Tuning the locally resonant phononic band structures of two-dimensional periodic electroactive composites

The band structures of two locally resonant phononic crystals (LRPCs) with periodic multilayered cylindrical inclusions embedded in an elastic matrix are investigated by the finite-element method. The inclusions consist of electroactive polymer layer(s). Tunability of the band gaps of the phononic crystals by applying electric field upon the electroactive layer is demonstrated. A simple analytical expression is presented on the relationship between the stop band boundaries and the electric field. Good agreement between the analytical and numerical predictions is obtained. The effects of initial stress on the band structures are explored. It is found that tensile initial stress shifts up the band gaps while compressive initial stress shifts down or even closes them.