On the wave propagation in fluid-filled phononic crystals: from wave-guiding effects to nonlinear phenomena caused by sloshing

Abstract

Periodic structures and phononic crystals, abbreviated PCs, constitute a topic of extensive research worldwide, thanks to the outstanding capabilities related to the control and manipulation of wave propagation they have to offer. Such periodic systems can be employed to control, shape, and guide waves traveling through a medium. They can also be used for passive vibration control, by utilizing the so-called bandgaps, i.e., frequency ranges where the propagation of elastic/acoustic waves is forbidden. Nowadays, less is known about fluid-filled PCs, in comparison to other deeply explored areas, such as those involving PCs made of single-phase or composite materials, that adopt piezoelectric patches for adaptability, and so on. Therefore, this research aims to investigate if elasto-fluid-acoustic interactions can enhance the wave attenuation properties of fluid-filled PCs for practical engineering applications. Since a confined fluid can significantly modify the fluid-structural behavior, one also aims to assess the PC's performance under different fluid fillings. Investigations of wave-guiding will also be pursued in this doctoral study. As main contributions of this work, one expects: the proposal of a tunability mechanism for bandgaps, which exploits fluid-fill percentage of unit cells; the assessment of nonlinear behavior induced by fluid sloshing inside unit cells' cavities; and to evaluate the influence, on the system dynamics, of channels used to communicate fluid cavities of adjacent unit cells. Nonlinear behavior, depending on vibration amplitude, will also be explored to try to broaden attenuation bands. Lastly, extensive experimental validations of performed numerical simulations will also be pursued.