ANALYSIS OF FLEXURAL BAND GAPS IN PERIODIC BALLASTLESS & BALLASTED RAILWAY TRACKS

Abstract

This work investigates the band gap characteristics of vertical and lateral flexural waves in both ballastless & ballasted railway tracks. The ballastless track supported on periodic sleeper blocks constrained by fasteners, is analysed using the Floquet-Bloch theorem in order to formulate dispersion relationships for both lateral and vertical waves. Finite element (FE) models are employed to verify the accuracy of the resulting dispersion diagrams. Resonance and Bragg band gaps are identified in both wave types within the examined frequency range, with the investigation extending to explore the influence of unit cell length and fastening stiffness on band gap properties. The study reveals that track parameters significantly alter band gap characteristics. Furthermore, in the case of ballasted track, analytical models to calculate the opening and closing frequencies of resonance band gaps have been developed. Also, these analytical equations are verified by FE models. Similar to ballastless track work, the influence of track parameters such as pad stiffness, sleeper mass, and ballast stiffness on stopband properties is thoroughly investigated. This comprehensive analysis enhances our understanding of wave propagation in railway tracks and provides valuable insights for optimising track designs to mitigate vibration and noise issues effectively.