Analytical solution of excitation of Lamb waves in plates by inter-digital transducers

An analytical method is presented to model the excitation and propagation of Lamb waves by inter–digital transducers (IDTs). The acoustic field underneath the IDT (i.e. near field) excited by the IDT was obtained by modelling both the electromechanical coupling effect and the interaction between the IDT and the host plate. The amplitudes of the Lamb waves propagating in the far field were computed through a mode–expansion method based on the acoustic solution of the near field excited by the IDT. Experiments were carried out to excite Lamb waves in an aluminium plate. The ratio of amplitudes from experimental results agrees with that from the analytical solution. This analytical method may provide guidance on design of IDTs.