Transmittivity of 2D graded phononic crystals in the frequency and time domains

Olivier Lenoir (1) , Kun Zong , Hervé Franklin (1) , Mihai Predoï

1 LOMC - Laboratoire Ondes et Milieux Complexes

The media of interest are composed of N parallel infinite rows of steel cylindrical shells, periodically spaced, immersed in water. The influence of geometrical perturbations from rows to rows are investigated. Either the inner radius of the shells between two adjacent rows is varied, or the spacing between the rows is changed. The steel rows can also be replaced by steel-polyethylene bilayers. Time domain simulations have been performed using COMSOL® to visualize the spread of wave packets in the structures. In the frequency domain, the stop bands and pass bands of the transmission coefficient in the different cases are compared. The perturbations cause either the appearing of narrow pass bands in the stop bands, or the widening of the stop bands. If a harmonic plane wave is normally incident on an infinite row, we highlight the transmission (resp. the total reflection) of the waves by the phononic crystal for certain frequencies located in pass bands (resp. stop bands). If the incident wave is sent normally to the N rows, deviations or focalizations of the transmitted waves with respect to the incident direction are observed.

Mots clés: 2D phononic crystals; multiple scattering; transmission; periodicity perturbations

Domaines: Acoustique [physics.class-ph]

Olivier Lenoir, Kun Zong, Hervé Franklin, Mihai Predoï. Transmittivity of 2D graded phononic crystals in the frequency and time domains. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810859⟩