8D-6 High Frequency Propagation in Structured Solids

In this work high frequency ultrasonic wave propagation in an immersed porous aluminium sheet is modelled and the results verified by experiment using focused broadband 50 MHz waves. The sample microstructure has a profound influence on the propagation which occurs as a single wavefront and facilitates transmission at angles far greater than the critical angles for a homogeneous solid. We also found that, in addition to specialist plastics, some common plastic extruded rods usually considered homogeneous exhibit anisotropic behavior.