Analysis on scattering characteristics of Love-type wave due to surface irregularity in a piezoelectric structure

Surface irregularity in piezoelectric sensors causes scattering of Love-type waves, which may lead to significant signal insertion loss. Also, as the reflected wave field in the piezoelectric sensor is increased due to surface irregularity, the input interdigital transducer (IDT) can be damaged. The present analysis confers the characteristics of Love-type waves scattered through surface irregularity in piezoelectric composite structures with different shaped surface irregularity, e.g., rectangular shaped, parabolic shaped, and triangular notch shaped. The expressions of phase and group velocities of scattered Love-type waves are derived for electrically open and short conditions. Also, expressions of mechanical displacement and electrical potential function due to incident and scattered Love-type waves are deduced for both electrical conditions. It is reported from the analysis that the increase in vertical irregularity parameter causes stronger reflected wave fields. Also, with the increase in piezoelectricity of the superficial layer, signal insertion loss and strength of reflected wave field diminish.