Generation of Lamb waves through surface mounted macro-fiber composite transducers

The paper describes a numerical approach for the analysis of Lamb wave generation in plate structures. Focus is placed on the investigation of macro-fiber composite (MFC) actuators and their directivity properties when actuated individually, or as part of rosette configurations. A local finite element model of the electro-mechanical behavior of the actuator/substrate system estimates the distribution of the interface stresses between the actuator and the substrate, which are subsequently provided as inputs to the analytical procedure that estimates the far-field response of the plate. The proposed approach allows handling of complex actuation configurations, as well as the presence of a bonding layer. The technique is first validated against the results available in the literature, and it is then applied to the analysis of macro-fiber composites. Rosette configurations show a rich directional behavior which can be tuned through the selection of phase and amplitude relations among the components of the rosette. The results suggest the potential of the approach as a tool for the optimization of the directivity of rosette actuators and for the prediction of the excitation provided by actuators of complex shapes.