Exact second order formalism for the study of electro-acoustic properties in piezoelectric structures under an initial mechanical stress

► Actual plane wave velocities differ from about 4% with the natural ones. ► Crosses appear between curves of actual quasi-shear velocity with the pre-stress. ► Coupling coefficient Kt is almost unchanged between the two coordinate systems. ► Electrical input admittance differ from few percents between both formalisms. ► Difference of pulse-echo responses can be compensated with quarter wavelengths.