Analysis of Radiation Absorption of Acoustic Lamb Waves in Plates Loaded with Inviscid Nonconducting Liquid

Abstract

The dependence of radiation losses in a liquid on the value of displacement component U₃ normal to the plate on the surface of a piezoelectric plate for Lamb waves of various orders has been experimentally investigated. The waves whose phase velocity V_n in the plate is greater than velocity V_l of the longitudinal volumetric acoustic wave in the liquid are considered. It is shown that at low values of U₃, there is no radiation into the liquid and the value of radiation losses is close to zero even at V_n > V_l, at high values of U₃, the value of radiation losses is large and for Lamb waves in the YZ–LiNbO₃ plate with a normalized wavelength thickness of 1.75 and a frequency of 16.97 MHz, it reaches a value of 4 dB/mm, comparable to the radiation losses of surface acoustic waves in the same material.