Rail Joints Research Articles

Effects of impact load caused by wheel passing rail joint on fatigue at the deck system of a steel box girder

Effects of impact load caused by wheel passing rail joint on fatigue at the deck system of a steel box girder

Developing Machine Learning-Based Models for Railway Inspection

Smart railway maintenance is crucial to the safety and efficiency of railway operations. Successful deployment of technologies such as condition-based monitoring and predictive maintenance will enable railway companies to conduct proactive maintenance before defects and failures take place to improve operation safety and efficiency. In this paper, we first propose to develop a classification-based method to detect rail defects such as localized surface collapse, rail end batter, or rail components—such as joints, turning points, crossings, etc.—by using acceleration data. In order to improve the performance of the classification-based models and enhance their applicability in practice, we further propose a deep learning-based approach for the detection of rail joints or defects by deploying convolutional neural networks (CNN). CNN-based models can work directly with raw data to reduce the heavy preprocessing of feature engineering and directly detect joints located on either the left or the right rail. Two convolutional networks, ResNet and fully convolutional networks (FCN), are investigated and evaluated with the collected acceleration data. The experimental results show both deep neural networks obtain good performance, which demonstrate that the deep learning-based methods are effective for detecting rail joints or defects with the expected performance.

The effect of rail joints on dynamic effort resulting from movement of bridge cranes wheels

The effect of rail joints on dynamic effort resulting from movement of bridge cranes wheels

Study on effect of dynamic load on rail joint bar by finite element method (FEM)

ABSTRACT The effects of vertical dynamic wheel loading and bolt conditions on rail-end joint bar by using the finite element method (FEM) in terms of vertical displacement, principal and shear stress are investigated. Preliminary results of dynamic load show that variation of either tight/loose-bolted joint bar has the response of rail-end joint varies, the joint bar vertical displacement, principal and shear stresses on the joint bar also vary. The test results show that contact force at the wheel-rail joint bar interface would not change monotonically with the variable train speed and the shear stresses calculated at joint bar significantly lower than the principal stress and stresses of the joint bar for a given speed. The tightly bolted joint bar is strongly recommended because of its high stiffness causing smaller deflection and smaller principal and shear stress on the joint bar can reduce initiation of failure around the joint.

Measurements of railway welded rail joints with a laser device

One of the methods of joining rails is welding with termite, which guarantees a secure and stable connection of two sections of the rail without the need to use additional connecting elements and supporting the welded place. After joining (making a weld), appropriate mechanical processing of the joint is required in order to obtain the given rail head profile. The quality and diligence of the connection made has a major impact on safety, noise emission during the journey (wheel rolling) and the comfort of travelers. This article describes selected methods of making railway rail joints and presents the results of measurements with a portable laser measuring device Calipri C40 of the rail head within the welded rail joint made by thermite welding. An attempt to use this device for measurements of welded rail joints is shown, advantages and disadvantages as well as conclusions from the performed measurements are described.

Effect of easement geometry on rail end fillet stress at bolted rail joints for transit track

Continuously welded rail (CWR) has become more popular than bolted joints because of the advantages of continuous geometry and stiffness and the resulting maintenance savings. Due to a variety of reasons, a considerable number of bolted joints are still in service in rail transit systems. With the high frequency of impact loads, rail at bolted joints are vulnerable to defects, such as cracking and head-web separation that could lead to more drastic failures and consequences (i.e. derailments, etc.). To prolong the service life of joint bars and rails, rail-end easements in the center of the bar were proposed and became standard in some freight rail companies. However, the effectiveness of a joint bar easement largely depends on the geometry of the easement. Therefore, the easement designed for freight track may not be effective for rail transit infrastructure. Further, the effect of easement geometry has not been thoroughly investigated and documented. Therefore, this study investigates the stress distribution at the rail end bolt-hole and upper fillet areas for joint bars with different easement geometries through a parametric analysis performed with Finite Element (FE) modeling. The FE model used in this study was developed specifically to study rail joints and was validated through full-scale laboratory testing. Results from this study show that a deeper easement yields lower contact stresses, while a longer easement does not necessarily reduce the contact stresses with the studied combination of rails and bolted joints for transit track. An easement may reduce the service life of the joint if the geometry of the easement is not properly engineered.

Experimental Study on Crack Detection at Bolt Hole Edge in Rail Joint Using the Third Harmonic

In this paper, a nonlinear ultrasonic detection method for detecting the hole edge crack in rail joint was proposed. The experimental results show that a single frequency sinusoid wave modulated by Hanning window is input to the rail specimen, there are higher order harmonics in the received signals for cracked rail, but there are no any harmonics for the rail with no crack bolt hole. That is to say the higher order harmonics can be used to indicate the presence of a crack. Furthermore, a nonlinear parameter μ is defined by the ratio of the third harmonic frequency peaks to the peak of the fundamental frequency. The relationship between nonlinear parameters and crack size is approximately linear, which means that the third harmonic not only can detect the presence of the hole edge crack, but also can assess the size of the hole edge crack.

Railway Traffic Monitoring System by Seismic Methods

This article describes a system for monitoring the movement of railway transport based on seismic methods. The current state and existing problems in the railway monitoring industry are briefly presented. It is proposed to use seismic signals in soils formed by passing trains in order to highlight information features and assess the characteristics of railway transport. These signals carry a large amount of useful information and can be used with proper processing and analysis. The characteristics of these signals are considered depending on the characteristics of rolling stock, such as speed and weight, and on a number of other external factors: the composition and condition of soils, the presence of rail joints and irregularities. An algorithm for processing seismic signals in order to distinguish the characteristicsof railway transport is described. In the final section, a diagram and a block of data collection are presented, as well as a brief description and features of the application of the developed monitoring system. This system will allow to accelerate the implementation of large-scale monitoring of the movement of railway transport, as well as to increase its efficiency and functionality, due to simpler and more inexpensive solutions.

Welding of differentially heat-strengthened rails. Laboratory studies

In laboratory conditions, influence of modes of welding with subsequent isothermal holding on quality parameters of welded joint was studied on rail steel samples. Samples were welded with pulses of alternating electric current after welding. Welding was carried out on MS-2008M resistance butt welding machine with a number of alterations of control actions. To measure temperature of the metal in heat affected zone (HAZ), chromel-alumel thermocouples were used. Collection and processing of data from thermocouples was carried out using TEMPOL measuring complex. Temperature of the weld (where it is not possible to install a thermocouple) was measured using HotFind-D thermal imager. Experimental results and physicomechanical properties of the samples are presented: HB hardness, HAZ length, yield strength, tensile strength, ultimate elongation, contraction ratio, and presence of non-metallic inclusions in weld metal. Deviations of hardness were calculated in comparison with the requirements established by GOST R 51685 – 2013 state standard on the surface of samples’ welded joints: decrease-increase and total deviation of hardness. Method of resistant butt welding is proposed, which makes it possible to obtain welded joint of items produced of rail steel with a uniform distribution of hardness and small zone of thermal influence. Dependence of microhardness on volume fraction of structural components was determined. Models of impact of pulsed contact post-welding heating parameters on lowering hardness of weld metal compared to the base metal and on the extent of heat-affected zone were constructed. The proposed method allows us to adjust structure of metal welded joints of rails without additional local heat treatment.

Microstructure-based approach to the evaluation of welded joints of bainitic rails designed for high-speed railways

Bainitic rails, due to their wear conditions, favorable mechanical properties and mechanical response under contact fatigue, have been widely investigated in recent years. In this research, the microstructure of a bainitic rail was analyzed after joining using the flash butt welding method. To date, the structural changes of bainitic rails after welding processes that directly affect their mechanical and functional properties have not been analyzed. The microstructure of the base material consisted of degenerated upper bainite, retained austenite and a negligible amount of cementite. No unfavorable martensite was found in the Fusion Zone (FZ), and its microstructure consisted of coarse degenerated bainite and retained austenite with a blocky and film-like morphology. In the High Temperature Heat-Affected Zone (HTHAZ), the bainitic structure was refined in comparison to the FZ, which resulted in a slight increase in hardness. In contrast, a drop in hardness was found in the HTHAZ. The microstructure of this zone consisted of bainite, polygonal ferrite, retained austenite and M/A constituents. The highest decrease in hardness was found in the Low Temperature Heat-Affected Zone (LTHAZ). In this zone, the retained austenite was completely decomposed into a mixture of ferrite and cementite particles.

Double heat treatment of welded butt joints of railway rails

Double heat treatment of welded butt joints of railway rails

Подвійна термічна обробка зварних стиків залізничних рейок

Подвійна термічна обробка зварних стиків залізничних рейок

An investigation into the fatigue failure of metro vehicle bogie frame

Metro vehicle bogie frame is usually subjected to complex external excitations. The fatigue damage accumulation of bogie frame is induced by multiple elements and may even lead to failure hazard. Therefore, a comprehensive investigation into the influencing elements was conducted in this paper. To achieve this purpose, a targeted field test was first carried out under normal operating conditions to obtain the dynamic stress and operating state data. Then, P2 resonance frequency of vehicle-track system was calculated, and rail corrugation and 8th order wheel polygon were determined. Damage analysis was performed for rail corrugation, wheel polygon, rail joint, velocity, and passenger capacity. The results indicate that rail corrugation accompanied with wheel polygon are the main reasons for the damage of bogie frame. This research will be beneficial for ensuring operation safety and developing reasonable maintenance schedule for metro vehicle.

The results prediction of iron oxides aluminothermy

"The paper presents the results and conclusions of the statistical processing of data on aluminothermic reduction reactions of iron oxides. Starting from the thermodynamic and chemical information regarding the aluminothermic reduction reactions of the iron oxide mixtures, their thermal and chemical effects were estimated and the information thus obtained was statistically processed. The results obtained by statistical processing of information obtained by theoretical reasons, presented in the form of regression equations or their graphical expressions, can be used to effectively determine the optimal phase composition of thermit kits based on iron oxides and forecast the value of reaction heat, resulting from the actual reactions development. The practical application of these results was ensured by the company QUARK IMPEX SRL, one of the main producers and users of thermit welding kits for rail joints by aluminothermal welding, in Romania. "

Design and implementation of a coal-dust removal device for heavy-haul railway tunnels

Abstract The Daqin Railway is China's first electrified double-track heavy-haul railway line dedicated to coal transportation. Over the years of operation, the tunnels have been covered with a thick layer of coal dust, which also pervades in the air. Worse is that the coal dust has even buried the rail joints in some sections, making the repair and maintenance of the line difficult. This paper introduces a coal-dust removal device for railway tunnels that integrates pipeline transportation with dust-collection techniques. The device is mainly composed of a power system, a conveying system, a dust-filtration and collection system, and a control and protection system. The key technical elements of the system, such as the dust-extraction method and dust-filtration and collection parameters, are optimized based on the characteristics of the coal dust in the tunnel (obtained via field trials), which greatly enhances the adaptability of the device. Coal-dust removal efficiency reached over 20 t/h, which improves the working environment, reduces the intensity of manual work required and solves the problem of coal-dust removal from the most polluted area—within 500 m of the tunnel entrance.

Study of wear resistance of railway rails welded joint

Welding joints of rails are a weak point of a jointless railway line, which stipulates actuality of studies on increasing their operational resistance. Microstructures of welded joints made by existing at present welding technology and by a new one were compared. Existing (base) technology comprises further thermal treatment of the welded joint, while the new technology comprises welding followed by a short-time electric current impact during the rail joint cooling. To study the microstructures of welded joints, samples were cut out the welded seam zone and heat affected zone, as well as out of the base metal. The study was carried out in the depth of 5 mm from the surface, after thin section etching by 4% solution of nitric acid in alcohol. In the macro-structure of the metal of welded joint, made by the base technology, an uneven heat affected zone was detected. The zone had the following dimensions: 51 mm – in the head, from 45 mm to 62 mm – in the neck and 64 mm – in the bottom (by each of the seal side). In the longitudinal mac- ro-template of sample Б (the new welding method), the heat affected zone was even and along the whole joint had the width of 22 mm (in each of the joint side). It was shown, that the new welding method of railway rails enables to decrease the extension of zone with sorbitic and granular pearlite at various stage of coagulation. A short-time impact of electric current during rail joint cooling ensures obtaining a zone with a decreased hardness of 15 mm extension and decrease of welded seam metal hardness relatively the lower border of base metal hardness by less than 15%. Application an additional local thermal treatment by a separate induction heating during base technology results in forming zones of 30 mm extension in the area of welded joint, which wear resistance is 4.5 times lower comparing with wear resistance of the rail base metal. At the new welding method application, the extension of the abovementioned zone does not exceed 10 mm and wear resistance was decreased by less than 2 times.

Результаты исследования вибрации в зоне рельсового стыка при рельсовых скреплениях различной упругости

Результаты исследования вибрации в зоне рельсового стыка при рельсовых скреплениях различной упругости

Оцінка якості зварних з’єднань високоміцних залізничних рейок сучасного виробництва з урахуванням вимог українського та європейського стандартів

Оцінка якості зварних з’єднань високоміцних залізничних рейок сучасного виробництва з урахуванням вимог українського та європейського стандартів

Evaluation of quality of welded joints of high-strength railway rails of modern production taking into account the requirements of ukrainian and european standards

Evaluation of quality of welded joints of high-strength railway rails of modern production taking into account the requirements of ukrainian and european standards

Welding of differentially heat-strengthened rails. Industrial testing

The article describes the study of welding processes with the subsequent control of cooling of full-profile rail joints, produced by passing alternating electric current pulses after welding. The influence of welding modes on the quality of welded joint was investigated. Welding was carried out on a resistance butt welding machine MCP-6301 in conditions of the rail welding company LLC “RSP-M” (RSP-29). For research, the samples of P65 type full-profile rails of DT350 category 600 mm long were cut out. The isothermal holding conditions after welding were controlled using a personal computer with a change in the program of the SIMATIC S7-300 industrial controller and the software SIMATIC STEP 7, which allows modes of controlled cooling to be set. The control program was written in the LAD graphic language. To search for optimal modes of controlled cooling, a complete factor experiment N = 2k was carried out. Non-heat-treated joints were tested for three-point static bending according to the state standard STO RZD 1.08.002 – 2009 “Railway rails, welded by electric contact method”. Static bending tests were carried out on the press of PMS-320 type. Values of the force arising during bending Pbend and the bend deflection fpr at which the control sample is destroyed, were determined, as well as maximum values of these indicators if the sample was not destroyed during the tests. During the experiments, regression models were obtained for output parameters of the bending force and bend deflection. Macrostructure of the samples and distribution of the metal hardness on rolling surface of the rails welded joint were studied. A new method of resistance butt welding was developed, which makes it possible to obtain a welded connection of P65 type rails of DT350 category with properties that exceed the technical requirements of the mentioned state standard.