Generating Traveling Vibration Waves in Finite Structures

This work is concerned with a method to generate pure traveling vibration waves in finite structures. Progressing elastic deformations, i.e. waves, are not common in forced vibrating structures since a structure is naturally vibrating in its, naturally occurring, normal modes that are usually referred to standing waves. This makes the generation of traveling waves in a structure a challenging task. In this work, external excitation is applied to the structure in order to create traveling waves in one dimensional structures. Based on a model of the structure and its boundaries, it is possible to calculate, theoretically, the required excitation, in order to generate a pure traveling wave in the structure. This calculation has little merit in practice since small model uncertainties and boundary dynamics effects may alter the generated waves such that they are far from being traveling waves. An iterative in situ method to tune the applied forces, until the desired traveling wave are formed, is presented. This method relays on estimating the current wave-vibrations state in a structure from measurements and tune the external forces toward a pure traveling wave state. An experimental validation of the theory is presented to support the theory.