Railway Vehicle Dynamics Research Articles

Analysis of the ‘dynamics of railway vehicles’ research field development using scientometric approach

The paper demonstrates the possibilities of a scientometric approach using CiteSpace II software analysis of the field of railway dynamics with detection of research front, main clusters of cross-cited papers, their evolution and pivotal points (see terms in Sections 2.1 and 2.2). The initial database contained 5126 Web Of Science records published between 1975 and 2019 (45 years). The linguistic analysis determined the evolution of burst terms and grouped the papers in 14 clusters that corresponded with the view of the specialists in the field. ‘Railway vehicle’, ‘Curved track’ (hunting stability and derailment risk), ‘Unconventional railway truck’, ‘Railway turnout (crossing)’ and ‘Polygonal wear’ clusters were analysed in more detail with a determination of top-cited papers in each cluster and papers that determined connections between clusters (pivotal papers). Two pivotal papers were verified with their authors.

An optimal tangential contact model for wheel-rail non-Hertzian contact analysis and its application in railway vehicle dynamics simulation

Relative to the Hertzian theory, the non-Hertzian contact model (NHM) can better reflect the contact characteristic between wheel and rail in railway vehicle dynamics simulation. In this paper, an optimal wheel-rail tangential contact model is determined for vehicle dynamics simulation. First, based on i) the modified Kik–Piotrowski (MKP) contact model, ii) four different ellipse-equivalent methods, and iii) the modified FASTSIM model or modified FaStrip model, eight NHMs are proposed. Then, taking the Kalker's variational method (KVM) as a reference, the computational accuracies of the eight NHMs for calculating the linear creep coefficient and the tangential forces for the typical tangential contact scenarios are compared. NHM II, that is, the model coupled with the MKP model, the ellipse-equivalent method adopted in the Kik–Piotrowski (KP) model, and the modified FaStrip model, shows the best computational accuracy. Finally, the traditional Hertzian & FASTSIM model, the NHM II model, and KVM model are applied to the vehicle-track coupled dynamics simulations, and the dynamics response of a high-speed train running on a slab track is calculated by different contact models. The comparison results show that the NHM II model exhibits better agreement with the KVM compared with the Hertz & FASTSIM model.

Comparison of the Maxwell model and a simplified physical model for a railway yaw damper in damping characteristics and vehicle stability assessment

The Maxwell damper model has been adopted in the simulation of railway vehicle dynamics for a long time and became a basic force element in the multi-body dynamics software. The main purpose of this article is to investigate the predictive accuracy of this model for a railway yaw damper in damping characteristics and vehicle stability assessment. To achieve this objective, a simplified physical damper model was developed for comparisons, which is accurate and at the same time presents low computational costs, being able to be adopted in the multi-body dynamics model of a railway vehicle to speed up the numerical simulations. It was suitably validated in the damper rig test, and simulation results for those two damper models were compared with measured data. Results showed that the traditional Maxwell model of this typical yaw damper cannot accurately describe its dynamic behaviors, while the simplified physical model can accurately reproduce the complex behavior of the actual damper system with a high computational efficiency. Comparisons of vehicle dynamics relevant to vehicle stability were then carried out, by integrating the Maxwell model and the simplified physical model presented in this work into a multi-body dynamics model of a high-speed train in China. It was found that the Maxwell model can reproduce the phenomenon of carbody instability accurately if an appropriate value of the dynamic stiffness is set in the Maxwell model. In the simulation of bogie instability, the Maxwell model overestimates the dynamic damping of this typical yaw damper, and as a result it leads to large errors in stability calculations.

Structural parameter effect of a railway hydraulic damper on its dynamic damping characteristics

A parametric dynamic damping characteristics model, which includes the dynamic force equilibrium equation, the flow continuity equation, the flow losses model, the comprehensive stiffness model and the valve dynamics, is established and validated by experiments. Numerical simulation of structural parameter effect on dynamic damping characteristics of the hydraulic damper is performed. The analyses show that increase of inner tube height would cause drop of dynamic stiffness of the damper, however, increase of piston diameter would lead to obvious increase of dynamic stiffness and dynamic damping coefficient, therefore, the biggest piston diameter under constraint is usually used in engineering; in addition, fluid leakage would apparently decrease damping capability of the damper, increase of leakage coefficient would lead to significant drop of dynamic stiffness and dynamic damping coefficient, and also remarkable damping force lag. The obtained full parametric model and analysis result in this work would be instructive and meaningful in further railway vehicle dynamics research and design procedures.

Identification of a dynamic friction model for railway disc brakes

Braking forces occurring during emergency brake applications of passenger trains are generated by disc brake units. The acting friction forces depend on the frictional properties between disc and brake pad and are influenced by relative velocity, temperatures and normal pressure of the contacting surfaces. In this work a mathematical model is developed which aims to link these influencing variables to the instantaneous acting friction coefficient in order to include the characteristic behavior of friction forces in the calculation of longitudinal dynamics of railway vehicles. The model is identified by the use of data recorded on a full-scale dynamometer test rig and verified regarding the estimation of the brake distance.

Wheel-rail wear simulation and rail cant optimisation based on railway vehicle dynamics

A numerical prediction model for the wheel-rail wear development on heavy-haul railway is established herein, and a corresponding program is written using MATLAB. Using Archard's material wear theory, wear distributions in the wheel-rail contact patch and along the rail profile are evaluated via vehicle-track dynamics simulation and wheel-rail rolling contact analysis. The established model is employed to study the influences of rail cant on the wheel-rail wear distribution and development. The following main conclusions are drawn. On straight railway section, the wheel-rail contact region and wear distribution become unreasonable when the rail cant exceeds 1/20. On curved section, the influences of rail cant on the wear of the inner and outer rails are different. The changes of rail cant also obviously impact the changing rules of wear with the vehicle speed. A rail cant of 1/30 is recommended for the curved section of heavy-haul railway.

Wheel-rail wear simulation and rail cant optimisation based on railway vehicle dynamics

A numerical prediction model for the wheel-rail wear development on heavy-haul railway is established herein, and a corresponding program is written using MATLAB. Using Archard's material wear theory, wear distributions in the wheel-rail contact patch and along the rail profile are evaluated via vehicle-track dynamics simulation and wheel-rail rolling contact analysis. The established model is employed to study the influences of rail cant on the wheel-rail wear distribution and development. The following main conclusions are drawn. On straight railway section, the wheel-rail contact region and wear distribution become unreasonable when the rail cant exceeds 1/20. On curved section, the influences of rail cant on the wear of the inner and outer rails are different. The changes of rail cant also obviously impact the changing rules of wear with the vehicle speed. A rail cant of 1/30 is recommended for the curved section of heavy-haul railway.

A novel methodology to automatically include general track flexibility in railway vehicle dynamic analyses

The interaction between the rolling stock and the infrastructure plays a crucial role in railway vehicle dynamics. The standard approach consists of using a multibody formulation to model the railway vehicles running on simplified tracks. The track model can be rigid, if it comprises only a geometric description of the rail; semi-rigid, if it considers an elastic foundation underneath the rail; or a moving track model, if it comprises a track section underneath each wheelset traveling with the same speed of the vehicle. Despite their computational inexpensiveness, these approaches do not provide a complete representation of track flexibility and disregard coupling effects with the vehicle and among the track components. This work proposes a methodology to automatically generate finite element models of railway tracks comprising its relevant flexible components, i.e., rails, pads, fastening systems, sleepers, and ballast or slab. The finite element mesh is generated based on a parametric description of the track that allows an accurate description of its geometry, including curvature, cross-level, grade, and irregularities. The methodology is demonstrated with a case study in which a track with a complex geometry is loaded with two different approaches. The first approach prescribes moving loads, which is a typical approach used to design or analyze the infrastructure. The second approach applies loads retrieved from the dynamic analysis of a complete vehicle. The results show the benefits of this method and reveal that prescribed loading underestimates the forces resulting from the vehicle dynamics, which is an important issue on curved sections.

State-of-the-art and challenges of railway and road vehicle dynamics with multibody dynamics approaches

A review of the current use of multibody dynamics methods in the analysis of the dynamics of vehicles is given. Railway vehicle dynamics as well as road vehicle dynamics are considered, where for the latter the dynamics of cars and trucks and the dynamics of single-track vehicles, in particular motorcycles and bicycles, are reviewed. Commonalities and differences are shown, and open questions and challenges are given as directions for further research in this field.

On the dynamics of a four-axle railway vehicle with dry friction yaw damping

In the paper, we investigate numerically the influence of dry friction yaw damping on the dynamics of a railway vehicle with four wheel sets. The speed of the vehicle is the control parameter. The stick/slip mechanism is considered. The first bifurcation points are found. The results demonstrate the influence of the stick/slip on the dynamics of the vehicle. For speeds above the critical speed, it is found that the symmetry of the dynamical problem is broken and erratic - possibly chaotic - motions appear. The paper ends with an investigation of the sensitivity of the results to different solvers from Matlab. It is found that ODE15s needs the largest computation time and it is more accurate than ODE45 with the same tolerances. ODE45 is satisfactory. It is fast, accurate and shows the same erratic features as ODE15s does. Dry friction damping is still used in almost all freight wagons in the world due to the low cost of the elements.

On the dynamics of a four-axle railway vehicle with dry friction yaw damping

On the dynamics of a four-axle railway vehicle with dry friction yaw damping

Application and Comparison of Uncertainty Quantification Methods for Railway Vehicle Dynamics with Random Mechanical Parameters

This paper aims to investigate uncertainties in railway vehicle suspension components and the implement of uncertainty quantification methods in railway vehicle dynamics. The sampling-based method represented by Latin Hypercube Sampling (LHS) and generalized polynomial chaos approaches including the stochastic Galerkin and Collocation methods (SGM and SCM) are employed to analyze the propagation of uncertainties from the parameters input in a vehicle-track mathematical model to the results of running dynamics. In order to illustrate the performance qualities of SGM, SCM and LHS, a stochastic wheel model with uncertainties of the stiffness and damping is firstly formulated to study the vertical displacement of wheel. Numerical results show that SCM, which can be easily implemented by means of the existing deterministic model, has explicit advantages over SGM and LHS in terms of the efficiency and accuracy. Furthermore, a simplified stochastic bogie model with three random suspension parameters is also established by means of SCM and LHS to analyze the critical speed, which is affected obviously by the parametric uncertainties. Finally, a stochastic vertical vehicle-track coupled model with parametric uncertainties is built comprehensively on the basis of SCM, by which the impact behavior of wheel-rail interaction under a rail defect is investigated and the dynamic response of vehicles under the track irregularity is explored in terms of the Sperling index. It concludes that the uncertainties of parameters have a significant influence on P2 force and Sperling index from the view of the running quality.

Wayside testing methods for high-frequency vertical wheel-rail impact forces and its applicability

Methods for measuring high-frequency wheel–rail impact forces are indispensable in the study of railway vehicle dynamics. Although there have been many methods proposed for impact force measurement, not all of them are accurate at high-frequencies. Additionally, most of the proposed measurement methods are quasi-static methods that require static calibration. Therefore, the accuracy and applicability of different high-frequency wheel–rail force measurement methods need to be studied and validated dynamically. In this paper, a refined numerical track structure model is constructed to simulate wheel–rail impact behaviors. Under dynamic loading conditions, compare the ‘equivalent value’ and ‘actual value’ of wheel-rail impact forces using different wayside testing methods. The simulation results are then dynamically verified using full-scale indoor test results. The rules dictating effective strain gauge arrangement and the application scope of each measurement method are then obtained, and the relationship between the layout of the strain gauges and the effective measurement length is clarified. The results of this study indicate that the high-frequency wheel–rail impact force measured on site is generally underestimated, and because rail joint splints change the supporting conditions of the rail, the accuracies of all high-frequency wheel–rail impact force measurement methods decrease obviously at such rail joints.

On the nonlinear dynamics of a high-speed railway vehicle with nonsmooth elements

• A comprehensive lateral mathematical model of a high-speed railway vehicle with nonsmooth elements is built. • Numerical methods are presented to investigate the nonlinear dynamics of high-speed railway vehicles. • Nonlinear dynamics of a Chinese high-speed railway vehicle is investigated. • Influences of primary system parameters on the nonlinear dynamics of a Chinese high-speed railway vehicle are illustrated. A comprehensive lateral mathematical model of a high-speed railway vehicle with 17 degrees of freedom is built to study its nonlinear dynamics on a straight line. The hunting stability is explored by using eigenvalue analysis , bifurcation diagrams and the first Lyapunov coefficient. Due to the non-smoothness in the wheel/rail contact table and the secondary suspension elements such as anti-yaw dampers, bump stops , etc., an event-driven strategy is applied in the integration process of the ODEs . As an example, the nonlinear dynamics of a Chinese Railway High-speed (CRH) vehicle (named CRH2) is investigated. The result shows that the stable equilibrium of the high-speed railway vehicle loses its stability through a supercritical Hopf bifurcation with the increase of the forward speed, and the stable periodic solution loses its stability through a grazing bifurcation with the decrease of the forward speed. The influence of primary system parameters on the hunting stability of the high-speed railway vehicle is also investigated.

A nonlinear rubber spring model for the dynamics simulation of a high-speed train

ABSTRACT A simple and more-accurate nonlinear rubber spring model is proposed for railway vehicle dynamics analysis. The characteristics of dynamic stiffness and damping are investigated through both simulations and lab tests with various displacement amplitude and frequency. Similar to the existing rubber models, the proposed model contains three components, an elastic force, damper force and the Maxwell element, which are used to present the frequency- and amplitude-dependence. The model has four nonlinear inputs, which are determined by test results. In order to utilise all the test results under various excitations, five extra constants are introduced during the model parameter identification to minimise the error between the computing results and tests. Comparative analysis shows that the computing results of the proposed model has an overall good agreement with measurements under various excitations at either low or high frequency under environment temperature −40°C to 50°C, and requires a lower computational cost than the existing rubber spring model with either friction or fractional calculus. Thus it is more suitable for the vehicle dynamics analysis of a high-speed train.

Review on model-based methods for on-board condition monitoring in railway vehicle dynamics

This article performs an extensive review on condition monitoring techniques for rail vehicle dynamics. In particular, the review focuses on applications of model-based approaches for on-board condition monitoring systems. The article covers condition monitoring schemes, fault detection strategies as well as theoretical aspects of different techniques. Case studies and experimental applications are also summarized. All the mentioned issues are discussed with the goal of providing a detailed overview on condition monitoring in railway vehicle dynamics.

Implementing railway vehicle dynamics simulation in general-purpose multibody simulation software packages

In terms of simulation efficiency, modelling and visualization, general-purpose multibody simulation (GPMBS) software packages have a lot of inherent advantages compared with specialized railway vehicle dynamics simulation software packages. However, their application is limited due to the absence of specialized force elements and contact models, and thus cannot be directly employed for railway vehicle dynamics simulation. To deal with this issue, this paper proposes a novel framework to use GPMBS software packages to simulate the dynamic behavior of the railway vehicle. This framework contains a loose coupling method, a sub-mechanism feature and a top-down modelling method and allows users to take full advantage of the advanced functionalities of the GPMBS software packages to improve the efficiency of railway vehicle dynamics simulation. The feasibility of this framework is verified by integrating extensions for two representative GPMBS software packages. In addition, the two comparisons between the self-developed extensions (for LMS Virtual.Lab Motion and Unity3D) and the widely used specialized railway vehicle dynamics simulation software (Simpack and Universal Mechanism), further confirm the validity of the framework.

Hardware-in-the-Loop Simulation for Active Control of Tramcars With Independently Rotating Wheels

The wheelset is an important part that affects the dynamics of railway vehicles. The main purpose of the wheelset is to solve the problem of stability, curve performance, comfort, and wear. A conventional railway vehicle adopts rigid-axle wheelset (RW) due to the self-centering mechanism. On the other hand, independently rotating wheels (IRWs) have not been widely applied in the railway industry, since they do not generate any self-centering mechanism. It creates excessive wear, and derailment may occur. However, the IRWs have excellent curving performance compared with the RWs, and it enables realizing a low-floor structure that is convenient for passengers to get on and off. The recent active control technology has made it possible to generate a centering force in the IRWs. There are still many obstacles for the practical use of this technology, and it is necessary to verify the control strategies through various test methods. In this paper, an analytical model is derived, and an active control strategy is studied. To verify the validity of the active control strategy, a novel hardware-in-the-loop simulation (HILS) configuration using a real-time model and a motor-generator set are proposed.

Research Topics on Railway Vehicle Dynamics

Engineering research subjects relating railway vehicle dynamics are described as a literature survey in this paper. Research works concerning to the motion of wheelset; pantograph-catenary interaction; aerodynamic relating problems on the vehicle; and application of control techniques are introduced firstly as the most distinctive subjects of railway vehicle dynamics. The topics on safety assessment and ride comfort evaluation are also dealt with since those are important research area in railway dynamics as public transportation system. The subject concerning to carbody elastic vibration, which is important relating to ride comfort, is also described. The effect of passengers on the elastic vibration of carbody has been introduced as the interesting (and something surprising) topic. The focuses in the literature survey are particularly on the research works from Japan, in this paper.

A co-simulation approach to the wheel–rail contact with flexible railway track

The standard approach to railway vehicle dynamic analysis includes running the vehicle multibody models in rigid railway tracks. The wheel–rail contact, independently of the rolling contact model used, is either handled online or via lookup tables. This traditional approach disregards the coupling effects between the railway vehicle dynamics and the railway track flexibility. In this work the assumption of rigidity of the railway track is relaxed and a finite element model of the complete track, i.e. rails, pads, sleepers, ballast and infrastructure, is used to represent the track geometry and flexibility. A rail–wheel contact model that evaluates the contact conditions and forces is used online. The dynamics of the railway vehicle is described using a multibody methodology while the track structure is described using a finite element approach. Due to the fact that not only the multibody and the finite element dynamic analysis use different integration algorithms but also because the vehicle and track models are simulated in different, codes a co-simulation procedure is proposed and demonstrated to address the coupled dynamics of the system. This approach allows us to analyze the vehicle dynamics in a flexible track with a general geometry modeled with finite elements, i.e. including curvature, cant, vertical slopes and irregularities, which is another novel contribution. The methodology proposed in this work is demonstrated in an application, in which the railway vehicle–track interaction shows the influence of the vehicle dynamics on the track dynamics and vice versa.