Modelling and numerical study of the electro-acoustic behaviour in integrated piezoelectric structures under external mechanical stress

We propose in this paper a modified KLM electroacoustic model of transducer that enables to take into account the effect of a mechanical pre-stress. Then, a numerical study of the electro-acoustic parameters for lithium niobate piezoelectric material (coupling coefficient, velocities and associated polarizations, and electrical input impedance) is led with regard to the azimutal and incident angles, as well as initial pre-stress values. Finally, we study the pulse-echo response of a complete piezoelectric transducer consisting in a piezoelectric film laid down upon a backing material and matching layers, with and without an initial stress, in order to highlight some benefits of a pre-stress load.