Rail Wear Research Articles

Effect of hollow-worn wheels on the evolution of rail wear

A non-uniform rail wear prediction model is developed to analyse the influence of hollow-worn wheels on rail wear. The rail wear prediction model considers the combination of vehicle-track coupled dynamics model, Kalker's variational method, and the material wear model developed by the University of Sheffield, together with a new sampling and accumulation strategy. Taking into account the track random irregularity, the rail wear distribution for particular cross-sections at regular intervals and its effect on wheel-rail dynamic interaction are investigated using a high-speed vehicle with different tread hollow–worn wheels that run on a tangent track. The simulation results indicate that hollow-worn wheels will give rise to noteworthy change on the non-uniform rail wear distribution, cause a significant increase in rail wear and have a distinct effect on the wheel-rail interaction.

Wheel wear prediction on a high-speed train in China

The number of operating high-speed trains in China is around 2800 today and 179,200 wheels are under maintenance in one reprofiling period. To help researchers to understand the evolution of the wheel profile and improve the reprofiling strategy of the wheels, this study predicts the development of wheel profiles on a high-speed train as function of mileage and compare simulated worn wheel profiles with measured ones. The methodology includes transient multi-body dynamic simulation, wheel–rail contact calculation and wear calculation with Archard’s model. Calibrated by analysing measurements of worn S1002CN profiles and performing parameters sensitivity study in the wear model, the model is then used to predict the development of a recently designed wheel profile, called S1002CN-RF. The simulation results for S1002CN and S1002CN-RF show that the predicted wheel profiles coincide with the measured ones. Wear prediction of another high-speed wheel profile (LMA) validates that the vehicle performance with respect to wear could be further improved compared to using S1002CN or S1002CN-RF. Finally, the influence of track alignment and operating speed is investigated. The wear increases with the speed increasing up to 300 km/h, but stays almost constant with a further speed increase from 300 to 400 km/h.

Experimental Analysis of Rail Contact Fatigue Damage on Frog Rail of Fixed Common Crossing 1:12

Assembled fixed common crossings of the steel grade R350HT with high switch angles are subjected to quick rail contact fatigue (RCF) deterioration. The crossings are a significant cost driver in railway maintenance and have an important influence on reliability and availability in railway transportation. The present paper is devoted to the experimental study of the deterioration causes that is based on inertial and geometrical measurements on one crossing during its full lifecycle. The causes are classified into primary technical ones and secondary ones, which depend on the operational work and maintenance of track and rolling stock. The primary causes are studied using analyses of the impact position and inertial measurements on the frog nose during the crossing lifecycle, the end of which is marked by RCF defects. An application of the machine learning technique t-distributed stochastic neighbor embedding (t-SNE) allowed to determine a small cluster of high-impact loadings that correspond to the future damage zone location. The appearance of the high-impact loadings group on a certain location is explained by the secondary causes: rail and wheel wear and wheel lateral position. A multivariate kinematic modeling of wheel passages from wing to frog rail provided the wheel trajectories, impact position, and trajectory kink angle in the impact point. The distribution of the calculated impact angles along the frog rail demonstrated the presence of a small cluster of high-impact angles outside of the zone subjected to the highest number of impacts. The results of the geometrical measurements correspond to those obtained by the acceleration measurements.

Mathematical model of the formation and development of wave-shaped rail wear when an electric locomotive operates in the traction mode in tangent sections of the track

The problem of wave-shaped rail wear is highly relevant for rail transport. The paper presents a mathematical model of the formation and development of wave-shaped rail wear. The task of estimating vertical wear of the rail head under the axles of electric locomotives passing in the traction mode is considered. A technique has been developed that allows building chain of calculations that determine the formation and development of a wave-shaped rail head wear. A specific calculation example is given, illustrating the process of propagation of a wave-shaped wear from the source of its formation in the direction of train motion. An example of the calculation allows drawing the following conclusions:1. Wave-shaped wear primarily occurs when the shock interaction of the wheel of an electric locomotive moving in the traction mode and a rail thread having imperfections of the rolling surface. Such imperfections, among others, may be a joint with a significant gap or a “step down” in the direction of the locomotive, as well as a welded joint with defect 46.3-4.2. Wavelength of the wave-shaped rail wear, its configuration and amplitude of the fundamental tone are determined mainly by joint oscillations of the wheel-motor unit of the locomotive and the track infrastructure in the field of high-frequency oscillations (120 – 180 Hz).3. Multivariate calculations showed that in steady state, the distribution speed of wave-shaped rail wear in the direction of train motion (as a function of the number of axles of electric locomotives passed in traction mode) is directly proportional to the vertical load at the wheel and rail contact in the slip zone 0≤Q≤F/(2nψk), is inversely proportional to wear resistance C and significantly depends on the parameters of the undercarriage of the electric train and the track superstructure.

Numerical prediction of the development of rail wear on high-speed railways

In this paper, a numerical prediction model was established to investigate the development of rail wear on high-speed railways, and a corresponding program was written using Matlab. According to Archard’s material wear theory, the wear depth distribution in the wheel–rail contact patch and along the rail profile was calculated based on a simulation of vehicle–track dynamics and a wheel–rail rolling contact analysis. In the dynamics model, various structural components and the complex nonlinear interactions between components were precisely simulated to ensure consistency with reality. Simulations were then conducted for every possible load case, and dimensionless weight factors were introduced to model the diverse operating conditions of a high-speed railway. An adaptive step algorithm was adopted to iteratively update the rail profile and reduce cumulative deviation or errors, improving the stability and reliability of the numerical model. Finally, a case study was conducted to investigate the development of wear in different track sections on a high-speed railway using the developed model. The results indicated that in the circular curve and transition sections, the side wear of the outer rail was obvious, and the wear of the inner rail was relatively smaller and mostly distributed in the middle of the railhead. The wear of the outer rail was more severe in the circular curve section compared to that in the transition sections. The closer to the rail shoulder, the greater the difference between the wear in the circular curve section and that in the transition section. In the tangent section, the wear of both rails was similarly distributed in the middle of the railhead and far less severe than in either the circular curve or transition sections. The agreement between the calculated results and field observations verified the rationality of the established rail wear model, which shows promise for improving the maintenance planning of high-speed railways and furthering the understanding of the rail wear processes.

Wear Resistance of Rails

The operational wear of rails is analyzed and the actual wear is determined in measurements within the OAO RZhD network and in the laboratory. The wear resistance of rail steel is investigated as a function of the chemical composition and the microstructure (specifically, the dispersity). The microstructure of rail steel with different wear resistance is investigated by means of an electron microscope. Metallurgical approaches to improving the wear resistance of steel are described. Operational measures are also noted.

Optimal profile design for rail grinding based on wheel–rail contact, stability, and wear development in high-speed electric multiple units

High-speed electric multiple units have numerous advantages. However, a number of critical maintenance issues arise in the operation of high-speed electric multiple units. The previous researches about rail profile design usually take only a single type of wheel profile into account, which would cause some other problems such as severe increase of hollow wear on the wheels. This study systematically investigates the influence of rail grinding on running stability and wear development in high-speed electric multiple units and designs a new rail profile as reference for grinding that takes all types of vehicle wheels running on a specific line into account, in order to design a ground rail which could match the wheel profile and thus improve the running stability of electric multiple units. All types of wheel profiles used on the Wuhan–Guangzhou railway line are taken as the design reference. A wheel–rail wear simulation program is constructed based on CONTACT numerical simulation software and SIMPACK vehicle system dynamics software. The simulation results show that both the wheel–rail contact relationship and the running stability of high-speed electric multiple units improved after rail grinding. The results of the wheel wear analysis show that when the rail is ground to the target profile, after a running mileage of 200,000 km, the wear area of the new wheel profile LMA and the greatest hollow wear wheel profile LMA-25 decreases by 1.13 mm2 and 9.86 mm2, respectively. In addition, this method can prolong the wheel reprofiling interval. For the Wuhan–Guangzhou railway line, normally the grinding interval for the tangent track and large-radius curve is 2–3 years, and for the entering and exiting tunnel sections, the grinding interval should be set for 1–2 years, which could remove the damaged layer of the rail surface and could restore the designed profile of the rail and prolong the rail service life.

Steering Performance Evaluation of Active Steering Bogie to Reduce Wheel Wear on Test Line

When a railway vehicle runs on a curved section, wear of wheels and rails occur. This is due to the attack angle of the wheel on the rails that occurs because the steering function of the bogie is insufficient. To overcome these problems, we developed an active steering bogie equipped with an electro-mechanical type of active steering system. The prototype of active steering bogie was manufactured and installed on a test train that operated in sections with many curved sections. Steering performance tests for the test train were carried out on commercial line as the test line. As a result of the test, the performance of curvature radius estimation of the active steering bogie showed a very good performance, with only 2.4% error compared with the track design value. The performance of steering angle implementation of the passive bogie running on the curved section is very poor, but that of the active steering bogie is very good. And the lateral force of the wheel, which is directly related to the wheel wear when running on the curved section, showed a maximum 88.1% reduction of the lateral force. Therefore, considering the test results of the active steering bogie in the test line, the steering performance of the active steering bogie developed for reducing the wheel and rail wear is evaluated to be very good. And the wear of wheel measured after test run was 0.54 mm flange wear in passive bogie, but flange wear was not occurred in active steering bogie.

Влияние конструктивных особенностей тележек моделей 18-4129 и 18-9817 с осевой нагрузкой 25 тс на динамические показатели грузовых вагонов

The performance of the wagons is directly related to the carrying capacity, which depends primarily on the permissible axial load. In this regard, the choice of the maximum permissible axial load is the most important factor determining the technical and economic characteristics of the wagons being designed. The issue of the permissible axial load has been discussed for many decades. To solve this task, an integrated approach is needed, associated both with improved riding quality of wagons and completion of track preparation and fixed track structures for handling freight trains with axial loads of 25 ton-force. The most innovative are the bogies of models 18-4129 and 18-9817, resulting from the modification of bogie 18-100. Bogie model 18-9817 is a joint development of the American company ASF Keystone and the Ukrainian Industrial and Investment Group InterCarGroup. Bogie design took advantages of structural solutions and technologies used in Motion Control bogie model, which is successfully in service on the railways of the United States and Canada. AdapterPlus adapters with a polymeric gasket are installed in the axlebox of the side frame. The use of this adapter will reduce wheel and rail wear . Bogie model 18-4129 was constructed by Sophia Invest LLC (Ukraine). The frame of the bogie is made of an open structure. Scheffel diagonal braces are used to reduce the lozenging of bogie side frames, reducing the wheel run-up angle on the rails and, consequently, the wear intensity of wheelset flange. Air-spring suspension in a bogie model 18-4129 is a central single-stage with friction wedge-type vibration dampers. The comparative analysis of the study results showed that the dynamic characteristics of the car on bogies 18-4129 and 18-9817 are generally higher than the dynamic parameters of the bogie 18-100; the best values are the coefficient of the vertical body dynamics and unsprung parts of the car in the bogie 18-9817; bogies 18-4129 showed the best value of the coefficient of horizontal dynamics of the body, as well as the frame forces; the acceleration of the car body in the vertical plane is approximately the samefor bogies 18-9817 and 18-4129, and the acceleration in the horizontal plane is less in the bogie 18-4129 with the exception of speeds over 100 km/h; the best value of the stability factor of the wheel against derailment in the loaded mode is for the bogie 18-4129 in the entire range of speeds, and in the empty state for speeds less than 90 km/h.

Measurements of transverse section wear of rails in tracks of tram-loop

In article the problems of classical methods of transverse section wear of rails replacement with new techniques based on electronic devices was concerned. Reasons of rails shape section changes were defined. Principles of rails waste inspection resulting from regulations were reminded. Review of practical measurement methods and devices were made. Shapes of nominal sections of rails used in tram tracks were analyzed. Realization of measurements executed with mechanical-electronic profile gauge and mechanical track gauge on tram-loop Sępolno in Wrocław were described. Proposal of graphic manner analysis of rail wear measurements in connection with track width measurements were proposed. In summary conclusions from effected investigations were formulated.

Numerical Analysis of Rail Wear Behavior in Railway Systems

Numerical Analysis of Rail Wear Behavior in Railway Systems

Assessment of non-Hertzian wheel-rail contact models for numerical simulation of rail damages in switch panel of railway turnout

Rail damages in railway turnout switch panels are closely related to the complicated wheel-rail contact conditions in the turnouts. In order to assess the applicability of different non-Hertzian contact models for simulating rail damages in railway turnout switch panel, three engineering approaches, i.e. Kik-Piotrowski, Ayasse-Chollet and Sichani, are adopted to simulate rail wear and surface initiated rolling contact fatigue (RCF) damages by studying a Chinese CN60-1100-1:18 high-speed turnout switch panel. A comparison is then carried out taking into account the results calculated by Kalker’s three-dimensional (3D) theory and an elastic-plastic FEM (Finite Element Method) model. The analyzed results show that the computational efficiencies of the three engineering approaches are all quite high for simulating rail damages in switch panel. Under elastic conditions, the calculation accuracy of the Sichani approach is found to be the highest, meaning that this would appear to be the preferred method for simulating rail damages in railway turnout switch panel. The research findings can be taken as theoretical guidance for selecting wheel-rail contact models and analyzing these types of damages in railway turnout switch panels.

Investigation of the influence of rail hardness on the wear of rail and wheel materials under dry conditions (ICRI wear mapping project)

Some railway managers and practitioners fear that introducing premium rail materials will have a detrimental effect on the wheels of trains that use the line. A review of relevant investigations across all scales in the laboratory, and in the field has been carried out. This showed that, as rail hardness increases, its wear, and overall system wear reduces. Wheel wear does increase with increasing rail hardness, but only for wheels running on rails that are softer than them. Similar trends were observed in all studies, so it seems that the fears were unfounded.While the wear trends appear well characterised some issues have been identified. One relates to the varying work hardening capability of wheel and rail materials. Often only bulk hardness is quoted, but work hardening can increase material surface hardness by up to 2.5 times and make materials that were initially softer, harder than the opposing material. Another related issue is test length. It is essential that enough cycles are applied such that the materials reach steady state wear, i.e., the point at which work hardening has reached its limit. In previous work it is not always clear that steady state wear has been reached. Some gaps have been identified in the current knowledge base, the largest of which is the failure to determine which mechanisms lead to the wear trends seen.Analysis of recent work on different clad layers on rail discs and premium rail materials allowed some of these gaps to be addressed. Results indicated that opposing wheel material hardened to the same level independent of rail hardness. Wheel wear is therefore stress driven under the conditions used, and dictated by the wheel material properties only. At higher slip levels relationships become less clear, but here temperature and therefore hot hardness is most influential and is as yet uncharacterised.

Root‐cause analysis of wear‐induced error motion changes of machine tool linear axes

Manufacturers need online methods that give up-to-date information of system capabilities to know and predict the performance of their machine tools. Use of an inertial measurement unit (IMU) is attractive for on-machine condition monitoring, so methods based on spatial filters were developed to determine rail wear conditions of linear guideways of a carriage from its IMU-based error motion. Rail wear-induced changes in translational and angular error motions as small as 1.5 μm and 3.0 microradians, respectively, could be resolved. A corresponding two-part root-cause analysis procedure was developed to determine the rail locations of error motion degradation as well as the most probable physical location of damage that causes the detected error motion changes. Another analysis method determined the root cause of non-localized damage along each rail. These approaches support the development of smart machine tools that provide actionable intelligence to manufacturers for early warnings of system degradation.

Modelling car motion and the calculation of the wear of wheels with the VNITsTT rolling surface profile

The wear problem of wheels along rolling surface or thin flange is currently involved a large circle of specialists. There are opinions that it is necessary to establish new limit values for wheel wear in operation, put into practice the re-profiling (profile grin ding) of rails, install a larger number of floor-mounted lubricators in places of increased rail wear intensity, but one of the priority direction in this area is the development of a new surface rolling wheel profile for freight cars, the use of which will help to increase the turnaround time and increase the service life of the wheels in operation. Geometry of the rolling surface profile of the wheel should allow to provide a contact form between the wheel and the rail conformal or close to conformal. This solution has already found its application and achieved desired results on foreign railways (North America, South Africa, China, etc.). Authors developed a technique for designing a new wheel profile, which was used to build a profile of the rolling surface made by the Russian Research Center for Transport Technologies (LLC “VNITsTT”). As part of the study, calculations were carried out using the method of mathematical modeling of a freight car motion in the MEDYNA software package and performance indicators were evaluated on the VNITsTT rolling surface profile in comparison with the profile made according to GOST 10791 – 2011, and the wheel wear rate produced on the section of the track close to the average network operating conditions. Additionally, critical speed of the sinuous motion of the car was evaluated, which showed that despite the increased equivalent taper, the critical speed remained almost unchanged (an increase of 6 %). Theoretical calculation of the wheel resource based on the results of mathematical modeling has been made. According to the calculations, it was determined that the resource of the flange before turning for the RDCTT profile is 409.3 thousand km, and for the rolling surface — 663.3 thousand km, for the profile made according to GOST 10791 – 2011, the resource for the flange was 285.6 thousand km, and for the rolling surface 401.2 thousand km. Thus, the use of the VNITsTT profile is more effective than the profile made according to GOST 10791 – 2011 by 30.2 % for the flange and 39.5 % for the rolling surface. The developed VNITsTT profile, in comparison with the profile made by GOST 10791 – 2011, according to the results of calculations, confirmed the provision of standard indicators of the dynamic qualities of a freight car.

Assessing the fast non-Hertzian methods based on the simulation of wheel–rail rolling contact and wear distribution

This paper aims at assessing several fast non-Hertzian methods, coupled with two wear models, based on the wheel–rail rolling contact and wear prediction. Four contact models, namely Kik-Piotrowski's method, Linder's method, Ayasse-Chollet's STRIPES algorithm and Sichani's ANALYN algorithm are employed for comparing the normal contact. For their tangential modelling, two tangential algorithms, i.e. FASTSIM and FaStrip, are used. Two commonly used wear models, namely the Archard (extended at the KTH Royal Institute of Technology) and USFD (developed by the University of Sheffield based on T-gamma approach), are further utilized for wear distribution computation. All results predicted by the fast non-Hertzian methods are evaluated against the results of Kalker's CONTACT code using penetration as the input. Since the two wear models adopt different expressions for calculating the wear performance, the attention of this paper is on assessing which one is more suitable for the fast non-Hertzian methods to utilize. The comparison shows that the combination of the USFD wear model with any of the fast non-Hertzian methods agrees better with CONTACT+USFD. In general, ANALYN+FaStrip is the best solution for the simulation of the wheel–rail rolling contact, while STRIPES+FASTSIM can provide better accuracy for the maximum wear depth prediction using the USFD wear model.

Numerical Analysis on the Transient Inductance Gradient of the Resistive Overlay Rail on the Sliding Electrical Contact

A resistive overlay rail for an electromagnetic launcher was tested and its inductance gradients were analyzed using 2-D and 3-D finite-element methods (FEMs). The overlay rail was consisted with outside copper rail for good conduction of current and inside steel one for the prevention of rail wear. When the armature slides along the steel rail, electrical current flows mainly through the copper rail before it reaches the armature tail and it penetrates the steel rail at the armature tail due to the velocity skin effect. The rail inductance gradient $L^{\prime }_{R}$ is obtained with 2-D FEM in both frequency and time domains without an armature and the propulsive inductance gradient $L^{\prime }_{P}$ are obtained with 3-D transient FEM with a moving armature. A C-shaped aluminum armature was launched with the velocity over 2 km/s on the resistive overlay rail and gouging was not induced, while it appeared in the experiment with a copper rail. Using the two obtained inductance gradients, the circuit simulation was conducted and it explains the experiment result with a good agreement.

A Wear Detection Parameter for the Wheel–Rail Contact Based on Emitted Noise

This article describes how a wheel–rail wear detection parameter based on noise was developed by running a rapid transit train instrumented with microphones in a depot with a small curve radius. This full-scale test made use of previous knowledge gained from lab-scale tests. The lab- and full-scale tests showed that noise could be used as an indicator of wear transition, when normal wear turns into severe or catastrophic wear. This transition was accompanied by a significant increase in sound pressure and a broader sound pressure amplitude spectrum; that is, a narrow initial amplitude distribution in the normal wear regime and a broader distribution in the severe wear regime. The measured noise from the inner/low and outer/high rails was analyzed in conjunction with the wear from the outer wheel and comparisons were made between cleaned (exposed to severe wear) and lubricated (no wear) rail. Based on those analyses, a wear detection parameter criterion was developed for this specific train. This wear parameter has been implemented in a real-time condition monitoring system so that warnings of the risk for severe wear could be sent to the maintenance department. Validation of the wear parameter and challenges linked to open system conditions are discussed in this article.

Effects of Laser Cladding for Repairing and Improving Wear of Rails

Laser cladding has been applied to reduce the wear on rails in a curved track. It is important to evaluate the wear and rolling contact fatigue (RCF) characteristics of laser cladding rails. This paper evaluated the wear characteristics of three types of laser cladding, i.e., Stellite 21, Inconel 625, and Hastelloy-C. The wear of Stellite 21 was reduced by 83% as compared to the untreated rail specimen, while those of Inconel 625 and Hastelloy C were decreased by 42% and 29%, respectively. Meanwhile, when laser cladding is applied, a cladding boundary between the rail and the laser cladding is created. The cladding boundary consists of the rail base material, the heat-affected zone, and laser cladding. At the cladding boundary, various types of microstructures are distributed, and as a result the hardness changes. The wear and RCF characteristics of the cladding boundary caused by rolling contact loads have been evaluated through twin-disc tests. Since Stellite 21 has low hardness at the cladding boundary, it suffered the most severe wear and damages in three types of laser cladding. If laser cladding is applied to reduce the wear of the curved track, the damage of the boundary, as opposed to the wear characteristics, should be taken into consideration. In this paper, Stellite 21 exhibits the best wear characteristics, but Hastelloy C is found to be the most appropriate when simultaneously considering both the wear and RCF of the cladding boundary.

Wheel–rail low adhesion issues and its effect on wheel–rail material damage at high speed under different interfacial contaminations

The objective of this paper is to ascertain the wheel–rail low adhesion mechanism using a high-speed wheel–rail rolling contact test rig under different interfacial contaminations. Based on the experimental results, a numerical method was proposed to investigate the wheel–rail wear and rolling contact fatigue due to low adhesion issues. The experimental results indicated that the wheel–rail low adhesion phenomena can happen under interfacial liquid contaminations, especially at high-speed running condition. Preliminary numerical investigations showed that the low adhesion condition can easily lead to sliding hence serious wear, especially at the speed between 160 km/h and 200 km/h. The temperature rise within the contact patch can be significantly more severe once wheel and rail are in full slip, causing rolling contact fatigue due to material softening.