A benchmark facility for guided elastic wave actuation by piezoelectric discs

Key aspects of piezoelectric actuation of circular-crested guided elastic waves (ccGEW) in homogeneous plates are investigated experimentally and studied with finite element analysis (FEA). The specific implementation of fiber-optic strain transduction presented offers virtually distortion-free conversion of radial GEW displacements with a flat transfer characteristic and negligible interference with the wave to be studied. Due to a concentric arrangement of actuator disc, fiber-optic transducer and circular plate, a shuttling GEW pulse packet can be retained over an exceptionally long period of time. Hence accurate long term measurements of the excited surface strain in response to piezoelectrical actuation becomes feasible for specific GEW modes. Presumably, traveling-wave-like behavior of compressional ccGEW pulses including the transition of converging into expanding wave packets around the symmetry axis is observed for the first time. Minor deviations between FEA predictions and measurement results can be traced back to imperfections of the experimental setup or inaccurate material data. The presented approach may be used for thorough characterization of piezoelectric disc actuators and studies of ccGEW propagation in various homogeneous materials.