Rail Joints Research Articles

Effectiveness of EU-funded R&I programmes from the perspective of the European railway sector stakeholders

The paper provides a methodology for measuring the adherence of Research & Innovation (R&I) actions in railways to the stakeholders’ requirements and expected benefits. After collecting the stakeholders’ requirements, the R&I objectives are extracted from high-level documents such as Europe's Rail Joint Undertaking Master Plan and Multi Annual Work Programme. Lastly, after standardization of the requirements and the technology concepts, a top-down analysis is performed. The results show that network management and vehicle technologies have the highest benefit for the stakeholders, and ERRAC and Regulatory Bodies’ requirements are well addressed. However, the end-users requirements are only partially fulfilled. The necessity of increasing multimodal transport and cooperation with other transport modes is shown, while stronger focus can be placed on the employees and education/training.

Rail Joint Gap Measurement Method using Train Frontal Images Captured by a Handy Video Camcorder

Rail Joint Gap Measurement Method using Train Frontal Images Captured by a Handy Video Camcorder

Unsupervised Discrepancy-Based Domain Adaptation Network to Detect Rail Joint Condition

Unsupervised Discrepancy-Based Domain Adaptation Network to Detect Rail Joint Condition

Bonded insulated rail joint monitoring using gap opening variation with fibre optic sensors: analytical validation and limits

The monitoring of bonded insulated joints makes it possible to overcome the limits dictated by cyclical scheduled maintenance, helping the infrastructure manager to anticipate the formation of possible failures. A field monitoring system that measures the joint gap opening variation was investigated, using optical fibres with Bragg gratings placed at the head of the two adjacent jointed rails. Through the application of the Zimmermann analytical model, a first quantitative validation of the data recorded by the monitoring systems measuring the joint gap opening variation was proposed. Based on the different types of failure of a bonded insulated joint, the debonded of insulating element of the joint was identified as a typical condition. Starting from this through a finite element analysis, some characteristic limitations of these monitoring systems were identified by assuming four different bonding scenarios.

Consensus and dissent for rail visions of 2050: Insights from a Delphi study

This study was undertaken to determine if the rail stakeholders agreed with the Rail Vision 2050 document and agreed or dissented with the vision statements contained within the document. This was important as the next generation of this document is intended to be the basis of a Strategic Research and Innovation Agenda (SRIA) for Rail. A Delphi survey revealed the consensus and the dissent in relation to the statements. The methodology is presented along with the results. The impact of this paper is that it has been used to inform the European Rail Research Advisory Council (ERRAC) to formulate the research priorities for the EU rail sector and in particular the strategic rail agenda, the SRIA. The SRIA is a key document for the rail sector and the preparation of Shift2Rail's successor within Horizon Europe: “Europe's Rail Joint Undertaking”.

Local vertical compressive stress in the crane runway beam web

In this paper, the authors analysed several variants of connections between a block rail (60 mm × 60 mm) and a crane runway beam (IKS 800-6). They compared local vertical compressive stress in the crane runway beam web, calculated using an analytical approach and numerical simulations. In the case of the continuous block rail rigidly fixed to the beam flange, satisfactory convergence was obtained. For the remaining types of connections the results based on the analytical method were different from the results of the numerical simulations. The difference resulted from the fact that the analytical method did not take into account the crane rail joint. Furthermore, the impact of the elastomeric bearing pad on the local stress value was taken into account in a simplified manner in the analytical method by increasing the effective length by approximately 30%. The local vertical compressive stress in the crane runway beam web was significantly affected by the connection between the rail and the crane runway beam, the crane rail joint type, the use of the elastomeric bearing pad, the length of the elastomeric bearing pad, and the crane rail wear.

Residual Stress Measurement Techniques for Metal Joints, Metallic Coatings and Components in the Railway Industry: A Review

Manufacturing and maintenance procedures in the railway industry regularly implement welding and metal deposition operations to produce joints, coatings and repair structures. During these processes, residual stresses arise through the generation of heat affected zones and plastic deformation. This makes accurate measurements of the internal stresses a critical aspect of manufacturing, monitoring, repair and model validation in the develop new metallic coating and joining technologies. Selection of an appropriate residual stress measurement method has many important factors including component size, resolution and the magnitude and location of internal stresses, often resulting in a combination of techniques required to obtain complete assessment of the stress state. This paper offers a review of residual stress measurement techniques for railway components including rail joints and coatings through comparison of destructive and non-destructive approaches, their measurement capabilities, benefits and limitations. A comprehensive discussion of different applications is provided with a summary of facilities available to both research and industry.

Study of Melting Methods by Electric Resistance Welding of Rails

An analysis of the results of rail operation shows that up to a third of all rail breaks in the railway line and up to 12.9% of all withdrawn acute defective rails are associated with welded joints. This is largely explained by the formation of structures with martensite sections in the welded joints of rails and the formation of burns. This work presents the results of studying welded joints, obtained under three welding modes (continuous flash welding, pulsating flash welding and combined flash welding). The conducted studies have shown that the flash welding mode significantly influences both the cooling rate value and the very nature of the thermal cycle of the welded joint as a whole. Changes in the cooling rate under different modes exert a significant influence on the structure and properties of the weld. Resistance welding of rails from the steel grade E76HGF by pulsating flash welding can result in the appearance of needle martensite areas, which is the reason for increased embrittlement of the weld and a decrease in its properties. The conducted field experiments have reliably shown that in the conditions of the combined welding mode it becomes possible to avoid these problems. Moreover, a slight increase in the mechanical properties of the weld in the range of 2–4% has been experimentally recorded, and the destructive load of the welded joint of the rail increases by 2–3% at high values of the bending deflection. In turn, these factors allow a significant reduction in the number of cases of rail welded-joint failures in real conditions of their operation.

Numerical investigation of the transient wheel-rail impact behaviour in high-speed turnouts caused by a bonded insulated rail joint

Bonded insulated rail joints (Bonded IRJ) are essential to insulate rails and ensure normal operation of track-circuit signalling. Therefore, bonded IRJs cannot be replaced by the continuously welded joints and are widely existing in high-speed turnouts, by which the wheel-joint impact has been severely threatening the ride safety and comfort. Few researchers are concerned about how the damaged bonded IRJ deteriorates the wheel-rail contact behaviour in high-speed turnouts. To this end, this paper proposed a transient wheel-rail impact model based on the actual irregularities. Results show two different wheel-rail impact modes. The concave shape of the irregularities will induce the discrepancy of impact position when the running speed varies, thus the increase in speed causes the peak wheel-rail force to decrease in downward impact mode as opposed to upward impact. Besides, wheel-joint impact induces greater contact stress and area of contact patches in the vicinity of the end-post, contributing to wider light bands which are consistent with the on-situ conditions. Therefore, the proposed wheel-bonded IRJ impact model can provide guidance in the research of RCF and wear on bonded IRJ, explore the forming reason of the depression and provide a valuable reference for maintenance or damage detection of bonded IRJ.

Dynamic response of vehicle-track interaction at the bolted rail joint in the presence of the polygonal wheel

Rail joints are the weakest link in the railway track structure due to the presence of discontinuities in the track stiffness and wheel-rail contact geometry. This paper presents the dynamic response of vehicle-track interaction at the bolted rail joint (BRJ) in the presence of polygonal wheel wear. A three-dimensional coupled vehicle-track dynamic model was established using the finite element method (FEM) and the multi-body system (MBS) approach, in which the flexibilities of the wheelset and track are taken into account. The proposed dynamic model is validated by the comparisons of field measurement and calculated vertical axle-box acceleration in time and frequency domains. The effects of the flexible wheelset in the presence of polygonal wear on the vehicle-track dynamic interaction at the BRJs are illustrated through comparisons with those obtained using without polygonal wheel model. The results show that the polygonal wheel wear and the rail joint irregularities can induce high-magnitude vertical wheel-rail contact force, and exacerbate the vibration responses of the axle box, the wheelset, and the rails. The simulation results also indicate that the wheelset bending modes, the P2 resonance due to rail joint excitation, and the track vibration modes have significant effects on the vertical vehicle-track dynamic interaction at the supported and suspended BRJs.

Profile evaluation of rail joint in a 3‐m wavelength based on unsupervised learning

AbstractPreviously, electronic straightedges with a length of 1 m were widely used to measure the longitudinal profiles of rail joints. However, owing to the lack of an efficient measurement device, rail joints with 3‐m wavelengths are seldom studied. In this study, a rail measurement trolley based on the chord‐reference method was developed with a measurement wavelength of up to 3 m. A field measurement was performed on a 53‐km metro line, and the waveforms of 4340 rail joints were obtained. First, to visualize the distribution of the dataset and to find out the common features, t‐distributed stochastic neighbor embedding dimensionality reduction was applied to the rail joint dataset, and each rail joint waveform was mapped to a point in a two‐dimensional space. Second, K‐means was applied to the rail joint dataset, and six categories of rail joints were obtained. The results indicated that there are two types of rail joints: M‐type and W‐type, accounting for 18.41% and 76.08% of the total number of joints, respectively, and the remainder are bolted rail joints. Third, to better evaluate rail joint status, the concept of rail joint triangle (RJT) is proposed, and five shape‐based features of a rail joint in 3‐m wavelength are defined. Finally, using RJT distribution analysis, we observed that the shape‐based features provide more essential information about a rail joint, such as symmetry, asymmetry, M‐type, or W‐type, compared with conventional indexes such as the quality index. Notably, compared with the waveform of a rail joint at 1 m, a 3‐m waveform provides significantly more essential information, which can be meaningful for future research on the dynamic impact of rail joints, as well as profile grinding around rail joints. To help other researchers follow our research, our dataset is available on Mendeley Data (RWJ‐3 m dataset).

CUFuse: Camera and Ultrasound Data Fusion for Rail Defect Detection

This paper proposes a multi-source data fusion algorithm for rail surface defect detection in both camera-based rail inspection images and ultrasound B-scan images. First, we design a rail surface segmentation algorithm based on image bilateral filtering, Sobel edge detection, and rail surface edge detection to extract the rail surface area. Second, we build a camera and ultrasound data fusion (CUFuse) model for rail surface defect detection, including two main networks: multi-source data feature extraction and multi-scale feature fusion networks. The multi-source data feature extraction network consists of two BoTNet 50 networks as feature extraction networks to extract five stages of features in camera-based images and ultrasound B-scan images. The multi-scale feature fusion network consists of five feature fusion modules to fuse the feature information output by the multi-source data feature extraction network. Finally, we use the CUFuse model to detect the rail surface defect dataset, and output five rail surface state types, including Light, Moderate, Severe, Normal, and Joint. The results show that the accuracy of the CUFuse model is 96.97%, which can accomplish the task of rail surface defect detection on railway sites.

Modified internal curvilinear distraction device with a pre-embedding guide rail, drive screw, and universal joint for curvilinear lengthening of the mandible: A finite element analysis and animal experiment

ObjectivesThe semiburied design of the traditional internal distractor has a relatively high risk of infection and aesthetic problems. To reduce these potential risks, a modified internal distractor with design of pre-embedding curvilinear rail, drive screw, and universal joint was invented. Its stress distribution characteristics and the effect on curvilinear distraction osteogenesis (DO) in vivo were further tested. Materials and methodsFinite element analysis (FEA) was performed on a model of the human mandible and distraction device to measure the stress distribution during curvilinear DO. Six beagles underwent curvilinear DO and consolidation using the new device. Radiological and histological examinations were performed on the new bone. ResultsOn FEA, the stress was concentrated in the condyle (128.6 MPa) and curved guide rails (324.8 MPa). Four of the six animals completed the DO period and were consolidated for 12 weeks. Secondary infections were not observed. Radiography showed that a new fan-shaped bone—15.5 ± 5.5 mm in length and 4.6 ± 1.6 mm in height—was formed in the bone gap. Micro-computed tomography and histological examinations of specimens indicated that the structure of the new bone was similar to that of the normal bone. ConclusionsThe modified internal curvilinear distraction device meets the mechanical strength requirement and achieve curvilinear DO in animal experiments.

Abnormal noise monitoring of subway vehicles based on combined acoustic features

Subways play a significant role in urban rail transit. A monitoring technology for abnormal noise in subway vehicles is studied in this paper to ensure safety. Microphones are placed near the bogie components to acquire acoustic signals during the subway operation. A modified time-spectral kurtosis (MTSK) feature parameter is proposed to take advantage of the sensitivity of the kurtosis to the impact signal and is combined with the mel-frequency cepstral coefficients (MFCC), which reflects the acoustic characteristics of the human ear, to build a neural network model. The normal background noise (including the wheel-rail impact signal at the rail joints) and abnormal impact sound in the bogie area of the vehicle are classified. The results are compared with those before the feature improvement. The experimental results show that the recognition performance of abnormal impact sounds is indeed improved using feature vectors, including MTSK and MFCC. The accuracy rate of the classifier constructed in this work is 99.6% at a speed of 20 km/h. It can also achieve 97.2% and 86.1% at 40 km/h and 60 km/h, respectively. The improvement of the proposed method is more effective even at a lower signal-to-noise ratio compared with other features.

Analysis on the Dynamic Characteristics of Cross-Tunnel Structures under Wheel-Rail Impact Forces

The dynamic behaviour of cross-tunnel structures under the wheel-rail impact forces of heavy-haul trains is complicated. This paper establishes an impact force excitation input model to simulate the wheel-rail vertical forces of rail welded joints. The calculated results of the correction formula of wheel-rail vertical forces for seamless rail joints are in good agreement with the measured data and meet the accuracy requirements. The present paper describes a 1/50 scale model experiment based on the case of the newly-built Jing-Zhang Railway underneath the existing Tang-Hu Heavy Haul Railway. Numerical simulation analysis uses FLAC3D to simulate the experiments and investigate the dynamic soil pressure characteristics under different factors. The test and numerical results showed that the dynamic responses of the upper tunnel monitoring points are stronger than the lower tunnel, but the maximum vertical settlement of the lower tunnel vault is bigger and prone to damage. As the depth increases, the stress of the surrounding rock interlayer at each monitoring point gradually decreases. In-depth, the surrounding rock stress decreased approximately non-linearly with increasing surrounding rock grade and surrounding rock interlayer thickness.

Effect of lateral misalignment defects of rail joints on dynamic derailment behaviour in railway turnouts

This study aims to investigate the mechanism of wheel jumping derailment in the railway switch panel after a freight wagon passes over a rail joint defect (RJD) situated before the switch. For this purpose, a 3D vehicle-track (turnout) coupled dynamic model that considers the elastic deformation of the rails and wheelsets has been established. Several extreme running conditions, including sharp curves, low-speed railway turnouts, lateral misalignment defects of RJs, and empty wagons are all considered in the simulation model. The vertical wheel rise limit for the railway switch panel is presented for the evaluation of a quasi-static derailment risk. The wheel-rail impact behaviour and the evolution of the derailment processes in the switch panel are revealed, and the effects of wagon load and misalignment width of RJ sections on the vehicle’s dynamic response and running safety are investigated. The results show that the root cause of the high derailment risk in the railway switch is a lower wheel rise limit at the front region of the switch rail when compared with the mainline. This dynamic derailment limit is sensitive to the car-body load and the misalignment width. Severe lateral defects of the RJ before the switch toe should therefore be avoided.

Deep neural network for diagnostics of railway track components

The problem of increasing the speed of railway transportation and ensuring reliability is associated with constant monitoring of the condition of the railway tracks. The modern track measuring cars are equipped with video cameras and computer equipment for processing the received information. However, manual processing of data by operators in real-time is not possible. The article proposes a deep convolutional neural network for automatically recognizing and classifying defects in rail joints on rail track images. The rail video observation forms the image array during the passage of the track recording car. The formation of classes of rail joints is described. Regular rail joints with connectors, insulating joints, and welded joints are considered. Additional classes are identified, corresponding to various anomalous configurations of rail joints in the images. A modified structure of a pre-trained deep convolutional network is constructed. When preparing training samples, the actual images of rail joints were supplemented with artificial images obtained by affine transformations. The process of training and testing the classifier based on the developed convolutional network is described. The Transfer Learning is used to train the neural network. As a result of the experiments, the accuracy of classifying rail joints and detecting defects was at least 96%.

PROCESSES OF WELDED JOINT STRUCTURE FORMATION DURING ELECTRIC RESISTANCE WELDING OF RAILWAY RAILS

During operation of a continuous welded rail track, most of the fractures occur in welded joints. Welded joints failures take place due to various reasons including the presence of the hardened areas in the welded joint and increased local wear of the rolling surface. The paper presents the dilatometry results and the obtained continuous cooling transformation diagram of the supercooled austenite decomposition for R350LHT rail steel, which make it possible to define the critical cooling rate. It was determined that during welding in hard modes the welded joint cooling rate is lower than the critical one which leads to the martensite formation in the welded seam. The positions of critical points and phase equilibrium areas for the given rail steel were also modeled. It is proposed to use a new method for welding railroad rails based on the knowledge of dependences of the structural components dispersity and, first of all, pearlite and carbide particles formed in the process of obtaining welded joints of rails on the composition of steel and the conditions of their cooling.

A Numerical Simulation of UIC60 Rail-Weld's Fatigue and Crack Growth under Wheel Frictional Contact and Bending

In service condition rail joints, especially the weldments are under the action of various loadings which are not only working in multiple axis direction but also time-dependent having a cyclic and mixed-mode in nature and non-relative to each other. The surface of the rail and its weldment is acted by very high repetitive stress through the wheel and because of this contact stress the running surface or subsurface may have cracks or fractures due to fatigue. This work is based on numerical simulation of an aluminum thermite weldment on a UIC 60 rail under multi-axial fatigue crack propagation under the friction with surficial interaction between weldment and wheel with bending load due to vertically applied load through the wheel on the weld. Since contact is highly influenced by vertical load and also for minimizing the simulation time the lateral and longitudinal traction forces are not included in this study. The work formulation and discretization have been done with the finite element method and a non-linear lagrangian algorithm solver is applied. A 3-D rail-weld wheel model assembly and a semi-elliptical crack as a flaw on the weld surface are used to identify 3-Modes of SIFs along with its graphical plot generation. Simulation is performed under multi-axial weld wheel surface contact at different locations on weld running surface, taking into account varying position of fracture crack on weld 3-D model to calculate fracture life of weld joint and observation of fatigue crack propagation. This work involves the numerical and theoretical approach of fracture mechanics on created FE fatigue model using the Linear Elastic Fracture Mechanics (LEFM) method following Paris law for fracture mechanics. All the numerical simulation for critical fracture dimension and cycle count with stress intensity factor for weld failure data is estimated using software ANSYS 2020 academic and plotted, then comparison of predicted and observed transverse crack growth behavior and fatigue life of weld, based on Millions Gross Tonnes (MGT) is discussed.

Determining the features of temperature influence on the load-bearing structure of a hopper car with a composite cladding when transporting pellets to metallurgical enterprises

This paper reports the improved load-bearing structure of a hopper car for transporting pellets and hot sinter. In order to increase the strength of the load-bearing structure of a hopper car under the influence of high temperatures from the transported cargo, the use of cladding made of composite material has been proposed. This solution also contributes to a 5 % reduction in the wagon's tare compared to the prototype car. The dynamic load on the load-bearing structure of a hopper car was determined. This study was carried out for the case where an empty wagon was moving over an irregularity between the rail joints. The calculations showed that the studied dynamics indicators did not exceed the permissible values. At the same time, the ride of a hopper car is rated as "excellent". The main indicators of the strength of the carrying structure of a hopper car were determined taking into consideration the proposed improvement. That took into account the temperature effect exerted on the load-bearing structure of a hopper car by hot sinter. It was established that the maximum equivalent stresses occur in the zone of interaction of the girder beam with the pivot beam and are about 290 MPa. At the same time, stresses in the cladding of a hopper car are about 200 MPa, which is 12 % lower than those in a regular structure. Modal analysis was carried out to determine the frequencies and shapes of the natural oscillations of the bearing structure of a hopper car with a composite cladding. The calculation results demonstrated that the first natural frequency exceeds 8 Hz. Therefore, the safety of the wagon is provided. The coefficient of fatigue resistance of the load-bearing structure of a hopper car was calculated. It was established that its value is almost twice as high as the permissible one. That is, the resistance to fatigue of the supporting structure is provided. The research reported here could contribute to ensuring the strength of the load-bearing structures of hopper cars, reducing the cost of maintenance, and increasing the efficiency of their operation.