Wheel-rail System Research Articles

Contact and creep characteristics of wheel–rail system under harmonic corrugation excitation

To study the wheel–rail contact and creep characteristics and the evolution law of corrugation with different wavelengths, the wave-like wear is idealized as continuous harmonic excitations consisting of three wavelengths and wave depths, and the vehicle–track space coupled dynamic model is established for specific analysis. The results show that when the wavelength is fixed and the wave depth increases, the average values of rail/wheel vertical vibration acceleration and wheel–rail longitudinal creepage/creep force increase and the average value of transverse creepage/creep force decreases. But, when the wave depth is fixed and the wavelength increases, the average values of rail/wheel vertical vibration acceleration and longitudinal creepage/creep force decrease and the average value of transverse creepage/creep force increases. Both longitudinal and transverse creepages/creep forces contain the characteristic frequency consistent with the passing frequency of initial irregularity. The characteristic frequencies of longitudinal creepages/creep forces tend to develop in the high-frequency band with the increase of wave depth, whereas the characteristic frequencies of transverse creepages/creep forces concentrate in the low-frequency band and decrease with the increase of wave depth. Under the condition of the same wavelength, with the increase of operation times, the wear amount increases slightly in the low-frequency band but greatly in the middle- and high-frequency bands, which shows that rail corrugation will gradually develop toward short wavelength corrugation at the constant velocity. When rail corrugation is formed, its development speed will gradually slow down with the increase of vehicle running times, and the development speed of short wavelength corrugation is faster than that of long wavelength corrugation.

Study on the Mechanism of the Abnormal Phenomenon of Rail Corrugation in the Curve Interval of a Mountain City Metro

An abnormal phenomenal of rail corrugation was found in the transition and circular curve interval of the mountain city metro, in which the rail corrugation on the outer rail is more serious and earlier than that on the inner rail, and the wavelengths are also different. In the present article, the frictional self-excited oscillation of the wheel–rail system and the feedback vibration of the rail corrugation are considered comprehensively to study the mechanism of rail corrugation. According to the dynamic analysis of the vehicle track system on the high-incidence section of rail corrugation, finite element models of wheelset–track systems on the smooth track and wear track are established. Then, the unstable vibration mode and dynamic response of the wheelset–track system are calculated by complex eigenvalue analysis and transient dynamic analysis. The consistency of the numerical simulation and field test indicates that the generation of rail corrugation may be affected by the frictional self-excited vibration of the wheelset–track system. Furthermore, the feedback vibration induced by the previous rail corrugation not only aggravates the original rail corrugation but also induces new rail corrugation.

An investigation into transient frictional rolling contact behaviour in a switch panel: validation and numerical simulation

To improve the understanding of wheel/rail contact behaviour and damage mechanisms in turnouts, the 3D explicit finite element model of a wheelset rolling over a switch is introduced. This takes into account the arbitrary geometrical profile of the wheel-rail system, the relative motion between switch/stock rail, the nonlinear materials and actual moving postures of the wheelset. Precise frictional rolling contact solutions and dynamic response, including contact stress, surface shear stress, microslip, roll angle and lateral displacement, are all studied to obtain a better understanding of the wheel-rail frictional rolling contact behaviour in the switch panel. The simulated results are then verified through field tests on the Qingdao-Jinan line. The results indicate that the proposed explicit finite element method can be an efficient tool for solving the problems of frictional rolling contact behaviour and damage mechanism in switch panels.

High Frequency Vibrations Arising in System Wheel-Rail. Part II. The Influence of High Frequency Vibrations on the Structure of Rail Steel M76

In this paper, the influence of high-frequency vibrations in the wheel-rail system is studied, the main causes of their occurrence are described, the study of the structure of M76 rail steel at operating stress levels of 700 MPa and more is given. Investigated the microstructures of samples cut from the actual rails, following the action of high-frequency loading by means of optical microscopy and micro hardness testers.

Influence of the temperature- and frequency-dependent dynamic properties of rail pads on the vibration characteristics of rails at low temperature

The dynamic properties of railway tracks and rail pads are significant for accurately predicting both the wheel–rail system vibration and rolling noise. The effect that the dynamic properties of rail pads have on the dynamic characteristics of railway tracks at extremely low temperatures was not adequately studied in previous research. In order to better predict the attenuation of the rail vibration, the viscoelastic dynamic properties of rail pads varying nonlinearly with temperature and frequency were first tested, in a wide temperature range (−60 ℃ to 20 ℃), and represented by the fractional derivative Zener model. Then, rail vibration and its attenuation characteristics were investigated by accounting for the frequency-dependent, temperature-dependent and frequency- and temperature-dependent properties, respectively. To be more specific, the frequency and amplitude of the rail first-order bending resonance and pinned–pinned resonance, as well as the rail decay rate were analyzed for the three cases. In conclusion, the study shows that the temperature/frequency-dependent properties of the rail pad have a significant effect on the first-order bending resonance of the rail, but no influence on the pinned–pinned resonance frequency. The rail decay rate indicates a clear increasing trend in the entire frequency domain with the decrease of temperature (especially below about −20 ℃). The frequency dependence mainly affects the vibration and its attenuation characteristics of the rail below about 400 Hz, which should not be ignored in the track dynamics modelling. Therefore, when the analyzed environmental temperature is below −20 ℃, the temperature dependence of rail pads should be considered.

The development of a method to reduce wear in the wheel-rail system

The article deals with the issue of friction reduction. Application of lubrication to decrease the intensity of wear in the wheel-rail system is widely-spread in rail transport. However, the lubricants used in this technology, even those which are made according to contemporary significant requirements relating to the environment, cause irreparable harm to the nature. The article suggests the application of lubrication based on reducing the temperature in the contact area by applying a refrigerant.

СМАЗОЧНЫЙ МАТЕРИАЛ ДЛЯ РОТАПРИНТНОЙ СМАЗКИ СИСТЕМЫ “КОЛЕСО—РЕЛЬС”

A multicomponent lubricant for increasing wear resistance in the wheel–rail system has been developed and studied. The lubricant composition effect on the wear intensity level of the wheel–rail system, the lubricant consumption and the friction coefficient in the wheel–rail system has been assessed based on simplex-lattice composition-property experimental designs. A reasonable composition of a three-component plastic lubricant consisting of 11% foam glass, 32% stearic acid, and 57% bitumen has been obtained. The industrial tests for the developed lubricant efficiency under the conditions of the North Caucasian Railway have been carried out. According to test results, the wear intensity level of the wheel flanges has exhibited a 28.4% decrease, whereas the lubricant consumption has shown a 29.5% decrease.

ОПТИМИЗАЦИЯ ТРИБОТЕХНИЧЕСКИХ ХАРАКТЕРИСТИК МОДИФИКАТОРОВ ТРЕНИЯ ПАРЫ “КОЛЕСО — РЕЛЬС”

Anti-friction materials were tested for friction and wear of the rail transport used in the wheel–rail system when sliding on an Amsler-type friction machine. The test results of antifriction materials are obtained and the dependences of their wear rate on the temperature of the wheel–rail contact are formed. Processing the experiment results allowed us to obtain a model of wear for antifriction materials. Based on the results of actual operating conditions, the developed anti-friction material allows reducing the wear rate of wheels from rail transport by 28.4%.

Research on the relationship between the rail corrugation and the vibration response of the wheel-rail system

Rail corrugation is a very common phenomenon in high-speed railways. Rail corrugation can cause increased vibration of trains and tracks, and may even affect the safety of train operation. Therefore, this paper will analyze the vibration of the wheel-rail system caused by the rail corrugation. The actual transient rolling contact model is established by using explicit and implicit finite element methods. Through the calculation of the wheel-rail contact force and the wheel-rail mode, the vibration relationship between the rail corrugation and the wheel-rail system is obtained. It can provide some references for further analysis of the cause of rail corrugation.

Determination of the Harmonic Response of a Railway Wheelset using the Finite Element Analysis Method

In this paper, the harmonic response of the railway vehicle wheelset is investigated by using the finite element analysis method. The study relies on the vibrations of a Minden Deutz bogie of a passenger coach, having brake shoes and currently in operation on Romanian railway network. It is well known that by analysing the frequency response it can be identified how the parameters of the wheel-rail system is influencing the level of vibrations and the amount of rolling noise generated. Nonetheless, the approach of determining the harmonic response using the finite element analysis method is the only approach to studying the behaviour of the wheelset at frequencies greater than 1500 Hz.

A finite element analysis-based study on the dynamic wheel–rail contact behaviour caused by wheel polygonization

In this study, an explicit finite element analysis method was adopted to investigate the wheel–rail impact response generated by wheel polygonization, using a three-dimensional wheel–rail rolling contact finite element model. In this model, the infrastructure below the rails and the stiffness and damping of the sleeper supports were considered. Then, the characteristics of the wheel–rail contact zone, the stress/strain state and the wheel–rail impact force of the polygonal wheel–rail system were presented and discussed and were compared with those of the ideally perfect wheel–rail system. A parametrical study was then carried out to examine the influences of train speed and the polygonal order of the wheel on the wheel–rail impact response. The finite element analysis results revealed that the vertical wheel–rail impact force induced by wheel polygonization is related to the wheel radial deviation; the maximum contact force, stress and strain are all elevated with the increase of the order of the polygonal wheel, which suggested that the wheel should be repaired when it is in the initial lower order polygonal state. These findings can provide some theoretical and technical support for the optimal design of the wheel–rail system and the safe operation of high-speed trains.

Fatigue life assessment of bogie frames in high-speed railway vehicles considering gear meshing

Railway welded bogie is usually subjected to extremely complex fatigue loads, producing huge failure hazard. However, only external excitations from the wheel-rail system are considered when assessing the fatigue performance by most of the standards. Therefore, a novel approach for assessing the lifetime of a powered bogie frame considering internal excitation was proposed in this paper. To achieve this, a modified torsional vibration model considering gear meshing was first established. The calculated results were then input into a rigid-flexible coupled vehicle dynamic model to estimate the dynamic response and hence the cumulative damage was determined. This approach was applied to assess the lifetime of a weld polished bogie frame. The results indicate that internal excitation should be considered to determine the service lifetime.

Development of the lubricant for side-mounted rail flange lubricators for traction rolling stock

Specificity of operating conditions of the rolling stock defines a number of requirements for lubricants intended for the wheel-rail tribosystem. Lubricants are used for “wheel — rail” contact, the aggregate state of which varies from liquid to solid. When evaluating the lubrication properties of these materials, a significant number of factors must be taken into account, in particular, influence of the environment, method of application, condition of the rail surface. The paper discusses the main operational requirements for lubricants operating in a wheel-rail tribosystem. Temperature ranges of the lubricants used for the “wheel — rail” contact on the railway network of the Russian Federation are given. As a result of the research, it was determined that none of the materials used for lubrication of the wheel-rail system satisfies the operating temperature conditions of the traction rolling stock. To solve this problem a lubricant was developed and tested in an industrial environment at the Rostov State University of Railway Transport. Its lubricant composition allows to significantly expand the temperature range of the lubricant. Complex of experimental studies and method of orthogonal central composite plan of the 2nd order established the optimum values of the thickness of the working shell of the 0.846 mm lubricating rod and the 50.411 % percentage of plastic lubricant, allowing to extend the temperature range of lubricant rods and, in particular, completely eliminate the lubricant flow to achieve a temperature of 126.034 °C. Proposed composition of the lubricant was tested on a freight electric locomotive of the VL80T series, equipped with non-power lubricators, under the conditions of the Bataysk — Likhaya section of the North Caucasus Railway. Intensity of wear of the wheel flanges of the traction rolling stock lubricated by the proposed material, compared with the intensity of wear of the wheel flanges without the use of lubrication systems is reduced by 2 times.

Tribological Behaviour of Oil Blended with Additives: A Review

Wear and friction in the moving link is the key factor for Power reduction in applications like Wind turbine gearbox, IC Engine, Bearing and wheel rail System etc., it can be governed by using modified oil. In latest years, multiple advanced oil and modern tribological techniques have been developed to reach up to level of superior lubricity and lengthier life in heavy-duty machines. This paper reports review on latest progress of several old and unconventional techniques refereed in tribological analysis of lubricant blended with additives. The tribological nature of oil blended with additives for various applications is also studied and reported in this paper. This review gathered the publications and abridgement for scope of further investigation grounded on facts collected. The outcomes & key extractions are presented as per gathered data.

Optimal Utilization of Adhesion Force for Heavy-Haul Electric Locomotive Based on Extremum Seeking with Sliding Mode and Asymmetric Barrier Lyapunov Function

An optimal utilization of adhesion force based on extremum seeking with sliding mode (SMES) and asymmetric barrier Lyapunov function (ABLF) is proposed for heavy-haul electric locomotives (HHELs), which can eliminate the wheel skidding at optimal adhesion point and achieves maximum traction for HHELs. First, the state equation of wheel-rail adhesion control system is described. The optimal utilization of adhesion force and anti-slip control are analyzed considering the condition changes at the wheel-rail surface. Then, the nonsingular terminal sliding mode observer (NTSMO) is designed to achieve the accurate adhesion coefficient of the wheel-rail. Finally, the SMES method for HHEL is developed to obtain the optimal slip speed and the maximum adhesion coefficient of the uncertain wheel-rail surface. Meanwhile, the ABLF controller is designed to achieve anti-slip control for HHELs in the optimal adhesion state. Comparing with the conventional differential acceleration control (DAC) method, the simulations and experiments verify that the proposed method can achieve optimal adhesion anti-slip control with quick dynamic response, and the HHEL achieves maximum traction.

Influence of Roughness of Working Surfaces of the Wheel–Rail System of Open-Pit Locomotives with an Implementable Adhesion Coefficient

The results of theoretical and experimental investigations of the interaction between the working surfaces of wheel treads of open-pit locomotives with rails are presented. The actual values of the height of microroughness when profiling the working surface of the rail head for reducing the running-in period of the wheel–rail system are determined, which positively influences increasing the adhesion coefficient and economic operation life of industrial railway transport. The optimal value of the height of microroughnesses of the interacting surfaces under rail-grinding, which can be within Rz = 40–20 μm, is determined. Guaranteeing the optimal height of microroughnesses of the working surfaces of the wheel–rail system, in turn, will make it possible to calculate the predicted design value of the friction coefficient of the wheel tread of the open-pit locomotive with the rail.

A computational simulation study on the dynamic response of high-speed wheel–rail system in rolling contact

The dynamic wheel–rail responses during the rolling contact process for high-speed trains were investigated using the explicit finite element code LS-DYNA 971. The influence of train speed on the wheel–rail contact forces (including the vertical, longitudinal, and lateral forces), von Mises equivalent stress, equivalent plastic strain, vertical acceleration of the axle, and the lateral displacement of the initial contact point on the tread, were examined and discussed. Simulation results show that the lateral and longitudinal wheel–rail contact forces are very smaller than the corresponding vertical contact forces, and they seem to be insensitive to train speed. The peak value of dynamic vertical wheel–rail contact force is approximately 2.66 times larger than the average quasi-static value. The elliptical wheel–rail contact patches have multiple stress extreme points due to the plastic deformation of the wheel tread and top surface of the rail. The vertical acceleration value of the axle in the steady condition is around ±5 m/s2 for the perfected wheel–rail system with the running speed below 300 km/h.

Design of a Novel Single-Angle Inclination HTS Maglev Train PMG Turnout

High-temperature superconducting (HTS) magnetic levitation vehicles are one of the next-generation high-level magnetic levitation (Maglev) transportation systems. With the development of high-temperature superconducting materials technology, in the future HTS Maglev train will be vigorously developed. The non-contact wheel–rail system causes many difficulties for the turnout system. In this paper, a novel mechanical permanent magnetic guideway (PMG) turnout system is proposed utilizing a single inclination permanent magnet (PM) for PMG turnout. To assemble the PMG turnout with the proposed single inclination PMs, the wedge-shape air gap between two fixed PMs is used to adjust the PMG body bending in the horizontal plane for Maglev vehicle guideway switching purposes. The relationship of the geometric dimensions of the single inclination PM and its inclination angle and the negative turning radius of the PMG turnout is successfully derived. The magnetic field uniformity of the PMG turnout under the condition of the minimum turning radius of 4 meters, which responds to angle 1.1459° of the single inclination PMs, has been simulated by the finite element method. The calculation results show that the influences of the wedge air gap on the magnetic field uniformity along the PMG longitude direction are small despite the turnout PMG being in a straight state or in a switching state. There are only minor differences in the magnetic fields on both sides of the PMG between the normal PMG and the turnout PMG in straight state and in switching state and so may not influence the HTS Maglev vehicles running stability during the PMG switching operation.

Numerical investigation of the effects of rail vibration absorbers on wear behaviour of rail surface

Rail corrugation refers to the periodic wear of the top working surfaces of rails. This problem has plagued the railway industry over a hundred years. In the present paper, the effects of rail vibration absorbers on wear behaviour of the rail surface have been studied. The dynamic model of a wheel–rail–absorber system is established. The friction contact coupling between the wheel and the rail are fully considered in this model. A wear model, in which the mass loss of unit area in contact patch is proportional to frictional work per unit area between the wheel and the rail, is developed to analyse the wear behaviour of the rail surface. Numerical results show that the saturated creep force-induced self-excited vibration of the wheel–rail system can result in short pitch rail corrugation on the rail surface. The maximum wear depth occurs at the positions close to mid-span of each sleeper bay. After the installation of rail vibration absorbers, the formation of short pitch rail corrugation can be suppressed effectively, and the wear on the rail surface becomes uniform and the growth rate of rail corrugation reduces considerably. Increasing the connection damping between the absorber and the rail web is beneficial to preventing the formation of short pitch rail corrugation.

Design of track structure for corridors of heavy- train traffic

The topical issues of the development of heavy-train traffic along the Central Siberian Main from the “Altaiskaya” station to the “Irtyshskoe” station of the West Siberian Railway are considered in this paper. For this purpose, the rational design of the track structure for increased axial loads and side forces was selected and analyzed, and measures to expand the operating domain of the continuous welded rail track by improving the design of sleepers and intermediate rail fasteners without changing the plan and profile of the track were considered. Adjusting the track gauge by surface and line is a critical task. The paper discusses the issues of ensuring the widening of the track gauge in curved sections with a radius of less than 350 m as one of the constraints to the development of the operating domain of the continuous welded rail track on the railways of JSC “Russian Railways” and on the West Siberian Railway. Two main ways of ensuring the widening of the track gauge are considered: by changing the structure of sleepers and by means of additional structural elements of intermediate rail fastenings, or a combination of both. This ensures the smoothness when guiding the rolling stock in the curve section of the track, improves the interaction in the wheel-rail system, reduces wear, and complies with requirements of existing regulatory documents. All this reduces the dynamic load on the track, including the subgrade, and extends the service life of the track structure in conditions of heavy-train traffic.