Railway-induced ground vibrations – a review of vehicle effects

This paper is a review of the effect of vehicle characteristics on ground- and track borne-vibrations from railways. It combines traditional theory with modern thinking and uses a range of numerical analysis and experimental results to provide a broad analysis of the subject area. First, the effect of different train types on vibration propagation is investigated. Then, despite not being the focus of this work, numerical approaches to vibration propagation modelling within the track and soil are briefly touched upon. Next an in-depth discussion is presented related to the evolution of numerical models, with analysis of the suitability of various modelling approaches for analysing vehicle effects. The differences between quasi-static and dynamic characteristics are also discussed with insights into defects such as wheel/rail irregularities. Additionally, as an appendix, a modest database of train types are presented along with detailed information related to their physical attributes. It is hoped that this information may provide assistance to future researchers attempting to simulate railway vehicle vibrations. It is concluded that train type and the contact conditions at the wheel/rail interface can be influential in the generation of vibration. Therefore, where possible, when using numerical approach, the vehicle should be modelled in detail. Additionally, it was found that there are a wide variety of modelling approaches capable of simulating train types effects. If non-linear behaviour needs to be included in the model, then time domain simulations are preferable, however if the system can be assumed linear then frequency domain simulations are suitable due to their reduced computational demand

Contributions of longitudinal track unevenness and track stiffness variation to railway induced vibration

© 2018 Elsevier Ltd Dynamic train-track interaction originates from excitation mechanisms such as longitudinal track unevenness, parametric excitation due to track stiffness variation and impact excitation due to wheel flats, wheel out-of-roundness and rail joints. Track stiffness variation can be regarded as longitudinal track unevenness in loaded condition, but for the mitigation of track geometry degradation it is important to distinguish between track unevenness in unloaded condition and track stiffness variation. This paper studies how longitudinal track unevenness and track stiffness variation contribute to railway induced vibration. A case study is performed for a railway line in Furet, Sweden. Based on measured track unevenness and stiffness data from the IMV 100 track recording car, the train-track interaction forces and free field vibrations are computed for each of these two excitation mechanisms separately, as well as for a combination of both. The computed free field vibrations are in good agreement with measured vibrations at the same site. The contribution of the track stiffness variation to the interaction forces and free field vibrations is much lower than the contribution of the longitudinal track unevenness. Track stiffness variation can also be modeled as equivalent track unevenness, leading to results slightly different from those obtained when track unevenness and track stiffness variation are modeled separately, and a poorer agreement with the measured vibrations.status: publishe

Simulation of vertical dynamic vehicle–track interaction – Comparison of two- and three-dimensional models

By using an extended state-space vector approach, the vertical dynamic vehicle–track interaction between a railway vehicle and a slab track is simulated in the time domain. Both two- and three-dimensional track and vehicle models are considered. In the two-dimensional track model, the rail, panel and roadbed are modelled using Rayleigh‒Timoshenko beam elements. In the three-dimensional track model, the rails are modelled using Rayleigh–Timoshenko beam elements, whereas the panel and roadbed are modelled by 3D brick elements. Based on Python scripts, the parameterised three-dimensional track model is developed in Abaqus, from which the system matrices are exported to Matlab where the dynamic analysis is performed. In the presented numerical examples, similarities and differences between the two models are discussed, and it is highlighted in what scenarios the different models are feasible to employ

Innovative methodology for heavy haul train-track interaction dynamics issues

With the introduction of higher axleload wagons and higher traction locomotives in Australia, more rail damage can be observed. To investigate rail damage due to wheel-rail dynamic interactions, a new method is introduced which uses a two-way co-simulation technique to link a detailed infinitely long track model that is written in FORTRAN and a detailed locomotive or wagon model that is developed using the GENSYS software package. The original finite length track model has been evolved into an infinite one by using the method described in [1], considering rails, fasteners, sleepers, ballast, and subgrade. The locomotive or wagon model considers the carbody, bogie frames and wheelsets. Traction motors and gear boxes are considered in the locomotive model. As the track model and vehicle model can run mostly independently, a parallel computing technique is applied to improve the simulation speed as well as to simplify the model integration process. The co-simulation method can be applied to understand the dynamic performance characteristics of high axleload wagons and high adhesion locomotives to give an accurate evaluation and assessment of rail damage based on simulation results. One simulation case is used to demonstrate the method’s effectiveness