Vertical vibrations of rail track generated by random irregularities of rail head rolling surface

The article deals with the determination of the dynamic loads arising in the running wheels of a conventional (standard) and modernized design during the movement of the cargo carriage of an overhead crane. The redesigned wheel has an insert made from 7-7130 rubber compound. Also, a method for diagnosing running wheels of conventional and modernized design was determined. The ZETLAB program was chosen as a program for signal registration and analysis. This program allows not only displaying the signal in real time with the possibility of scaling, but also allows you to digitize the signal with the possibility of further processing the results in various standards. Finding out the occurrence of a defect in wheels and rails is mainly carried out by two methods, when shock pulses appear and according to an increased background of vibration. In practice, there is a process of "dry" rolling friction, and this means that the method of shock pulses for diagnosing the condition of wheels and a rail track can be used only in some cases in the form of extreme wear of the friction pairs of a wheel and a rail. That is, the method of spectral analysis of fluctuations in the power of random vibration can be successfully applied to diagnose the state of the rail track and crane wheel. The diagnostic method based on the overall vibration level allows for an overall assessment of the technical condition. Such diagnostics makes it possible to identify defects only at the very last stage of development, when they lead or have already led to partial destruction of the rolling surface of the wheel and the surface of the rail, that is, to an increase in the overall level of vibration. The performance evaluation criteria are fully focused on the corresponding standard vibration levels for the investigated friction pair. A friction pair is considered to be defective, the vibration of which exceeds the general standard. When determining an increased overall level of vibration, maintenance personnel must make a decision to replace parts or a unit to prolong its operation. The results obtained indicate the advisability of using the wheels of the modernized design on the cargo carriage of an overhead crane.

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COMPARISON OF CHARACTERISTICS OF SEARCHING SYSTEMS OF MOBILE MEANS OF RAILS OF RAIL DEFECTOSCOPY

Kontrol Diagnostika ◽

10.14489/td.2020.10.pp.040-048 ◽

2020 ◽

pp. 40-48

Author(s):

V. F. Tarabrin

Keyword(s):

Low Temperatures ◽

High Reliability ◽

Type System ◽

Propagation Time ◽

Search System ◽

Rail Head ◽

High Speeds ◽

Working Face ◽

Rolling Surface ◽

Complex Design

The characteristics of wheel-type search systems and sliding systems used for ultrasonic rail monitoring are considered, and their comparison is performed. It is shown that the use of a wheel-type system, the acoustic path of which contains a liquid medium with an increased propagation time of ultrasonic vibrations, limits the control speed to 60 km/h. It is noted that when passing a wheel-type search system of curved sections of track and rails with lateral wear, a change in the direction of propagation of the ultrasonic beam is observed due to a change in the tilt of the wheel relative to the rolling surface of the rail head, which reduces the reliability of detection of rail defects. The disadvantages of the wheel system also include a complex design, low maintainability, poor protection when operating at low temperatures and mechanical stresses, limitations on the ability to operate at high speeds, complicated alignment and, in general, the complexity of maintenance. The characteristics of the retrieval sliding system developed by the specialists of JSC Firma TVEMA are given that provide detection of rail defects with high reliability, operate at low temperatures, and realize a control speed of up to 140 km/h, including in curved sections of the track. The advantages of the proposed non-contact magnetic centering system of the search system, excluding mechanical contact with the rail and the dependence of the centering accuracy on the state of the working face of the rail head, providing unhindered passage of turnouts, including without reducing the speed of control, are presented.

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Best practices about rail defects: a review of the book “Defects of rails. Stresses and Damages”, Vol. 1 by K.-O. Edel, G. Budnitskiy, T. Schnitzer

Vestnik of the Railway Research Institute ◽

10.21780/2223-9731-2021-80-3-182-185 ◽

2021 ◽

Vol 80 (3) ◽

pp. 182-185

Author(s):

E. A. Shur

Keyword(s):

Best Practices ◽

Statistical Data ◽

Defect Formation ◽

Publishing House ◽

Contact Fatigue ◽

Test Methods ◽

Rail Head ◽

Rolling Surface ◽

Damage Diagnostics

The review analyzes a monograph published by Springer Vieweg publishing house, which presents scientific approaches to the problems of defect formation in railway rails. The advantages of the book under review include the analysis of statistical data on rail failures, description of test methods and damage diagnostics. The book discusses in detail the widely occurring types of contact-fatigue defects formed during operation in the rail head: internal longitudinal shelling, multiple parallel head checks, surface squats und studs in the middle of the rolling surface with a greater or lesser degree deformations

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STUDY OF TRANSPORTATION PROCESS AS A FACTOR OF RAILWAY TRACK OPERATION

Transport systems and transportation technologies ◽

10.15802/tstt2020/217403 ◽

2020 ◽

pp. 60-65

Author(s):

М. А. АРБУЗОВ ◽

Є. В. АРБУЗОВА

Keyword(s):

Lateral Force ◽

Railway Track ◽

Rolling Stock ◽

Operational Parameters ◽

Rail Head ◽

Rolling Surface ◽

Transportation Process ◽

Longitudinal Slope ◽

Technical Systems ◽

Regional Branch

Abstract. The transportation process depends on the state of the technical systems involved. Technical systems depend on the organization of the transportation process. The paper considers the influence of operational parameters on the condition of the railway track. To study this problem, the most difficult section of the Slavsko-Lavochne-Beskid-Volovets track was chosen at the Lviv Railway regional branch. The influence of the missed tonnage, radius of the curve, longitudinal slope, speed and increase of the outer rail on the lateral wear of the rail head was investigated. It is established that all factors are influential. But the most influential - the longitudinal slope, in second place - speed, in third place - the radius of the curve. The effect of the slope on the rise was greater than the effect of the slope on the descent 3.3 times. A multiparametric mathematical law is established, which reflects the process of lateral wear of the rail head depending on the operational factors. This function allows you to predict the amount of lateral wear of the rail. Significant deviation of actual wear from the calculated, called excessive wear. From the analysis of data of the regional branch "Lviv Railway" it follows that 40% of the curved sections of the track with excessive wear are located on the section Slavsko-Lavochne-Beskid-Volovets. During the Lavochne-Beskid 1629 km pk9 race on the odd track, the test section of the track was equipped with strain gauges and prognometers, which were installed in the places of the smallest and largest lateral wear. There was an increase of 34% in lateral force in the cars in front of the pusher locomotive. No exceedance was detected. Observations at the Lavochne-Beskid race showed that the rolling stock was moving at a speed of 35 km/h. Thus, the established speed of movement of freight trains makes 60 km / h and during calculations is accepted as the minimum freight. That is, there is an under-realization of speed. Calculations show that this reduces the service life of the rails by 38%. Metal ingots in the shape of a wheel crest and a rolling surface were also found in the track. These ingots, formed from scales and drops of metal, are formed as a result of excessive braking in the pass sections, which is a consequence of the heavy weight of the train and steep descents. The paper develops recommendations for the transportation process in areas of complex plan and profile.

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

Vestnik of the Railway Research Institute ◽

10.21780/2223-9731-2019-78-3-131-140 ◽

2019 ◽

Vol 78 (3) ◽

pp. 131-140

Author(s):

A. Ya. Kogan

Keyword(s):

Mathematical Model ◽

High Frequency ◽

Welded Joint ◽

Electric Locomotive ◽

Specific Calculation ◽

Rail Head ◽

High Frequency Oscillations ◽

Rail Wear ◽

Rolling Surface ◽

Electric Train

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

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Prediction of Fatigue Crack Propagation of Rail Material Using 2D Finite Element Modeling

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.165.16 ◽

2012 ◽

Vol 165 ◽

pp. 16-20

Author(s):

N.A. Akeel ◽

Z. Sajuri ◽

Ahmad Kamal Ariffin

Keyword(s):

Finite Element ◽

Fatigue Crack ◽

Stress Intensity ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Stress Intensity Factors ◽

Intensity Factors ◽

Rail Track ◽

Rail Head ◽

Head Surface

Fatigue crack propagation in two-dimensional rail track model under constant amplitude loading was analyzed using finite element method. The stress intensity factor was predicted using the displacement correlation method that was written in FORTRAN code and exported to Post2D to run the program and utilizing the singular elements around the crack tip area with automatic remeshing model. The fatigue crack propagation is modeled through the successive linear extensions under the linear elastic assumption. To simulate the propagation a single edge angled-crack was introduced to calculate the accurate values of stress intensity factors. The fatigue crack propagation for rail track under four point bend loading model was successfully simulated. The crack was initially propagated in direction inclined to the rail head surface but changed its direction 90° to rail head surface after certain crack length. The mix mode stress intensity factors were also successfully determined through the proposed model.

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Performance of a low-frequency hybrid vibration isolation platform for vibration-sensitive devices

Journal of Low Frequency Noise Vibration and Active Control ◽

10.1177/1461348418791336 ◽

2018 ◽

Vol 37 (4) ◽

pp. 1164-1175 ◽

Cited By ~ 3

Author(s):

Xiling Xie ◽

Jianchao Diao ◽

Yinglei Xu ◽

Zhiyi Zhang

Keyword(s):

Root Mean Square ◽

Vibration Isolation ◽

Low Frequency ◽

Vertical Direction ◽

Mean Square ◽

Frequency Range ◽

Isolation System ◽

Rolling Surface ◽

Vertical Vibrations ◽

Hybrid Isolation

For preventing the fragile optical communication devices from malfunction caused by the low-frequency seismic excitation, a novel three-dimensional hybrid isolation platform is proposed in this paper. To isolate the horizontal and vertical vibrations simultaneously, the platform is designed as a combination of a rolling isolation system and four three-parameter isolators with active damping. By deriving the governing equations of the three-parameter isolators and the profile of the concave rolling surface, the dynamic model of the whole platform is constructed. Numerical results indicate that the isolation platform has an effective suppression of the horizontal and vertical vibrations. To verify the isolation performance of the hybrid isolation platform, an experiment is conducted in the targeting frequency range. Compared to the amplification factor of 6.2 dB of the three-parameter isolator, the test results exhibit that the hybrid isolation shows no amplification effect in the vertical direction, and the root mean square value of acceleration responses can be decreased by more than 65% in the frequency range of 0–32 Hz. In the horizontal direction, the reduction of the root mean square value of acceleration responses is up to 85% in the same frequency range.

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Stochastic load generated by the beam irregularities

MATEC Web of Conferences ◽

10.1051/matecconf/201821111007 ◽

2018 ◽

Vol 211 ◽

pp. 11007 ◽

Cited By ~ 1

Author(s):

Piotr Koziol ◽

Dariusz Kudla ◽

Cristinel Mares

Keyword(s):

Statistical Analysis ◽

Stochastic Analysis ◽

High Speed ◽

Practical Application ◽

Rail Track ◽

Rolling Surface ◽

Analysis Of Results ◽

Stochastic Load ◽

Railway Engineering ◽

Moving Train

The problem investigated in this paper comes from railway engineering. It is known that geometrical irregularities of the rail head rolling surface produce additional force when the train runs on track. This force can be quite significant and should not be neglected in the analysis, especially when one deals with high-speed railways. In this paper, an analytical method of modelling of such irregularities is presented. The detailed description of this method is associated with its practical application to the analysis of the rail track dynamic response to moving train. However, stochastic analysis of the presented model is omitted in this paper and left for further work. This should include a number of realisations along with statistical analysis of results, or description of the rail track subjected to moving train in terms of stochastic differential equations, which is the main direction of the authors future investigations.

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INVESTIGATION THE INFLUENCE DIFFERENCE OF THE WAGON’S WHEELS DIAMETERS ON ITS DERAILMENT BY QUASI-DYNAMICS METHOD

Criminalistics and Forensics ◽

10.33994/kndise.2019.64.57 ◽

2019 ◽

pp. 608-614

Author(s):

A. Kuzyshyn

Keyword(s):

Lateral Force ◽

The Body ◽

Rolling Stock ◽

Wheel Pair ◽

Rail Head ◽

Rolling Surface ◽

Significant Difference ◽

Negative Effect ◽

The Difference ◽

Dynamics Method

In the article the author notes that the horizontal forces arising in the process of pressing the wheel flanges to the working edge of the rail, under certain conditions can be very significant. These forces, in combination with the wheel unloading, caused by the geometric deviation of the track in the plan and profile, can lead to rolling the wheel of the wheelset onto the rail head and, as a consequence, to the stock derailment. Such pressing of the wheel to the rail head in the straight part of the track can occur when faults in the running gears of the wagons: non-parallelism of the axles of the wheel pairs of the bogie frame by the difference in the bases of the side frames, wear of the guide axle-box openings; the difference of the flanges on one wheel pair is more than permissible, wear of the body and bogie bolster center plates, step bearing; a significant difference in the diameters of the wheels of the wheelset caused by the intense wear of the rolling surface of one of them, etc. The article deals with the investigation of the influence of the wheels’ diameters difference of the wheelset on the amount of lateral force for the empty and loaded state of the rolling stock wagon. The results obtained made it possible to conclude that an increase in the wheels’ diameters difference of the wheelset of a loaded wagon of rolling stock leads to more intensive growth of the lateral force, as compared with the exhaust. This is caused by the linear dependence of the lateral force on the mass of the wagon of the rolling stock. However, for both the empty and the loaded wagon, the increase in the lateral force value has a negative effect. In conjunction with the unloading of the wheel it increases the probability of rolling in the wheel of the wheelset on the rail head. Also, an increase in the action of the lateral force from the wheelset on the rail, causes increased wear of the rail, the wheel flange, which is pressed. At the same time, rolling surfaces of an irregular shape are formed on the surface of the other wheel. Therefore, it is important to ensure the maintenance of the wheels of a wheel pair with the smallest difference in its diameters. Key words: rolling stock, diameter difference of wheels, quasi-dynamics method.

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Development of the structure of differentially hardened 100 m rails during their long operation

Izvestiya Ferrous Metallurgy ◽

10.17073/0368-0797-2020-2-108-115 ◽

2020 ◽

Vol 63 (2) ◽

pp. 108-115 ◽

Cited By ~ 1

Author(s):

V. E. Kormyshev ◽

E. V. Polevoi ◽

A. A. Yur’ev ◽

V. E. Gromov ◽

Yu. F. Ivanov

Keyword(s):

Impact Strength ◽

Strain Hardening ◽

Cross Section ◽

Materials Science ◽

Structural Phase ◽

Term Operation ◽

Rail Head ◽

Rolling Surface ◽

Head Surface

Using methods of modern physical materials science, structural-phase states and mechanical properties of the rolling surface have been analyzed at distance of 0 to 22 mm along the central axis and along the fillet of differentially hardened 100 m rails of DT 350 category manufactured by JSC “EVRAZ – United West Siberian Metallurgical Plant” after their long-term operation (passed gross tonnage of 1.411 million tons) on experimental test ring. In terms of chemical composition, metal of the rails meets TU 0921-276-01124323 – 2012 requirements for E76KhF steel. Impact strength and hardness on head surface and along cross-section meet TU specifications. Microstructure of rails metal is represented by finely dispersed plate perlite of 1.5 points with inclusions of excessive ferrite along the grain boundaries (1.5 points by GOST 8233 scale No. 7). Interlamellar distance in the rail head varies between 0.10 and 0.15 microns. Long-term operation of rails is accompanied by development of gradient structure, manifested in regular change in hardness, microhardness, impact strength along cross-section of the rail head. Microhardness at 2 mm depth from the rolling surface is 1481 – 1486 MPa. At 10 mm depth microhardness decreases to 1210 – 1385 MPa, which is caused by an increase in interlamellar distance and decrease in the level of strain hardening of metal during long-term operation of rails. It has been suggested that this may be due to an increase in interlamellar distance and a decrease in level of strain hardening during long-term operation.

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