Vibration response of a railway track obtained using numerical models based on FEM (original) (raw)
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Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 2012
This article presents a mathematical model aimed at predicting wheel–rail contact vibration force arising from wheel profile irregularities. Prediction of vibrations caused by a passing train is a basic factor in environmental impact studies related to planning new railway lines. The prediction model is useful during the development of a project as it facilitates selection of the most suitable track for reducing vibration levels. This article presents the model, analyses the influence of the track base on the vibration-generating mechanisms, and compares the dynamic behaviour of the most widely used urban railway tracks.
Dynamic Analysis of Wheel/rail Interaction Using Finite Element Method
The dynamic interaction of wheel and rail is a key problem in a railway system. Vibration of the whole system is very noteworthy in terms of the service-life of the components, driving safety and passenger comfort. With the increasing speed of rail carriages it is a vital problem that should be analysed before designing of railway components including the bogies, wheel sets, rails, pads, sleepers and ballast. In this study, the dynamic interaction of the wheel and rail in a railway system has been studied. The dynamic model of the vehicle body, a freight bogie and the truck systems of UIC60 rail were modelled and analysed using an explicit method with a commercial FE software considering the real parameters of the vehicle and truck for a vehicle speed of 72 km/h. An artificial defect has been also formed on the head of the rail in order to compare the effects of the dynamic interaction of it with the smooth rail. Analyses results were given for the both cases and then the formation mechanism of corrugation was discussed in terms of short and long pitch wave vibration behaviour of the truck.
Numerical Analysis of Railway Track Vibrations
The numerical prediction models are used both for evaluation of the track-soil interaction forces as well as for prediction of the ground-borne vibrations. The dynamic track-soil interaction forces are calculated using a detailed train model and the dynamic behaviour of the layered spring-damper system and the through-soil coupling of the sleepers for the soil model [1,2,3,6,7]. The calculation of the groundborne vibration level at the distance is based on the viscous-elastics soil model, too. In the frequency domain free-field response numerical results are presented using the response spectra and the frequency response function (FRF) of the viscoelastic soil medium at the distance, [6,8,9,10,11]. In the next step these functions can be applied to the structure (e.g. engineering and building) dynamic response calculation arising railway traffic using the relevant computational building structure model.
RAILWAY TRAFFIC VIBRATIONS: GENERATION AND PROPAGATION - THEORETICAL ASPECTS
The interest in vibrations due to railway traffic is increasing in all developed countries, and it requires to develop both experimental and theoretical studies. In fact, innovative track can reduce the transmission of vibrations toward buildings and people, but also a better knowledge of the physical phenomenon can be useful to apply other methodologies, like a better control of contact surface characteristics. Theoretical mechanical models, based on the analysis of dynamic interaction between wheel and rail, and between track and formation soil, are the key tool to understand the phenomenon and evaluate interventions. In the paper, after a review of principles of vibration theory, two different calculation models are presented: the first one is a mathematical model for the analysis of dynamic loads caused by rail and wheel irregularities, the second one is useful to study the transmission of vibrations in the railway track and soil. The models, which can be used in sequence, are valid for various applications, in particular concerning the analysis of the role of different system components (wheels, rail, track) and their importance in the generation and propagation problems of railway vibrations.
Transport Problems
This paper presents an insight into mathematical analysis of dynamic models of the vehicle-track system. After identification of its advantages and disadvantages, an improved three-dimensional "vehicle-track" system of a mathematical model is presented. It not only assesses the influence of realistic track irregularities but also on all elements of the railway structure: rail, rail pads, sleepers, ballasts, and subballast parameters on the wagon's movement smoothness. Based on the expanded mathematical model of the "vehicle-track" dynamic system, the dynamic process of the wagon was theoretically studied, and the effect of track with irregularities on the vibrations of the wagon elements was studied. The final conclusions and recommendations are presented.
Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics, 2020
In order to control the wheel–rail coupling vibration of an urban railway system, a combined elastic wheel damping structure is proposed where the key parameters that determine the structural damping and thereby control the vibration of the railway system are explored. The vertical acceleration of the elastic wheels is obtained for a range of stiffness coefficients as the wheel moves on an irregular track, which is calculated by the [Formula: see text] method in the time domain. The results show that the vertical acceleration changes with a V-shaped trend, with an increase of wheel stiffness coefficient, which allows the optimum stiffness coefficient for minimum vertical acceleration of the elastic wheel to be obtained. It is observed that when attempting to suppress wheel vibration, an elastic wheel with a larger stiffness coefficient is needed as the degree of track irregularity reduces. This paper provides new insights into the effect of wheel elasticity on vibration characterist...
Railway traffic induced vibrations: comparison of analytical and finite element models
Journal of Vibroengineering, 2013
The recent increase in the use of the railway and the establishment of more restrictive policies of harmful environmental effects of railway transport highlights the need to investigate ground vibrations related to trains. Therefore models to evaluate how this phenomenon affects have been performed. This article aims to expose both analytical and 3D-FE models and to compare theoretical formulation and results. Models have been calibrated and validated with real data. Furthermore, a simulation of the acceleration level of different railway infrastructure elements has been achieved.
Numerical Modelling of Train Induced Vibrations
Procedia - Social and Behavioral Sciences, 2012
A numerical model to predict train induced vibration is presented. The dynamic computation considers mutual interactions in vehicle/track coupled systems by means of a finite and discrete elements method. The rail defects and the case of out-of-round wheels are considered. The dynamic interaction between the wheel-sets and the rail is accomplished by using the non-linear Hertzian theory. The strong point of this study consists in the model used to simulate the behaviour of pads. The rail-sleeper contact is assumed extended to an area defined such a contact-zone, rather than a single point assumption which fits better real case studies. Experimental and numerical validations show how prediction fits well experimental data.
Modeling of Train Track Vibrations for Maintenance Perspectives: Application
European Scientific Journal, 2014
The change of geometries, heterogeneities, degradation of components and the increase of maintenance cost of the railway track are due to the phenomenon of vibrations, which is the main problem of structural dynamic. The aim of this work is to propose a dynamic model for the prediction of rail vibrations during starting and steady state response. The DEM (Discret Elements Method) is adopted for the modeling of the vehicle. Thus components are assumed as rigid bodies mounted on series of springs and dampers with several degrees of freedoms. The rail road is discretized and modeled using FEM (Finite Elements Method). Rail-pad is modeled as a massless series of springs-dampers connected along the total contact area in between the rail and the m th sleepers. The sleepers are modeled as rigid elements connected by spring-damper. The ballast is modeled as separate vibrating mass connected by spring-damper coupled together vertically and horizontally while only the stiffness and damping effects of the subgrade is taken into account. The wheel-rail contact is modeled according to Herzian theory. Newmark time discretization and Newton Raphson iteration method have been used for models simulation in MATLAB. Displacements, velocities and accelerations of each modeled subsystem of components during starting and steady state response of the vehicle are calculated. The evolution of the wheel-rail contact load is also evaluated. Proactive maintenance actions are proposed in design.
A new wheel–rail contact model for railway dynamics
Vehicle System Dynamics, 2007
The guidance of railway vehicles is determined by a complex interaction between the wheels and rails, which requires a detailed characterization of the contact mechanism in order to permit a correct analysis of the dynamic behavior. The kinematics of guidance of the wheelsets is based on the wheels and rails geometries. The movement of the wheelsets along the rails is characterized by a complex contact with relative motions on the longitudinal and lateral directions and relative rotations of the wheels with respect to the rails. A generic wheel-rail contact detection formulation is presented here in order to determine online the contact points, even for the most general three dimensional motion of the wheelset. This formulation also allows the study of lead and lag flange contact scenarios, both fundamental for the analysis of potential derailments or for the study of the dynamic behavior in the presence of switches. The methodology is used in conjunction with a general geometric description of the track, which includes the representation of the rails spatial geometry and irregularities. In this work the tangential creep forces and moments that develop in the wheelrail contact area are evaluated using alternatively the Kalker linear theory, the Heuristic nonlinear model or the Polach formulation. The discussion on the benefices and drawbacks of these methodologies is supported by an application to the dynamic analysis of the bogie of the railway vehicle.