A Double-Rail Phononic Crystal Model for the Ballasted Track

Abstract

To investigate the properties of elastic waves propagating in the periodic ballasted track, a double-rail phononic crystal (DRPC) model which consists of two parallel rails fastened on equally spaced sleepers supported by ballast is proposed in this study. The presented numerical results show that there are twelve characteristic waves occurring in the DRPC. These waves can be divided into three kinds. Within the calculated frequency range, the first kind of characteristic wave always propagates except an initial lower frequency range. The second kind of characteristic wave has alternative pass bands and stop bands, showing obvious phononic property of the DRPC. The wavenumbers of the third kind of characteristic wave have larger imaginary parts, implying that this kind of wave is evanescent wave and can only propagate a few spans of the track away from the source. The numerical results show more advantages of the DRPC for explaining the elastic wave propagation mechanism in the ballasted track than the single-rail phononic crystal (SRPC) model.