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Railway systems play a pivotal role in modern transportation networks, contributing to both efficiency and environmental sustainability. This study investigated the multifaceted aspects of wear phenomena in railway engineering, focusing on their significant implications for environmental costs and operational efficiency. Experimental trials were conducted using a high-performance bi-disc apparatus, evaluating a range of materials, contact pressures, and lubrication conditions. Shakedown maps were employed to assess ratcheting behaviour, while the wear rate was analysed as a function of the fatigue index (FI). The results reveal the intricate interplay of contact pressure, slip ratio, material properties, and lubrication in determining wear and ratcheting behaviour. Oxidative and mild wear mechanisms were identified, and wear debris composition and morphology were characterised. The outcomes from this research clarify the pivotal role that wear processes play within railway systems and the far-reaching environmental repercussions they entail. This exploration contributes to the ongoing optimisation of railway operations, offering valuable insights aimed at mitigating unavoidable pollution sources and strengthening sustainability efforts. By delving into the intricate dynamics of wear phenomena within wheel–rail material, this research paves the way for innovative solutions that not only enhance operational efficiency but also minimise the ecological footprint of railway transportation. [ABSTRACT FROM AUTHOR]

When high-speed trains operate under braking conditions, the wheel-rail interaction increases significantly, which can lead to more serious wear problems. To analyze the evolution of wheel wear and the dynamic characteristics of wheel-rail under braking conditions, this paper first carries out long-term monitoring of the service state of wheel-rail during the operation period. The study analyzed the matching characteristics of the measured wheel-rail profile and calibrated the wear model by using the collected data. The resulting wear prediction model was then used to examine the wheel wear characteristics under braking conditions. The research results indicate that during the operation period, the wheel experiences tread concave wear within a range of ±20 mm of the rolling circle, at a rate of approximately 0.05 mm per 10,000 km. Meanwhile, the rail experiences top surface wear at a natural rate of about 0.09 mm per year. Concave wear causes the contact point of the wheel-rail to appear in two zones, resulting in a sudden change of contact geometric parameters. The concave worn wheel and rail with a 60 N profile have better matching compared to the 60 rail profile. Increasing the braking torque and wheel-rail friction coefficient will significantly increase the wheel wear depth on straight sections. On small-radius curve sections, rail side lubrication can significantly reduce high rail side wheel flange wear. A worn concave wheel can lead to unfavorable wheel-rail contact geometry characteristics and increase low-frequency components in the vehicle's lateral dynamic response. [ABSTRACT FROM AUTHOR]

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Urban rail transit usually contains many small radius curved tracks, and wheel flange wear is prominent, which greatly reduces the service life and increases the maintenance and replacement costs of wheelsets. Two metro lines in Shanghai of China had suffered from severe flange wear since 2017, and the flange wear rate increased gradually over the next three years. This paper presents the understanding and treatment of severe flange wear through field measurement and numerical simulation. The investigation results indicated that the key factors causing severe flange wear were poor rail gauge face lubrication, the use of a low conicity wheel profile for trains running on the two metro lines containing many small radius curved tracks, and the lack of timely maintenance of low rail profiles. Three countermeasures were proposed to mitigate wheel flange wear, which were evaluated through wheel–rail matching analysis and wheel wear prediction. Then, two countermeasures, i.e. improving rail gauge face lubrication and employing the LM-30 wheel profile, were verified through field tests. [ABSTRACT FROM AUTHOR]

Rail wear occurs continuously owing to the rolling contact load of trains and is fundamental for railway operational safety. A point‐based manual rail wear inspection cannot satisfy the increasing demand for rapid, low‐cost, and continuous monitoring. This paper proposes a depth‐plus‐region fusion network for detecting rail wear on a running band, which is a collection of wheel–rail interaction traces. The following steps are involved in the proposed method. (i) A depth map estimated by a modified MiDaS model is utilized as guidance for exploiting the depth information of the running band for rail wear detection. (ii) The running band of a rail is segmented and extracted from images using an improved mask region‐based convolutional neural network that uses the scale and ratio information to perform instance segmentation of the running band images. (iii) A two‐channel attention–fusion network that classifies rail wear is constructed. In this study, we collected real‐world running band images and rail wear‐related data to validate our approach using a high‐accuracy rail‐profile measurement tool. The case‐study results demonstrated that the proposed method can rapidly and accurately detect rail wear under different ambient light conditions. Moreover, the recall rate of severe wear detection was 84.21%. [ABSTRACT FROM AUTHOR]

Rail corrugation is very serious in Cologne egg fastener track; effective control measures are still lacking. The cause of the corrugation wear on a curved metro track is analyzed based on the friction-induced vibration theory. A finite element model is established to study the frequency domain and time domain features of the friction-induced oscillation of this system. The influences of the fastener spacing and the fastener support length on the corrugation wear are investigated to develop countermeasures. The simulation results show that the friction-induced vibration of the wheel-track system is the wavelength-fixed mechanism of the corrugation wear of rail of the curved Cologne egg fastener track. There are two reasons why the low rail corrugation wear is more serious. The contact resultant force between the low rail and the wheel is obviously bigger than that between the wheel and the high rail, resulting in a higher wear rate of the low rail. The contact force fluctuation of the low rail caused by the friction-induced vibration is more severe, resulting in a higher corrugation wear evolution speed on the low rail. The friction-induced oscillation cannot be eliminated only by adjusting the fastener support length and spacing. However, the long-wavelength corrugation wear instead of the more harmful short-wavelength corrugation wear can be produced by adjusting the fastener support length and the fastener spacing to alleviate the influence of corrugation wear on the vehicle-track system. [ABSTRACT FROM AUTHOR]

Polygonal wear is a type of damage commonly observed on the railway wheel tread. It induces wheel-rail impacts and consequent train/track components failure. This study presents a finite element (FE) thermomechanical wheel-rail contact model, which is able to cope with the three possible generation and development mechanisms of polygonal wear: initial defects, thermal effect, and structural dynamics. The polygonal wear-induced impact contact and further development of wear are simulated. The simulated elastic contact solutions are verified against the program CONTACT. Different material properties (elastic, elasto-plastic and elasto-plastic-thermo, i.e. with thermal softening) and initial polygonal profiles are then applied to the FE model to investigate the influence of wheel/rail material and wear amplitude on wheel-rail contact stress and wear development. The simulations indicate that the wheel-rail impact-induced temperature may reach up to 362 ℃ at the contact interface, and the high temperature at the contact area influences wheel-rail contact stress and wear depth. • An innovative thermomechanical FE model is presented to study polygonal wear growth. • The simulated contact solutions are verified against the program CONTACT. • Using elastic material models causes overestimation of contact stress and wear depth. • Incorporating thermal effects is crucial for wear predication with high slip ratio. • The simulated contact temperature reaches up to 362 ℃ at the wheel-rail interface. [ABSTRACT FROM AUTHOR]

Metro trains often encounter the problem of wheel flange wear when they pass through sharp curves, especially for the poor wheel–rail profile matching or lack of lubrication, evidently increasing the maintenance and replacement costs for wheelsets and rails. Based on the field investigation and numerical simulation, the cause of severe flange wear of the original S1002 wheel profile on a Chinese metro line is analysed. An optimised wheel profile is proposed according to the rolling radius difference (RRD) for improving vehicle curving performance and mitigating wheel flange wear. A wheel wear prediction model is developed by combining the metro vehicle dynamics model considering multipoint contact with the long-term wear simulation model, and then validated with the field measurement results. The performance of the optimised wheel profile is evaluated numerically. The results indicate that the root cause of the wheel flange wear is the improper matching of wheel and rail profiles. The optimised wheel profile generally proves to perform better in terms of wheel–rail contact geometry, mechanical properties, vehicle running stability, curving negotiation and wear performance. The wheel flange thickness loss of the optimised wheel profile is decreased by 55.7% compared with that of S1002 profile. [ABSTRACT FROM AUTHOR]

Track–vehicle severe interaction on track with small curve radius results in rail wear and corrugation, and wheel polygonization, which drain considerable resources for rail grinding and wheels re-profiling in metro lines. To reduce the damage caused by track-vehicle severe interaction, the paper analyzes the reasons leading to rail wear and then proposes an architecture of a metro vehicle with independently rotating wheels driven directly by permanent magnet synchronous motors. The architecture is axle guidance, offered by passive linkages, which ensures that all axles are oriented radially, while control strategy was kept as simple as possible, identifying only two basic traction conditions. The concept is first discussed and then validated through a comprehensive set of running dynamics simulation performed with a multibody software to evaluate rail wear and rolling contact fatigue in traction/braking, coasting with different cant deficiency/excess conditions. The multibody dynamics simulation shows that the proposed architecture is virtually capable of avoiding both wear and rolling contact fatigue damages, and achieves the highest possible track friendliness. The concept of the proposed architecture is a track-fiendly metro architecture and could be a good reference for reducing rail-track interaction damages and maintainace cost. [ABSTRACT FROM AUTHOR]

Wear and Rolling Contact Fatigue (RCF) on wheels and rails are influenced by relative motions between the studied rail and wheel pair, and therefore influenced by train dynamics. Wear and RCF assessments using a train dynamics approach provide more accurate and comprehensive results comparing with conventional assessments that often do not consider train dynamics. In addition, considering material property differences, currently available rail wear maps are not able to accurately describe the wear performance of materials that have significantly different properties. This paper presented a method for rail/wheel wear and RCF assessments using 3D train dynamics models. The use of train models allows the consideration of coupler forces, traction, and brakes during the assessment. Wear assessments were conducted by using an in-house rail wear map model developed from the twin disc wear machine at the Centre for Railway Engineering (CRE). The new rail wear map was developed by using the AS 60 rail material (hardness 340 HB). The results indicated that the methods proposed in this paper could be used for rail/wheel wear and RCF assessments. Traction/braking forces and coupler lateral forces had evident influences on wear and RCF assessment. Different wear maps were also shown to have significant influences on the wear rate results. • A more comprehensive method to assess wheel-rail wear and RCF. • A new wear map for the AS 60 rail material. • Evidence of influences of traction/brake, coupler forces, and wear maps for wear and RCF assessment. [ABSTRACT FROM AUTHOR]

• The model can account for the non-linear lifting of the flange groove and the effects of wheelset traverse and side roll. • The wheel tread and flange are alternately loaded with two wheel load transition areas in the frog area. • Wear in the flange bearing area is significantly higher than in the tread bearing area, with an increase of 59.7%. • RCF damage dominates in the wing rail and the two wheelload transition areas. • Reducing the speed to 15 km/h significantly improves the service performance of the fixed frog. The tram No. 3 turnout fixed frog uses a variation in the depth of the flange groove so that the wheel rolls over the frog area in a continuous flange bearing. This method of travelling over the turnout requires the wheel load to transition back and forth between the tread and the flange, resulting in wheel-rail impact, which in turn affects service life. In order to investigate its service characteristics, this paper has established a transient wheel-rail rolling contact finite element model for the No. 3 turnout fixed frog. The macroscopic dynamic response and microscopic wheel-rail contact solution as the tram passes through the turnout at different axle weights and speeds are analysed in detail, and the changing patterns of wear and fatigue damage are investigated. The research shows that rail wear is particularly severe in the wheel flange bearing area, approximately 1.6 times greater than in the tread bearing area. In addition, when tram speeds are reduced to 15 km/h, there is a significant reduction in wheel-rail impact and wear, thereby improving ride smoothness and safety. The results of this study are of great significance to the operation and maintenance of the No.3 fixed frog turnout. [ABSTRACT FROM AUTHOR]

The worn status of wheel/rail profiles could change the wheel-rail contact and influence the wear rates of the wheel and rail. Worn wheel profiles of a Chinese intercity train and the worn rail profile of curved tracks were taken into account in this work. According to the dynamics model of the vehicle, teh wheel-rail three-dimensional steady-state rolling contact model, and the Archard wear model, a new fast calculation method of wheel wear rate was proposed. Simulation results show that obviously severe wear would distribute in the flange when the wheel and rail were worn. The side wear of rail gauge corner will seriously aggravate the wear of new wheel flange. The wear of the wheel is serious for teh worn wheel in the initial phase of service. Therefore, the re-profiling of wheels and rails should be scheduled cooperatively, and the wear of flange in the initial phase of service should addressed. [ABSTRACT FROM AUTHOR]

Nonlocal peridynamic (PD) theory is widely used in damage and thermomechanical coupling simulations. This study applied ordinary state-based PD thermomechanics to model the wheel-rail contact bringing temperature-dependent materials. A two-dimensional coupled thermomechanical model was developed to predict the evolution of the thermomechanical response, thermal damage, and wear in railway rail. The model was verified based on the displacement and temperature fields of the rail. The model results correlated well with the finite element model and analytical method results. The influence of the vehicle speed, rail surface cracks, and wheel idling on the thermomechanical response of the rail was also evaluated in detail. The results show that the influence of the vehicle speed on the temperature field is much greater than that of the contact stress. The contact temperature under the critical creepage could lead to the formation of a brittle white etching layer (WEL). Cracks on the rail surface increased the contact stress and temperature peaks. Thermomechanical loading also promoted rail surface damage. Continuous thermomechanical loading due to wheel idling softened and removed rail surface materials, forming wear pits and a WEL, known as wheel burns. • A 2D thermomechanical coupled PD model of the wheel-rail sliding contact is established. • A novel and concise wear prediction method is provided based on the PD damage model. • The interaction of rail surface cracks and contact thermomechanical loads is studied. • Rail wear and WEL formation (wheel burns) during wheel idling are explored. [ABSTRACT FROM AUTHOR]

A model which can predict the length of the surface crack and crack depth in rails was developed in a previous study by the authors B. Dirks, R. Enblom, A. Ekberg, M. Berg (2015) [1] . In the present study, verification of this crack prediction model in combination with a wear prediction model was done against wheel measurements. For a period of 15 months, the wheels of three units of a Stockholm commuter train were measured with respect to wear and crack development for verification of the wheel life prediction tool. Vehicle–track dynamics simulations were used to calculate the forces and contact positions for the wear and crack prediction models. It can be concluded that the wear prediction model gives reasonable results, especially considering the large scatter in the wheel profile measurements. Although the wheel life prediction tool could not be verified, since the crack prediction model had to be recalibrated for the current wheel application, the results appear promising. [ABSTRACT FROM AUTHOR]

The objective of this study is to evaluate the effect of slip ratio on the wear and rolling contact fatigue (RCF) of wheel/rail materials using a rolling–sliding wear testing apparatus. The results indicate that two wear types are presented in terms of wear rate: type I (mild wear) and type II (severe wear). In type I wear, cracks propagate parallel to the surface. While in type II, the peeling is aggravated and spalling can be observed. With the slip ratio increasing, the wear mechanism of rollers transforms from slight oxidation wear and peeling to severe fatigue wear and spalling. Due to the mild wear and light plastic deformation in type I, the angle and depth of cracks show no obvious differences between the wheel and rail rollers. The crack depth and angle increase in type II wear owing to severe plastic deformation, while the depth is smaller on the wheel rollers. The size of flake wear debris presents an increasing trend and the main composition is Fe 2 O 3 and metallic iron, and the content of iron diminishes with increasing oxidation. [ABSTRACT FROM AUTHOR]

Rolling contact fatigue (RCF) and wear are competing phenomena in railway wheels, but they are typically studied as independent events. In this work, preliminary tests are carried out with a twin-disc bench to explore the relationship between RCF and wear. First, the collected tests are reported on the shakedown maps to assess the cyclic response and calculate the fatigue index parameter used to predict the surface-initiated fatigue damage. Second, the fatigue index and material cyclic yield strength are related to the experimental wear rate. This work proposes maps to predict how the wear rate and cyclic response change by varying the contact conditions (clean or contaminated with water or sand), slip ratio and extraction position of specimens. Furthermore, the estimated wear rate is superimposed to the shakedown map to investigate a possible relationship between RCF and wear. The proposed approach allows to understand how a railway wheel steel behaves as a function of the working conditions and whether some working parameters can be changed without compromising the material performance. • Predictive maps for bi-disc tests are proposed. • Wear rate is superimposed to shakedown maps. • A higher fatigue index results in a higher wear rate. • Water contaminant drastically reduces the wear rate. • Reprofile operations increase the fatigue index and wear in clean contact. [ABSTRACT FROM AUTHOR]

There is an increased demand for railway services, which has resulted in an increase in speeds and axle loads. The increase in axle loads and speeds have resulted in an increase in severity of wheel and rail wear. The aim of this work was to investigate wear and rolling contact fatigue (RCF) performance of class B wheels against R350HT and R260 rail under different slip ratio using a twin-disc setup. The results showed that severity of wear was heavily dependent on slip ratio. It was found that class B wheels' wear rate was better against R260 rail than against R350HT rail. Three wear regimes were identified from plots of wear rate versus wear index (Tγ/A) being mild, severe and catastrophic. • Wear performance of class B wheel against R260 and R350HT rail steels was investigated across different slip ratios. • Slip ratio influences coefficient of friction, wear rate and depth of plastic deformation on both wheel and rail steels. • Three wear regimes were identified being mild, severe, and catastrophic [ABSTRACT FROM AUTHOR]

• Rail and wheel materials from different standards were tested. • Wear maps of different standards were displayed. • In this study, the sliding speed is the most influencing parameter. Wheel and rail materials are exposed to a large number of factors that affect their wear-resistant performance such as, large contact pressures, sliding speeds, high temperatures, material degradation by natural and artificial contaminants, etc. This directly affects the maintenance operations, so, an accurate wear prediction is required. Wear maps are an important tool to predict and identify wear regimes that impact maintenance schedules and consequently cost reduction. This work aimed to develop wear maps for a 115RE rail material and an ER8 wheel material, which are materials used in railways systems in Mexico, as well as identify the wear regimes and wear mechanisms replicating the wheel-rail interface conditions. Metallographic analysis and hardness tests were carried out for both materials. Wear tests were carried out by using a pin-on-disk tribometer. The resulting wear maps showed that a catastrophic wear regime occurs at medium sliding speed and low contact pressure values for the wheel. On the other hand, for rail, catastrophic wear regime occurs at high sliding speed and low contact pressure values. [ABSTRACT FROM AUTHOR]

The simultaneous prediction of wheel surface wear is one of the most challenging tasks in the railway field, which requires the knowledge of vehicle–track dynamics, rolling contact mechanics, and other tribological phenomena. In this paper, a new model for predicting wheel profile wear is presented to study in detail the characteristics of wear in the railway. The model is able to consider the effect of track flexibility on wheel wear evolution. The proposed modelling approach includes a vehicle–track coupled model for vehicle dynamical simulation, the local contact model for wheel–rail interaction, and an energetic approach for surface wear evaluation. The whole model has been validated by the comparison with experimental data coming from Chinese high-speed railway lines. The results show that the new model assures high computational efficiency as well as reaches a good prediction accuracy. The proposed model allows the investigation of the role played by different track parameters related to track flexibility on the wheel and rail wear evolution. The influence of the fastener and railpad stiffness on the wheel wear evolution is presented, using the proposed model. • A wear prediction model applied for predicting wheel evolution in high speed railway. • The model enables the consideration of track flexibility, through a vehicle–track coupled model for dynamics simulation. • Validation of the numerical model is obtained by comparison with measured results. • The influence of the fastener and railpad stiffness on the wheel wear evolution is presented. [ABSTRACT FROM AUTHOR]

The effects of the brake force, normal load, and carbon content on friction, wear, and spalling behaviours of the wheel steel are investigated in detail in rolling–sliding contact, using a new rolling testing apparatus developed on a tension–compression hydraulic machine with a high precision. Wear scars are examined and analysed by various microscopic examinations. The results show that the friction coefficient of the wheel steel increases and the wear mechanisms would change with increasing brake force. Furthermore, an increase in the brake force and normal load would cause an increase in the wear depth of the wheel steel and aggravate the spalling damage on the wear surface. The hardness, wear, and spalling behaviours of the wheel steel depend strongly on the carbon content of the material. Decreasing carbon content of the wheel steel may alleviate spalling damage evidently, but would rapidly increase the wear depth of the specimen. [ABSTRACT FROM AUTHOR]