the lateral vibration modes of the present authors identified more than one kind of wave in the piezocomposites. This work investigates the relevance of the stiffness, impedance and attenuation coefficient of the polymer in the lateral vibration modes. Circular plates of 1-3 composites of PZT+1 wt% Nb/polymer have been prepared with a ceramic square rod geometry and to volume fraction around 34%. The polymeric phases were prepared using polyurethane and an epoxy resin with different stiffness. The lateral vibration modes were identified in the electrical impedance and acousto-electrical responses for the samples containing the different kinds of polymer. The role of the interfacial adhesion between PZT the and the polymer in the generation of lateral resonances is examined. Finally we characterized the influence on the lateral resonance of two backing layers: polymer and polymer-PZT.