Transmission and band gaps of elastic SH waves in functionally graded periodic laminates

Time-harmonic plane elastic SH-waves propagating in periodically laminated composites with functionally graded (FG) interlayers are investigated in this paper. A finite stack of periodic layers between two identical elastic half-planes is considered. Two different power laws are used to describe the property variation of the FG interlayers within the unit-cell. Two different models are developed to deal with the FG interlayers, namely, the explicit FG model and the multilayer model. In conjunction with the transfer matrix method, the wave reflection and transmission coefficients, and band gaps of the FG periodic laminates are computed. Numerical results are presented and discussed to reveal the influences of the FG and homogeneous interlayers, the incidence angle of time-harmonic plane SH wave on the location and width of band gaps. The explicit FG model developed in this study is accurate and capable to simulate the full wave pattern within the periodic laminates, and it can be easily extended to periodic laminates with defects. The corresponding results presented in this paper may have important applications in optimizing and developing novel acoustic devices such as wave filters and noise insulators.