Elastic wave propagation in one-dimensional phononic crystal with defects

Abstract

The possibilities of manipulating the behavior of propagating waves using only the appropriate choice of materials is a field of interest in engineering. Phononic Crystals (PnCs) come precisely as a proposal for a device to work with waves, defined as artificial materials obtained from a periodic arrangement of unit cells. This configuration can provide frequency bands where waves cannot propagate (bandgaps). However, this property can be directly influenced by the break in the periodicity pattern of the structure when geometric and/or material parameters are changed in a single part of the unit cell. New propagating modes appear inside the bandgaps, presenting characteristics of localized modes. Different length and diameter combinations are applied to establish the defective cell and verify the existence of defect modes that reveal the degree of influence on the creation of these new modes within the bandgap region. Spectral Element (SEM) and Finite Element (FE) methods are adopted to model the PnCs analysis and the frequency response functions (FRFs). The initial results show that the PnCs with geometric defects have an expressive sensitivity to variations in geometric parameters, mainly variations in the length of the defective cell. A break in periodicity in terms of material will also be performed.