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This paper presents a method for reducing vertical vibrations in a railway vehicle carbody by supporting underfloor equipment using high-damping elastic mounts. This is a kind of dynamic vibration absorber utilizing underfloor equipment as a mass element which has been introduced based on the inspiration of the damping effect of passengers. Numerical studies were firstly carried out to check the feasibility of the idea using simple two degree of freedom model representing carbody and underfloor equipment. Then a prototype of the elastic supporting member was built as a simple rubber mount and two type of excitation tests were conducted using a Shinkansen type test vehicle. The authors conducted excitation tests in the rolling stock testing plant to examine the carbody vibration reduction effect due to track irregularity. As a result, two dominant peaks in the acceleration power spectrum densities of floor corresponding to different elastic vibration modes were reduced simultaneously when the proposed method was applied. The vibration reduction effect became large as the elastically supported mass of underfloor increased. Then, to examine the vibration isolation performance of the developed rubber mount, excitation tests were conducted by a vibration exciter installed on the underfloor equipment. From the random wave excitation, the authors confirmed that the vertical vibration of carbody floor is reduced over a wide frequency band.

After the Mid Niigata Prefecture Earthquake in 2004, research and development of earthquake countermeasures has started for Shinkansen trains. Some technologies for improving running safety of the Shinkansen trains during an earthquake have been applied to commercial lines and vehicles. Regarding conventional lines, earthquake countermeasures are also taken a growing interest, especially in metropolitan areas. At first, conventional guard angles which are usually placed on sharp curves are considered as the earthquake countermeasures due to cost restrictions. For the trains which have yaw dampers, this paper proposes to change the layout of the yaw dampers to longitudinally symmetrical position in bogie as another countermeasure against an earthquake. This paper also numerically clarifies that the proposed layout of yaw dampers improves running safety against sinusoidal oscillation. In addition, the actual bogie oscillation test is performed to valid the numerical results. From probabilistic perspective the authors show that the conventional guard angle and the proposed layout of yaw dampers have almost the same effects on improving running safety for seismic vibration of track.

A wireless power transmission (WPT) system using the high temperature superconducting (HTS) coil for a railway vehicle is required to transmit the electric power of several hundred kW in a short time (60 s). In order to design the WPT system using HTS coil with the thermal stability, and it is necessary to clarify the thermal characteristics of the HTS coil at the operating current in kHz band and the operating conditions considering thermal stability in the WPT system. We analyzed the frequency characteristics of the critical current in the HTS coil above 1 kHz and investigated the operating conditions considering thermal stability in the WPT system for the railway vehicle using HTS coil in liquid nitrogen. As a result, the critical current of the HTS coil in the kHz band decreased with the frequency. This is because the AC loss in the HTS coil increased with the frequency, and the critical current density of the HTS coil decreased with increasing the surface temperature. In order to design the HTS coil with thermal stability in the kHz band, and it is necessary to operate the HTS coil on alternating current less than about 50% of the critical current measured by direct current. We found that the thermally stable WPT system capable of fast charging for 60 seconds can be realized by operating current at the frequency of about 2 kHz. [ABSTRACT FROM AUTHOR]

The paper herein analyzes the ride comfort at the vertical vibrations of the railway vehicle, evaluated by two methods—mean comfort method and Sperling's method. The two methods have in common that the estimation of the comfort sensation is conducted with the comfort indices, namely ride comfort index NMVZ and ride comfort index Wz. The values of these indices are derived from numerical simulations. The advantage of using the results of the numerical simulations versus using experimental results, on which most previous research is based, resides in the fact that the ride comfort indices can be examined while taking into account the influence of velocity and certain parameters altering the behavior of vertical vibrations of the carbody, i.e., carbody flexibility and the suspension damping. The numerical simulation applications have been developed based on a theoretical model of the vehicle that considers important factors affecting the behavior of vertical vibrations of the carbody, by means of a 'flexible carbody' type model and an original model of the secondary suspension. The results presented mainly show that the two assessment methods lead to significantly different outcomes, in terms of ride comfort, under identical running conditions of the vehicle. [ABSTRACT FROM AUTHOR]

The OOR (out-of-roundness) wheel is one of the main excitation sources causing vehicle vibration. However, the OOR wheel occurs randomly, indicating that the vibration behavior of a vehicle cannot be comprehensively evaluated using a deterministic approach. Thus, a probability analysis framework is proposed to obtain vehicle vibration characteristics while considering the randomness of the OOR wheel. The probability model of the random OOR wheel is derived by reducing the high-dimensional variables into a few independent variables of the radius, amplitude, and phase. Then, the vertical vehicle-track coupled system with OOR wheels is modelled. A DPIM (direct probability integral method) is further developed to analyze the evolution of excitation to response probabilities. Finally, the statistics of the random vibration of the vehicle are calculated. The proposed framework is verified using a numerical case. Results show that the PDF (probability density function) shape of the vehicle random vibration, induced by the Gaussian-distributed OOR wheel, deviates from the Gaussian distribution due to the nonlinear wheel/rail contact force. Instead, it exhibits a right-skewed shape, significantly impacting the dynamic performance. As the mean or coefficient of variation of the OOR wheel amplitude increases linearly, the reliability of the vehicle Sperling index experiences a quadratic or double-sloping decrease. Consequently, a maintenance threshold for OOR wheel amplitudes is given based on reliability considerations. Compared to Monte Carlo simulation, the proposed framework offers a computational efficiency improvement of at least one order of magnitude. [ABSTRACT FROM AUTHOR]

This article deals with computer analyses of output quantities of a railway vehicle depending on changing of parameters of suspension system. A passenger car was chosen for dynamic analyses. An analysed passenger railway vehicle uses two stage suspension system composed of coil springs and hydraulic dampers. Stiffness of coil springs of primary and secondary suspensions were defined for two states and its influence on output values in terms of quality and quantity was evaluated. As output variables, values of forces in a wheel/rail contact and accelerations in several locations on a wagon body floor were chosen. Values of forces in a wheel/rail contact indicate dynamic response of a railway vehicle running in terms of running safety and values of accelerations serve as important input for evaluation of passenger ride comfort.

The paper studies the determination for one of the dynamic quality parameter (PDK) of railway vehicles - car body lateral acceleration - by using of computer simulation system for railway vehicles dynamic Simpack Rail. This provide the complex simulation environment with variable velocity depending on the train schedule. The rail vehicle model of typical 1520 mm gauge fright locomotive section used for simulation has been verified by means of the chair "Electric multiple unit cars and locomotives" in the Russian University of Transport (RUT (MIIT)). Due to this homologation the questions of model creating and verification in preprocessor are excluded in this paper. The paper gives the detail description of cartographic track modeling in situation plane, heights plane and superelevation plane based on the real operating data. The statistic parameters (moments) for the rail related track excitation and used cartographic track data of the specified track section in this simulation are given as a numeric and graphical results of reading the prepared data files. The measurement of the car body residual lateral acceleration occur under consideration of the earth gravity acceleration part like the accelerometer measurement in the real world. Finally the desired quality parameter determined by simulation is compared with the same one given by a test drive. The calculation method in both cases is based on the middle value of the absolute maximums picked up within the nonstationary realizations of this parameter. Compared results confirm that this quality factor all the first depends on the velocity and track geometry properties. The simulation of the track in this application uses the strong conformity original track data of the test ride track section. The accepted simplification in the rail vehicle model of fright electric locomotive section (body properties related to the center of gravity, small displacements between the bodies) by keeping the geometric and force law characteristics of the force elements and constraints constant allow in Simpack Rail the simulation with necessary validity of system behavior (reactions).

Abstract Different wind models are being used for the operational safety evaluation of a high-speed train exposed to crosswinds. However, the methodology for simulating natural wind is of substantial importance in the wind–train system, and different simplified forms of natural wind result in different levels of accuracy. The purpose of the research in this paper is to investigate the effects of different wind models on the operational safety evaluation of high-speed trains. First, three wind models, namely, steady wind model, gust wind model, and turbulent wind model, are constructed. Following this, the algorithms for computing the aerodynamic loads using the wind models are described. A multi-body dynamic model of a vehicle is then set up using the commercial software “Simpack” for investigating the dynamic behavior of a railway vehicle exposed to wind loads. The rollover risks corresponding to each wind model are evaluated by applying the definition of characteristic wind curves (CWC). The results indicate that the CWC computed using the gust wind model is marginally higher than that computed using the turbulent wind model; the difference is less than 1%. With regard to the steady wind model, the assurance coefficient substantially affects the final CWC. A reasonable agreement of CWC between the steady wind model and turbulent wind model can be obtained by applying an “appropriate value” of the assurance coefficient. This study included a systematic analysis of the operational safety evaluation results using different wind models; the analysis can serve as a reference basis for different engineering accuracy requirements.

A generalized railway vehicle model is built to study the coupled vibrations between a flexible car body (CB) and the equipment suspended beneath it by taking the complex suspension characteristics of the equipment into consideration. Associated theories for the determination of the suspension parameters for CB suspended equipment are summarized systematically, including the vibration isolation methods and the dynamic vibration absorber (DVA) theories for both undamped and damped cases. The equipment is then grouped into four categories by weight, location, and the excitation that it is subjected to. A general principle for the determination of the suspension parameters is proposed for better vibration isolation effects concerning bogie hunting, the elastic modes of the CB and its excitations. Analysis based on DVA theory shows that 1) siting equipment heavier than 2 t near the CB center can reduce the structural vibrations of the CB considerably, 2) siting medium-weight equipment near one end of the CB is good for absorbing the vibrations resulting from bogie hunting, and 3) a rigid connection is suggested for light equipment. Furthermore, on-track field tests of a high speed train confirmed that the heavy equipment vibrated violently upon absorbing some of the CB vibration energy resulting from bogie hunting. However, solid proof of the vertical bending of the CB was not obtained yet because it was sufficiently damped and is not the first natural mode of a modern aluminum-alloy CB. Further research on the lateral flexibility of the CB and its coupled vibrations with the heavy equipment mounted near its center are in need.

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.

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.

This paper investigates the possibility of developing a new method for fault detection of a damper in the primary suspension of the railway vehicle, based on the analysis of the vertical vibration’s response of the bogie. To this purpose, experimental data are used, along with results from numerical simulations regarding the Root Mean Square (RMS) accelerations measured/simulated in four reference bogie points—two points on the chassis, against the suspension, and two points located against the axle boxes. The experimental data are utilized to define the normal area of operating and the damper failure area in the bogie primary suspension, as well as a basis for validating the results of numerical simulations. The numerical simulations are developed on the basis of two original models of the vehicle–track system, rigid-flexible coupled type, which take into account the elasticity of the vehicle carbody and the elasticity of the wheel-rail contact: a reference model with 15 degrees of freedom, for simulating the bogie response to vertical vibrations for the normal operating of the primary suspension dampers, and an extended model with 20 degrees of freedom, for simulating the bogie vibration response to the failure damper of a primary suspension. The presented results show that there are clear premises on the possibilities of developing a fault detection method of any of the four dampers of the primary suspension corresponding to a vehicle bogie, based on the RMS accelerations measured only in two reference points of the bogie.

To study the impact of suspended equipment on the ride comfort in a railway vehicle, a rigid flexible general model of such a vehicle is required. The numerical simulations is based on two different models, derived from the general model of the vehicle, namely a reference model of a vehicle with no equipment, and another model with six suspended elements of equipment mounted in various positions along the carbody. The objective of this paper arises from the observation that the literature does not contain any study that highlights the change in the ride comfort resulting exclusively due to the influence of equipment. The influence of the suspended equipment on the ride comfort is determined by comparing the ride comfort indices calculated in the carbody reference points, at the centre and above the two bogies, for a model with six elements of equipment and a model of the vehicle with no equipment.

Purpose. The article aims to estimate the stability of the railway vehicle motion, whose oscillations are described by Lagrange equations of the first kind under the assumption that there are no nonlinearities with discontinuities of the right-hand sides. Methodology. The study is based on the Lyapunov’s stability method of linear approximation. The equations of motion are compiled in a matrix form. The creep forces are calculated in accordance with the Kalker linear theory. Sequential differentiations of the constraint equations reduced the equation system index from 2 to 0. The coefficient matrix eigenvalues of the system obtained in such a way are found by means of the QR-algorithm. In accordance with Lyapunov's criterion of stability in the linear approximation, the motion is stable if the real part of all eigenvalues is negative. The presence of «superfluous» degrees of freedom, which the mechanical system does not have (in whose motion equations there are left only independent coordinates) is not trivial. Herewith the eigenvalues and eigenvectors correspond to these degrees of freedom and have no relation to the stability. In order to find a rule that allows excluding them, we considered several models of a bogie, with rigid and elastic constraints of high rigidity at the nodes. In the limiting case of high rigidities, the results for a system without rigid constraints must coincide with the results for a system with rigid constraints. Findings. We carried out the analysis and compared the frequencies (with decrements) and the vibration modes of a three-piece bogie with and without constraints. When analysing the stability of the system with constraints, only those eigenvalues are of interest whose eigenvectors do not break the constraints. The values of these numbers are limits for the eigenvalues of the system, in which rigid constraints are replaced by elastic elements of high rigidity, which allows us to leave the Lyapunov’s criterion unchanged. Originality consists in the adaptation of Lyapunov's stability method of linear approximation to the case when the equations of railway vehicle motion are written in the form of differential-algebraic Lagrange equations of the first kind. Practical value. This written form of the equation of motion makes it possible to simplify the stability study by avoiding the selection of a set of independent generalized coordinates with the subsequent elimination of dependent ones and allows for the coefficient matrix calculation in an easily algorithmized way. Information on the vehicle stability is vitally important, since the truck design must necessarily exclude the loss of stability in the operational speed range.

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]

In order to realize the tram's low-floor structure, most of the trams that have been recently introduced adopt an independently rotating wheelset. In the case of trains driving in two regions with different gauges, an independently rotating wheelset may be applied to utilize the variable track technology. Since the independent rotation type wheelset has no rotational restraint of the left and right wheels, the difference in rotational speed between the outer and inner wheels occurs naturally during curved driving, and it is applied to railroad vehicles traveling in sharp curve sections because it smoothly drives curved driving. However, the longitudinal creep force and the lateral restoring force are weakened as the left and right rotational constraints disappear. Lack of lateral direction restoring force weakens stability while causing continuous flange contact driving or zigzag phenomenon against disturbance. Under the conditions of driving in a sharp curve, these railway vehicles generate excessive wear, noise, and lateral pressure, as well as deterioration of ride comfort and derailment. In order to overcome these drawbacks, a method has been proposed in which the torque of a motor mounted on each wheel is individually controlled to generate lateral restoring force or to improve driving performance through lateral displacement control using a yaw moment. In this paper, development using HIL (hardware in the loop) simulator was performed to check the performance and stability of the individual motor torque control technology before verifying by applying the individual motor torque control to the actual vehicle. HIL simulator were constructed by combining a real-time dynamic analysis model of a railway vehicle with a drive motor to which real individual motor control was applied. Under the conditions of driving the test track where the actual test vehicle was tested, the analysis of the driving characteristics and the control characteristics of the disturbance was performed to confirm the proposed individual motor torque control performance. [ABSTRACT FROM AUTHOR]

A passenger railway vehicle’s lightweight design is an efficient technique of reducing energy consumption and dynamic forces between wheel and rail. However, light design results in resonant vibration in a car body. To restrain resonant vibration, a correlation between the suspended equipment variables and the car body’s modal frequency was investigated in this paper. A rigid–flexible general model was developed to examine the impacts of different equipment suspended under the chassis based on mass, location, and frequency on the car body mode. In addition, the numerical model is validated through the experimental result in terms of ride quality. The results demonstrate that the underframe equipment’s suspension characteristics have a significant impact on the mode of the car body, particularly the frequency of the first bending mode. Equipment with a considerable mass should be suspended near the center of the car body to optimize the frequency of the car body’s high-frequency bending. The weight of the equipment has a significant impact on the car body’s first bending frequency. The frequency of heavy equipment should be low enough to promote high-frequency transmissibility and improve the vibration characteristics of the car body.

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.

The vibration data of the gearbox on a high-speed train was measured, and the vibration characteristics were analyzed in this paper. The dynamic stress of the gearbox under the internal and external excitation was examined by a railway vehicle dynamic model with a flexible gearbox and a flexible wheelset. The ideal 20th polygonal wear was considered, and dynamic stresses of the gearbox under different polygonal wear amplitudes were calculated. The gear transmission model was established to study the dynamic stress of the gearbox under the influence of the time-varying stiffness of the gear meshing. Based on the rigid–flexible coupling model, and considering the influence of wheel polygonization, gear meshing time-varying stiffness, and wheelset elastic deformation, the dynamic stress of the gearbox was investigated with consideration of the measured polygonal wear and measured rail excitation. The results show that the dynamic stress of the gearbox is dominated by the wheel polygonization. Moreover, not only the wheel polygonization excites the resonance of the gearbox, but also the flexible deformation of the wheelset leads to the deformation of the gearbox, which also increases the dynamic stress of the gearbox. Within the resonant bandwidth of the frequency, the amplitude of the dynamic stresses in the gearbox will increase considerably compared with the normal case.

In this paper, the development of railway vehicles random analysis procedure (RVRAP) based on the pseudo-excitation theory is described in detail; the procedure helps predict the structural random response of railway vehicle. As traditional finite element method (FEM)-based random vibration analyses are too complex, and time consuming to be carried out by engineer, limited studies have been conducted in the related field. By using the pseudo excitation method (PEM), a stochastic vibration analysis of the railway vehicle system is conducted while the vehicle is modelled by FEM and its mode results are stored as substructures. With the primary and secondary suspension system, the FE-based vehicle configuration is assembled, a structural random vibration analysis is conducted, and the running quality and fatigue life is predicted accurately. Experimental results are compared with the those of a railway vehicle numerical simulation; the accuracy of the random vibration vehicle system is tested and the reliability of the PVRAP is verified. [ABSTRACT FROM AUTHOR]

An on-site test has been performed to address the problem of feet numbness caused by the floor vibration of high-speed railway vehicles. Analysis of the floor vibration performance indicates that the vibration of the car body chassis transmitted to the floor by the elastic supports is significantly amplified in the frequency range of 20–50 Hz. This overlaps with the frequency range in which human lower extremities are most sensitive, leading to feet numbness. A refined finite element model of the car body, including the floor panels is developed to further study the vibration mechanism of the floor. Results show that due to the inappropriate design of the elastic support stiffness, the deformations of the floor above the bogie centre for several typical modes in the frequency range of 20–50 Hz are significantly amplified. When the excitation frequencies transmitted from the car body chassis were close to the eigenfrequencies of the floor, the local resonance of the floor will occur, which is the root cause of human feet numbness. The dynamic stiffness of the elastic support is further optimised, and the experimental verification shows that the vibration transmissibility from the car body chassis to the floor in the frequency range of 20–50 Hz has been significantly reduced, and the problem of feet numbness has been solved. [ABSTRACT FROM AUTHOR]

The theoretical research on means to reduce the vertical vibrations and improve the ride comfort of the railway vehicle relies on a mechanical model obtained from the simplified representation of the vehicle, while considering the important factors and elements affecting the vibration behaviour of the carbody. One of these elements is the anti-yaw damper, mounted longitudinally, between the bogie and the vehicle carbody. The anti-yaw damper reduces the lateral vibrations and inhibits the yaw motion of the vehicle, a reason for which this element is not usually introduced in the vehicle model when studying the vertical vibrations. Nevertheless, due to the position of the clamping points of the anti-yaw damper onto the carbody and the bogie, the damping force is generated not only in the yawing direction but also in the vertical and longitudinal directions. These forces act upon the vehicle carbody, impacting its vertical vibration behaviour. The paper analyzes the effect of the anti-winding damper on the vertical vibrations of the railway vehicle carbody and the ride comfort, based on the results derived from the numerical simulations. They highlight the influence of the damping, stiffness and the damper mounting angle on the power spectral density of the carbody vertical acceleration and the ride comfort index. [ABSTRACT FROM AUTHOR]

In Japan, most of the gear units for transmitting driving force in railway vehicles employ one-stage speed reducers. The gear unit is composed of a pinion connected to a traction motor via a coupling mechanism, a gear installed on an axle, and a gear case that covers them. In their rotating parts, tapered roller bearings are mainly used, and are lubricated by gear oil splashed by the rotating gear. In order to prevent seizure of the bearings and to improve the reliability of the gear units, it is important to appropriately adjust the bearing clearance. The bearing clearance can change from its initial value during the travel of the vehicles due to an atmospheric temperature and its initial value when assembling the gear unit, and can affect the performance of bearings. In this research, an actual gear unit was subjected to bench rotation tests under various bearing clearances and various atmospheric temperatures. The bearing temperature and torque were measured, and changes in bearing clearance were estimated. As a result, it is found that the bearing clearance decreases immediately after the rotation starts, and this tendency becomes more remarkable as the initial bearing clearance is smaller and as the atmospheric temperature is lower.

Interior design of train cabins play an important role in providing comfortable transportation, since visual stimuli have major psychological impact on passengers. To evaluate the amenity of cabin’s interior design, we focused on data of brain activity which lead to intuitive favorability obtained by NIRS in addition to a subjective evaluation by questionnaire. We made an intuitive sight evaluation of interior design for Shinkansen by observing brain activity in reaction to a variety of image showing different combinations of cabin facilities’ colors and lighting color temperature to propose appropriate conditions for a comfortable cabin environment. As a result, on the whole, lighting color temperatures of 5000K were more highly regarded except in the case of blue facilities. However, blue facilities were favored at illumination temperatures of 3500K. On the other hand, the case of red facilities was more highly regarded in the highest lighting color temperature of 6500K. Moreover, to verify the impact of visual stimuli while train is in motion, subjects wearing virtual reality headsets were seated in a train-riding simulator, and stress brain indices and mood brain indices were measured in addition to a subjective evaluation. In the case of blue (3500K), the subjects consistently felt stress-free. We found that a combination of cool-color of facilities and warm-color light temperature is most preferable, which shows good agreement with the results obtained from subjective evaluation by questionnaire. Consequently, NIRS is useful to evaluate the amenity of cabin’s interior design.

Helical spring is used as primary suspension to absorb shock and vibration in rail vehicle system which calls for investigation under failure response because of different loading conditions. This paper is based on the categorical literature review on case study of failure response of suspension spring of railroad vehicle. Here, the investigation of a multibody framework approach is introduced that can be utilized to create complex model of railroad vehicle suspension system. The literature presented encounters results in various domains of analysis including static and dynamic analytical analysis, experimental investigation, dynamic model and finite element analysis for its failure study and examination. It has been observed that the stress may initiate at the inside diameter of spring due to curvature effect during manufacturing occurs residual stress. Also, it induces due to lateral and longitudinal load due to curving and tracking of the rail vehicle system. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomer is a new kind of intelligent material that mainly incorporates micron-sized ferromagnetic particles into a polymer. A dynamic vibration absorber that is based on the controllable shear modulus of magnetorheological elastomer is widely used in vibration systems. In the study, a flexible carbody model with a magnetorheological elastomer dynamic vibration absorber is established. A design method of a semiactive dynamic vibration absorber that is based on magnetorheological elastomer is introduced, and the operational principle of the semiactive dynamic vibration absorber is also discussed. To improve the vibration absorption performance of the magnetorheological elastomer dynamic vibration absorber, via multiple regression analysis, the optimal design frequency expressions for both the rigid vibration and the elastic vibration of the carbody are fitted. Parameter determination for the magnetorheological elastomer dynamic vibration absorber is investigated in detail. Then, the effects on the rigid vibration and the elastic vibration with the magnetorheological elastomer vibration absorber both with the passive vibration absorber and without a vibration absorber are analyzed. Finally, Sperling's riding index is used to evaluate the feasibility and the performance of the magnetorheological elastomer dynamic vibration absorber in a practical application. The results demonstrate that the vibration of the carbody can be effectively reduced by using the magnetorheological elastomer dynamic vibration absorber instead of the dynamic vibration absorber without the magnetorheological elastomer. The magnetorheological elastomer dynamic vibration absorber that is modified by the optimum frequency provides superior vibration reduction performance and improves the riding quality of the railway vehicle. [ABSTRACT FROM AUTHOR]

An individual motor torque control technology to improve the lateral restoring performance of the independently rotating wheel type railway vehicle, which has been applied for reasons such as low floor structure of the vehicle and application of variable gauge technology, has been developed. A new bogie analysis model and a small-scale roller-rig test bench respectively were developed to verify the control technology. A new bogie analysis model has been developed to improve the accuracy of analysis of the lateral and yaw motion of the actual vehicle. The model was verified through the response of the disturbance and critical velocity analysis. The performances of proposed control logic were verified by accomplishing a small-scale roller-rig test and simulation with improved analytical model. Lateral displacement control performs the opposite phase control by the control torque applying in the opposite direction to the front and rear wheelset, while yaw control performs the same phase control by applying the control torque in the same direction. Afterwards the yaw moments of the wheelset are combined to create a yaw moment of bogie, reducing the yaw angle and lateral displacement together. It was verified through analysis and test that the lateral restoring control performance based on the yaw angle (same phase control) was superior to the based on lateral displacement (opposite phase control). [ABSTRACT FROM AUTHOR]

To improve the fuel economy of rail vehicles, this study presents the feasibility of using power regenerating dampers (PRDs) in the primary suspension systems of railway vehicles and evaluates the potential and recoverable power that can be obtained. PRDs are configured as hydraulic electromagnetic-based railway primary vertical dampers and evaluated in parallel and series modes (with and without a viscous damper). Hydraulic configuration converts the linear behavior of the track into a unidirectional rotation of the generator, and the electromagnetic configuration provides a controllable damping force to the primary suspension system. In several case studies, generic railway vehicle primary suspension systems that are configured to include a PRD in the two configuration modes are modeled using computer simulations. The simulations are performed on measured tracks with typical irregularities for a generic UK passenger route. The performance of the modified vehicle is evaluated with respect to key performance indicators, including regenerated power, ride comfort, and running safety. Results indicate that PRDs can simultaneously replace conventional primary vertical dampers, regenerate power, and exhibit desirable dynamic performance. A peak power efficiency of 79.87% is theoretically obtained in series mode on a top-quality German Intercity Express track (Track 270) at a vehicle speed of 160 mile/h (∼257 km/h). [ABSTRACT FROM AUTHOR]

Under dynamic conditions, the dynamic force between the suspended equipment and the car body is substantially increased. This increase not only affects the ride comfort but also substantially raises the likelihood of fatigue damage to the suspended equipment. A multiobjective analytical target cascading (ATC) optimization is proposed to improve the ride comfort of high-speed trains and reduce the vibration of the suspended equipment. A mathematical simulation model of the vehicle equipment system is established, and the acceleration frequency-response function expression of the car body and the suspension system is obtained. The comfort index of the car body and the acceleration root mean square (RMS) of the suspended equipment are calculated by combining the German vertical irregular track spectrum and the comfort filter function. Meanwhile, the ATC method is used to optimize the car body comfort index and the acceleration RMS of the underframe suspended equipment. Then, the availability of the optimization method is evaluated via numerical simulation. Compared with the original suspension scheme of the underframe equipment, when the running speed of the vehicle is 300 km/h, the RMS value of the vibrational acceleration of the underframe equipment after optimization decreases by 19.9 %, and the ride comfort indexes at the car body center and above the front and rear bogies are improved by 6.4 %, 0.1 %, and 1.1 %, respectively. Simulation results demonstrate that ATC optimization can improve the railway vehicle ride comfort and reduce the vibration of the suspended equipment. This paper provides a new approach to the suspension parameter design of equipment. [ABSTRACT FROM AUTHOR]

Reducing railway vehicles' three-dimensional (3D) elastic vibration is needed to improve passenger comfort. This paper presents a 3D analytical model and parameter determination method for the elastic vibration of a carbody. The carbody is modelled as a simple box-type structure consisting of an anisotropic 3D elastic body treated as a continuous system. This model can express complicated 3D elastic vibration (such as lateral–vertical coupled vibration) with fewer degrees of freedom and at a lower computational cost than the detailed finite element model. A model parameter determination method using particle swarm optimisation was also proposed. Application to a Shinkansen-type test vehicle showed good agreement between measured and calculated results with a maximum natural frequency differences of the targeted six elastic vibration modes within 0.86%, indicating the effectiveness of the proposed model and parameter determination method. [ABSTRACT FROM AUTHOR]

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This paper investigates the influence of tread conicity variation on hunting dynamical changing features for railway vehicle. Nonlinear contact force between wheels and rail is estimated by Vermeulen–Johnson creep force law. And a piecewise linear function is employed to appropriate the collision between wheel flange and rail. Hunting asymmetrical motions are analyzed by lateral bifurcation behaviors between maximum and minimum of car body lateral displacement. The result shows that the critical speed decreases with the increase in tread conicity, while the speed gap between linear and nonlinear speeds is narrowing. Compared with wheelsets, lateral amplitudes of the bogies are vulnerable to the tread conicity and decrease gradually. Besides, more asymmetrical motions are put into consideration with regard to tread conicity variation. Similarly, one asymmetrical behavior with small amplitude difference originates from the same chaotic attractor at both sides. And small interactive amplitude jumps in two sides at chaotic or periodic occasions are revealed. Distinguishingly, the other new asymmetrical type is found at a certain tread conicity that amplitudes of the hunting motion in positive and reverse directions no longer coincide and go away in opposite directions when the tread conicity increases to a certain value. And this particular asymmetrical motion disappears with further growth of tread conicity. [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]

In the present study, a method for modelling and simulating the transient vibrations of a system comprising a steel-concrete bridge, ballasted track and moving high-speed train is proposed. The proposed approach uses advanced LS-DYNA simulation software based on finite element (FE) analysis and is applied to a series of single-span simply supported steel-concrete bridges. The theoretical span lengths of the bridges are 15, 18, 21, 24 and 27 metres. The bridge-track-train system is assumed to be fully symmetric. The reinforced concrete platform is homogenized based on the quasi-uniform distribution of the rebars in the specified sections. The bridge FE model does not include transverse bracing between the steel main beams, and the track rail-line axes are rectilinear. The ICE-3 highspeed multiple-unit train is considered at service velocities ranging between 200 and 300 km/h. FE analysis reveals deflection of the bridge at mid span. The results are plotted as a function of train velocity, thus permitting an assessment of the dynamic response of the bridge for each span length. [ABSTRACT FROM AUTHOR]

In order to further reveal the vertical random vibration characteristics of railway vehicles, using the system engineering method, taking the passenger, the train system, and the track system (ballast track) as a unified whole, a passenger-train-track vertical coupling dynamic model is established, and the vibration differential equations of the model are derived. In the model, passengers are regarded as a single-degree-of-freedom system attached to the bottom of the carriage, the train system is represented as a 10-degree-of-freedom multi-rigid body model, the track system is regarded as the infinite long Euler beam model with three layers of continuous elastic point support, and the Hertz nonlinear elastic contact theory is applied to the wheel and rail coupling relationship. Based on this, the time-domain numerical solution of the passenger-train-track vertical coupling dynamic model is given by using Newmark- β implicit integration algorithm, and the correctness of the model is verified by the real vehicle test. This study can provide some theoretical basis for the design of railway vehicles and provide fundamentals for the coordinated control and system optimization of railway vehicle ride comfort. [ABSTRACT FROM AUTHOR]

The design trend for future high-speed trains is envisaged to be lightweight, rising the cost of structural vibration due to the extra flexibility. In this context, studies have looked into the suppression of such vibrations via the use of either (conventional actuators) active suspensions or by structural damping via piezoelectric actuators. The addition of extra macro-actuators will highly impact vehicle weight and is subject to location constraints, while the use of only piezo-actuators normally does not reach the required force levels for appropriate suppression. However, piezo-actuators provide appropriate complementary action with conventional active suspension. In this paper, we present a decentralised control scheme for suppressing the vertical vibration of the vehicle body, combining active structural damping via frequency-weighted H 2 control and active suspension control using skyhook damping via structured H ∞ synthesis. A vertical side-view model of a flexible-bodied railway vehicle is used for the control study, with the configuration of piezoelectric actuators and sensors determined via structural norms. Stability robustness of the controller is analysed with respect to parametric and dynamic uncertainties using μ analysis techniques. Results illustrate the effectiveness of the proposed control scheme for both flexible and rigid modes while guaranteeing robustness to model uncertainty. [ABSTRACT FROM AUTHOR]