Band structure of a phononic crystal plate in the form of a staggered-layer structure

This study investigates the propagation of Lamb waves in a phononic crystal plate in the form of a staggered-layer structure. Using the analyses of the band structures and the transmission spectra, a significant modulation to the lower-order Lamb modes is demonstrated due to the staggered arrangement. The modulation leads to remarkable changes in the location and width of the phononic band gaps. We further identify the physical mechanism for the effects of the staggered-layer through the particle displacement fields of the eigenmodes. The symmetric mode converts to the antisymmetric mode and vice versa with the existence of the staggered arrangement. In addition, we find that the phononic band gaps are very sensitive to the degree of stagger, which could be indispensable to practical applications such as band gap tuning. (C) 2011 American Institute of Physics. [doi:10.1063/1.3561864]