Polygonal Wear Research Articles

Analysis of the features of wheel out-of-roundness and construction of the wheel roughness spectrum of high-speed trains

ABSTRACT Wheel out-of-roundness (OOR), especially wheel polygonal wear, occurs frequently in high-speed wheels in China and has a significant influence on vehicle operation and wheel maintenance. The authors’ team has measured wheel OOR for more than 30,000 wheels with high-precision measuring instruments on nine types of high-speed EMUs over the past decade. In this study, the features of the wheel OOR are analyzed in detail and the wheel roughness spectrum is determined in both the narrow band and the 1/3 octave band. A method for inverting the wheel polygonal with the sine and catenary type is proposed. The analysis of the wheel OOR features, the establishment of the wheel roughness spectrum, and the resampling of wheel out-of-roundness profile from a roughness spectrum are of great importance for the simulation analysis of the dynamic wheel – rail interaction and rolling noise, as well as for the design of vehicle and track components.

Investigation on influencing factors of wheel polygonization of a plateau high-speed EMU train

PurposeThis study aims to investigate the cause of high-order wheel polygonization in a plateau high-speed electric multiple unit (EMU) train.Design/methodology/approachA series of field tests were conducted to measure the vibration accelerations of the axle box and bogie when the wheels of the EMU train passed through tracks with normal rail roughness after re-profiling. Additionally, the dynamic characteristics of the track, wheelset and bogie were also measured. These measurements provided insights into the mechanisms that lead to wheel polygonization.FindingsThe results of the field tests indicate that wheel polygonal wear in the EMU train primarily exhibits 14–16 and 25–27 harmonic orders. The passing frequencies of wheel polygonization were approximately 283–323 Hz and 505–545 Hz, which closely match the dominated frequencies of axle box and bogie vibrations. These findings suggest that the fixed-frequency vibrations originate from the natural modes of the wheelset and bogie, which can be excited by wheel/rail irregularities.Originality/valueThe study provides novel insights into the mechanisms of high-order wheel polygonization in plateau high-speed EMU trains. Futher, the results indicate that operating the EMU train on mixed lines at variable speeds could potentially mitigate high-order polygonal wear, providing practical value for improving the safety, performance and maintenance efficiency of high-speed EMU trains.

Investigation into fatigue failure of cable brackets and vibration suppression methods

The cable bracket is one of the most important components of high-speed EMUs, as it supports the cables of sensors. The fatigue failure of the bracket can severely affect the operation of the vehicle. In this study, the dynamic response of the cable bracket, including dynamic stress and acceleration, is obtained through field tests. The results show that the modal vibration of the bracket excited by high-frequency excitation in the wheel–rail system is an important cause of fatigue failure of the bracket. Rail welded joints in the track and polygonal wear of the wheelset further exacerbate the vibration and of the bracket. A model of the virtual vibration table is proposed to simulate the actual excitation experienced by the bracket. The effects of the cantilever beam length, steel plate thickness, and pre-tightening torque of the bolts on the dynamic stress of the bracket are studied using the virtual vibration table. Several vibration suppression methods are proposed. The results indicate that the dynamic stress of the bracket caused by the rail welded joints can be effectively reduced through the adjustment of the pre-tightening torque of the bolts or the appropriate reduction of the cantilever beam length. The findings of this study can serve as a reference for suppressing vibration and preventing fatigue failure of the bracket.

The mechanism of polygonal wheel wear considering a three-dimensional profile

Wheel polygonal wear is one of the most serious problems in the railway industry nowadays. To study the mechanism of wheel polygonal wear, the wear prediction model was established. The three-dimensional wheel profile model and the improved USFD wear prediction algorithm were used to research the wear state of the wheel. The vehicle system dynamic characteristics and wheel wear state under different running speeds are studied. The results show that the vibration state of the wheel will be affected by the vertical and lateral coupling vibration of the wheel when considering the three-dimensional wheel polygonal wear. Due to the influence of coupled vibration, the wheel will appear larger wheel-rail force fluctuation points at different phase angles. The large wheel-rail force fluctuation at these different phase angles is one of the reasons for the formation of wheel polygonal wear. At the same time, the natural mode of the vehicle system will also affect the order of the wheel polygon and the amplitude of the wheel polygon. This study provides a new idea for the research of the wheel polygon mechanism.

Study on the allowed maximum amplitudes of low-order polygonal wear on resilient wheels based on operational safety

Following the extensive use of resilient wheels on trams, several subways in China have started pre-launch testing of resilient wheels. While it remains at an early stage, the long-term behavior of the wheel has become a great concern for subway operators and wheel suppliers. To address the concern, this study focuses on derailment risk by evaluating the allowed maximum amplitudes of low-order polygonal wear on resilient wheels. Firstly, a metro vehicle-track dynamic system model equipped with resilient wheels is built. Then, based on the operation safety index and current re-profiling regulations for conventional wheels, the influence of wheel axial and radial stiffness on the radial amplitude limits of resilient wheel polygonal wear is analyzed. To perform the analysis, firstly the commonly-used stiffness for a resilient wheel (300 kN/mm in radial direction and 50 kN/mm in axial direction) is adopted to study the effect of resilient wheel polygonization on wheel load reduction ratio. Then, wheel load reduction ratio is predicted for different radial (up to 600 kN/mm) and axial (up to 100 kN/mm) stiffnesses of the resilient wheel and different orders (up to 10) of wheel polygonization of 1 mm amplitude. A contour plot is provided to illustrate how the wheel load reduction ratio varies with the harmonic order and amplitude of wheel polygonization under different combinations of resilient wheel’s equivalent axial and radial stiffnesses. It is found that, with the increase of the amplitude of the polygonal wear of a certain harmonic order on resilient wheel, the number of the available combinations of the equivalent stiffnesses adopted by the resilient wheel becomes less by considering the operation safety indexed with wheel load reduction ratio. Besides, depending on the stiffness of the resilient wheel, the allowed amplitude corresponding to the polygonization of each order has been suggested with the contour plots.

Analysis of the dynamic contact behaviour of high-speed train transmission gear excited by wheel defects

Studies on wheel flatness and polygonal wear have demonstrated that wheel defects cause severe impact forces at the wheel–rail interfaces. This study investigated the dynamic contact mechanical behaviour of high–speed train transmission gears when subjected to wheel defects. First, a train-track coupling dynamics model was established, considering the localized contact characteristics of transmission gears. This model was developed using the slice method and the Hertz contact model, exploring the spatial coupling effects between the gear contact interface and the train–track interface. Subsequently, the dynamic model was employed to extract essential contact mechanical parameters of the transmission gear under the influence of wheel defects, including gear meshing load, gear contact stress, and sliding velocity. Furthermore, an analysis was conducted to uncover and elucidate the mechanism by which wheel flatness and polygonal wear impact the dynamic contact behaviour of the transmission gear. This study underscores the importance of considering wheel defects when assessing the contact fatigue and wear performance of high-speed train transmission gears.

Dynamic characteristics of electromechanical coupling of body-suspended drive system for high-speed trains under wheel polygonal wear

Wheel polygonal wear can trigger intense wheel–rail interactions in railway vehicles, posing a significant threat to traffic safety. However, the mechanism and interaction of the influence of wheel polygonal wear on the electromechanical coupling characteristics of high-speed trains remain unclear. Therefore, this paper proposes a joint simulation modelling method that takes into account the integration of the electrical subsystem with the complete mechanical subsystem. A comprehensive analysis is conducted on the dynamic response of the high-speed train’s body-suspended drive system under a wide range of frequency excitations arising from harmonic torque, gear meshing, and wheel polygon wear. The results indicate that the electrical system generates a substantial amount of harmonic frequency components, resulting in a significant increase in the vibration of the train. The wheel polygon wear causes a broadening of the low-frequency resonance band, revealing a relatively prominent observation interval for the dynamic characteristics. Concurrently, it is discovered that the 23rd-order wheel polygon wear excites the system’s resonance frequency, and as the wavelength of the wheel polygon increases, the acceleration vibrations intensify progressively. Research reveals first the interaction of electrical system and mechanical system under wheel polygon wear, especially in the resonance gain characteristics under polygons and harmonic torques.

Study on the sound radiation characteristics of polygonal wear wheels of CRH3 high-speed train

Abstract Due to the increase in train operating speed, the phenomenon of collision vibration between wheels and rails becomes more and more obvious, and the degree of wheel wear increases dramatically. As a result, the wheel-rail noise problem has become more and more complex. The wheel polygonal wear is also widespread on the train. For the wheel in the form of polygonal wear of the wheel-rail vertical force, combined with the principle of wheel-rail noise, we conduct an in-depth study. An aerodynamic mutual coupling model for CRH3 high-speed vehicles is proposed. The role of the amplitude of 0.03 mm, i.e., the twentieth-order polygonal abrasion rate on the wheel-rail force is analyzed at the speed class of 200~350 km/h, and the acoustic radiation characteristics of the wheels are investigated at different speed classes. The results show that under different speed classes, when the wheel polygon order is in the twentieth order, the wheel-rail vertical force rises with the increase of speed, and the wheel sound power is also affected by a great change. There is a significant increase in the sound power from the low frequency of 20 Hz to 100 Hz and a peak in the mid-frequency up to 1, 000 Hz. Secondly, when the wheel radiated sound pressure levels at different speed levels, significant changes also occurred, with the sound pressure reaching a maximum of 110 dB at 350 km/h.

A critical review of wheel/rail high frequency vibration-induced vibration fatigue of railway bogie in China

PurposeThis review aims to give a critical view of the wheel/rail high frequency vibration-induced vibration fatigue in railway bogie.Design/methodology/approachVibration fatigue of railway bogie arising from the wheel/rail high frequency vibration has become the main concern of railway operators. Previous reviews usually focused on the formation mechanism of wheel/rail high frequency vibration. This paper thus gives a critical review of the vibration fatigue of railway bogie owing to the short-pitch irregularities-induced high frequency vibration, including a brief introduction of short-pitch irregularities, associated high frequency vibration in railway bogie, typical vibration fatigue failure cases of railway bogie and methodologies used for the assessment of vibration fatigue and research gaps.FindingsThe results showed that the resulting excitation frequencies of short-pitch irregularity vary substantially due to different track types and formation mechanisms. The axle box-mounted components are much more vulnerable to vibration fatigue compared with other components. The wheel polygonal wear and rail corrugation-induced high frequency vibration is the main driving force of fatigue failure, and the fatigue crack usually initiates from the defect of the weld seam. Vibration spectrum for attachments of railway bogie defined in the standard underestimates the vibration level arising from the short-pitch irregularities. The current investigations on vibration fatigue mainly focus on the methods to improve the accuracy of fatigue damage assessment, and a systematical design method for vibration fatigue remains a huge gap to improve the survival probability when the rail vehicle is subjected to vibration fatigue.Originality/valueThe research can facilitate the development of a new methodology to improve the fatigue life of railway vehicles when subjected to wheel/rail high frequency vibration.

A finite element thermomechanical analysis of the development of wheel polygonal wear

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.

On the Polygonal Wear Evolution of Heavy-Haul Locomotive Wheels due to Wheel/Rail Flexibility and Its Mitigation Measures

Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track, and ultimately, lead to the shortening of service life of railway components. At present, wheel/rail medium- or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels, which are potentially resulted by the flexible deformations of the train/track system or other external excitations. In this work, the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations, in which different flexible modeling of the heavy-haul wheel/rail coupled system is implemented. Further, the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are discussed. The results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and rails. Execution of mixed-line operation of heavy-haul trains and application of multi-cut wheel re-profiling can effectively reduce the development of wheel polygonal wear. This research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.

The parameter identification of metro rail corrugation based on effective signal extraction and inertial reference method

Rail corrugation is a severe track damage and failure problem in metro lines. So, the accurate assessment of rail corrugation is significant for the safety and comfort of vehicles. It is an efficient means to detect rail corrugation through the acceleration signal. However, the acceleration signal contains the mixed signal caused by vehicle component noise and wheel polygonal wear, resulting in poor rail corrugation detection accuracy. Therefore, a new method is presented to extract the effective signal components and accurately identify the rail corrugation. Firstly, the Cubic mapping, modified sine algorithm, and Lévy flight are introduced into the dung beetle optimizer algorithm. A new improved dung beetle optimizer (IDBO) algorithm is presented to optimize the hyperparameters of the VMD algorithm, which can increase the signal decomposition performance of the VMD. Secondly, the fast independent component analysis method separates the independent components (ICs) from the VMD modes and original acceleration signal. Based on the selection criteria of ICs, the dominant signal components related to rail corrugation are determined. The rail corrugation amplitude can be obtained through the inertial reference method. The experimental results demonstrate that the presented method has better rail corrugation recognition accuracy, the root mean square error is smaller than the comparison method, and the corrugation wavelength of the straight track is larger than the curve track.

Effect of train traction on the wheel polygonal wear of high-speed trains

High-order polygonal wear of wheels is one of the most severe technical challenges for China's high-speed trains at present, and its formation mechanism has not been thoroughly understood. The effect of train traction on the wheel polygonal wear of high-speed trains was studied based on a wheel/rail rolling contact finite element model. The frequency domain characteristics of unstable vibration of the wheel/rail system under rolling/sliding contact were studied by using the finite element complex modal analysis method. We also examined wheel/rail contact forces and friction in the time domain. The cause of the high-order polygonal wear of Chinese high-speed train wheels was revealed. The effect of the vehicle speed and the wheel diameter on wheel polygonal wear were investigated. The results show: the friction-induced vibration of the wheel/rail system will be excited when the rolling/sliding contact between the wheel and rail. The radial zoom modal of the wheel is an unstable mode, which is the main cause of the 21-22 order polygonal wear of the high-speed train wheels in China. Additionally, vehicle speed has a linear relationship with the order of polygonal wear. Reducing the vehicle speed helps to control the polygonal wear of the wheels. Wheels of different diameters exhibit varying degrees of polygonal wear, with smaller wheels being more resistant to friction-induced vibrations.

A quantitative detection method for wheel polygonization of heavy-haul locomotives based on a hybrid deep learning model

Wheel polygonization poses severe threat to the operational safety of railway vehicles. To improve running safety, condition monitoring of wheel polygonization based on axle box acceleration (ABA) signals is an effective method. However, the signals usually contain strong noise, making it difficult to diagnose polygonal wheels quantitatively. To address these issues, this paper presents a quantitative detection method for wheel polygonization based on a deep learning (DL) model that integrates Convolutional Neural Network (CNN) with Long Short-term Memory (LSTM). The CNN is responsible for automatically extracting the sensitive spatial features from the original input and it can retain effective signal components. The LSTM is introduced to fuse the local features and conduct sequence modeling for polygonal wear amplitude estimation. Both dynamics simulations and field tests are carried out to verify the feasibility of the proposed method. The detection results indicate that the proposed model can accurately estimate the wear amplitudes.

Initiation and evolution of wheel polygonal wear: Influence of wheel-rail hardness ratios

Railway wheel polygonization is a type of uneven wear of material which worsens the running stability of trains. As a significant factor influencing the wear, wheel-rail hardness matching (i.e., the hardness ratio HW/HR) might affect the formation of a polygonal wheel. Thus, rolling-sliding wear tests were conducted using three wheel steels matching two rail steels to explore the influence of HW/HR (ranging from 0.649 to 1.263) on the initiation and evolution of wheel polygonal wear. The results show that when matching the softer rail, the wheel was less likely to become polygonal with an increase in HW/HR. When matching the harder rail, the wheel presented earlier polygon initiation under a moderate HW/HR of 0.792. The largest HW/HR of 1.263 presented the best anti-polygon condition for wheel material. The wear mechanism of polygonal wheel was dominated by abrasive, fatigue and oxidative wear at the crest and fatigue wear at the trough.

Impact of Wheel Polygonal Wear on the Operational Performance of Electric Traction Drive Systems in Locomotives

Impact of Wheel Polygonal Wear on the Operational Performance of Electric Traction Drive Systems in Locomotives

Dynamic response of axle box bearing for high-speed train considering wheelset flexibility and polygonal wear

In this study, a flexible wheelset was added to a rigid-flexible coupled vehicle dynamics model, in which the axle box bearings are accurately modeled. The measured wheel’s polygon wear profile and Wuhan-Guangzhou track spectrum are used in the model to define the wheel tread and track irregularity, respectively. We conducted a field test on the Wuhan-Guangzhou railway line to validate the model. Then, we investigate how the dynamic properties of the axle box bearing are impacted by the wheelset flexibility and polygonal wear of wheel. We found that the polygonal wheel with a rigid wheelset causes high-frequency vibration in wheelset and axle box, and increases the axle box bearing’s internal contact force. Additionally, the flexible wheelset with a normal wheel tread can alleviate the wheel/rail impact and reduce the axle box’s vertical vibration as well as the axle box bearing’s internal contact force. When the vehicle is running at v = 300 km/h, the excitation frequency caused by the wheel's 20th-order polygon is 576.5 Hz, and the flexible wheelset's 20th-order modal frequency is 577 Hz. The two frequencies are similar, when considering the polygonal wheel and flexible wheelset simultaneously, the wheelset will resonate. And the resonate of wheelset will increase the local deformation of the axle end and deteriorate the bearing operating environment, causing a significant increase in the bearing contact force. Finally, the axle box bearing’s dynamic characteristics are summarized when vehicle velocity varies from 50 to 350 km/h and wheel polygon wear amplitude ranges from 0.01 to 0.05 mm.

Wear and RCF problems of metro wheel/rail systems: Phenomena, causes and countermeasures in China

Wear and rolling contact fatigue (RCF) problems observed on metro wheel/rail systems in China in the last 15 years are summarized and explained from the aspects of phenomena, causes, and validated countermeasures. Presented wheel/rail wear in the lateral direction includes wheel flange wear, rail side wear, and abnormal wear of wheels such as differential, hollow, groove, and channel wear. As for irregular wear on wheel and rail running surfaces, the focus is on four and two important cases for wheel and rail, respectively, i.e., low-order wheel polygonal wear, high-order wheel polygonal wear, wheel stochastic out-of-roundness (OOR), wheel corrugation, short-pitch rail corrugation on the tracks with resilient and conventional fasteners, and rail corrugation on damping sleeper tracks. Finally, some unusual RCF problems occurring on wheel and rail surfaces are presented.

Effect of polygonal wheel on the vehicle-track dynamic interaction in turnout and its transmission to the trailer bogie wheels

The dynamic interaction between the vehicle and track is strongly influenced by out-of-round wheels and turnout rail profile geometries, which result in high-magnitude contact forces and abnormal vibrations. This study presents the dynamic response of the tram-turnout interaction due to polygonal wheel wear and analyses its transmission between the wheelsets. A three-dimensional coupled tram-turnout dynamic model was formulated, taking into account the polygonal wear on the front bogie wheelsets. Through numerical simulations, the dynamic characteristics of a tram passing through the turnout switch and crossing panels under the influence of polygonal wear were simulated. Furthermore, the impact of polygonal wear amplitudes and tram speeds on the transmission of dynamic impact forces and vibrations from the front bogie wheelset to the trailer bogie wheels are described. According to the numerical findings, when the flexible wheelset experiences polygonal wear, it can lead to substantial impact forces and vibrations as the tram moves through the turnout switch and crossing zones. Moreover, the transmission of dynamic impact forces and vibrations from the front bogie wheelset to the trailer wheels increases as the wheel wear amplitude and the vehicle speed increase.

Monitoring and Evaluation of High-Speed Railway Turnout Grinding Effect Based on Field Test and Simulation

Turnouts are the weak spot in high-speed rail systems, and it is simple for the phenomenon of the wheel–rail force and the carbody lateral acceleration over-limit to arise when the train passes through, which affects the service life of the rail and the running stability of the train. In this paper, the turnout with wheel–rail force over-limit and carbody lateral acceleration over-limit is selected for analysis, and the profiles of the wheel and rail are monitored. Then, the vehicle–turnout coupled multi-body dynamics model is simulated. Additionally, the portable vibration analyzer, the comprehensive inspection train, and the wheel–rail contact dynamic stress tester monitors the data and evaluates the impact of rail grinding on high-speed railway. The results of this study demonstrated that the turnout profiles are in good agreement with the standard wheel profiles following grinding, and the wheel–rail contact point and equivalent conicity both improved. When the train passes the ground turnout at high speed with and without the wheel polygonal wear, the wheel–rail force and the carbody acceleration were clearly improved. Using the wheel–rail contact dynamic stress tester, the comprehensive inspection train, and the portable vibration analyzer monitoring the changes in the carbody acceleration, the wheel–rail force and the carbody acceleration are definitely better after grinding. Similar to the pattern in the simulation, the train’s running steadiness increased by grinding.