Experimental observations in 2D phononic structure with granular crystals

The author deal with a two-dimensional phononic structure (PC) composed by a matrix of nylon with cylindrical holes filled with air. The fabrication process is 3D selective laser sintering where a pulsed laser is used to raise a powder at the temperature of diffusion to a solid state. A piezoelectric transducer emits a longitudinal wave and another transducer acts as a receiver, this basic set-up leads to the experimental spectrum of the transmission coefficient in the PC. The results are compared with the numerical dates and dispersion curves (ω, k), the existences of forbidden frequency bands are experimentally shown. The extension of this experimental study into other phononic crystals could lead to new physical phenomena at different scales and novel design of engineering devices.