Lamb waves generation in plates using glued piezoceramics

In this work, Lamb waves have been generated in a thin aluminum plate by bonding a piezoceramic actuator onto the plate. The acoustic pressure immediately above the plate was measured by a needle hydrophone, coupled to the plate through a thin oil layer, across several centimeters. Use of a 2D FFT algorithm then provides the dispersion curves which compare well to the analytical solution calculated using the dispersion equation. Next, the Lamb modes were selectively reinforced or cancelled by bonding another piezoceramic to the plate at an appropriate location. If the second actuator is excited in phase with the first one the symmetric mode, S0, can be reinforced whereas the antisymmetric mode, A0, is partially cancelled. If the two actuators are excited out of phase, the A0 mode is then enhanced respect to the S0 mode.