A Parametric Sonic Crystal Modal Analysis Using Finite Element Modeling

Sonic crystals are typically materials with millimeter scale arrays of acoustic resonators embedded in a matrix material. They provide sound attenuation in acoustic band gaps at frequencies approximately two orders of magnitude lower than those predicted by Bragg’s theory of reflection. There are many potential applications of sonic crystals as filters and frequency selective acoustic damping devices. Performance characteristics of single-cell and double cell based sonic crystal structures were computationally evaluated using finite element methods. In this work, the sonic crystal consisted of cylinder inclusions encased in a soft polymer coating and embedded in a block of epoxy matrix material. Parametric studies were performed to evaluate the effects of material properties of the inclusion, coating and matrix. Mode shapes were determined. A preliminary comparison with Local Interaction Simulation Approach (LISA) is presented. The influence of material property variation, without changing geometric features, on single-cell and double-cell sonic crystal performance is discussed.