High-speed Train Model Research Articles

Study of the Differential Wear of Wheel Profiles on Motor Cars and Trailers of High-Speed Trains

As the operation speed of China’s high-speed trains continues to increase, a variety of complex wheel wear problems continue to emerge. Many line tests show that the differential wheel wear of the motor car and trailer car is obvious. The aim of this paper is to explore the differential wear mechanism of motor cars and trailers and their effect on dynamic performance. Firstly, this paper established a high-speed train model, which consists of two motor cars and two trailers. Then the causes of differential wear of the high-speed train from the perspective of wheel-rail contact and wheel wear were analyzed, and the Jendel wear model was used for wheel wear prediction. The wear model was verified through measured wheel wear data. Lastly, the dynamic performance of the differential wear of the high-speed train was analyzed. The results showed that the different distribution of the adhesive sliding zone in the contact patch, the different wheel-rail normal force, and tangential forces are the reasons for the differential wear. The established dynamic model and wear model can effectively predict the differential wear of the motor cars and trailer, and the maximum wear depths of the motor car and the trailer wheel were 0.886 mm and 0.721 mm. This verified the validity of the simulation model. When wheel differential wear occurs, the overall dynamic performance of the trailer is superior to that of the motor cars.

Decentralized learning control for high-speed trains with unknown time-varying speed delays

Treating the multi-point-mass dynamic model of high-speed trains as an interconnected system, this study proposes a decentralized iterative learning control scheme for high-speed trains to achieve the trajectory tracking goal. By making reasonable estimates of the interaction term and compensating for it, the proposed control scheme utilizes only local information from each carriage and does not need any inter-carriage information exchange. The zero-error tracking of the desired trajectory is guaranteed even in a restricted communication environment. Considering unknown time-varying speed delays in the actual high-speed train operations, a modified decentralized iterative learning control scheme is also provided to address the negative impact of speed delays. The convergence of tracking errors is strictly proven by constructing appropriate composite energy functions. Numerical simulations further verify the theoretical results.

EFFECTS OF CROSSWINDS ON THE FLOW STRUCTURE AROUND A NEXT-GENERATION HIGH-SPEED TRAIN EXITING A TUNNEL

This study investigates the effect of crosswind on the aerodynamic behavior of the Next-Generation High-Speed Train (NG-HST) model when exiting a tunnel. Utilizing a 1/25th scale model, three distinct train exit positions and four crosswind yaw angles (15°, 30°, 45°, and 60°) were considered. Computational Fluid Dynamics (CFD) simulation with the k-ε turbulence model was used to simulate the flow structure around the train at the crosswind velocity of 25 m/s. A mesh independence study was performed to ensure that the results were not influenced by mesh sizing. Furthermore, existing wind tunnel experiment data was used to validate the mesh setup. The results showed that the crosswind angle had a significant effect on the aerodynamic flow behavior of the train as it exited the tunnel. The airflow pattern on the train surface exhibited significant changes, and variations in pressure distribution were observed on both the leeward and windward sides of the train. Moreover, the cars outside the tunnel experienced greater pressure than the cars inside the tunnel. As the last car of the train emerged from the tunnel, the strong crosswind altered the vortex structure, particularly around the head car, emphasizing its critical role in ensuring safe train operation. The results can be used to improve the design of wind barriers and other infrastructure along the railway tracks to improve the operational stability and safety of high-speed trains.

The analysis for fatigue caused by vibration of railway composite beam considering time-dependent effect

The time-dependent effects in steel-concrete composite beam bridges can intensify track irregularities, subsequently leading to amplified train-bridge coupling vibrations. This phenomenon may increase the stress amplitudes in the bridge steel, thereby impacting the fatigue performance of the composite structures. This paper employs multiple rigid body dynamics to construct a high-speed train model and utilizes the finite element method to develop a steel-concrete composite beam element model that accounts for time-dependent effects, interfacial slip, and shear hysteresis. This approach enables the computational analysis of the train-bridge coupling system, facilitating an investigation into the influence of concrete’s time-dependent effects on the fatigue performance of railway steel-concrete composite bridges. Focusing on a 40-m simply supported composite bridge, the train-bridge coupling dynamic responses were computed for each operational year within a decade of the completion of construction. Applying the P-M linear fatigue damage accumulation theory, statistical analysis of stress history data across various operational periods was conducted to quantify the fatigue damage induced by a single eight-car high-speed train on the lower flange of the mid-span steel beam and the beam-end studs. The findings reveal that the beam-end studs sustain greater damage than the mid-span steel beam. Moreover, the detrimental impact of time-dependent effects diminishes with the increase of operational years. Notably, compared to the initial year, the fatigue damage to the lower flange of the mid-span steel beam by an eight-car train in the tenth year has surged by 39.3%. Conversely, the damage to the beam-end studs has decreased by 47.5%.

Numerical Analysis on The Aerodynamic Performance of A High-speed Train Operating on Various Embankment Heights Under The Influence of Crosswinds

Given the unavoidable geographical surface, railings must be raised above ground level in some cases, which is known as an embankment. It was discovered that the height of the embankment had a significant influence on the slipstream on the train's leeward side especially during crosswind conditions. The primary objectives of this study were to investigate the impact of varying embankment heights on the aerodynamic characteristics of a high-speed train under different crosswind conditions using computational fluid dynamics (CFD) analysis. The German Aerospace Center DLR's Next-Generation High-speed Train (NG-HST) model has been used for this study. The yaw angles (ψ) are ranging from 10° to 50° in 10° increments. The Reynolds number based on the model's height and freestream velocity at the computational domain is 1.3 x 106. In the results, it shows that embankment height and crosswind ψ has a significant impact on the aerodynamic characteristics. Essential aerodynamic parameters that have a significant impact on train stability, such as the drag, lift, and side force coefficients, as well as the roll, yaw, and pitch moment coefficients, revealed that the higher the ψ, which included 40° and 50°, produced poor results compared to the lower ψ, which included 10°, 20°, and 30°. In terms of visual appearance, rising of crosswind angles have a greater impact on the formation of vortices on the leeward side of the train body and embankment. Thus, it can be concluded that the embankment heights and crosswind angles are crucial in determining train safety operations.

Improving the energy efficiency and riding comfort of high-speed trains across slopes by the optimized suspension control

As the link between cities, the high-speed train (HST) not only effectively enhances national and regional accessibility, but also induces much energy consumption. On the other hand, passengers have a higher requirement for riding comfort of HST than before. Considering the impacts of slope gradient on energy consumption and vertical carbody acceleration, this paper optimizes the scale factor of the damper controller depending on the running condition to juggle the energy efficiency and riding comfort when HST is across slopes. Firstly, the multibody dynamics simulation model of HST is established to evaluate the energy consumed by motion resistances and carbody vibrations. Then the Skyhook control strategy is applied to the secondary vertical damper of the vehicle model. The effects of vehicle speed, slope gradient, and scale factor of the Skyhook controller on energy saving and vertical carbody acceleration of HST are investigated. Based on the simulation results, the Gaussian process regression model is established to predict the vehicle performance and describe the bi-objective optimization problem. It is demonstrated that the optimized Skyhook control system can at most save energy consumed by motion resistances by 8.52 % or reduce vertical carbody acceleration by 37.14 % without sacrificing the other target. Finally, a comprehensive feasibility and economic analysis of the proposed control system is carried out to promote its practical implementation.

Dynamic behaviour of bridges under critical conventional and regular trains: Review of some regulations included in EN 1991-2

In the field of structural analysis dedicated to the study of vibrations of high-speed railway bridges, one reference load model is the well-known HSLM-A, which limits of validity are stated in Eurocode EN 1991-2, Annex E. In a recent paper published in the Journal of Rail and Rapid Transit, the authors investigated the degree of coverage provided by HSLM-A to critical articulated trains. Now in the present article, the authors have extended those analyses to critical conventional and regular trains as well. This is an important aspect because HSLM-A as such is an articulated-type model, so it is of interest to understand how it deals with covering the various resonance phenomena generated by other train types. Therefore, the main goal of this work is to establish whether the conventional and regular trains that stem from the validity rules given in Annex E/EN 1991-2, produce vibratory effects that are duly covered by HSLM-A. Following the aforementioned validity rules, one first aspect analysed is the importance of near-to-integer wheelbase ratios in the coupled vibrations produced by conventional trains. Subsequently, seven realistic, conventional and regular high-speed train models have been synthesised; these models have been made publicly available in Mendeley Data, and comprise almost 3800 different sequences of axle loads. Finally, the response of simply-supported bridges has been analysed with a view to compare the seven synthesised models versus HSLM-A. The exceedance and required speed increase have been computed for both displacements and accelerations, in a comprehensive ensemble of spans and speeds. The results provide a diagnosis of the degree of coverage of HSLM-A with respect to those conventional and regular trains compliant with Annex E/EN 1991-2.

Dynamic model of high-speed maglev train-guideway bridge system with a nonlinear suspension controller

To improve the anti-interference ability of maglev trains, a dynamic model of the high-speed maglev train with a nonlinear suspension controller for the guideway system is proposed in this paper. Based on the nonlinear characteristics of the magnetic suspension system, a nonlinear decoupling controller is designed using the feedback linearization theory. Then, a high-speed maglev train model is refined with a guideway coupling system, consisting of a maglev train simulated as a multi-body dynamics model with 537 degrees of freedom and a spatial finite element model of the guideway. Taking the Shanghai high-speed maglev train as an example, the correctness of the computational model is verified by comparing the modeling results with field measurement data, and the control effectiveness of the nonlinear controllers and the traditional PD controllers is compared considering different train speeds and disturbance forces. The results show that the suspension gap under the decoupling control is smaller than that under the PD control during the train operations. Under the same disturbance force, the decoupling control exhibits better control performance than the PD control. The variation amplitudes of the magnetic pole gaps are generally linearly related to the disturbance force.

High-Speed Train Running Characteristics Assessments Using Multibody Dynamics Simulation

The development of railway transportation in Indonesia in recent years has increased the number of new vehicles with various types and specifications. These new vehicles should pass a series of running characteristics assessments against standards to ensure safety and comfort in operation. Before the field testing, the assessments using numerical simulation in the design stage need to be done. This study aims to assess the high-speed train running characteristics through modeling and testing using multibody dynamics simulation software. The standards used for the assessments refer to EN 14363 – Testing and Simulation for The Acceptance of Running Characteristics of Railway Vehicles. The high-speed train model was built and validated through four methods with comparative values calculated analytically. The validated model was then run in the simulation to get the parameters for assessment. The parameters include the coefficient of flexibility, critical speed, safety against derailment with various methods, ride comfort, and vibration mode. The parameters obtained from the simulation are compared to the acceptance criteria specified in the standard. The results show that the vehicle performance fulfills the requirement prescribed by EN 14363 standard. After the vehicle and the track infrastructure are ready, they need to be confirmed by a series of testing performed on the main line. This study supports the development of high-speed trains in Indonesia and is expected to give more insight into the usefulness of numerical simulation to predict the characteristic of dynamic performances of railway vehicles in actual operating conditions.

Six-dimensional force/torque sensor for aerodynamic characteristic study of high-speed train with different wind angles under stationary tornado.

Researchers conducted an investigation by tornado simulator to study the impact of wind angle on the aerodynamic characteristics of a reduced (1:150) high-speed train model using six-dimensional force/torque sensor. The reduced scale model size can match the relative size relationship between high-speed train and tornado vortex core in real condition. Results show that the wind angle affects the mean value and standard deviation of the force and moment coefficient of the high-speed train at the same radial position. The variations of the mean value and standard deviation of the pitching moment coefficient of the high-speed train carriage model at 60°and 90°are different from that at other wind angles. The variations of the mean value of the pitching moment coefficient of the high-speed train head model at 0°, 15°and 30°are different from that at other wind angles. The variations of the standard deviation of the pitching moment coefficient of the high-speed train head model at 60°,75°and 90°are different from that at other wind angles. This research will help the further study of the operation safety of high-speed train in the event of a tornado impacting a high-speed train network.

Identification of switched dynamic system for electric multiple unit train modeling

A new iterative algorithm is proposed to identify the high-speed train model which is described as a switched dynamic system including a fast switched nonlinear static subsystem followed by a non-switched linear dynamic subsystem. The non-switched property of the linear part leads to a more complex dynamics of the whole system, compared to the switched Hammerstein system which linear part switches synchronously with its nonlinear part. The proposed iterative algorithm alternates between identifying the switched nonlinear static subsystem and the linear dynamic subsystem. The switched nonlinear subsystem identification incorporates a quadratic error bound constraint with respect to nominal values of model parameters, and is formulated as a second-order cone program. Properties of convergence and asymptotic unbiasedness of the obtained estimates are proved under some necessary assumptions. With real data and simulation examples, the proposed iterative algorithm produces convergent and asymptotically unbiased estimates. In the simulation results, incorporating the quadratic error bounds results in a fast convergence rate in the presence of a small noise variance, and also produces a smaller identification error in the presence of colored noises with a non-zero mean and a large variance.

Research on railroad locomotive driving safety assistance technology based on electromechanical coupling analysis

Abstract The reliability and effectiveness of a high-speed train’s operation depend heavily on the traction drive system. The purpose of this project was to construct an electromechanical connection model for a bullet train. The model contains the gear-to-gear connection, the differential output of the transmission, which circuits similar to those found in motors, and indirect power management. The purpose of this research is to investigate how modern railroad systems have implemented locomotive driving safety assistance technologies in order to get a deeper understanding of the effects that technological progress has on train operators. The purpose of this study is to learn how technological developments have altered the job of train operators. We will investigate the feasibility, compatibility, and potential consequences of introducing innovative technologies into established workflows. We will look at how well it works with current technologies, too. The current investigation has the authority to look at these issues. The ultimate goal of this project is to improve railway operations by providing essential insights for guaranteeing a balance between technological progress and human skill. The ultimate purpose of the project is to enhance the efficiency and security of railway operations. This may be achieved by strengthening the effectiveness and security of railway operations. In addition, the high-speed train model is simulated numerically to maintain that steady rate of travel, and grip, while slowing. The study determined that the stator current is the result of the interaction between the fundamental frequency and the higher harmonics of the rotational frequency. Furthermore, both frequencies can be detected even when traveling at a constant speed. Despite this, unless the rotation frequency is increased, they are often not visible. During traction, the root-mean-square (RMS) values of the rotor and stator currents are lower than that during braking. There is a significant rise in current when the wheels and brakes are first applied. The RMS value of the current lowers dramatically as grip and braking improve. As a result, it is essential to carefully consider how the change may influence the reliability of the system.

Snow accretion on a model train: Climate wind tunnel experiments

Snow and ice accumulation on the main parts of rolling stock can lead to malfunctions and safety issues. This paper presents the results of snow accretion tests conducted in a climate wind tunnel to investigate the icing process on a model train at various ambient temperatures. A simplified 2/3-scale EMU-320 high-speed Korean train model was used without electrical power or heat sources. Before testing, the snow flux and liquid water content of snow were measured to enable their use as input conditions in future simulations and to inform further analysis of the icing process. Both qualitative and quantitative data from the tests were analyzed, including photographs and snow density and thickness measurements. Snow accretion was broader at higher ambient temperatures, and snow accretion on the nose tended to be thicker further away from the stagnation point at higher temperatures. Snow accreted on all components of the bogie, and the thickest snow accretion on the wheels occurred at arc angles of 15–40° for cases of lower temperature while occurring at a larger angle at the highest temperature. The comprehensive data from these experiments is expected to support future analysis and development of anti-icing systems.

Influence of Variable Height of Piers on the Dynamic Characteristics of High-Speed Train–Track–Bridge Coupled Systems in Mountainous Areas

With the increase in the occupancy ratio of bridges and the speed of trains, the probability of trains being located on bridges during earthquakes increases, and the risk of derailment increases. To investigate the influence of unequal-height piers on the dynamic response of high-speed railway train bridge systems, a seismic action model of high-speed train–track–bridge dynamic systems was established based on the in-house code using the finite element method and multi-body dynamics method. It is found that (1) compared to equal-height piers, the peak lateral dynamic response of unequal-height piers (with gradually increasing pier heights) decreases, while the peak vertical dynamic response increases; (2) the peak lateral dynamic response of unequal-height piers (with a steep increase in pier height) increases sharply, while the peak vertical dynamic response decreases; and (3) the safety indicators of equal-height piers are significantly superior to the two unequal-height pier operating conditions.

The Analysis of Utilizing Multiple Fences in High-Speed Tracks on the Aerodynamic Characteristics of a High-Speed Train Model

The Analysis of Utilizing Multiple Fences in High-Speed Tracks on the Aerodynamic Characteristics of a High-Speed Train Model

Wear rate and profile prediction of Cu-impregnated carbon strip for high-speed pantograph

The wear status of pantograph carbon strips has a crucial impact on the receiving quality of high-speed trains, and accurate wear rate prediction is essential for timely maintenance and replacement. In this study, the wear mechanism of Cu-impregnated carbon strip is analyzed through micro-analysis, and an improved method for calculating wear rate is proposed by enhancing the original Holm-Archard adhesive wear model. The proposed approach considers the collecting current of the pantograph, burning arc, and contact loss rate of the pantograph, thereby improving the accuracy of wear rate calculation. Moreover, the study validates the relationship between contact resistance and contact force by comparing the model's results with experimental data. Furthermore, the wear profile of MCS is predicted and calculated by considering the wear position of the zigzag catenary on the sliding plate, which provides a more comprehensive analysis of the wear behavior of MCS. To validate the proposed model, actual wear and operation data of an eight-unit high-speed train's pantograph are employed, and the results indicate an average absolute error of 0.19 mm at the deepest wear depth (−16 mm–16 mm) of MCS, which demonstrates the feasibility and effectiveness of the proposed model.

A framework for simulating snow accumulation and ice accretion on high-speed trains

A simulation framework for three-dimensional particle trajectory tracking, snow accumulation and ice accretion modelling on solid bodies in high-speed air flow is presented. The framework, named HADICE, solves the aerodynamic flow field as Reynolds averaged Navier-Stokes (RANS), with optional hybrid RANS/LES capabilities for modelling complex turbulent flows. Particle trajectory tracking is performed in an Eulerian-Lagrangian approach and wall collision is modelled using a hard collision model with reflect condition and a momentum based trap condition. A novel accurate and robust iterative evaluation method for the local collection efficiency is proposed for arbitrary 3D geometry and flow. Ice accretion is modelled in a multi-step approach and iced geometry is updated through mesh deformation using a radial basis function (RBF) interpolation method. Snow accumulation and ice accretion predictions based on the framework are validated against climatic wind tunnel experimental measurements. A full 3D simulation is demonstrated for snow accumulation and ice accretion on a 1:8 scaled high-speed train model. Using the presented framework, snow accumulation and icing simulation for high-speed trains can be conducted in an accurate and efficient manner, which is of great importance for physical investigations and the design of anti-snow and ice protection systems.

Optimal design of variable suspension parameters for variable-gauge trains based on the improved CRITIC method

ABSTRACT The gauge differences of international rail lines have led to the emergence of variable-gauge trains. High-speed variable-gauge trains operating on different lines should meet the dynamic requirements. In order to achieve the above purpose and obtain better dynamic performance, a parameter optimization method for variable suspension systems is proposed. The SIMPACK dynamic model of high-speed variable-gauge trains is established. Six key parameters of the suspension system are chosen, and different suspension parameters are combined using the optimal Latin hypercube. Seven dynamic indices of the vehicle running on three different gauge tracks are solved separately. Weighted SNR is used to perform the multi-objective optimization. The improved CRITIC method is used to solve for the weight coefficients of each index, and find the optimal values of the key suspension parameters. The objective of adjusting the variable suspension parameters of variable-gauge trains is presented. Results from simulation show that the optimized suspension parameters can improve the dynamic performance of the variable-gauge vehicle, especially the derailment coefficient, the wheel load reduction rate, and the axle lateral force. The vehicle can operate with better dynamic performance on both gauge lines by using the designed variable suspension parameters.

Effect of non-fully enclosed windshield on aerodynamic and acoustic behaviors of high-speed train.

In the design of the outer windshield of high-speed trains, the non-fully enclosed windshield structure is widely used. Based on the cavity flow-induced vibration theory and FW-H acoustic equation, the flow field and acoustic characteristics of three high-speed train models with different windshield configurations are compared and analyzed. Numerical simulations were validated by full-scale experiments. The results show that the noise generated from the windshield area is mainly composed of low-frequency peak resonance noise and broadband turbulent noise. A typical Helmholtz resonator cavity is composed of inner and outer windshields. The position and number of windshield openings affect the airflow structure inside the windshield and the train wake. In addition, the hole as a potential aerodynamic noise source determines the vortex shedding and cavity resonance frequency, resulting in different acoustic feedback. The energy of windshield noise is mainly concentrated in the low frequency range below 400Hz. The windshield configuration of M1 and M3 shows tonal noise characteristics, while the M2 model eliminates the generation of low-frequency resonance noise. Compared with the M1 and M3 models, the noise generated by the windshield and the whole train of the M2 model is reduced by 3.83 dB and 1.77 dB, respectively.

Study on the seismic influence coefficient of track irregularity on the train dynamic effect of high-speed railway bridge

Track irregularity is an important factor affecting the train-track-bridge system interaction, and for the seismic design of the track-bridge system, the study of the law of the influence of track irregularity on the train dynamic effect is of great theoretical significance. Based on this, the finite element models of China railway track structure (CRTS) II plate high-speed railway simple-supported girder bridge and CRH2C high-speed train model are developed and compared with the shaking table test results to verify their validity. Considering track irregularity and earthquake randomness, a sample library of the train dynamic effect of the track-bridge system under earthquake is established, the probabilistic statistical characteristics of the train dynamic effect are analyzed, and the influence level of track irregularity on the train dynamic effect of the track-bridge system under earthquake is studied, and the standard value of track irregularity influence coefficient of train dynamic effect based on probability guarantee rate is proposed. The results indicate that: the influence of track irregularity on the seismic response of bridge structure is slight, with their greatest impact not exceeding 1%. However, it has a significant impact on the seismic response of track structures. The standard values of the sliding and mortar layers’ track irregularity influence coefficients are 1.49 and 1.71, respectively, at 0.1 g. Under various peak ground acceleration (PGA) settings, the fasteners’ standard values for the track irregularity influence coefficient are less than 1.1. Additionally, the degree of influence of track irregularity on the seismic response of track structure decreases significantly as the PGA increases.