Analysis of Sound Radiation Characteristics of Rail by BEM

摘要

Sound radiation characteristics of vertically vibrating rail are investigated to clarify the nature of rolling noise of high-speed railway, since the contribution of wheel movements to rolling noise is verified to be very small. The slab track is considered and steady-state vibration responses of an infinite-length rail excited by a concentrated harmonic force is first obtained for various frequencies on the ground of the Bernolli Euler beam theory and by applying the Fourier transform. Then, by using the Boundary Element Method based on the Helmholtz equation, the generated sound pressure is calculated under the boundary conditions of rail surface movements and rigid ground. and the sound radiation characteristics are examined especially from the view-point of directivity. Besides, the influence of restoring and damping effects of the foundation of rail on the sound pressure level is studied. Finally, the theoretical results of sound pressure distribution are compared with the existing experimental results, and it shows fairly good agreement.