Rail Life Research Articles

Experimental Analysis of Dynamic Vibrations in Rails by Using Different Types of Vibration Absorption Pads

Railway pads are a type of component that is used in railway construction and maintenance. They are typically made of rubber or similar material and are placed between the railway sleeper and the rail itself. Railway pads provide a layer of cushioning and insulation between the rail and the sleeper, which helps to reduce noise and vibration from passing trains. Railway pads can also help extend the rail's life by reducing the wear and tear caused by constant friction between the rail and sleeper. They are especially useful in areas where noise pollution is a concern, such as residential areas or near hospitals and schools. Several types of railway pads are available, including continuous, discrete, and ribbed designs. The specific type of pad used will depend on factors such as the type of rail being used, the expected loads and speeds of passing trains, and the requirements of the railway system. Overall, railway pads are an important component in the construction and maintenance of railway systems, helping to reduce noise and vibration while also prolonging the life of the rail and other components. In this paper, we are testing three types of vibration rubber pads i.e., Ethylene Propylene Diene Monomer (EPDM), High-Density Polyethylene (HDPE), nitrile and comparing three vibration frequencies. The dynamic frequency of welded rails with HDPE pads has having 1190 Hz mean value. The dynamic frequency of rail tracks with single- and double-layer EPDM pads their mean values are 499 Hz and 335 Hz respectively. The experimental values clearly show that single- and double-layer EPDM pad dynamic frequencies are reduced by up to 58% and 71%, respectively, over the HDPE pad.

Причины возникновения и развития дефектов рельсов в кривых на участках обращения поездов повышенной массы и длины

Purpose: determine the causes of defects in rails in areas of circulation of trains of increased weight and length through modeling the operation of rails in curved sections of the railway track using digital twins. Methods: t study the influence of various factors on rail wear in curved sections of the track, software systems were used ased on the numerical solution of differential equations for the movement of rolling stock and the operation of the railway track under the train. To determine the stresses in the rails in order to predict the development of contact-fatigue defects, dynamic calculations using the finite element method were used. Results: it was revealed that in order to reduce rail wear in a curved section of the track in sections with predominantly freight traffic, the elevation of the outer rail must be calculated based on the actually realized speeds of freight trains. It has been established that at the moment the influence of the amount of rail inclination on rail wear has not been sufficiently studied. As an analysis of the position of the rails at various inclines has shown, for the curve under consideration it is most advisable to use a 1/30 inclination within the limits of a circular curve and with a 1/20 to 1/30 inclination within the transition curve. To reduce the likelihood of contact-fatigue defects occurring in such areas, it is necessary to provide for the implementation of measures to lubricate the side working edge of the outer rail thread and the rolling surface of the inner rail thread within the entire curve. Practical importance: the research results indicate the need to revise the approach to calculating the elevation of the outer rails in curves with heavy freight train traffic. The possibility of extending the service life of rails by revising the system for planning and implementing work on lubricating and grinding rails in curves in areas where trains of increased mass and length operate

Fatigue life assessment of thermite welded rails based on laboratory tests and field measurement data

This in-depth study assesses the fatigue life of thermite-welded 60E1 rails by combining fatigue experimental tests with field measurement data. Material characterization, conducted using X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Scanning Electron Microscopy (SEM), aimed to understand the fatigue behavior of these materials. The research was particularly focused on high-speed rail lines in South Korea, targeting areas with influence of track condition to collect strain data. By combining dynamic modulus calculations from high-speed tensile tests with the rain flow counting method for determining wheel loads, and employing the Linear Cumulative Damage method for estimating rail fatigue life, this study provides novel insights into the maintenance and durability of thermite welded rails. The integration of detailed laboratory experiments with field stress data offers a significant contribution to the predictive maintenance and lifecycle management of high-speed railway infrastructure.

Predicting the remaining useful life of rails based on improved deep spiking residual neural network

the remaining useful life (RUL) of rails is important to ensure safe and reliable operation of railway transportation lines. However, the severity of deterioration of rails from different types of damage varies. Multichannel vibrational data collected by sensors can be utilized to identify the relevant complex correlations and temporal relationships; however, existing methods struggle to predict rail damage accurately. Thus, this paper proposes a RUL prediction method for rails based on an improved deep spiking residual neural network. First, multichannel data collected by sensors are used directly as input to the predictive network without requiring a separate feature extraction step. Additionally, an encoding module is designed to adaptively convert the temporal sequences of data into spiking signals to reduce the information loss during the encoding process. Second, a spiking residual convolutional neural network (CNN) is incorporated into the proposed method to extract optimal features. The separable, spiking CNN can model the relationships among multichannel data accurately, and an attention mechanism is implemented to recalibrate the spiking feature maps such that the predictive network can distinguish between items of information effectively. Third, the spiking residual connections are altered to mitigate network degradation caused by the incompatibility between the conventional residual connections and the spiking neural network. Finally, the obtained spiking features are input to a fully connected layer to predict the rail RUL. Experimental results demonstrated that the proposed method can predict the rail RUL accurately, and validation results obtained on a rolling bearing dataset demonstrated the high generalizability of the proposed method.

Research on Overload Early Warning System for Railcars

Railcars are prone to suffer from overloading problems during its operation, which seriously affects the service life of railcars and rails, while posing a serious potential safety hazard. This paper In this paper, the weight of the car load is calculated by installation of a gravity sensor on the railcar and collection of the data from the gravity sensor through applying the A/D conversion module of the MCU. The overloading warning function of railcars is realized according to the drive alarm indicator of overloading information, and displaying the overloading information on the liquid crystal display screen.

Rail surface damage management through monitoring and modelling

ABSTRACT Rolling contact fatigue (RCF) cracking and wear significantly impact rail surfaces. The interaction between them is crucial; wear dominance can remove initiated cracks, while low wear rates may escalate crack propagation, elevating rail failure risks. Grinding, a preventive maintenance technique, removes remaining cracks, applied in fixed-interval or condition-based regimes. Operational constraints, favouring cyclic regimes, may potentially reduce rail life and increase costs. Thus, an optimal asset management strategy involves grinding based on current RCF condition and its predicted growth rate, considering its interaction with wear. London Underground employs diverse rail inspection methods, including advanced MRX-RSCM technology, to measure crack depth. Research used its measurements, developing a novel Combined Shakedown Map and Tγ approach. This predicts RCF growth under wear interaction, indicating the material to be removed by grinding. Its results are displayed for high and low rails of curved track sites, compared with monitoring measurements, enabling observation of changes in damage susceptibility and related grinding requirements over different rails.

Rough surface rolling contact fatigue crack stress intensity factor calculation for modern rail steels

For premium grades (and rail surface treatments such as ‘laser cladding’) there is little plastic damage expected during typical operating conditions, and smooth surface contact models predict a long life. However, damage still develops, including rolling contact fatigue, affecting premium steels from multiple suppliers. A model is described predicting stress intensity factors and indicative crack growth rates for cracks driven by surface roughness stresses. Accompanying field data quantify the asperity separation and tip radii for rails from metro, mixed traffic and a freight line in ground or unground conditions. The results predict that in rough surface contact small surface cracks (50–100 μm, exceeding microstructural dimensions) can grow faster than crack removal by wear, even when smooth surface models predict no growth. The model has application in identifying how rail grinding marks or wheel roughness may be an important factor in determining rail life through raised stresses at the rail surface (leading to wear), and increased stress intensities and growth rates for incipient cracks.

The effect of the track plan on the damage to rails by contact fatigue crambling

An analysis of foreign and domestic experience in improving traffic safety while extending the service life of rails and improving their interaction with the wheels of rolling stock shows that the working conditions of rails are much more difficult in curved sections of the track, especially in the outer thread, due to the intense impact of the ridges of the wheels of rolling stock on the lateral working One of the reasons for the formation of contact fatigue stains on the lateral working surface of the rail head is the presence of tangential stresses that occur in the absence of perpendicular pressure of the wheel on the rail head. In addition, the movement of the wheels on the rails is accompanied by slippage, which appears due to the taper of the wheels and the occurrence of the wheel crest on the rail head. A typical case of the wheel crest running over the rail head is the movement of the crew along curved sections of the track. In this case, the guide axle runs over one of the wheels on the rail head. As a result, there is a transverse slip of the wheel on the rolling surface and friction forces between the wheel and the rail are appropriately oriented to the axes. These processes, enhanced by an increase in dynamic action, cause more intense damage to the rail heads by defects 11 in the curves, while defects mostly appear on the outer rail thread.

Прогнозування залишкового ресурсу рейок залізничних доріг

The article is devoted to defining modern methods for assessing the residual resource of railway tracks. Since steel rails are one of the main components of railway transportation, predicting the service life and determining the residual resource of rails are important for ensuring the safe operation of railways. The main sectoral international and domestic regulatory documents have been analyzed, and the general state of the problem has been investigated. It has been estab-lished that the service life of railway tracks is determined mainly by the degree of dynamic loading, the number of initial defects during manufacture, the quality of steel rails, and the in-fluence of climatic and electromagnetic loads. Some methods and approaches to determining the residual resource in the world practice, which are based on experimental laboratory tests for the durability of decommissioned defective rails, have been studied. On the basis of the discov-ered mechanisms for the formation and development of defects, some specific recommenda-tions have been developed in order to increase the operational resource of railway tracks. How-ever, these methods do not take into account the stochastic aspects of the physics of degradation and destruction processes. Therefore, the most effective method for determining the residual resource of various objects is the probabilistic-physical method, which is based on the analysis of the dynamics of the change of the determining parameter. In accordance with the methodolo-gy of DSTU 8646:2016, given the data on the initial, current, and limited missed tonnage in which there are no rail failures, the calculation of the residual resource of railway rails is given. Calculations of the residual resource using the probabilistic-physical method on the example of heat-treated rails of passenger railways and using the relative values of the resource parameter have shown results that correspond to statistical data from the operation. The use of the method based on DM-distribution of failures helps to extend the life of rails and reduce operating costs by optimizing maintenance and repair processes.

Sliding Friction and Wear Behavior of Flash-Welded U75V Steel Joints in Air and Water Environments

U75V high-strength steel has been widely used to improve the service life of high-speed rails. Considering the consecutive cold and wet condition of the Sichuan–Tibet highway, water plays an important role in the wear process of U75V welded joints. In this study, we investigated the wear behaviors of flash-butt-welded U75V joints in dry air and water environments using a ball-on-disk sliding wear tester. The worn surfaces were tested using optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The cross-sectional profiles of the wear scar were tested using a wear volume tester. The results show that the U75V welded joint has a lower wear resistance than the base metal owing to its nonuniform structure and exhibits a high friction coefficient (0.64) and wear loss (0.21 mm3) in dry air. Water exerts a lubricating function on the fretting wear of U75V welded joints and reduces the friction coefficient (0.36) and wear loss (0.15 mm3). Furthermore, abrasive wear and micropitting are predominant in water environment, accompanied by the formation of a protective-oxide layer on the surface. In contrast, microcutting and microcracking are the dominant wear mechanisms of U75V welded joints in dry air.

Incentivized decarbonization through safer and more efficient heavy haul operations

The improvement in component service life and railway service reliability has been viewed from an environmental perspective. Delays and train accidents carry enormous costs and greenhouse gas (GHG) emissions potential due to the increased fuel burn and the need to replace heavy equipment prematurely. The use of higher-performance materials, more efficient vehicle design, and modern technology by Canadian railways to reduce service interruptions are presented. Their resulting cost savings not only can provide financial incentives for the continuous optimization of asset utilization but can also lead to significant contributions to the decarbonization of the railway industry. The authors have estimated a total reduction of 2.4 kt-CO2e per year in embodies carbon emissions due to life extensions of wheelsets compared to 2017 levels on a Class 1 railway. System-wide, the rail life extension has resulted in a saving of 8.1 kt-CO2e per year compared to 2017 for the same railway. Compared to 2004, the Canadian railway industry has achieved an annual reduction in embodied carbon emission of 6.7 Mt-CO2e from the reduction in mainline derailments.

Grinding limit and profile optimization in the high-incidence section of rail corrugation in mountainous city metro

As the most common and direct control method for rail corrugation, the rail grinding can effectively improve the service life of rails, but requires scientific theoretical guidance to achieve the efficient grinding. Therefore, it is necessary to formulate corresponding grinding limits and profile optimizations for different characteristics of rail corrugations. According to the on-site investigation of rail corrugation in the overlapping section of horizontal-vertical curves of the mountainous city metro, the corresponding dynamic model of vehicle-track system is constructed. Through the safety evaluation of the dynamic characteristics of the vehicle-track system, the safety limit of the rail corrugation grinding is preliminarily determined. Then, based on the wheel-rail friction-coupled vibration theory, the finite element model of the wheel-rail system is built. By exploring the wheel-rail friction-coupled vibration characteristics in the corrugated section with typical characteristics, the optimal limit of rail corrugation grinding is further confirmed. Finally, the treatment effects before and after rail grinding are compared using the profile optimization. Results show that when the corrugation wavelengths in the overlapping section are 30 mm, 40 mm, 50 mm, 60 mm, and 70 mm, the safety limits for rail corrugation grinding are 0.03 mm, 0.04 mm, 0.05 mm, 0.08 mm, and 0.15 mm. For the typical rail corrugation with the wavelength of 50 mm, the optimal limit of the rail corrugation grinding is 0.02 mm. Moreover, the earlier the rail corrugation is polished, the better the relative optimization effect is, but it is necessary to consider the grinding cost for targeted grinding.

Yüksek Hızlı Tren Hatlarında Rayların Yeniden Profillendirilmesinde Döner Taşlama Metodunun Uygulanabilirliği: Ankara-Eskişehir Hattı Örneği

Demir yolu rayları uzun süreli ve emniyetli kullanım için bakım planlaması yapılması gereken en önemli üst yapı elemanlarındandır. Rayların optimum profile sahip olması, sürüş konforunun arttırılması ve ray ömrünün ekonomik olarak uzatılabilmesi için rayların belirli periyotlarla yeniden profillendirme yapılması gereklidir. Bu çalışmada Yüksek Hızlı Tren Hatlarında rayların yeniden profillendirme çalışmalarında mobil ray taşlama makinesi ile döner taşlama metodunun uygulanabilirliği Ankara-Eskişehir hattı özelinde araştırılmıştır. Çalışmada öncelikle yeniden profillendirme stratejileri ve metotları ele alınmıştır. Çalışma öncesi hattın durumu incelenerek ön ölçümler alınmıştır. Değerlendirme sonucu belirlenen tolerans ve kalite gereksinimlerine göre döner taşlama uygulaması yapılmış olup alınan ölçümler incelenmiştir. Çalışma sonu yapılan değerlendirmede söz konusu metodun Yüksek hızlı Tren Hatlarında uygulanabilir olduğu görülmüştür. Bahse konu çalışmanın literatürde yeteri kadar yer almaması karşısında Yüksek Hızlı Tren Hatlarında yeniden profillendirme stratejilerinin oluşturulmasına katkı sağlayacağı düşünülmektedir.

Methodology for the formation of rail repair profiles by grinding

The formation of a rail transverse profile to reduce contact loading and wear from railway rolling stock wheels is one of the main tasks of rail grinding. At present, when designing a rail grinding technology, a future rail profile contour is selected from a set of repair profiles available in a database. Frequently, the profile selected from the database is less than optimal, as it does not provide the required interaction in the wheel-rail system for a particular track section, and its formation requires excessive metal removal, which reduces the rail's lifespan. The paper proposes a new methodology for designing rail repair profiles based on a fundamentally new approach, consisting in designing rail geometric parameters at the stage of preparing the technological process of its grinding. This approach to the rail grinding technology design allows specifying a geometric profile for the certain railway track operating conditions and the worn rail condition, thus bringing metal removal from a rail head to required minimum and, as a result, increasing the service life of rails and the performance of a rail grinding train. To assess the efficiency and applicability of the proposed method for different railway track operating conditions, a comparative modelling of the existing approach in selecting a rail repair profile with the proposed approach to its design was carried out. The proposed method showed the best result in all cases.

Predictive maintenance in railway systems: MBS-based wheel and rail life prediction exemplified for the Swedish Iron-Ore line

A successful predictive maintenance strategy for wheels and rails depends on an accurate and robust modelling of damage evolution, mainly uniform wear and Rolling Contact Fatigue (RCF). In this work a life prediction framework for wheels and rails is presented. The prediction model accounts for wear, RCF, and their interaction based on the output from MBS simulations to calculate the remaining life of the asset, given in mileage for wheels and MGTs for rails. Once the model is calibrated, the proposed methodology can predict the sensitivity of the maintenance intervals against changes in operational conditions, such as changes in contact lubrication, track gauge, operating speeds, etc. The prediction framework is then used in two operational cases on the Swedish Iron-Ore line. The studied cases are, the analysis of wheel life for the locomotives, and the analysis of rail life for gauge widening scenarios. The results demonstrate the capabilities of the MBS-based damage modelling for predictive maintenance purposes and showcase how these techniques can set the path towards Digital Twins of railway assets.

Evolution of Rail Contact Fatigue on Crossing Nose Rail Based on Long Short-Term Memory

The share of rail transport in world transport continues to rise. As the number of trains increases, so does the load on the railway. The rails are in direct contact with the loaded wheels. Therefore, it is more easily damaged. In recent years, domestic and foreign scholars have conducted in-depth research on railway damage detection. As the weakest part of the track system, switches are more prone to damage. Assessing and predicting rail surface damage can improve the safety of rail operations and allow for proper planning and maintenance to reduce capital expenditure and increase operational efficiency. Under the premise that functional safety is paramount, predicting the service life of rails, especially turnouts, can significantly reduce costs and ensure the safety of railway transportation. This paper understands the evolution of contact fatigue on crossing noses through long-term observation and sampling of crossing noses in turnouts. The authors get images from new to damaged. After image preprocessing, MPI (Magnetic Particle Imaging) is divided into blocks containing local crack information. The obtained local texture information is used for regression prediction using machine-supervised learning and LSTM network (Long Short-Term Memory) methods. Finally, a technique capable of thoroughly evaluating the wear process of crossing noses is proposed.

Влияние формы внутренней поперечной трещины на усталостную прочность балки при циклическом изгибе

The paper studies the effect of the shape of the internal transverse defect on the fatigue crack resistance of the beam. The beam on a solid elastic foundation with a cross-section in the form of an unequal I-beam is subjected to cyclic bending by concentrated force. Various schematizations of the defect are considered, namely, a crack of circular shape, elliptical, oval, and oval of the fourth degree shape. A comparative analysis of stress intensity factors is performed. The dependence of the permissible number of loading cycles on the applied force for circular and oval cracks has been established, taking into account the boundaries of the body. The proposed calculation scheme is used to estimate the residual life of railway rails.

Guidelines for rail reprofiling

The condition of the rails affects the comfort and safety of railway transport. Managing the rail life cycle on modern railway networks has been playing an increasingly important role. Inspection, preventive and corrective maintenance of rails are significant activities in the integral maintenance of the railway superstructure and substructure. The competitiveness of railway transport on the traffic market requires the realization of maintenance activities in short periods of line closure. The paper presents guidelines for rail reprofiling based on the experiences of railway Infrastructure Managers and the recommendations of European technical regulations. The need for grinding new rails after laying the track was pointed out. The advantage of preventive over corrective reprofiling is emphasized. Different types of target profiles of the reprofiled railhead are presented. This paper aims to improve the knowledge of experts in the field of railway infrastructure maintenance.

Estimation of fatigue life parameters of an Alumino Thermic weld on UIC60 rail joint using LEFM

At wheel track contact point, the high stress concentration, poor weld quality, and heterogeneity of weld material are the main factors that cause fatigue crack on any rail weld. Railway network agencies are concerned about the safety of the railway track when it comes to detecting and fixing weld faults to avoid vehicle derailment and loss of lives. This study analysed a numerical simulation of fatigue crack and its evolution under loaded service condition. A 3-D CAD wheel rail weld assembly model was built to study an AT welded joint under fatigue, and for stress concentration factor (SIF) calculation. The results are found by inserting a semi elliptical crack on the rail weld head surface with ANSYS, and then numerical simulation has been performed to get the different three modes of SIF at rail weld crack. The analysis findings data was recorded with critical fracture parameters of SIFs and its number of cycles to failure using LEFM technique and respective results have been plotted. With ANSYS the stress intensity on a crack will be resulted. By using numerical method, the critical crack size and number of cycle load with fatigue life of rail would be determined. The numbers of rail weld inspection per year has been determine by using the maximum number of cycle. The aim of this paper is to develop an effective inspection and maintenance frequency based on rolling contact surfaces crack propagation analyse. This will help to prevent the occurrence of rail failure by taking the required action at the right time, and extend the rail life expectancy, reduce the rail maintenance work and its cost.

Fracture mechanisms in rails with mechanically and thermomechanically-induced white etching layers under three-point bending

White etching layers (WELs) on rail surfaces play a crucial role in dictating rail life and guaranteeing safety during transport. It has been reported that the presences of WELs correlate with wheel-rail tribological properties and rail defects, including squats and studs. It is impossible to directly measure fracture mechanisms in WELs when rails are in service because they are subject to numerous wheel passage cycles, and WELs are routinely spalled due to dynamic impact throughout their lifetime. Consequently, samples containing mechanically and thermomechanically-induced WELs, as well as WEL-free samples were sectioned from ex-service rails and subjected to three-point bending to investigate crack initiation in WELs and compare the subsequent propagation of cracks into the base material leading to fracture. The results show that WELs are subject to intergranular brittle fracture and promote ductile crack growth before macroscopic river-like cleavage failure. In contrast, the WEL-free rail fails via a mixed-mode of quasi-cleavage fracture. Mechanically-induced WELs are more detrimental to rail life compared to their thermomechanically-induced counterparts on account of the former’s high hardness and ultrafine microstructure resulting in more severe and numerous cracks. Moreover, the heavily deformed pearlite at mechanically-induced WEL-base material interfaces contributes to the lower fracture resistance and enhanced crack penetration from WEL to rail.