On a coupling between the Finite Element (FE) and the Wave Finite Element (WFE) method to study the effect of a local heterogeneity within a railway track

Abstract

Railway rolling noise is the main source of noise from trains at speeds below about 300 km/h. At the wheel–rail contact area, the track and the wheel are dynamically excited and vibrate together to emit the well-known rolling noise. The rail lies on elastomeric pads, which are essential parts concerning wave propagation. Stiff pads are advantageous as they increase the track decay rate and perform better acoustically.The Wave Finite Element Method (WFEM), based on the theory of periodicity, has been widely used to compute the response of infinite periodically supported railway tracks. However, the track should not always be regarded as a perfect infinite periodic system: a breakdown of the periodicity can be due to a local increase of the stiffness of the supports due to the wheel load, a transition area, geometric irregularities of the track, or to the use anti-vibration supports.The goal of this paper is to compute the dynamic response of an infinite railway track including a heterogeneous part. This zone is made of supports whose stiffness is different from the ones in the homogeneous part. To compute the dynamic response of the track, an extended Finite Element (FE) – Wave Finite Element (WFE) coupling method is proposed. It consists in dividing the heterogeneous part into several FE different supports linked with internal WFE wave-guides. This part is then coupled with semi-infinite WFE wave-guides. The proposed method is validated with experimental data of a track on uniform supports. Then, the dynamic response of the track with different supports is computed. Finally, the performances of an anti-vibration support is evaluated and discussed in terms of the drive point mobility and the track decay rates.