Estimation, tuning, and evaluation of propagation direction behavior in superimposed orthogonal two-dimensional structure-borne traveling waves

Abstract

Abstract Structure-borne traveling waves (SBTW) are observed in nature as a means for propulsion and locomotion of creatures on land and in the ocean. Recently, various approaches have been investigated to replicate this phenomenon. Previous studies have successfully generated SBTWs suitable for propulsion applications and particle motion on active surfaces. Much recent literature has focused on generating traveling waves that propagate only along a single axis for 1D and 2D structures. This limits their potential and does not take advantage of the full potential of 2D structures.
This study examines the potential of employing superposition to control the propagation direction of 2D SBTW. This is investigated numerically using an experimentally validated Finite Element model of a 2D plate with piezoelectric actuators. The individual SBTWs are superimposed by simultaneously exciting two pairs of actuators that are aligned orthogonally on the surface of a plate. Traveling waves are excited in the plate using two-mode excitation. Structural intensity is utilized to develop quantifiable metrics to describe the overall propagation direction and uniformity, which are necessary for describing the complex propagation patterns encountered with 2D SBTW. The potential of the proposed approach along with developed tuning and evaluation methods are demonstrated through case studies of two plates, one square and one rectangular. For both cases, the overall direction of the SBTW is tuned to propagate for any direction between the individual SBTW. This was achieved while maintaining a high-quality overall SBTW. With this approach, 2D SBTW can be steered for wave-driven motion applications such as propulsion of the structure itself or conveying particles in any direction along the structure's surface without compromising the quality of the overall traveling wave.