Generating and tailoring Structure-Borne Traveling Waves on two-dimensional surfaces

Structure-Borne Traveling Waves (SBTWs) have significant potential as a means of underwater propulsion and drag reduction, but there is limited understanding of how to tailor SBTWs, especially on the two-dimensional (2D) surfaces needed for these applications. To tailor SBTWs on 2D surfaces they must propagate in defined directions and have controlled patterns (e.g. wavelength). This study presents the initial step towards tailoring application-ready SBTWs on 2D surfaces. A finite element model is developed for a realistic system, correlated with test, and then used to perform a case study on tailoring SBTWs. The model represents a thin plate with electro-mechanically coupled piezoelectric actuators, elastic boundary conditions, and internal pre-stresses. Experimental validation demonstrates that the model accurately captures both the modal properties and SBTW generation of the realistic system. This enables the model to investigate the underlying dynamics and tailoring of SBTWs without the need for time-intensive experiments. A quality metric is also introduced which quantifies, for the first time, the quality of SBTWs on a 2D surface. The correlated model and quality metric are then used in a case study to tailor SBTWs on the 2D surface at three different frequencies. These SBTWs are tailored through definition and then manipulation of the actuation configuration (location, number, and phasing of actuators) to excite specific mode shapes and control the SBTW pattern. The resultant, tailored SBTWs propagate in defined directions and have controlled patterns, providing insight into the underlying dynamics of SBTWs. The novel quality metric, tailored SBTWs, and SBTW insights represent a substantial step towards realizing application-ready SBTWs on 2D surfaces.