Railway Components Research Articles

A Vision Based Condition Monitoring Approach for Rail Switch and Level Crossing using Hierarchical SVM in Railways

Rail track, t urnout and level crossing are critical parts of railway components. So faults of rail surface are directly related to the operation safety. The defects occurring in switches can lead to accidents and the derailment of the train. Therefore, it is necessary to utilize advanced technology to monitor rail damage of the switch and level crossing zones. In this study, the switch and level crossing detection are performed with vision based contactless image processing techniques. Edge detection algorithm, image processing filters, morphological feature extraction, Hough transform and hierarchical SVM classifier are utilized to detect turnout and level crossing regions in the railway images. While switch points are detected, images of the area in front of the train are continuously taken from camera placed on the train. These images contain foreign objects such as buildings, trees, etc. The foreign objects existing in the railway image make it difficult to detect accurately the rail track. The turnout and level crossing detection cannot also be performed using the information of the rail track that cannot be correctly detected. The several processes, such as some image processing filters and morphological feature extraction, have been performed to solve this problem. With destroying the foreign objects from the railway images, both the accuracy rate of the proposed method has been increased and real-time implementation of the method is provided. The Hough transform is utilized to detect rail track, switch and level crossing in the proposed method. The turnout detection is performed by applying SVM classifier to railway image. The proposed method provides real-time rail track, level crossing and turnout detection. Furthermore, this method has gained dynamic feature due to not be utilized any template image for switch detection. When evaluated from these aspects, both the proposed method is superior to other methods in literature and results were obtained in a shorter time thanks to applying ROI Segmentation to the railway image.

Wheel–rail dynamic interaction due to rail weld irregularity in high-speed railways

Rail weld geometry irregularity is one of the main excitation sources for vehicle–track coupled dynamic system, and it has a direct effect on the wheel–rail dynamic interactions, which are responsible further for the wheel–rail noise, railway component damages, and track deteriorations. In many previous studies, the rail weld irregularity was usually modeled as a single or composite concave cosine wave based on field investigations on traditional railway lines or researchers’ experiences. These investigations were mainly concentrated on the maximum value of the rail weld irregularity. However, the geometrical shape was usually ignored. In this paper, a series of rail weld irregularities measured on Beijing–Shanghai high-speed railway passenger-dedicated line in China are presented. Based on the analysis of the measured rail surface geometry in the weld zones, some typical theoretical models of the rail weld irregularity are established. Then, the effectiveness of the established rail weld irregularity models are demonstrated for dynamic evaluation of the rail weld irregularity in high-speed railways by comparison between the wheel–rail dynamic responses excited by the measured and the modeled rail weld irregularities, respectively. Finally, the influences of different rail weld irregularities on the wheel–rail dynamic interactions are investigated using the vehicle–track coupled dynamics model and the established rail weld irregularity models. The results are expected to be capable of providing references for the analysis and evaluation of the rail weld irregularity in high-speed railways.

On the fatigue performance of laser hybrid welded high Zn 7000 alloys for next generation railway components

The fatigue behavior of laser hybrid welded 7000 series aluminum alloys with high Zn was investigated by electron backscattered diffraction, transmission electron microscopy, energy-dispersive spectroscopy, basic mechanical tests, fatigue cracking rate, synchrotron radiation X-ray computed micro-tomography, high-cycle fatigue and residual stress-based fatigue crack growth simulation. The results show that hybrid laser welding process leads to essential changes of microstructure and micro-hardness. It has also been found that the fatigue performance of grinded laser shock treated joints is significantly improved compared with that of as-received welded joints. Besides, hybrid laser welded joints present slightly higher fatigue crack propagation rate than base metal under load ratios of R=0.1 and 0.3, which can be intrinsically attributed to the higher crackability of weld and inner porosity in terms of grain disorientation and three-dimensional gas pores. Based on finite element modeling, a new fatigue crack propagation life model is established by incorporating weld residual stress, and the predictions are in good agreement with experimental results under different welding parameters.

Induction thermography: principle, applications and first steps towards standardisation

A survey on theory, characteristic quantities and the experimental technique of induction thermography is given. Induction thermography is used for surface defect detection in forged parts of ferromagnetic steel at typical frequencies of 100–300 kHz. The sensitivity for crack detection is comparable to magnetic particle inspection. A hidden defect in ferritic steel with a coverage of 140 μm was detected by lowering the induction frequency down to 1500 Hz. Defects of fibres were detected in carbon fibre reinforced polymer (CFRP). Inductive excitation is complementary to flash excitation. By increasing the induction frequency up to 52 MHz, surface heating of CFRP can be realised. Cracks in silicon solar cells were detected. The crack tip is revealed with very high contrast. A new field is crack detection in railway components like rails and wheels. In rails, a larger defect could be detected from a test car moving at a speed of up to 15 km/h. A fully automated wheel testing system was built up as a demonstrator, that can detect defects with comparable sensitivity to magnetic particle testing. Standardisation of thermography has gained progress in the last years and will lead to standards on active thermography, flash excited and induction thermography in the next future.

Using vibrations to detect high wear rates in rolling contact fatigue tests

Rolling contact fatigue (RCF) plays a critical role in railway components, and the characterization of materials used, in terms of RCF life, is still an open task, made complex by the interactions of different phenomena. The contact surface has a direct impact on the pressure exerted and can change during the test, due to wear. The procedure proposed consists in using vibrations of a test bench during RCF?life tests to identify when wear increases and causes a quick flattening of the specimen’s surface, and when this process is complete. The procedure is applied to two case studies regarding wheel and rail steels. In the tests, a wheel steel specimen rotates against a rail steel specimen, while pressed against each other by a constant force. At regular intervals weight loss and surface analysis are performed, while vibrations and torque are monitored continuously. Destructive tests are carried out at the end of each test. Results from non?destructive measurements were used to provide input data to a numerical simulation, used to determine the cyclic plasticity properties of the material. The methodology proposed shows the potential application of vibration measurements for detecting wear rates thus allowing supporting or partially supplanting destructive testing.

1B13 A case study of the application of bioplastic to a railway vehicle interior component(Vehicles-System)

1B13 A case study of the application of bioplastic to a railway vehicle interior component(Vehicles-System)

Evaluation of the Environmental, Social Effects for the Egyptian National Railways Restructuring

This paper presents the main findings of the environmental and social impact assessment (ESIA) for the Egyptian national railways restructuring. This paper consists of the two parts: 1) modernizing the signaling system on the Arab El Raml-Alexandria Line and creating a Central Traffic Management Center in Tanta; and 2) renewing 200 km of track in Lower and Upper Egypt. The purpose of this evaluation is to identify and examine the potential socio-cultural, economic, and physical impacts of the railway restructuring, and propose measures to mitigate its adverse impacts, and develop plans for managing and monitoring the environmental aspects of the railway restructuring. This paper describes outlines of the environmental and social sensitivities of the railway restructuring area, potentially significant impacts of the proposed project and plans for their mitigation. Detailed information on the environmental and socio economic settings of the railway restructuring, components and activities of the proposed project and the results of the environmental and social impact assessment studies are presented in the body of the paper.

The Use of Deconstructed Tires as Elastic Elements in Railway Tracks.

Elastic elements such as rail pads, under sleeper pads and under ballast mats are railway components that allow for a reduction in track deterioration and vibrations. And they are furthermore commonly used to obtain an optimal vertical stiffness of the infrastructure. However, the use of elastomeric materials can increase construction costs and the consumption of raw materials. Thus, the utilization of used tire layers offers an alternative to reuse an abundant waste reducing the cost of elastic elements. In addition, an innovator technique allows deconstructing tire layers without grinding up the material, reducing production costs at the same time that tire properties are remained. This research is focused on the study of the viability of developing elastic components from used tire layers by evaluating the influence of thickness, the resistance capacity of the elements and their behavior in a ballast box. Results indicate the ability of tire pads to manufacture elastic elements (rail pads, under sleeper pads and under ballast mats) to be used in railway tracks.

Fatigue in Railway Components - Understanding vs. Resolution

The consequences of surface finish and decarburization on the fatigue performance of cast and forged steel components in the railway industry is substantial, and means that fatigue cracking is an ongoing issue across the industry. Examples of loading spectra for coupler forces and track loads are presented, along with data from past investigations showing the severe penalty in terms of fatigue life caused by inadequate surface finish at critical locations of components under fatigue loads. Managers in railway industry need to understand the technical case for increased manufacturing requirements, as costs from operational losses may well have made the economic case for increased requirements more compelling. Various options for improving the surface finish at critical locations that are prone to fatigue are available, and should be explored to reduce the vulnerability of these components to failure via fatigue cracking.

The effect of anisotropy on crack propagation in pearlitic rail steel

One of the main sources of damage in railway components is the large plastic deformations that accumulate in the surface layer under rolling contact loading. Large irreversible deformations in components made of pearlitic steel induce anisotropy in mechanical properties of the material in the surface layer. In the present work the influence of the anisotropic layer on propagation of cracks in rail head is investigated. Based on the concept of material forces, a computational framework for simulation of propagation of planar cracks is formulated where the propagation rate is linked to a crack-driving force. An anisotropic fracture surface model is employed to capture the effect of changes in the resistance against crack propagation in different directions and depths in the surface layer. Results of simulations for cases with different characteristics in the surface layer show that the anisotropic layer has a substantial influence on the crack path.

Increasing the service life of railway engineering components by induction surfacing

The reduction of the extent of wear of components in service is one of the main tasks of industry. The method, described in this study, was introduced in the 1980s in railway engineering where the problem of wear was especially acute. After testing and introducing the methods, it has been possible to increase the time between repairs of a single section (e.g. automatic clutches) from 2 months to 3 years or more. And this is not the limit. Evaluating the advantages of these methods, the leadership of the Ministry of Transport of the Russian Federation has introduced this method in planned repairs of wagons in companies to increase the service time of passenger rolling stock between the repairs.

Multi-parameter Fatigue Equivalence Loadings for Specification Applications

This paper deals with a method to define Equivalent Fatigue Loads (EFL) from in-service load measurement in the case of a structure subjected to multiple variable fatigue loadings. EFL can be used in order to define tests on full scale structures for an experimental validation approach. It can be also used for the evaluation of the severity of the in-service loads, useful step in a reliability approach, in order to optimize the geometry with respect to the fatigue damage. The aim of the paper is to define the mathematical and mechanical concept of the Equivalence Fatigue Method in the case of multi-parameters loading for specification application. This method uses fatigue damage evaluation from statistical in-service measurement data. The specificity of the method presented here is to use a fully multi-parameters equivalence method. Damages is evaluated using life prediction method based on multiaxial criteria. The method is used for rotating structures, applied to a specific family of structure: train wheels. Train wheels are critical safety railway components mainly subjected to random multiaxial fatigue induced by multi-parameters loading. In this paper an approach to evaluate damage from this measurement in order to find the EFL with a damage equivalence optimization is developed.

Enhance the Environmental Performance of Railway Infrastructure

In recent years, environmental awareness has increased: governments, the public and industry now take environmental issues seriously. Railways are no exception. Infrastructure managers have made efforts to systematically manage environmental issues of their assets. Railways have considerable effects on the environment. Because of superior energy efficiency it is easy to forget that there is still huge potential for railways to have a negative environmental impact, largely related to extensive land use and large amounts of materials in use. Recently, infrastructure managers have started introducing environmental management systems into their business processes, based on the ISO 14000 standards, to mitigate environmental risks posed by infrastructure. Infrastructure organisations have developed tools to assist the environmental management, but they have been doing this in isolation from each other, resulting in a lack of compatible language and solutions, such as a lack of common guidelines for environmental procurement. The InfraGuidER Coordinated Action compiled requirements for environmental management processes of European Infrastructure Managers. InfraGuidER compiled understanding of environmental aspects of railway infrastructure and how to minimise the environmental impacts from operation, construction, maintenance, upgrading and disposal. This includes knowledge of significant environmental issues of railway infrastructure material, including system boundaries, stocks and flows, and an overview of applicable management processes, international legislation and standards. A major InfraGuidER delivery is the proposal for an UIC guideline for eco-procurement of railway infrastructure materials and components, similar to already existing UIC leaflet 345 for rolling stock. The tools presented within InfraGuidER can improve the environmental impact of railways by supporting environmental decision making processes for railway infrastructure renewal and planning. A new board within the European Railway Purchasing Conference will further deal with these issues. InfraGuidER also compiled proposals for future research activities addressing identified, significant needs concerning the environmental performance and environmental monitoring of railway soil pollution.

Fatigue Crack Growth Simulation in Railway Axles

In order to carry out the railway axle design according to the “Damage Tolerance” philosophy, reliable crack-growth models for these kind of components are necessary. Indeed, damage tolerance principles have received more and more attention from railway technical community, thanks to its ambitious task concerning the inspection intervals prevision of railway components subjected to non-stationary loading conditions. In this paper, a simple routine is exposed that is able to calculate the characteristic parameters of the Linear Elastic Fracture Mechanics (LEFM) for a generic cracked mechanical component. Such parameters are then used in a two parameters propagation law to estimate the necessary time for a crack to become critical.

On site mechanical characterization of the ballast state

Ballast is a major railway component whose behaviour is still not sufficiently controlled. The identification of mechanisms leading to track ageing is difficult to achieve as the process occurs over several years at particle scale. Models have been proposed to take into account ballast characteristics and provide a description of geometrical and structural modifications of ballast particles through time. To be relevant, these models must be supplied with reliable and realistic input data such as on-site density and stiffness modulus. This article presents results that could provide these parameters, starting with on-site tests that link them with cone penetration energy.

Analysis Method of Crack Propagation Data by Genetic Algorithms

A practice for analyzing some raw data from fatigue crack growth tests, carried out on specimens obtained from a railway component (wheel), is presented. Despite the data sample is small, it allows to identify the material parameters of the “threshold” propagation model that make this latter amazingly realistic for the examined material. The proposed analysis method is based on the Evolutionary Algorithms theory and uses raw data obtained from C(T) specimens instrumented with crack gauges.

Failure and damage tolerance aspects of railway components

Railway structures such as rails and axles are safety relevant components since any failure includes the risk of catastrophic derailment. This paper gives a brief overview on the most important potential failure scenarios driven by fatigue crack initiation and propagation and discusses the effects of important influencing factors such as vehicle weight and speed, track quality and environmental conditions. The present paper summarizes earlier work of the authors in this field.

A combined multibody and finite element approach for dynamic interaction analysis of high-speed train and railway structure including post-derailment behavior during an earthquake

A combined multibody and finite element approach is given to solve the dynamic interaction of a Shinkansen train (high-speed train in Japan) and the railway structure including post-derailment during an earthquake effectively. The motion of the train is expressed in multibody dynamics. Efficient mechanical models to express interactions between wheel and track structure including post-derailment are given. Rail and track elements expressed in multibody dynamics and FEM are given to solve contact problems between wheel and long railway components effectively. The motion of a railway structure is modeled with various finite elements and rail and track elements. The computer program has been developed for the dynamic interaction analysis of a Shinkansen train and railway structure including post derailment during an earthquake. Numerical examples are demonstrated.

Modeling and proving functional completeness in formal verification of counting heads

The demand for safety of electronic devices is high. Especially in safety-critical systems, e.g. electronic railway interlocking systems, safety is an important issue. Nowadays these systems are tested and simulated with a manually created set of test cases. But testing is a very cost-intensive procedure and can never reach a complete coverage for large designs. Hence, an efficient way to formally verify these systems is required. In this paper we present a formal verification flow, including the modeling, for counting heads (CHs) for railways, a real-time system that is used in most electronic railway interlocking systems from SIEMENS.1 The approach shown here is based on SystemC, a powerful system description language. In this way efficient modeling and simulation-based verification of railway components and systems becomes possible. For the formal verification part bounded model checking algorithms are applied, i.e. a set of properties is formally proven to be correct. Additionally the completeness of this set is formally and efficiently determined.

Experiments of Laser Surface Engineering for the Green Remanufacturing of Railway Coupler

To achieve sustainable development and to solve the question of resource recycling and environment protection, green remanufacturing should be considered in the life cycle of the used railway rolling-stock components. These invalidated components resulting from fatigue and wear, such as coupler, could be remanufactured using laser surface hardening technology as the key processing. The objective was to harden the coupler backend pinhole interface, and to repair the layer with wear and fatigue crack on the wall of pinhole. Laser transformation hardening and laser melt-solidification hardening was used to the new manufacturing process to improve wear resistance of the surface of coupler backend pinhole. Laser surface cladding was used to repair lost material area for the reason of wear or fatigue, in order to offset the geometry size and satisfy the assembly relationship, and to increase the strength, the hardness and the wear resistance of the substrate. To the E class steel, typical coupler metal, the related laser process variables and materials were test and optimized. For the sake of verification these tests, related hardening area mechanical behaviors examinations including hardness, wear resistance, impact resistance and metallographic examinations were given. The result of the examinations show that the laser hardening area joins with the substrate being metallurgic join, and the behaviors examined were equal or best than the substrate. These means that laser surface hardening technology could be applied to the green remanufacturing of railway couplers as key processing.