ACOUSTIC BAND GAPS TUNED BY TRANSLATION GROUP SYMMETRY IN TWO-DIMENSIONAL PERIODIC COMPOSITES

摘要

The acoustic band structures of two kinds of acoustic crystals (two-dimensional periodic arrays of rigid solid rods embedded in air with two different configurations) have been studied by the plane-wave expansion (PWE) method based on super cell calculation. The translation group symmetry of the acoustic crystal is changed by changing the area of the cross section of adjacent rods. We found that by changing the translation group symmetry, one can effectively adjust the acoustic band gaps (ABGs). In the case that the cross section of scattering rods is square without any rotation, the decrease of translation group symmetry is advantaged to form ABGs. But when the cross section of scattering rods is square with a rotation of 45, the decrease of translation group symmetry is disadvantaged to form ABGs.