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In railways, weigh-in-motion (WIM) systems are composed of a series of sensors designed to capture and record the dynamic vertical forces applied by the passing train over the rail. From these forces, with specific algorithms, it is possible to estimate axle weights, wagon weights, the total train weight, vehicle speed, etc. Infrastructure managers have a particular interest in identifying these parameters for comparing real weights with permissible limits to warn when the train is overloaded. WIM is also particularly important for controlling non-uniform axle loads since it may damage the infrastructure and increase the risk of derailment. Hence, the real-time assessment of the axle loads of railway vehicles is of great interest for the protection of railways, planning track maintenance actions and for safety during the train operation. Although weigh-in-motion systems are used for the purpose of assessing the static loads enforced by the train onto the infrastructure, the present study proposes a new approach to deal with the issue. In this paper, a WIM algorithm developed for ballasted tracks is proposed and validated with synthetic data from trains that run in the Portuguese railway network. The proposed methodology to estimate the wheel static load is successfully accomplished, as the load falls within the confidence interval. This study constitutes a step forward in the development of WIM systems capable of estimating the weight of the train in motion. From the results, the algorithm is validated, demonstrating its potential for real-world application.

Objective: In order to predict the injury parameters of the occupants corresponding to different experimental parameters and to determine impact injury indices conveniently and efficiently, a model forecasting occupant impact injury was established in this work., Methods: The work was based on finite experimental observation values obtained by numerical simulation. First, the various factors influencing the impact injuries caused by the interaction between unrestrained occupants and the compartment's internal structures were collated and the most vulnerable regions of the occupant's body were analyzed. Then, the forecast model was set up based on a genetic algorithm-back propagation (GA-BP) hybrid algorithm, which unified the individual characteristics of the back propagation-artificial neural network (BP-ANN) model and the genetic algorithm (GA). The model was well suited to studies of occupant impact injuries and allowed multiple-parameter forecasts of the occupant impact injuries to be realized assuming values for various influencing factors. Finally, the forecast results for three types of secondary collision were analyzed using forecasting accuracy evaluation methods., Results: All of the results showed the ideal accuracy of the forecast model. When an occupant faced a table, the relative errors between the predicted and experimental values of the respective injury parameters were kept within ± 6.0 percent and the average relative error (ARE) values did not exceed 3.0 percent. When an occupant faced a seat, the relative errors between the predicted and experimental values of the respective injury parameters were kept within ± 5.2 percent and the ARE values did not exceed 3.1 percent. When the occupant faced another occupant, the relative errors between the predicted and experimental values of the respective injury parameters were kept within ± 6.3 percent and the ARE values did not exceed 3.8 percent., Conclusions: The injury forecast model established in this article reduced repeat experiment times and improved the design efficiency of the internal compartment's structure parameters, and it provided a new way for assessing the safety performance of the interior structural parameters in existing, and newly designed, railway vehicle compartments.

It is a challenging task to accurately diagnose a railway bearing fault since bearing vibration signals are under strong interferences from wheel–rail excitations. The commonly used Kurtogram-based methods are often trapped in components induced by the wheel–rail excitations while adaptive mode decomposition methods are sensitive to input control parameters. To address these issues, based on a recently developed powerful signal decomposition method, that is, adaptive chirp mode decomposition (ACMD), a novel method called bandwidth-aware ACMD (BA-ACMD) is proposed in this article. First, the filter bank property of ACMD is thoroughly analyzed based on Monte-Carlo simulation and then a bandwidth expression with respect to the penalty parameter is first obtained by fitting a power law model. Then, a weighted spectrum trend (WST) method is proposed to partition frequency bands and then guide the parameter determination of ACMD through the integration of the obtained bandwidth expression. In addition, according to the order of magnitude of the WST in each band, the BA-ACMD adopts a recursive framework to extract signal modes one by one. In this way, dominating signal modes related to wheel–rail excitations can be extracted and then subtracted from the vibration signal in advance so that the bearing faults induced signal modes can be successfully identified. Both simulation and experimental validations are conducted showing that BA-ACMD can effectively detect single and compound faults of railway bearings under strong wheel–rail excitations. [ABSTRACT FROM AUTHOR]

The running stability of a railway vehicle, which is highly relevant for operational safety, strongly depends on the shapes of the profiles of wheel and rail, which change during the progress of wear. The model-based condition monitoring of a key parameter, such as the wheelsets equivalent conicity, is one of the approaches to realize condition-based maintenance and ensure railway vehicles reliability and running safety. A constrained nonlinear estimation technique is developed in this paper concerning the monitoring of the equivalent conicity. Suitable modelling of the railway vehicle dynamics is presented for the model-based estimator synthesis to perform the equivalent conicity monitoring employing only the carbody and bogie frame measurements, taking into account the track adhesion level variation. This approach allows avoiding the wheelset sensorization affected by a harsh and vibrational environment, thus reducing the possibility to produce inaccurate measurements. Another direct consequence of this approach is the reduction of costs relative to vehicle sensorization. Moreover, the possibility to constraint the estimated vehicle states and parameters allows considering their operative acceptance limits. [ABSTRACT FROM AUTHOR]

Within the research of electromagnetically excited torsion oscillations in the mechanical part of traction drive systems of modern railway vehicles, which has been realized at the Faculty of mechanical engineering at the CTU in Prague, there are two separate simulation models in use. The basic calculation model, which is utilized to gain basic characteristics of the torsion system as natural frequencies and natural modes of oscillations. And the complex simulation model, which simulates a drive of the vehicle. This contribution is focused on the basic calculation model, which has been built in MATLAB. This model in its first version did not apply the contact between wheels and rails. It was necessary to find out, if this simplification is relevant with respect to subsequent simulations within the complex simulation model and its results. Therefore, the contact interaction as a traction force in longitudinal direction in the wheel-rail contact was realized via the Kalker's linear theory. This article deals with the comparison between models with and without the implementation of the wheel-rail contact and its influence on the damping within the torsion system and retuning of the torsion system. [ABSTRACT FROM AUTHOR]

Active railway vehicles such as tilting trains and active steering bogies are being developed to improve the curve running performance of railway vehicles. In this case, a technology for sensing a curve and extracting curve information such as a curvature in real time is required. The existing railway curve detection technology has the disadvantage of requiring many calibration processes through test driving and being affected by running speed. In order to overcome these disadvantages, this paper proposes a very simple and efficient curvature estimation method. A curvature sensor prototype was manufactured and a test run was performed on the test track. As a test result compared with the track inspection data, the minimum deviation was 0.8%, the maximum deviation was 4.0% and the average deviation was 2.8%, showing good curvature measurement performance. It was also confirmed that the effect of the running speed was very small and the accuracy was high in the small curve with a large curvature. Therefore, the developed curvature measurement sensor is expected to be used very practically in the field of curvature detection and curvature extraction to control the vehicle in the curve section. [ABSTRACT FROM AUTHOR]

Improving the track friendliness of a railway vehicle can benefit the railway industry significantly. Rail surface damage in curves can be reduced by using vehicles with a lower Primary Yaw Stiffness (PYS); however, this can reduce high-speed stability and worsen ride comfort. Previous studies have shown that this trade-off between track friendliness and passenger comfort can be successfully combated by using an inerter in the primary suspension; however, these utilise simplified vehicle models, contact models, and track inputs. Considering a realistic four-axle passenger vehicle model, this paper investigates the extent to which the PYS can be reduced with inertance-integrated primary lateral suspensions without increasing root-mean-square (RMS) carbody lateral accelerations. The vehicle model, with these enhanced suspensions, has been created in VAMPIRE ® , with the dynamics being captured over a range of vehicle velocities and equivalent conicities. Based on systematic optimisations using network-synthesis theory, several beneficial inertance-integrated configurations are identified, and the PYS can be reduced by up to 47% compared to the default vehicle (a potential Network Rail Variable Usage Charge saving of 26%), without increasing RMS carbody lateral accelerations. Further simulations are performed to investigate the vehicle's performance in curve transitions and when subject to one-off peak lateral track irregularities. [ABSTRACT FROM AUTHOR]

There is an increasing desire in the railway industry to improve the longevity of wheels and rails without reducing performance in other ways (e.g. worsening passenger comfort). One way of reducing track and wheel wear is to reduce the primary yaw stiffness, significantly diminishing the costs associated with maintenance and emergency repairs, resulting however in reduced passenger comfort and high-speed stability. This paper, using a two-axle railway vehicle case study, demonstrates the potential of using passive, inerter-based suspensions to concurrently improve ride comfort and reduce track wear. The industrial parameter T γ is used to quantify the frictional energy lost at the contact patch under curving conditions, and the lateral RMS carbody acceleration is used to quantify passenger comfort under straight running conditions, with lateral track disturbances taken from real track data. Optimisation results conclude that, with the default yaw stiffness value, compared with the default spring-damper configuration in the primary lateral suspension, employing beneficial inerter-based configurations can improve passenger comfort by up to 43%. If the yaw stiffness is reduced such that the track wear is improved, similar improvements in passenger comfort can still be achieved with lateral inerter-based suspensions; for example, an improvement of 33% can still be achieved with a 50% reduction in yaw stiffness. Furthermore, when an inerter-based lateral suspension is used together with a Hall-Bush longitudinal suspension, the passenger comfort rises to 40%, which relates to a 25% improvement when compared with a non-inerter lateral plus Hall-Bush longitudinal setup. [ABSTRACT FROM AUTHOR]

• Additive manufacture is a potential technology for advanced railway components. • Internal defect is a critical issue to assess the fatigue resistance. • Damage tolerance is urgent for the additively manufacture metal components. Additive manufacturing (AM) is being increasingly applied in aerospace, healthcare, automotive, and energy fields. Despite good design flexibility, short lead times, and high material utilization, the application of AM by the railway industry is still on the way to engineering, particularly when compared with those of the aerospace and automotive industries. In addition, the role of various AM components in maintenance, optimizing design and production is not fully understood. To this purpose, the advantages and challenges in the utilization of AM technologies are well summarized, and the fatigue assessment aspects of AM components have been emphasized. Potential design methods to tackle the challenges including the well-recognized structural integrity, and future prospects are discussed in details. The findings are not only beneficial to the development of AM for railway engineering, but also for enabling the lightweight design of metallic components, and improving the performance evaluation and safety inspection strategies. [ABSTRACT FROM AUTHOR]

This paper discusses the possibilities of mitigation of the rolling noise in the railway vehicles by means of the rail dampers. In this context, the generation mechanism for this type of noise is therefore described. The active techniques and methods of control over the rolling noise, focused on the track infrastructure and the rolling stock are enumerated. The highlight is the rail damper from the perspective of its practical implementation and the review of the most important results concerning the reduction of the rolling noise in many European countries. The conclusions validate the difficulty found in a correct evaluation of the efficiency in the rail dampers and of their effect upon the track infrastructure – requirements for costly investments. [ABSTRACT FROM AUTHOR]

Vibration in trains constitutes one aspect of the physical environment that can cause discomfort to passengers. In order to assess the vibration, a variety of techniques have been developed and used. The general approach is to acquire acceleration at the passenger–train interface, and to then process these acceleration signals in order to calculate human comfort. However, the comfort index so calculated is independent of the seat characteristics and human parameters. Thus, a human biodynamic model with dynamic seat characteristics is necessary in order to perform true comfort analysis. The biodynamics of human subjects has been a topic of interest over the years, and a number of mathematical models have been established. However, there are only a few studies incorporating biodynamic models in railway applications. So, the present work proposes to evaluate Sperling’s Ride Index for a low–medium speed railway vehicle and further to calculate root mean square acceleration of different body parts, as per the International Organization for Standardization (ISO) 2631 guidelines, through bond graph technique. Car body flexibility is also incorporated using modal expansion of a free–free beam. Physiological effects of the vibrations on the human body were analyzed using the criteria specified in ISO 2631. [ABSTRACT FROM AUTHOR]

In railway vehicles, excessive sliding or wheel locking can occur while braking because of a temporarily degraded adhesion between the wheel and the rail caused by the contaminated or wet surface of the rail. It can damage the wheel tread and affect the performance of the brake system and the safety of the railway vehicle. To safeguard the wheelset from these phenomena, almost all railway vehicles are equipped with wheel slide protection (WSP) systems. In this study, a new WSP algorithm is proposed. The features of the proposed algorithm are the use of the target sliding speed, the determination of a command for WSP valves using command maps, and compensation for the time delay in pneumatic brake systems using the Smith predictor. The proposed WSP algorithm was verified using experiments with a hardware-in-the-loop simulation system including the hardware of the pneumatic brake system. [ABSTRACT FROM PUBLISHER]

The paper focuses on a nonlinear model to represent the mechanical behaviour of a mix coil spring - rubber used in the secondary suspension of passenger rail vehicles. The principle of the model relies on overlapping of the forces corresponding to three components - the elastic component, the viscous component and the dry friction component. The model has two sources on non-linearity, in the elastic force and the friction force, respectively. The main attributes of the model are made visible by its response to an imposed displacement-type harmonic excitation. The results thus obtained from the applications of numerical simulation show a series of basic properties of the model, namely the dependence on amplitude and the excitation frequency of the model response, as well as of its stiffness and damping. [ABSTRACT FROM AUTHOR]

The equipment mounted on the carbody chassis of the railway vehicles is a critical component of the vehicle in terms of ride comfort. The reason for that is their large mass, able to visibly influence the vibrations mode of the carbody. The paper examines the influence of the equipment upon the mode of vertical vibrations of the carbody in the high-speed vehicles, reached on the basis of the frequency response functions of the acceleration in three carbody reference points - at the centre and above the bogies. These functions are derived from the numerical simulations developed on a rigid-flexible coupled model, with seven degrees of freedom. As a rule, the results herein prove the influence of the equipment mounting mode (rigid or elastic), along with the speed regime, upon the level of vibrations in the carbody reference points, at the resonance frequency of the symmetrical bending mode. Similarly, it is also demonstrated how the equipment mass and the damping degree of the suspension system affect the level of the vibrations in the carbody. [ABSTRACT FROM AUTHOR]

This paper presents the dynamic ride forces generated at the wheel-rail interface during the running of a railway vehicle over a track with vertical irregularities derived from the overlying of the local discontinuities coming from the track joints and geometric irregularities. The dynamic ride forces are obtained from numerical simulations, developed on the basis of a 'rigid body' type vehicle with 10 degrees of freedom, where the inputs are represented by the track irregularities, analytically introduced. The results here featured make a point from the influence of velocity and the amplitude of the track geometric irregularities upon the value of the dynamic ride forces, depending on the axle position within the running gear. [ABSTRACT FROM AUTHOR]

The paper herein focuses on the dynamic response of a two-bogie vehicle to the excitations derived from the track vertical irregularities. The symmetrical and antisymmetrical modes due from the bounce and pitch motions of the axles' planes in the two bogies are being considered. The analysis of the dynamic response in the vehicle relies on the response functions in three reference points of the carbody, composed by means of these response functions to the symmetrical and antisymmetrical excitation modes. Similarly, the dynamic response of the vehicle to the track stochastic irregularities is examined and expressed as a power spectral density of the carbody vertical acceleration and the root mean square of the acceleration and the index of the partial comfort to the vertical vibrations is calculated. The paper is structured into two parts. The Part I includes all the theoretical elements required for the analysis of the dynamic response in the vehicle, while Part II introduces the results of the numerical analysis. [ABSTRACT FROM AUTHOR]

The paper examines the dynamic response of a two-bogie vehicle to the symmetrical and antisymmetrical excitations, due to bounce and pitch of the axles' planes, derived from the track vertical irregularities. Part I introduced the theoretical model and the response functions of the vehicle, as well as the theoretical elements required for the analysis of the dynamic response of the vehicle to the track stochastic irregularities. Part II comprises the results of the numerical analysis of the vehicle dynamic response in three reference points of the carbody, based on which a series of properties of the vertical vibrations behaviour of the railway vehicle is pointed out at. The excitation modes that trigger the carbody response in its reference points are identified. Hence, the influence of the geometrical filtering effect of the excitation modes upon the ride quality and ride comfort is established. [ABSTRACT FROM AUTHOR]

The paper describes a simulation study that provides a comprehensive comparison between full-active and semi-active suspensions for improving the vertical ride quality of railway vehicles. It includes an assessment of the ride quality benefits that can theoretically be achieved with idealised devices, and also examines the impact of real devices based upon hydraulic actuation technology. [ABSTRACT FROM AUTHOR]

The paper focuses on a method to synthesize the track vertical irregularities, with the possibility of application in the simulation of the dynamics in the railway vehicles. The basic elements of the method are the power spectral density of the track irregularities and the quantities describing the track geometry quality, as they have been adopted in compliance with the ORE B 176 report and UIC 518 leaflet. A major contribution of this method is the extension of the interval specific to the wavelength of the track vertical irregularities, so that this interval be representative for the frequency range of the vertical vibrations in the railway vehicle. The results of the numerical simulations of the dynamic behavior in a vehicle while running on a tangent track with vertical irregularities being synthesized as above demonstrate its efficiency. [ABSTRACT FROM AUTHOR]

This research paper determines the eigenvalues of main rigid bodies i.e. car body, bolsters, bogie frames and wheel axles of a 37 DoF coupled vertical-lateral model of a General Sleeper ICF coach of Indian Railway formulated using Lagrangian dynamics. The primary and secondary hunting speeds of the railway vehicle are determined to investigate the dynamic stability. Critical parameters which influence the railway vehicle dynamic stability are analysed. [ABSTRACT FROM AUTHOR]

This paper focuses on safety investigations for pregnant occupants, in particular, on their interactions with an interior feature, fixed bay tables, in railway vehicles. The computational pregnant occupant model Expecting has represented pregnant travellers in railway vehicle environments. Expecting is a computational pregnant occupant model developed at Loughborough University, in order to investigate the dynamic response of pregnant women to impacts. It has been successfully utilised by the authors in earlier studies, in various automobile crash investigations, such as frontal impacts with real and simplified crash pulses. In this study, a model of a network train carriage is generated and used together with Expecting to assess the suitability of fixed bay table designs for pregnant occupants. Investigations of potential injuries in this paper are believed to contribute to the design of more suitable interior features and hence improve safety and quality of life for pregnant women as travellers in railway vehicles. [ABSTRACT FROM PUBLISHER]

Abstract: While railway vehicle braking, Anti-slide control system will detect operating status of each wheel-sets e.g. speed difference and deceleration etc. Once the detected value on some wheel-set is over pre-defined threshold, brake effort on such wheel-set will be adjusted automatically to avoid blocking. Such method takes effect on guarantee safety operation of vehicle and avoid wheel-set flatness, however it cannot adapt itself to the rail adhesion variation. While wheel-sets slide, the operating status is chaotic time series with certain law, and can be predicted with the law and experiment data in certain time. The predicted values can be used as the input reference signals of vehicle anti-slide control system, to judge and control the slide status of wheel-sets. In this article, the RBF neural networks is taken to predict wheel-set slide status in multi-step with weight vector adjusted based on online self-adaptive algorithm, and the center & normalizing parameters of active function of the hidden unit of RBF neural networks’ hidden layer computed with K-means clustering algorithm. With multi-step prediction simulation, the predicted signal with appropriate precision can be used by anti-slide system to trace actively and adjust wheel-set slide tendency, so as to adapt to wheel-rail adhesion variation and reduce the risk of wheel-set blocking. [Copyright &y& Elsevier]

Based on Kalker's linear theory and the heuristic nonlinear creep model, the nonlinear coupled differential equations of motion are derived for a vehicle model with 20 degrees of freedom, considering the lateral displacement and yaw angle of each wheelset, the lateral displacement, vertical displacement, roll angle and yaw angle of the bogie frame, and the car body moving on a curved track. The dynamic responses of a railway vehicle with wind loads acting laterally and vertically, and wind moments acting about the longitudinal axis of the car body are investigated. The analysis results indicate that the oscillation amplitude of the car body increases as the wind speed increases. Furthermore, the average amplitude of oscillation of the wheelset increases with the wind speed as well. It is concluded that the influence of wind loads on the dynamic stability of a vehicle cannot be ignored. [ABSTRACT FROM AUTHOR]

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Abstract: The realization of movement by railway vehicles creates a problem that is connected to the wear process for elements of a tribological wheel–rail system. Wheel–rail wear is a complex phenomenon that depends on many factors. One of the main wear zones is the contact area between a wheel flange and a rail gauge. As is well known, wear in this contact zone occurs when a railway vehicle moves on curved parts of track, realizes tractive, braking efforts or moves in a high-speed mode. In this case, the solution of this kind of wear problem can be found by means of lubricant implementation. The choice of a lubricant requires information about contact characteristics at the moment of a vehicle''s movement. This paper focuses on the modeling of the temperature process in the contact between a wheel flange and a rail gauge. Examples of temperature calculation with some experimental data as input for this computation are presented. The obtained values of the temperature allow for making the correct choice of lubricant type. [Copyright &y& Elsevier]

In this paper, it is aimed to investigate semi-active suspension systems using magnetorheological (MR) fluid dampers for improving the ride quality of railway vehicles. A 17-degree-of-freedom (DOF) model of a full-scale railway vehicle integrated with the semi-active controlled MR fluid dampers in its secondary suspension system is proposed to cope with the lateral, yaw, and roll motions of the car body, trucks, and wheelsets. The governing equations combining the dynamics of the railway vehicle integrated with MR dampers in the suspension system and the dynamics of the rail track irregularities are developed and a linear quadratic Gaussian (LQG) control law using the acceleration feedback is adopted, in which the state variables are estimated from the measurable accelerations with a Kalman estimator. In order to evaluate the performances of the semi-active suspension systems based on MR dampers for railway vehicles, the random and periodical track irregularities are modelled with a uniform state-space formulation according to the testing data and incorporated into the governing equation of the railway vehicle integrated with the semi-active suspension system. Utilising the governing equations and the semi-active controller developed in this paper, the simulation and analysis are presented in Part II of this paper. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the generation and propagation of ground vibrations induced by railway traffic, more specifically in the case of urban vehicles. The complete vehicle—track—soil model is developed according to an uncoupled approach: the vehicle—track subsystem is first simulated so as to provide the ground forces which, in turn, are applied to the model of the soil. The vehicle—track model is built with the help of the home-made C++library [ABSTRACT FROM AUTHOR]

This paper analyses the influence of mechanical loads on railway vehicle solid wheel reliability. Reliability calculations is carried out according to the specifically set methodology — reliability is calculated according to the data about working loads and critical stress distribution. The influences on solid wheel reliability that are analysed are the following: standard deviation of lateral force distribution and mathematical expectation and standard deviation of the vertical force. [ABSTRACT FROM AUTHOR]

This paper proposes a new rail vehicle concept: a 'three-axles-one-unit' vehicle, with a self-steering single axle. Usually, a single-axle vehicle requires a short and wide car body, which is a system design of the next generation of railway vehicles. The authors propose a new 'three-axle-one-unit' vehicle steering a single-axle truck for the railways. This proposed vehicle uses three trucks and has the standard body length of a conventional train. It has the merit of decreasing elastic-body vibration by using a lightweight car body and by setting a truck in the middle of the car body. This system design can provide high performance with respect to stability, curving performance, and axle load limitation. Analyses were made with multi-body dynamic simulations and the basic characteristics were cleared. Finally, 1/10-scale model was made and tested. The proposed vehicle's potential for high performance was proved from running experiments, including curving. [ABSTRACT FROM AUTHOR]

This paper is devoted to the problems of stability of railway vehicles in a curved track. The applied method is well known as bifurcation approach, based on the analysis of bifurcation diagrams being the result of numerical simulations. Nevertheless, the original elements existing in the method enable the studies of stability in curved tracks. The main new content within this article is a study of influence of two factors on the stability of two-axle railway vehicle model in curved track, and straight track as well. These two factors are the variations in rail inclinations and the way of mean rolling radius determination. Four different values of the inclination for the three wheel-rail profile combinations and four different ways of determination of mean rolling radius are the case studies here. All of them are illustrated, discussed and supplemented with concluding remarks. At the end, more general conclusions are drawn, summarising all results. [ABSTRACT FROM AUTHOR]

In recent years, railway vehicles have become lighter, corresponding to improvement in the running speed. However, this causes the deterioration of the body rigidity, and leads to the increase in a vertical bending vibration of the body, because the natural frequency of the first bending vibration overlaps with a human's uncomfortable and sensitive frequency band. Many vibration suppression strategies have been proposed, i.e. a method to conduct active control for the secondary suspension system between the body and bogie, and a method to attach visco-elastic layers and constraint layers on the outside sheeting of the car body. In this paper, new control methods by shunt damping using stack type piezoelectric devices are proposed and the effectiveness and the robustness of designed circuits were confirmed through 1/6 scale model experiments. [ABSTRACT FROM AUTHOR]

In this paper, a synthesised performance analysis with modal parameters (SPAMP) method is proposed to solve vibration problems of railway vehicle. With the SPAMP method, relations between modal parameters, physical parameters and ride quality are built at first with a unified 'track-vehicle-human' model. Then they are used with experimentally identified modal parameters and response power spectral densities to find ways to improve ride quality. Using this method, the low-frequency vibration problem of a kind of speed-up vehicle in China is researched. It was found that low-frequency vibration of the vehicle is mainly caused by lower sway mode vibration, whose identified damping ratio is very low. So once excited, it cannot be effectively suppressed. With the help of relations built with a virtual prototype, the physical parameters of the bogie are changed, and then the low-frequency vibration problem is solved. [ABSTRACT FROM AUTHOR]

The realization of maximum adhesive forces for a railway vehicle is a very difficult process, because it involves using tractive efforts and depends on friction characteristics in the contact zone between wheels and rails. Tractive efforts are realized by means of tractive torques of motors, and their maximum values can provide negative effects such as slip and skid. These situations usually happen when information about friction conditions is lacking. The negative processes have a major influence on wearing of contact bodies and tractive units. Therefore, many existing control systems for vehicles use an effect of a prediction of a friction coefficient between wheels and rails because measuring a friction coefficient at the moment of running vehicle movement is very difficult. One of the ways to solve this task is to use noise spectrum analysis for friction coefficient detection. This noise phenomenon has not been clearly studied and analyzed. In this paper, we propose an adhesion control system of railway vehicles based on an observer, which allows one to determine the maximum tractive torque based on the optimal adhesive force between the wheels (wheel pair) of a railway vehicle and rails (rail track) depending on weight load from a wheel to a rail, friction conditions in the contact zone, a lateral displacement of wheel set and wheel sleep. As a result, it allows a railway vehicle to be driven in a tractive mode by the maximum adhesion force for real friction conditions. [Copyright &y& Elsevier]

Abstract: A unique and important task in the seismic design of railway structures is to evaluate the running safety of trains undergoing seismic motion. In the current design practice, however, when compared with the technical advances in the safety assessment of railway structures, the progress in running safety assessment (RSA) of trains is still insufficient, because of the complexity of the problem. In order to develop a practical methodology for the RSA, the dynamic response behavior of railway vehicles is investigated with a simplified analytical model. As a result, a code-type provision based on the concept of energy balance, in which the spectral intensity (SI) is employed as an index for assessment, is proposed in this study. The adequacy of the provision is verified by comparing with the results from rigorous numerical simulation of running vehicles. Moreover, the proposed provision has been applied to the practical design and its applicability has been demonstrated by dealing with different cases, where various types of structures and/or soil profiles are taken into account. [Copyright &y& Elsevier]

• A novel technique for the real-time monitoring of the railway anti-yaw damper is presented. • A nonlinear constrained approach is employed. • An estimator design model is derived. • Demonstrated effectiveness by means of comparative studies. The real-time monitoring of railway vehicles is becoming a key factor for safety and the optimization of the maintenance costs. In this context, the secondary anti-yaw suspension system represents a key element, subjected to degradation phenomenon. This paper presents a model-based real time monitoring technique of the anti-yaw damping. The approach is based on a constrained nonlinear estimation procedure that employs a railway vehicle modelling characterized by the presence of a random walk model for the wheel-rail interaction. The technique allows to employ a model-based approach, with advantages in terms of robustness respect to the interaction parameters, a priori no knowledge of the track irregularities and constraints applied to the estimated states. [ABSTRACT FROM AUTHOR]