Actual Railway Vehicle Research Articles

Real-scale experiments of resistive heating laminate composite panels for radiant heating in railway vehicles

Railways, as one of the representative mass transit systems, are vulnerable to highly contagious respiratory diseases due to their operation in densely populated environments. Notably, the current convective heating system creates an environment susceptible to virus transmission within railway vehicles. To improve this situation, there have been attempts to introduce radiant heating systems to reduce the risk of virus transmission and create a comfortable indoor environment. Previous studies focused on developing radiant heating composite material for railway vehicles by incorporating a carbon fiber heating element within a glass fiber composite to enable heat generation through joule heating. However, this development was limited to the specimen level. In contrast, this study aims to demonstrate their applicability and performance for actual railway vehicle parts at the component level. Specifically, resin flow and manufacturability were analyzed to assess applicability to railway vehicles. Additionally, heating performance and heat flow characteristics were evaluated to determine heating effects. Based on these results, it is anticipated that the application of multifunctional composite materials in the railway industry will improve the vulnerability to winter viruses and indoor environments and expand the utilization of multifunctional composite materials in various fields.

Analysis of Non-Road Mobile Machinery Homologation Standards in Relation to Actual Exhaust Emissions

This article presents issues related to the current approval procedures in the group of off-road vehicles. Our research aimed to demonstrate significant differences between actual railway vehicle operation and stationary homologation tests regarding exhaust emissions. The research cycle consisted of analyzing emissions of toxic compounds from exhaust systems under real operating conditions, supplemented by a temporal share analysis based on the denormalized NRTC test upon which the tested object was homologated. Based on the conducted analyses, a significant difference was found between the actual operation of the tested railway vehicle and the stationary homologation test. By interpreting emission intensities within the parameter ranges of the propulsion unit’s operation, key areas with a significant impact on the vehicle’s overall emissions were identified. Based on the obtained results, a critical opinion is expressed regarding current homologation standards for the off-road vehicle group and the necessity for further empirical research in the area of actual operation of the tested vehicle group.

A Methodology of Condition Monitoring System Utilizing Supervised and Semi-Supervised Learning in Railway.

In this paper, research was conducted on anomaly detection of wheel flats. In the railway sector, conducting tests with actual railway vehicles is challenging due to safety concerns for passengers and maintenance issues as it is a public industry. Therefore, dynamics software was utilized. Next, STFT (short-time Fourier transform) was performed to create spectrogram images. In the case of railway vehicles, control, monitoring, and communication are performed through TCMS, but complex analysis and data processing are difficult because there are no devices such as GPUs. Furthermore, there are memory limitations. Therefore, in this paper, the relatively lightweight models LeNet-5, ResNet-20, and MobileNet-V3 were selected for deep learning experiments. At this time, the LeNet-5 and MobileNet-V3 models were modified from the basic architecture. Since railway vehicles are given preventive maintenance, it is difficult to obtain fault data. Therefore, semi-supervised learning was also performed. At this time, the Deep One Class Classification paper was referenced. The evaluation results indicated that the modified LeNet-5 and MobileNet-V3 models achieved approximately 97% and 96% accuracy, respectively. At this point, the LeNet-5 model showed a training time of 12 min faster than the MobileNet-V3 model. In addition, the semi-supervised learning results showed a significant outcome of approximately 94% accuracy when considering the railway maintenance environment. In conclusion, considering the railway vehicle maintenance environment and device specifications, it was inferred that the relatively simple and lightweight LeNet-5 model can be effectively utilized while using small images.

Practical wheel/rail tangential contact force model for vehicle dynamics analysis combining Levi-Chartet’s formula with adhesion coefficient-velocity relational expression

This paper describes a practical wheel/rail tangential contact force model for railway dynamics analysis under running in rainy conditions. In our previous studies, it was confirmed that experimental results of tangential contact force measurement are agree well with Kalker’s rolling contact theory under dry condition with low humidity around contact surfaces. Here, it can be considered that if the ambient humidity around the contact surface become high infinity, the contact surface is under wet lubrication conditions. On the basis of this assumption, in this study, a practical estimation model for characteristics of tangential contact force under running in rainy conditions is proposed by combining the relationship between the adhesive coefficient and velocity measured on running experiments using actual railway vehicles and Kalker’s linear rolling contact theory. Therefore, to verify the proposed model, the tangential contact force measurement experiment using a twin-disk rolling sliding machine was carried out. As a result, it is confirmed that estimated formulae based on the proposed model are well agreed with experimental results even under different velocity conditions, comparing the relationship between tangential contact force coefficient and slip ratio. From these verified results, the proposed model is considered to be a practical wheel/rail tangential contact force model for vehicle dynamics analysis under rain conditions, because the proposed model has the advantage of low calculation cost and can be easily applied to vehicle dynamics analysis based on multi-body dynamics theories.

Energy-Management Method to Reduce the Capacity of Lithium-Ion Batteries in Hybrid-Voltage-Source Three-Level Inverter for DC-Electrified Railway Vehicles

The hybrid-voltage-source three-level inverter is a traction circuit system aimed at realizing energy savings with lithium-ion batteries for direct-current-electrified railway vehicles. However, this system has the limitation of being unable to freely control the power flow of the batteries owing to the pulse width modulation. However, because this system has batteries, energy management is required for the batteries. Therefore, it is necessary to propose an energy-management method that achieves the required energy-saving effect while considering the constraints of the battery power control. In this paper, a management method is proposed to control the power flow of the batteries by determining the pulse mode of the inverter and the modulation wave offset based on the state of the charge and inverter frequency. In a 0.75-kW class mini-model verification, the effectiveness of the proposed energy-management method is then confirmed based on the state of the charge, inverter frequency, offset, and battery power. Subsequently, we evaluate the energy-saving effect of this hybrid system using a numerical simulation while considering an actual railway vehicle. In addition, the optimal capacity of the batteries is investigated. As a result, the best energy-saving effect is obtained when two of the assumed batteries are connected in series and three in parallel, and the power consumption is reduced by approximately 21%.

Practical wheel/rail tangential contact force model for vehicle dynamics analysis under running in rainy conditions

This paper describes a practical wheel/rail tangential contact force model for railway dynamics analysis under running in rainy conditions. In our previous studies, it was confirmed that experimental results of tangential contact force measurement are agree well with Kalker’s rolling contact theory under dry condition with low humidity around contact surfaces. Here, it can be considered that if the ambient humidity around the contact surface become high infinity, the contact surface is under wet lubrication conditions. On the basis of this assumption, in this study, a practical estimation technique for characteristics of tangential contact force under running in rainy conditions is proposed by combining the relationship between the adhesive coefficient and velocity measured on running experiments using actual railway vehicles and Kalker’s linear rolling contact theory. Therefore, to verify the proposed technique, the tangential contact force measurement experiment using a twin-disk rolling sliding machine was carried out. As a result, it is confirmed that estimated formulae based on the proposed technique are well agreed with experimental results even under different velocity conditions, comparing the relationship between tangential contact force coefficient and slip ratio. From these verified results, the proposed technique is considered to be a practical wheel/rail tangential contact force model for vehicle dynamics analysis under rain conditions, because the proposed technique has the advantage of low calculation cost and can be easily applied to vehicle dynamics analysis based on multibody dynamics theories.

철도차량 속도구간별 가감속 특성의 객체지향 모델링 기법

Railway vehicles have different traction and braking forces depending on their speed, which can be divided into constant torque areas, constant power areas and characteristic areas. The 4th order Runge-Kuta method was applied as a method for simulating these characteristics, and object model for railway vehicle was constructed using the overloading function of the function. The characteristics of the vehicle were calculated and compared with the actual values by applying the constructed model. We also calculated TPS (Train Performance Simulation) from the actual railway rail data and confirmed that it was similar to the characteristics of the actual railway vehicle.

Simulation of Energy Absorption Performance of the Couplers in Urban Railway Vehicles during a Heavy Collision

Railway vehicles are generally operated by connecting several vehicles in a row. Mechanisms connecting railway vehicles must also absorb front and rear shock loads that occur during a train’s operation. To minimize damage, rail car couplers are equipped with a buffer system that absorbs the impact of energy. It is difficult to perform a crash test and evaluate performance by applying a buffer to an actual railway vehicle. In this study, a simulation technique using a mathematical buffer model was introduced to overcome these difficulties. For this, a model of each element of the buffer was built based on the experimental data for each element of the coupling buffer system and a collision simulation program was developed. The buffering characteristics of a 10-car train colliding at 25 km/h were analyzed using a developed simulator. The results of the heavy collision simulation showed that the rubber buffer was directly connected to the hydraulic shock absorber in a solid contact state, and displacement of the hydraulic buffer hardly occurred despite the increase in reaction force due to the high impact speed. Since the impact force is concentrated on the vehicle to which the collision is applied, it may be appropriate to apply a deformation tube with different characteristics depending on the vehicle location.

Basic study on improvement of tangential force between wheel and rail by injecting dry gas

This paper presents a basic study for developing a new adhesion improvement method for railway vehicles, focusing on the tangential force characteristics between wheels and rails. In our past studies, the following phenomena have been confirmed. First, the tangential force of the wheel/rail is increased by repeated rolling and sliding frictional force, and the tangential force is stabilized by the oxide film covering the contact surface. In addition, the tangential force under the condition where the humidity around the contact surface is low tends to be larger than that under high humidity condition. And finally, these phenomena indicate that the friction coefficient of wheel/rail can be increased by instantaneously reducing the humidity around the contact surface. Therefore, in this paper, we propose a method for improving the frictional force that reflects the above-mentioned results in our pas studies. In the proposed method, assuming that it is applied to re-adhesion control of railway vehicles, the frictional force of the wheel/rail contact is temporarily reduced by lowering the humidity around the contact surface by injecting dry nitrogen gas. To verify the proposed method, using a pair of the small cylindrical specimen, tangential force was measured under the conditions with different humidity. In addition, in order to confirm the effect on the braking performance of actual railway vehicle, numerical analysis was carried out. As a result, the experimental result shows the frictional force increases up to approximately 40% under high humidity condition, and was confirmed by the numerical analysis that the proposed method has an improvement effect on the reduction of braking distance during dry nitrogen gas injection even if the humidity condition around the contact surface is high.

A Simple Active Power Control for a High-Power Wireless Power Transmission System Considering Coil Misalignment and Its Design Method

A series–series compensated capacitors topology of the wireless power transmission (WPT) system has a characteristic of increasing active power at coil misalignment when controlled using the conventional secondary dc-link voltage control. This results in a larger total capacity of the primary and secondary sides’ converters. To cope with these problems, this paper proposes a simple constant secondary active power control method, where the secondary dc-link voltage is regulated according to the onboard active power rating and secondary current. The effectiveness of the control method is verified by 100 W experimental systems. The numerical simulation that considers the harmonic components is established to be compared and justified by the experimental results, which is then used to design the capacity of a 300 kW WPT system assuming actual railway vehicle application. By the proposed method, the design criteria of the rating voltage and current of the primary and secondary sides’ components can be determined.

Damping control method utilizing overvoltage resistor under light load condition

High feedback gain of the light‐load regenerative brake control increases the regenerative brake power. However, if the regenerating load changes suddenly, higher gain causes more rapid change of the motor current. And because of the delay in the motor control, it increases the filter capacitor (FC) voltage and may activate the overvoltage protection. This letter proposes a damping control method to reduce the spike of the FC voltage utilizing the overvoltage resistor. The proposed method is verified by numerical simulation assuming an actual railway vehicle under the condition of load shutdown. By means of this method, the overvoltage resistor can be effectively utilized to reduce the FC voltage spike, which results in saving the substation energy. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

弾性トーラスによる鉄道車両の車体弾性振動低減効果（実車を用いた制振効果の確認と制振メカニズムの数値的検討）

弾性トーラスによる鉄道車両の車体弾性振動低減効果（実車を用いた制振効果の確認と制振メカニズムの数値的検討）

Lüders Band Propagation Monitoring in Railway Steels

The tensile failure behavior of railway wheelset materials was studied with the aid of infrared thermography technology. The tensile specimens were prepared from the actual railway vehicle parts, which were used for over 20 years. Generally, the Lüders bands are appeared and observed in annealed soft steel like low-carbon steel, during yield point phenomenon due to the unbalance of strain. During the tensile testing, a high-speed infrared camera was employed to monitor surface temperature changes in specimen. During the tensile testing, the formation of Lüders bands was clearly observed. Moreover, the propagation of bands along the 45 degree direction of loading axis was also observed. In this investigation, the yield point phenomenon with Lüders band in railway wheelset materials was introduced, and the interpretation of tensile behavior was also discussed.

Experimental and numerical study on the effect due to passengers on flexural vibrations in railway vehicle carbodies

The effects of passengers on vertical flexural vibrations of railway vehicle carbodies have been investigated experimentally and numerically. The primary focus is the damping effect caused by passengers. Vibration measurement tests, including stationary excitation tests and a running test on a commercial line, were conducted on three different types of actual railway vehicles for varying the numbers, postures and distributions of passengers. The measurement results showed that the peak frequencies in the measured FRF (frequency response function) and acceleration PSD (power spectral density) in response to excitation force or acceleration changed only a little; in contrast large reduction of the peak values was observed when passengers were aboard. These results show that passengers behave not as additional mass but as damping elements upon the carbody flexural vibrations. The damping effect by passengers appeared over several flexural modes and was significantly induced even by few passengers. Numerical studies were also carried out to develop analytical models for representing the measured results of the vibrations of carbody with passengers. It was shown that the change of the carbody FRF due to passengers could be simulated well by using a simple one-degree-of-freedom passenger model comprising a mass–spring–dashpot with a large damping ratio.

Investigation of Noise Spectrum Characteristics for an Evaluation of Railway Noise Barriers

Most of the test methods used for determining the acoustic performance of the noise barriers in Korean standards address the sound-proof panels but refer to noise barriers as a whole system or their in-situ performances less. Many new types of trains with different operating speeds have been developed and produced, and civil appeals against railway noise are becoming quite extensive. Considering these latest changes of circumstances, it is necessary to investigate the current standards and specifications pertaining to railway noise barriers. In this paper, criteria for the measurements and evaluations of noise barriers and sound-proof panels are examined and experimental studies are introduced. In order to suggest more efficient methods for reasonable evaluations of the noise barriers, frequency spectrums of the noise source, the power of the actual railway vehicles, are investigated and introduced.

435 床下機器の高減衰弾性支持による鉄道車両の車体弾性振動低減

This report presents a simple method to reduce flexural vibrations in a railway vehicle carbody just by supporting underfloor equipments using high-damping elastic mounts. Recent studies by the authors show that on-boarding passengers have large additional damping effect on the carbody flexural vibrations. Since a human as a elastic body itself has relatively large damping coefficient, we tried to simulate the additional damping effect of passengers by supporting underfloor equipments using high-damping elastic material. Some numerical studies are firstly carried out to check the feasibity of the idea using simple single degree of freedom and two degrees of freedom systems. Then, two types of elastic mounting devices are built for actual railway vehicle. A series of excitation tests are conducted in the rolling stock testing plant in the Railway Technical Research Institute (RTRI) using a commuter type test vehicle by applying those elastic mounting devices, and good vibration reduction performances are observred by the tests.

542 乗客による鉄道車両走行時の車体弾性振動減衰効果(自動車・鉄道車両の制震,OS-3 ダンピング,総合テーマ「伝統を,未来へ!」)

The effect of passengers boarding on a railway vehicle is usually considered as additional mass in designing carbody. This means that natural frequencies of flexural vibrations of a carbody are decreased as the number of passenger increases. However, previous researches, in which some stationary excitation tests were carried out for actual railway vehicles, indicate that on-board passengers behave not as additional mass but as damping. In this report, the authors examine the damping effect by passengers in running condition. A series of running test using a Shinkansen-train was conducted, and relatively large reduction of flexural vibration of carbody was observed when passengers were on-board. We also tried to imitate or simulate the damping effect by passengers using flexible polyethylene tanks filled with water. As a result of excitation test for a commuter-type test vehicle, at least two-different modes of flexural vibration were reduced when water tanks (total 630-1050 kg) were loaded.

319 AMDを用いた鉄道車両の車体弾性振動の多モード振動制御(車両サスペンションおよび振動制御,OS-16 運動と振動の制御,総合テーマ「伝統を,未来へ!」)

The vertical elastic vibrations of railway vehicle carbodies are needed to reduce from the viewpoint of riding quality. The first bending mode and diagonal distortion mode are commonly observed almost all railway vehicle carbodies. The natural frequencies of the two modes exist around 10Hz which is known to be a sensitive frequency for human. In this paper, a vibration reduction method about the two modes by using active mass dampers is suggested. A stationary excitation test for an actual railway vehicle is conducted to confirm the feasibility of this method. As a result of the excitation test, two modes of above mentioned elastic vibration of the carbody are reduced successfully.

Modal Analysis of Railway Vehicle Carbodies Using a Linear Prediction Model

This paper reports on a study regarding modal property identification for railway vehicles using a linear prediction model. The relationship between input (excitation force or axlebox acceleration) and output (carbody acceleration) of an actual railway vehicle obtained by stationary or running tests is expressed by means of an ARX (Auto-Regressive eXogenious) model, and the procedure for the extraction of modal properties is described in detail. Determination of an appropriate model order (i.e., the order of the prediction coefficients in the ARX model) is specifically discussed from the viewpoint of practical use. The implementation of average estimation errors for two different parts of the analyzed data is proposed, and their effectiveness in determining the model order is evaluated. Suitability for the MIMO (multiple-input multipleoutput) problem using the ARX model is also described. It is shown that detailed modal characteristics can be successfully identified using the proposed method from measured data for both stationary and running tests.

261 箱形構造物としての鉄道車両の車体上下弾性振動解析 : 車体側面の曲率を考慮した曲がりはりの導入

An analytical method to treat flexural vibration of railway vehicle carbody is investigated. From several measurement results for actual railway vehicles, it has been found that the relative vertical displacement between roof and floor couples strongly with lateral deformation of side panels. An analytical model, therefore, has to express such coupling effect correctly. A curved beam, in which circumferential and radial deformation couples each other, is introduced to express the deformation of side pillar in this study. The strain energy of the curved beam is derived based on a shell theory, and some numerical calculations are carried out. A straight and curved beam coupled system is proposed as a reduced system representing side panel of a railway vehicle carbody. Numerical result shows that the beam system can express the coupling effect between roof-floor relative vertical displacement and side panel lateral deformation successfully.