Acoustic stop bands of surface and bulk modes in two-dimensional phononic lattices consisting of aluminum and a polymer

Spatial and frequency distributions of forbidden bands of both surface and hulk acoustic waves are studied theoretically for two-dimensional (2D) periodic elastic structures consisting of aluminum and polymer. The surface is perpendicular to the 2D periodic arrays of circular cylinders embedded in a background material. The dispersion relations of the surface and bulk modes with wave vectors parallel to the surface are calculated for triangular lattices, and the stop hand distributions are plotted in a form relevant to the comparison with ultrasound imaging experiments. [S0163-1829(99)03033-X].