Rail Gauge Research Articles

Designing the key parameters of EMU bogie to reduce side wear of rail

A long term investigation of the wheel and the rail wear condition reveals that wheel flange wear and rail gauge corner wear are serious problems for EMU vehicles and narrow curved tracks. In order to solve the problem, the effects of bogie key parameters on the vehicle dynamic behaviour were studied using an EMU vehicle dynamic model and the improved parallel inverse design method was employed to design a new wheel profile. The results show that under the condition of a high primary yaw stiffness, the yawing motion of the wheelset is limited, which leads to a high-angle of attack between wheel and rail on narrow curves. Then two-point contact between the wheel and the rail could occur and cause serious wheel flange wear and rail gauge corner wear. The new designed profile can reduce wheel flange wear and rail gauge corner wear, while meeting the safety requirement of vehicle running performance on tangent track. The primary yaw stiffness affects the curving negotiation performance significantly.

Воздействие длинносоставных поездов на путь

The article presents results of pilot and theoretical studies of JSC VNIKTI in the field of interaction of railway track and a rolling stock and perspective of their application. Questions of longitudinal dynamics in the conditions of different types of braking of trains of increased weight and lengths and their influence on infrastructure are considered. Analysis of dynamic qualities and indicators of impact of model of coupled trainset on track is carried out by means of computer modeling, and impact evaluation of action of longitudinal force on carriage indicators, both dynamic and by impact on track, is given at different conditions of railway track. As a result of testing in 2015 of doubled trains weighing up to 14,200 tonnes at various types of braking the following conclusions were obtained: 1. The considerable array of experimental data on interaction of a rolling stock and way at emergency braking is received allowing a quantitative assessment to this process. 2. When performing asynchronous emergency brakings the “practical top” of the compressive forces in the train (1600 kN) has been for the first time reached and the moment of loss of stability of a rolling stock in a rail gauge has been recorded. 3. When performing synchronous braking sufficient stability of the conducted locomotive and nearby the standing car is confirmed at influence of longitudinal forces. 4. The received results of pilot and theoretical studies can be used for modification of normative documentation for development of local instructions for safe driving of the coupled trains, and furthermore at the organization of pilot trips of the coupled trains of higher weight.

1E13 Evaluation of a steering bogie about running resistance and power consumption(Environment and Energy)

There are many problems in a sharp curve negotiation such as large lateral force, squeal noises and excessive wear of wheel flange and rail gauge corner. To solve these problems, a single axle steering truck has been developed by Tokyo Metro and Nippon Steel & Sumitomo Metal Corporation, and Tokyo Metro adopted this newly developed steering bogie for the new train series 1000 for Ginza Line. Previous study has not clarified advantages of a steering bogie about running resistance and power consumption. This report shows comparison between a steering bogie and a conventional bogie about curving performance with a full scale bogie on roller rigs.

CWR Study of the Mechanical Properties of the Finite Element Method-Based Bridge Vertical Plate Non-Ballasted Track

With economic development, China’s railway construction is also rapidly developing and its technical requirements are also increasing. In recent years, CWR technology is most used in railway construction, the railway built using this technology is not only smooth, comfortable, but also long life and low maintenance costs, being widely used in railway construction. However, due to restrictions on the production technology and construction conditions, CWR will also be worn, broken, bent, etc., which requires people to continue to study techniques to prevent crawling or off the seam value of rail gauge, to ensure that rail transport safety. This article focuses on the finite element method-based bridge vertical plate non-ballasted track CWR mechanical properties.

A 3D dynamic model to investigate wheel–rail contact under high and low adhesion

In this article the finite element elastic-plastic code ANSYS/LS-DYNA was utilised to investigate the stress states and material response of wheel/rail under three contact situations, which included high and low adhesion, and full slip. Canted and non-canted rails were considered to measure how the cant angle affected the contact stress levels. Furthermore, the effects of the contact curvatures on the contact zone and contact pressure were also examined. The simulation of wheel flange contact was conducted to compare the stress state of the rail head and rail gauge. The results showed that a higher level of adhesion would enlarge the slip region in the stick/slip contact patch and widen the surface damage to a larger area. Moreover, the worn wheel/rail profiles would result in a non-elliptical contact patch and an increase of the contact pressure. Based on the shakedown map, it was anticipated that the rail would be damaged from the ratchetting response of the material. • New and worn profiles of wheel and rail were introduced in the contact analysis. • Canted and non-canted rails were applied to evaluate its influence on the contact stresses. • The stress states were determined under high and low adhesion, and full slip contact conditions. • The material response of rail to contact loading was predicted by the shakedown map.

Solving conformal wheel–rail rolling contact problems

The stresses between railway wheels and rails can be computed using different types of contact models: simplified methods, half-space-based boundary element approaches and finite element models. For conformal contact situations, particularly the contact between flange root and rail gauge corner, none of these models work satisfactorily. Finite element methods are too slow, half-space approaches ignore the effects of conformality, and simplified approaches schematise the elasticity of the material even further.This paper presents a thorough investigation of the conformal wheel–rail rolling contact problem. We use CONTACT's boundary element approach together with numerical influence coefficients, that are computed using the finite element approach. The resulting method is fast and detailed and can be embedded into vehicle system dynamics simulation. The results indicate that the contact area is longer and narrower, with smaller area and reduced stiffness, than is predicted by the half-space approach. The predicted maximum pressures are increased by 30%. Finally the longitudinal and lateral forces changed up to 15% of the Coulomb maximum.

Failure Analysis of the Rail

The paper describes the rail failures occurring repeatedly in the same distance from the rail butt weldment. The results of this investigation, especially fractographic analysis of the fracture surface of rail, evaluation of its macrostructure and microstructure, EDS analysis and hardness measurements revealed that transverse crack initiated in the foot of rail gauge and propagated by fatigue mechanism until the final cleavage fracture.

Experimental Prediction of Wear Rate on Rail and Wheel Materials at Dry Sliding Contact

This research is aimed at predicting the rail gauge and wheel flange contacts and their influences to wear rate using pin-on-disc method. A real model using a pin to represent a wheel component and a disc to represent a rail component were fabricated for the experiments. The experimental results were analyzed and the empirical formula of the wear depths as functions of applied load, bulk temperature and sliding velocity were obtained to describe the behavior of the systems. The results showed that the wear depth increased linearly with the increasing in applied load and temperature, while it decayed exponentially with the sliding velocity. The results were found to agree with the twin disc models from previous research works.

Assessment of lubricant applied to wheel/rail interface in curves

Lubrication between wheel and rail in curves is generally known to decrease the friction between wheel and rail, resulting in the reduction of wear of wheel flange and rail gauge corner in high rail, corrugation growth in low rail and noise generation at both of high and low rails. However, the selection of kinds of lubricants and their application methods adopted by railway companies are not necessarily reasonable or effective. This paper describes the results of fundamental studies on the basic characteristics of various lubricants applied to the wheel/rail interface, such as the effect on vehicle traction behavior, spread extent on rail surface, the effect on vehicle/track dynamic behaviors (focused on the lateral force interacting between wheel and rail) and the vehicle braking performance. Finally, a direction for the selection of suitable kinds of lubricants and lubrication methods are proposed according to the results obtained by the above studies.

Influence Evaluation of Fastener Stiffness Match on Subway Rail Switch Safety

To study the influence law of fastener stiffness match on subway rail switch safety, and select appropriate stiffness, the No.9 subway switch was taken as an example in this paper to carry out all the following work. Based on finite element method, the influence of fastener stiffness match on the vertical dynamic relative displacement of switch rail and dynamic gauge widening were analyzed. The result shows that: the design concept of 'soft upper and rigid lower' can effectively decrease the vertical relative displacement of switch rail, and avoid the load of switch rail in advance, and ensure the safety of structure strength; It also could slow down dynamic gauge widening and serpentine movement amplitude, and improve the safety and stability of train; To ensure the safety of train, the design conception of soft upper and rigid lower should be applied for the subway switch.

Prediction of Rail Profile Wear with the Increase of Vehicle Speed

A method to simulate rolling contact wear in a rail surface was developed using the finite elements method and numerical analysis. A two-dimensional finite elements model was used in order to reduce the calculation time and boundary conditions to prevent excessive deformation of a wheel and a rail were applied. A numerical analysis of rail wear at rolling contact was predicted using the Archards equation. In addition, the characteristics of rail wear with the increasing speed of vehicle were analyzed. Results show that there was not a large difference in the depths of wear on the rail head with increasing vehicle speed, but the wear on the rail gauge corner increased with increasing vehicle speed.

Development of the New Concept Steering Bogie

There are many problems in sharp curves negotiation such as large lateral force, squeal noises and excessive wear of wheel flange and rail gauge corner. To solve these problems, single axle steering bogie (proto type: FS576) has been developed by Tokyo Metro and Nippon Steel & Sumitomo Metal Corporation. The authors confirmed good curving performance by FS576 on the result of field test. Therefore, Tokyo Metro adopted this newly single axle steering bogie (production type: SC101) for new series 1000 in Ginza line. SC101 improves lateral force, noise level, and lateral acceleration of rail in passing curves. In this paper, the design concept and outline of steering bogie SC101 for series 1000 are described. And the curving performance of SC101 is evaluated based on the result of field test and commercial service. Language: en

A feasibility study on railway ballast damage detection utilizing measured vibration of in situ concrete sleeper

Ballasted track plays an important part in railway transportation systems. Given the importance of railway safety, research work with industrial applications has been carried out. The current railway track monitoring system is comprehensive and efficient methods are available for monitoring railway level and alignment, rail gauge, and so forth. However, the detection of ballast damage still relies on visual inspection and destructive core test. Although visual inspection is useful to identify ballast damage on the surface, ballast damage under the sleepers, which is believed to be the most critical for ballasted track safety, is extremely difficult if not impossible to detect in this way. A practical on-site test that can provide additional information for inspectors or engineers to quantify the “health” status of ballast under sleepers is in great demand. The rail–sleeper–ballast system can be considered as a beam on an elastic foundation. When the ballast under a sleeper is damaged, the stiffness that it should provide to support the sleeper is reduced. As a result, the vibration characteristics of the in situ sleeper will be altered. One possible way of applying this idea to ballast damage detection is to employ a model updating approach. This paper focuses on a feasibility study on the detection of ballast damage utilizing the measured vibration of the in situ concrete sleeper by following the model updating method. This paper reports not only the theoretical development of the proposed methodology, but also the numerical and full-scale experimental verifications. The numerical and experimental verification results are very encouraging, showing that it is possible to quantify the “health” status of ballast by calculating the reduction in stiffness of the ballast under the sleeper. Some observations and discussions based on the verification results are provided at the end of the paper.

Crack propagation in rails under rolling contact fatigue loading conditions based on material forces

Tools for the prediction of crack growth in rails are of vital importance for the railway industry. In this paper, numerical simulations of crack growth in rails are presented. More specifically, the focus is on short surface head check like cracks, often observed at the rail gauge corner. A fatigue crack propagation model expressed in terms of a crack driving force, derived from the concept of material forces, is presented. It is shown that only the component parallel to the crack tip of the crack driving force is a reliable quantity that can be used in numerical simulations of a Rolling Contact Fatigue (RCF) situation. In addition, it is shown that one term in the expression of the crack driving force (Gsur) is dependent on the computational mesh. The propagation model has been used for parametric studies of crack propagation to investigate key parameters such as loading and crack geometry. Results from these studies suggest that anisotropic effects from the highly deformed surface layer may need to be included in order to simulate head check growth in rails accurately.

On the mechanism of squat formation on train rails – Part I: Origination

A phenomenological investigation of squat defects on rail grade R260Mn is performed. The surface-breaking crack pattern, which is either linear or branched (V-shaped), shows a typical position and orientation in the running band. Particular characteristics are asymmetry of this pattern, with the presence of a leading and a trailing branch, and crack reflection or deviation at the running band border. Bending tests reveal a 3D internal crack pattern, with a pair of crack planes or ‘wings’ enclosing a wedge at the surface. Microstructural analysis of the rail upper layer shows metallurgical principles of crack initiation: delamination and transverse fracture of white etching material at the surface. This analysis moreover reveals a 3D anisotropic texture of the upper layer under combined bi-directional tangential surface stresses. Mechanical interpretation of the crack morphology shows that the leading or single branch of the surface-breaking crack pattern is a shear-induced fatigue crack, following the anisotropic microstructure when growing into the rail. The trailing crack of a branched squat is explained as the result of a subsequent transverse, wedge-shaped brittle failure mechanism of the surface layer of the rail, developing within the actual elliptical Hertzian contact patch – or the envelope of potential contact ellipses at the leading crack position. It is driven by the transverse shear loading towards the rail gauge face.

Modeling railroad track structures using the finite segment method

In the finite segment method, the dynamics of a deformable body is described using a set of rigid bodies that are connected by elastic force elements. This approach can be used, as demonstrated in this investigation, in the simulation of some rail movements. In order to ensure that the rail geometry is not distorted as the result of the finite segment displacements, a new track model that consistently integrates the absolute nodal coordinate formulation (ANCF) geometry and the finite segment method is developed. ANCF finite elements define the track geometry in the reference configuration as well as the change in the geometry due to the movement of the finite segments of the track. Using ANCF geometry and the finite segment kinematics, the location of the wheel/rail contact point is predicted online and used to update the creepage expressions due to the finite segment displacements and rotations. The location of the wheel/rail contact point and the updated creepage expressions are used to evaluate the creep forces. A three-dimensional elastic contact formulation (ECF-A) which allows for wheel/rail separation is used in this investigation. The rail displacement due to the applied loads is modeled by a set of rigid finite segments that are connected by a set of spring-damper elements. Each rail finite segment is assumed to have six rigid body degrees of freedom. The equations of motion of the finite segments are integrated with the railroad vehicle system equations of motion in a sparse matrix formulation. The resulting dynamic equations are solved using a predictor–corrector numerical integration method that has a variable order and variable step size. The finite segments may be used to model specific phenomena that occur in railroad vehicle applications, including rail rotations and gauge widening. The procedure used in this investigation to implement the finite segment method in a general purpose multibody system (MBS) computer program is described. Two simple models are presented in order to demonstrate the implementation of the finite segment method in MBS algorithms. The limitations of using the finite segments approach for modeling the track structure and rail flexibility are also discussed.

2402 車輪フランジ接触面形状の評価手法(OS4 接触問題とトライボロジ,オーガナイズド・セッション(OS))

This paper describes the measurement method of the contact condition between the wheel flange and the rail gauge corner. One of the most essential factors causing the flange climb derailment is the increase of coefficient of friction which is closely related to the surface condition of wheel flange. The purpose of this study is to clarify the mechanism of the increase of coefficient of friction from the aspect of visualization of the contact condition. In this study, we have proposed the measurement method for the contact shape and pressure distribution between the wheel flange with complicated surface figure and the rail gauge corner using the ultrasonic technique and the subtraction imaging method. And, we have confirmed the shape and pressure distribution of contact area by this method.

Finite element modelling of the rail gauge corner and underhead radius stresses under heavy axle load conditions

Highly localized stresses generated at the gauge corner of the outer rail cause fatigue cracking. The longitudinal bending stresses in the rail underhead radius position are of special interest, as tension spikes have been identified at this location during in-track measurements under high axle load conditions. The tension spike is a result of vertical and lateral head bending on the web. This effect is highly localized and is additional to the stresses generated due to vertical and lateral bending of the whole rail profile (the so-called global bending). This study examined contact and bending stresses by modelling the rail on a discrete foundation using finite elements and by considering the loading to be a fully slipping elliptical Hertzian contact patch. The analysis revealed that the tensile longitudinal stress was highly dependent on several service conditions: the contact patch offset from the rail centreline, the ratio of lateral ( L) to vertical ( V) loads, the direction of lateral traction, foundation stiffness and seasonal temperature variations. The tension spike increases, and the depth below the contact surface at which the stresses become tensile reduces, as the contact patch offset and/or the L/ V ratio increases. Both these enhance the tendency for rolling contact fatigue cracks to turn downwards and become transverse defects. This is because an increase in tensile bending stresses together with both residual and thermally induced stresses can facilitate cracks to turn perpendicular to the tensile stresses once they reach a critical length. Shear traction towards the gauge corner was found to be the most damaging phenomenon.

3212 超音波法による車輪フランジ接触面形状測定の試み(OS4-2 摩耗の予測・測定,OS4 接触問題とトライボロジ,オーガナイズド・セッション(OS))

3212 超音波法による車輪フランジ接触面形状測定の試み(OS4-2 摩耗の予測・測定,OS4 接触問題とトライボロジ,オーガナイズド・セッション(OS))

Experimental simulation and prediction of wear of wheel flange and rail gauge corner

Abstract The experimental research on the wears of wheel and rail has been carried out using a large rolling-sliding contact test machine with the actual profiles of wheel and rail. Primarily, the effects of axle load, the angle of attack, rail hardness and lubrication on wear behaviors of wheel flange and rail gauge corner have been particularly focused in research. Based on those experimental results, the Archard wear coefficients of Japanese track were calculated under various conditions. A wear prediction model of rail profile taking into consideration contact stress, slip ratio at contact patch and material hardness was established based on the experimental results and the wheel–rail contact analyses. The prediction results were compared with the measured values of the actual rail and the effectiveness of wear prediction methodology was verified for the actual railway system.