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Two types of high power alternating current (AC) locomotive in China are prone to serious high-order polygonal wear, which has significant negative effects on the operation of locomotives. This study investigates factors influencing polygonal wear in locomotive wheels and determines methods of minimizing operation damage. We designed experiments to analyze the process of polygonization formation of wheels to identify the key influencing factors, finding that natural vibration of wheelsets is the central inherent factor of wheel polygonization and that these vibrations can be easily stimulated by wheel or rail irregularities. We found that poor re-profiling quality is the key external factor in these irregularities. The wheelset bending resonance is activated when the remaining wheel polygonal wear has a wavelength of 200 mm in the 1/3 octave band, in turn leading to significant increases of wheel polygonal wear. In this study, we review a new wheelset design that can mitigate and/or eliminate the polygonal wheel wear due to increased stiffness in wheel bending. We evaluate the potential capacity of the newly designed wheelset and propose two proven effective measures to further improve the wheel re-profiling quality for polygonal wear.

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 t...

High-order polygonal wear wheels have been detected on metro express train operating on one metro line in China, which cause fatigue failures of steel coil springs in the primary suspension. A seri...

Discrete irregularities are a common issue occurring on locomotive wheels. The wheel roughness measured in the field sites indicates that some wheels suffer from discrete wheel irregularities, such...

Affected by the traction/braking, creep control and wheel-rail interface environment, wheel wear of locomotives is more complicated than that of other rolling stock. A locomotive wheel wear simulation model is developed, which includes a 3D locomotive track coupling dynamics model, a rolling contact model for rail traction vehicles based on Kalker's simplified theory, a PI-based creep control model and a wheel material wear model based on frictional power. The advantages of the dynamics model built in this paper are evaluated through two typical simulation cases. The effects of traction/braking and creep control on wheel wear are comprehensively investigated. The results indicate that the natural vibration characteristics of the locomotive/track system can be well reflected, and their influence on wheel wear can be taken into account. Traction and braking have a great influence on wheel wear, which should be considered for locomotive wheel wear simulation. It is a better way to control creep by using a control mode with variable creep threshold value.

Wheel flange wear often occurs on metro trains when they negotiate sharp curves, especially for the poor matching of wheel and rail profiles or lack of lubrication, which evidently increases the maintenance and replacement costs of the wheelsets and rails. The reason for severe flange wear of the original wheel profile on one metro line in China is investigated through field experiments and numerical simulations. An optimal wheel profile is presented based on the rolling radius difference (RRD) to improve curving performance of the vehicle and mitigate flange wear. A wheel wear prediction model, coupling a metro vehicle dynamics model considering multipoint contact with a long-term wear simulation model, is developed, which is validated using field measurement results. The capability of the optimal wheel profile is numerically evaluated. The results show that the improper wheel-rail profile matching of the original wheel profile is responsible for wheel flange wear. The large proportion of sharp curves and the abnormal rail cant also contribute to flange wear. The optimal wheel profile proves to work fine in terms of wheel/rail contact geometry and wear performance. The wheel flange wear of the optimal wheel profile is decreased by over 60% compared with that of S1002 profile.

Wheel polygonisation is a wavy wear on wheel’s circumference, which aggravates the wheel-rail interaction and prematurely invalidates or damages the components of vehicle-track system. This paper presents an investigation into the formation mechanism of high-order polygonal wear of metro train wheels through field experiments and numerical simulations. Some necessary field experiments are conducted to obtain the characteristics of the irregular wear of the wheels and the dynamics responses of the vehicle components. The numerical modal analysis of vehicle’s key components is performed. Furthermore, a long-term wheel wear model is built including a vehicle-track dynamics model coupled with a local wear model. The metro vehicle-track coupled dynamics model considers the flexibilities of the wheelset and track, where the wheelset and track are modelled using finite element method. The effects of elastic deformation of the wheelsets and rails on creepages, creep forces and wheel wear can be considered in the model. The investigation results indicate that the dominating order of wheel polygonal wear is 11–16, corresponding to wavelengths of 165–240 mm. The formation mechanism of high-order wheel polygonal wear is the P2 resonance of some types of track structure, and the first bending resonance of the wheelset can accelerate the development of wheel polygonal wear.

The objective of this study is to develop a new online model for wheel wear that takes into account the track flexibility. The proposed model consists of two parts that interact with each other, namely, (a) a locomotive/track coupled dynamics model considering the track flexibility, which is validated by field measurement results, and (b) a model for the wear estimation. The wheel wear prediction model can be employed in online solutions rather than in post-processing. The effect of including the track flexibility on the wear estimation is investigated by comparing the results with those obtained for a rigid track. Moreover, the effect of the wheel profile updating strategy on the wheel wear is also examined. The simulation results indicate that the track flexibility cannot be neglected for the wheel wear prediction. The wear predicted with the rigid track model is generally larger than that predicted with the flexible track model. The strategy of maintaining unchanged wheel profiles during the dynamic simulation coincides with the online updating strategy in terms of the predicted wear.

This paper presents an investigation into the mechanism of polygonal wear of metro train wheels through experiments conducted at field sites. The experiments comprise dynamic behaviour test of vehi...

In a railway vehicle air brake system, a brake pipe is used to connect all related elements, for example, the air source system, brake control device, and brake valve. The brake pipe has a significant impact on the safety and reliability of trains. This paper presents a fracture analysis of a brake pipe installed on the bogie of a metro train running on one metro line in China. The analysis was conducted using a brake pipe modal test in a depot, a bogie vibration test, and a brake pipe dynamic stress measurement applied at the field site. The field experiment results indicate that the main cause of a brake pipe fracture is the coupling resonance between the first-order lateral bending eigenmode of the brake pipe (74 Hz) and the eigenmode of the reverse yawing of two side beams of the bogie frame (73 Hz). The wheel out-of-roundness is the main excitation source. To solve the pipe fracture problem, a dynamic stress analysis method that considers the frequency and time domains is presented to assess the possible measures. The measures investigated in this study are the pipe wall thickness, pipe clamp stiffness (elastic modulus), and pipe clamp numbers. The simulation results and on-track tests show that doubling the pipe wall thickness and decreasing the elastic modulus of the pipe clamp by 5.67 fold can reduce the dynamic stress amplitude of the pipe by approximately 60%. If a pipe clamp is added at the middle position between the two pipe clamps on the pipe, the dynamic stress amplitude of the pipe will decrease by 94% compared to the present pipe structure. This is because the additional pipe clamp alters the frequency of the first-order lateral bending eigenmode of the brake pipe to avoid being equal to the eigenfrequency of the reverse yawing of the two side beams of the bogie frame. After the metro corporation added a pipe clamp and applied a regular wheel re-profiling, no brake pipe fracture occurred on the investigated metro line.

Severe high-order polygonal wear has been found on metro train wheels of one metro line in China, which causes considerable vibration of vehicle components and disturbing interior noise. Field tests and numerical simulations were conducted to investigate the formation mechanism and key influencing factors of wheel high-order polygonisation. Wheel out-of-roundness (OOR), vibration behavior of vehicle components, and rail surface irregularities were tested. On-site measurement results indicate that the wheels exhibit 13th- to 16th-order polygonal wear. The dominant wavelengths are about 165–203 mm. The experimental results show that the wheel polygonisation is related to the first-order bending vibration of the wheelset and the P2 resonance generated on ladder sleeper tracks and steel spring floating slab tracks. A long-term wear model was developed to further study the cause of wheel polygonisation, which included a vehicle–track coupled dynamic model, considering the flexibility of the wheelset and track, as well as a wear model. The effects of operating speeds, P2 resonance frequencies for different tracks, and wheelset flexibility on the development of wheel polygonisation were investigated. Based on the experimental and simulation results, it is further believed that the P2 resonance is the main cause of the higher-order polygonal wear of wheels, and the first-order bending vibration of the wheelset can exacerbate the wheel polygonisation.

Experiments were conducted at field sites to investigate the mechanism of the polygonal wear of electric locomotive wheels. The polygonal wear rule of electric locomotive wheels was obtained. Moreover, two on-track tests have been carried out to investigate the vibration characteristics of the electric locomotive's key components. The measurement results of wheels out-of-round show that most electric locomotive wheels exhibit polygonal wear. The main centre wavelength in the 1/3 octave bands is 200 mm and/or 160 mm. The test results of vibration characteristics indicate that the dominating frequency of the vertical acceleration measured on the axle box is approximately equal to the passing frequency of a polygonal wheel, and does not vary with the locomotive speed during the acceleration course. The wheelset modal analysis using the finite element method (FEM) indicates that the first bending resonant frequency of the wheelset is quite close to the main vibration frequency of the axle box. The FEM...

In this paper, we present a comprehensive model for the prediction of the evolution of high-speed train wheel profiles due to wear. The model consists of four modules: a multi-body model implemented with the commercial multi-body software SIMPACK to evaluate the dynamic response of the vehicle and track; a local contact model based on Hertzian theory and a novel method, named FaStrip (Sichani et al., 2016), to calculate the normal and tangential forces, respectively; a wear model proposed by the University of Sheffield (known as the USFD wear function) to estimate the amount of material removed and its distribution along the wheel profile; and a smoothing and updating strategy. A simulation of the wheel wear of the high-speed train CRH3 in service on the Wuhan-Guangzhou railway line was performed. A virtual railway line based on the statistics of the line was used to represent the entire real track. The model was validated using the wheel wear data of the CRH3 operating on the Wuhan- Guangzhou line, monitored by the authors’ research group. The results of the predictions and measurements were in good agreement.

We present a detailed investigation of the mechanism of metro wheel polygonal wear using on-site experiments and numerical simulation. More than 70% of metro wheels exhibit 6th–8th harmonic-order polygonal wear; the excitation frequency of the polygonal wear is located in the 50–70 Hz interval at an operating speed of 65–75 km/h. To determine the root cause of the polygonal wear, a dynamic train behavior test is conducted immediately after wheel reprofiling. The results suggest a natural mode resonance in the vehicle/track system, whose frequency coincides with the passing frequency of the 6th–8th order polygonalization. The magnitude of the resonance increases significantly when the vehicle runs on a monolithic concrete bed with DTVI2 fasteners. Thus, a corresponding coupled vehicle/track dynamic model is established and validated by comparing the calculated frequency response functions (FRFs) of tracks and dynamic responses of axlebox acceleration with the measured values. Using multiple timescales, the dynamic model and Archard wear model are integrated in a closed loop for long-term polygonal wear prediction. The simulated and measured evolution of polygonal wear show good agreement. By combining simulation results and experimental data, we suggest that the P2 resonance is the main contributor to the high amplitude of wheel/rail contact forces in the 50–70 Hz frequency range and the reason for subsequent polygonal wear. Parametric studies show that the dominant order decreases as vehicle speeds increase, representing a “frequency-constant” mechanism. The wheelset flexibility, especially the bending mode, would aggravate the wheel/rail creepage and further accelerate the formation of polygonal wear. Higher rail pad stiffness will increase P2 resonance frequency and shift the dominant wheel to higher polygonal orders.

Three non-elliptic contact models, namely Kik–Piotrowski method, STRIPES and ANALYN, are first compared to the Hertz theory and the CONTACT code in terms of the normal contact solution. Further, for the contact models except for CONTACT, the tangential contact solutions are calculated by a modified simplified theory of Kalker (FASTSIM) based on the normal ones to compare with that of CONTACT. Afterwards, a wheel wear prediction model, consisting of a multi-body dynamic model of the railway vehicle, a wheel–rail contact model and a wear function developed by the University of Sheffield, is developed. The influences of the five contact models mentioned above on the wheel wear prediction are investigated from viewpoints of calculation efficiency and accuracy. The results indicate that using Hertz theory and FASTSIM to solve the normal and tangential contact problem, respectively, in the wheel wear simulation is a good choice in order to consider a compromise between the calculation efficiency and accuracy.

This paper presents a detailed investigation of out-of-round electric locomotive wheels through extensive measurement conducted at field sites. More than 2000 wheels, of seven types of locomotives widely used in China, have been measured since April 2013. The measurement results indicate that two types of freight traffic locomotives suffer serious polygonal wear problems with center wavelengths ranging from 160 to 315 mm. The dominating wavelength is 200 mm. Therefore, the investigations are mainly focused on the two locomotive types. The other types, which are taken for comparison, do not exhibit obvious polygonal wear. However, they exhibited more or less eccentricity. The effect of wheel re-profiling on the wheel polygon is also investigated and discussed. The dominating harmonic orders and center wavelengths after re-profiling are consistent with those before re-profiling at the correct circumstances, if the center wavelength of the polygonal wear is about 200 mm.

A wheel wear model that considers the effects of temperature during tread braking was established on the basis of Archard's wear model. In the model, the temperature field of wheel tread was calculated using a numerical algorithm based on finite element method. The influences of temperature on the size of contact patch, division of adhesion/slip zone, wear coefficient and wear depth are studied by taking the effects of temperature rising on wheel material properties, such as elastic modulus, tensile strength and hardness, in consideration. The results show that the area of contact patch, wear depth and worn area increase with temperature caused by tread braking.

This paper presents the results of a detailed experimental investigation of the abnormal vibration of the electric locomotive. A locomotive suffered from serious vibration problem was chosen for the test and its normal operations kept unchanged during the test. The wheel out-of-roundness (OOR) and vibrations of key components including the axle box, the bogie frame and the car body were measured before and after wheel re-profiling. The measured OOR results indicate that the wheels exhibit the OOR with orders 12 to 22 before re-profiling, i.e. with the center wavelengths of 200–315 mm in 1/3 octave bands. The wheel polygonal wear cannot be absolutely removed by the wheel re-profiling. The 16th–19th order OOR becomes to be dominant after re-profiling. The vibration test results show that the axle box, the bogie frame and the car body vibrate with the same dominant frequency before re-profiling. The dominant frequency of the vibration is approximately equal to the passing frequency of a polygonal wheel. The vibrations are significantly reduced after re-profiling. The wheel polygonal wear is the root cause of the abnormal vibration.