Wheel–rail-induced derailment analysis: a comprehensive literature review of experimental and simulation-based approaches

A topical problem for the Ukrainian railway transport is its integration into the world’s transport system. The Ukrainian and the European railways differ in rail track parameters, which complicates railway communication. As shown by international experience, the most promising way to resolve this problem is to use gage-changeable wheelsets, which may be adjusted to different track gages. Besides, the Ukrainian and the EU railways use different wheel and rail profiles, whose shape greatly affects the rail?vehicle interaction. In service, the profile geometry may change significantly due to contacting pair wearing-in, which may result in a number of negative consequences caused by rail and wheel profile mismatch. The aim of this work is to study the effect of the wear-caused change of the initial rail and wheel profiles on the elastically deformed state of wheel?rail pairs for wheelsets operating on 1,520 mm and 1,435 mm gage railways without truck change. Worn wheel and rail profiles were studied by mathematical and computer simulation. The elastically deformed state of a wheel?rail pair was studied by the finite-element method, which allows one to analyze various complex-geometry engineering structures and perform a 3D simulation of physical processes. The interaction of worn wheels and rails with initial profiles used on 1,520 mm and 1,435 mm gage railways was analyzed to give the contact stress distribution over the wheel and rail profile zones for wheel?rail contact pairs theoretically possible in Ukraine?EU railway communication. This made it possible to assess rail?vehicle interaction conditions in Ukraine?EU railway communication without wheelset change. The results of the study of the effect of wheel profile change on the elastically deformed state made it possible to formulate recommendations on the practicability of existing profiles and direct ways to improving the profile geometry of wheelsets operating on 1,520 mm and 1,435 mm gage railways without truck change.

The LM wheel profile and profile of Chinese 60 kg/m rail (LM&CHN60) are commonly used in the Chinese metro. However, the poor matching between wheel and rail profiles as well as the instability of the vehicle often occur on some curved sections due to wear. Therefore, it is necessary to design compatible rail profiles for the worn wheel profiles as a replacement for the old rail in these sections. This paper first presents the analysis of using the worn wheel and rail profiles as well as LM&CHN60 with a three-dimensional vehicle-track coupled model. Then, an optimization of the rail profiles for the worn wheel profiles is implemented in terms of both worn and unworn profiles, which is not only to improve the stability of the vehicle but also to minimize the rail wear by taking the curve performance into consideration. An inverse design method is proposed for rail profile design to improve the wheel–rail contact properties. Then, the wear of the optimized rail profiles is calculated with two types of track, which is the basis for selecting the optimal profile of a specific curve. Furthermore, the evaluation of the vehicle-track dynamic behavior with optimum rail profiles is also performed by comparison with the worn rail profiles. The entire design process is completed in a procedure programmed in MATLAB. The application of the optimized rail profiles significantly slows down the growth rate of rail wear. Additionally, the maintenance intervals for rail reprofiling have been doubled.

Optimal design of wheel profile for railway vehicles

A novel idea for predicting the equivalent conicity is presented, based on the inclinations of the wheel thread at the running circle and the rail profile at top-of-rail.Both the shape of the wheel profiles and the shape of the rail profiles can be acceptable in today’s standards, but together the wheel/rail profile combination can lead to an unacceptable high value of the equivalent conicity, which can make the vehicle unstable. By introducing two gradient indices, one for the wheel and one for the rail, it is possible to separate the equivalent conicity into two parts, which also make it possible to put limit values on wheel and rail profiles separately. The indices are combined into a joint index, GIP. The new GIP index is compared to the equivalent conicity for a large number of worn rail and wheel profiles, and show promising results.KeywordsEquivalent conicityInstabilityWheel-rail contactWheel profileRail profileGradient indexGradient Index ProfileGIPGIPwGIPr

Egyptian rails have gotten worn as a result of a lack of upkeep and inadequate rail grinding. If the new locomotives are designed to work with standard tracks, they should be able to move more efficiently and safely on standard rails than worn ones that were not designed for standard tracks. The contact stress variation brought on by variations in the wheel-rail contact profile has a significant impact on the safety of railway traffic. In this article, a standard rail UIC54 and a wheel profile as per Egyptian Railway standards are taken into consideration to explore the impact of interacting wheel and rail profile topology. Standard rail and a real worn rail from the Egyptian National Railways (ENR) have different rail profile radii. The problem is undertaken using ANSYS Finite Element Method (FEM). All required elements of the rail system were modeled for analyses., such as rail, wheel, and axle. These tools obtain the distribution of contact stress, contact pressure, and fatigue for standard and damaged rail profiles. Using stress distribution obtained through FEM analysis, the effects of the change in Egyptian rail profiles with ENR New locomotives’ wheel on the contact stress is investigated. Contact stresses for the worn rail profile are up to 40% lower than those for an unused ENR rail profile. As the worn rail has a larger contact area than the standard rail, there is a reduction in the life cycles to failure., and fatigue damage rises as the contact stresses decrease.

The article considers rail head wear mechanisms in curved sections of the railway track. Based on various schemes of interaction between the wheel and the rail, determined by railway track operating conditions, the advantages and disadvantages of various contact schemes are revealed. The necessity of forming asymmetric rails profiles is indicated and the concept of conformal wheel-rail contact is considered. The conformal contact occurs when the running rail fillet and the wheel flange wear down to common profile due to intense flange contact at the curves. Due to the conformal contact, the relative slip expands the contact zone, the specific pressure decreases, meanwhile the rail and wheel profiles, worn to the corresponding configuration, successfully show good performance in terms of fatigue endurance. Thus, it is recommended that the wheel and rail profiles are conformal. Such a profile can be given to wheels and rails during current maintenance; the rails can be tramped or profiled immediately after railing. It is noted that this profile is approximately the same under various conditions of flange contact on different railways. Recommendations are given to reduce the intensity of rail wear in curved track sections based on the formation of asymmetric profiles of inner and outer rail faces. Based on the proposed recommendations for reducing the rail head wear, general principles of designing repair profiles have been developed in order to reduce their defects. The requirements for repair profile design are developed, taking into account the structural and operational characteristics of the railway track.KeywordsRailCross-section profileAsymmetric profileWheel-Rail contactRail wear

This study presents a systematic framework for optimising wheel and rail profiles and its application in a North American heavy-haul railway. The network suffers from severe low-rail RCF in tight curves with widened gauge, while high-rail damage remains limited due to effective friction management. To address this imbalance, a two-phase optimisation strategy was developed in order to consider the demands and constraints imposed by the stakeholders: first, a wheel profile was designed to reduce low-rail damage across varying gauge conditions while maintaining or reducing high-rail damage in sharp curves; second, two new rail profiles were introduced for mild curves and tangent track to ensure compatibility with the new optimised wheel profile and to reduce contact stresses in these sections. Wheel profile optimisation markedly reduces low-rail subsurface stress, but tread modifications compromise its performance on larger-radius curves. Optimising rail profiles for wide curves and tangent track resolves this shortcoming. Overall, integrated wheel-rail optimisation outperforms wheel-only strategies and is practically achievable via adjustments to existing rail grinding templates, underscoring the value of a system-level approach to managing RCF and wear in heavy-haul operations.

The dynamic interaction that occurs at the rail/wheel interface of any rail system is significantly influenced by rail and wheel profiles. In an effort to enhance this interaction, railways and transit systems often employ rail grinding as a means to maintain a defined rail profile. The cost to perform this procedure can be very high, sometimes exceeding $DLR25,000 per day for the use of a large grinding machine (with up to 128 grinding motors--each motor being 20 hp or more). Because of this, it is imperative that the work be done efficiently and accurately. In recent years there has been substantial research into the optimization of rail profiles. The National Research Council (NRC) of Canada is one research facility that has generated a unique, precise set of specified profiles for use in heavy-haul railway operations. To implement these profiles in a consistent manner, during rail grinding operations, requires some type of measurement system that provides feedback to the field staff. Up until recently, this has been accomplished with a manual BAR gauge that is fitted with a set of accurate profile templates. The BAR gauge, which initially was fitted with four specified templates, is now equipped with ten such templates. To obtain the full potential of benefits from these profiles requires more precise grinding than that which has been achieved in the past. The other problem with the current manual profile measurement (BAR) method is that it is somewhat slow and cumbersome and the differences between profiles is quite small (i.e. 0.020 inch or less). In order to enhance their rail grinding management support, ARM pursued an automated system that would optically measure rail profiles very fast and accurately from a hy-rail vehicle and compare them with the NRC profiles. Another important feature that was desired in this system was the ability to measure the relative position of one profile with respect to the other (i.e. left versus right rail). Such a system would thus be able to look at both rail profiles in one x-y plane, which is what the manual BAR gauge provides, to produce an electronic simulation of the desired templates oriented with each other in the proper manner, and compares this with the actual profiles. In order to compare actual profiles with the NRC profiles, it is necessary that both rails be looked at simultaneously in one x-y plane. This is mandatory if you want to duplicate the capabilities of the manual BAR gauge. Other parameters such as cant angle, head loss, track gauge, and section rail weight are also calculated at the same time. After evaluating various technologies, ARM selected the Electronic BAR Gauge, manufactured by Range Vision Inc. of Canada. The Electronic BAR Gauge is a second generation piece of equipment that enables you to measure rail profiles and wear within a resolution of 0.001 inch. It is utilized ahead of the grinding program to create a pre-grind survey plan and during grinding operations as a quality control device to verify desired profile installation and to monitor metal removal rates. The Electronic BAR Gauge will help ARM move towards the next generation of rail grinding strategy; namely being able to grind in a true preventive manner, whereby the work is carried out in a predictive manner with just the right amount of metal being removed from the rail in just the right places. This is referred to as the 'magic wear rate'. This paper presents the features of the Electron BAR Gauge, concentrating on how the system has been specifically designed to meet the needs of ARM for their rail grinding applications. Another section describes the accuracy requirements of the system and provides insight on the technology utilized.

During the last decades substantial progress has been made in design of railway vehicles and running gears. Tilting trains, high speed trains, active steering wheelsets and many other sophisticated solutions have been implemented in recent years on the railways. But despite this progress, the mechanics of railway wheelset remains the same and an inappropriate combination of wheel and rail profiles can easily diminish all this technological advances. Besides, many old fashioned vehicles are still in too good condition to be replaced. They have a special need for appropriate combinations of wheel/rail profiles since such vehicles do not have high-tech devices which improving performance. The paper presents a procedure for optimal design of a wheel profile based on geometrical wheel/rail contact characteristics such as the rolling radii difference (RRD). The procedure uses an optimality criteria based on a RRD function. The criteria accounts for stability of wheelset, cost efficiency, minimum wear of wheels and rails as well as safety requirements. The shape of the wheel profile approximated by a piecewise cubic Hermite interpolating polynomial is varied during the optimisation process in order to satisfy the optimality criteria. The optimization problem described above has been solved using the MARS method (Multipoint Approximations based on Response Surface fitting). The method has been specifically developed for problems where multiple response analyses and (time consuming) simulations are involved. Finally dynamic simulations of vehicle with obtained wheel profile have been performed in ADAMS/Rail program package in order to control wheel/rail wear and safety requirements. A solution of the optimization problem is then taken as a new wheel profile. Wheels with such profile have the given contact characteristics, which results in improved wheelset dynamics and in reduction of wheel wear. The proposed optimum design procedure has been applied to improve the performance of the metro trains in Rotterdam, The Netherlands (RET), which were suffering from severe wheel wear and as a result the hunting of the vehicles. The results of the optimisation have shown that the performance of railway vehicle can be improved by improving the contact properties of the wheel and rail. Using the proposed procedure a new wheel profile has been obtained and applied to the RET metro trains. Due to the application of the optimised wheel profile the instability of the metro trains has been eliminated and the lifetime of the wheels has been increased from 15000 km to 114000 km.

No matter which methodology is used for the computational modelling and analysis, the wheel-rail interaction plays a fundamental role on the dynamic response of railway vehicles. For that, fast and accurate evaluation of the contact interaction is demanded. Bearing that in mind, realistic contact conditions must be taken into account to replicate as detailed as possible this interaction, namely in what concerns with the consideration of actual wheel and rail profiles. Often, parametric surfaces are used to describe their geometry; however, it is shown that the search for potential contact points may become troublesome when the contacting surfaces are conformal. In this work, a methodology to deal with contact detection between general wheel and rail profiles with conformal contact scenarios is presented. This method consists of the division of the wheel into strips together with a search approach to detect the contact between each strip and the rail surface. The static interaction between UIC54 rail and a wheel profiles is used as case study to demonstrate the effectiveness of the methodology described here. The results obtained show that the proposed approach is able to properly describe the contact zone and calculate the penetration along the patch.

Safety and economy of railway traffic is enormously influenced by the contact stress variation caused by wheel rail contact profile changes. A change in designed surface topology may result from wear that brings in a wide change in contact geometry and stresses. To study the influence of interacting wheel and rail profile topology of standard rail UIC60, the standard wheel profile as per Indian Railway standards are considered in this paper. Rail profile radii, wheel profile radii and wheel profile taper are chosen for six different values. The analytical formulation is based on Timoshenko’s approach and Finite Element Method (FEM) based simulation of the problems is undertaken. With these tools, distribution of contact zones, contact stress and contact pressure for different configuration of the wheel and rail profiles are obtained. The mesh density in contact region is found to have a direct influence on the accuracy of the solution [1]. To standardize the analysis of the contact region, mesh with an element size of 1 mm for all the configurations are chosen. Using stress response obtained through FEM analysis and multiaxial fatigue crack initiation model, the effects of vertical loading on fatigue crack initiation life are investigated. This may allow a direct design application for railways in particular.

Dynamics Analysis of Wheel Rail Contact Using FEA

The project DynoTRAIN, which was funded under the European Seventh Framework Programme, was set-up in order to close the open points in the Technical Specification of Interoperability (TSI) of the trans-European rail system. The project was divided in seven work packages. The focus in work package 3 (WP 3) was the contact geometry between wheels and rails. More general information about the DynoTRAIN project is given in the foreword of this special edition. WP 3 was split into several tasks. In the first and second tasks worn wheel and rail profiles were collected. Since the wear behaviour of wheels and rails depends (among other factors) on bogie design, operating conditions, rail inclination and curve radius, a large number of wheel and rail profiles were investigated in order to obtain a representative picture of the contact conditions on the trans-European network. The wheel and rail profiles were analysed in terms of equivalent conicity, which is an important indicator for the running stability of railway vehicles. Based on the collected data, reference profiles for wheels and rails were defined for the calculation of conicity maps. The reference wheel and rail profiles act as a sort of coordinate (scaling) system for the conicity maps. The conicity maps were calculated from selected wheel and rail profiles that had the same frequency distribution as the whole sample. The conicity maps were calculated for different speed categories and for wheels operating on networks with rail inclinations of 1/20 and 1/40. Finally, limit values of the equivalent concity for the authorization of vehicles and in-service limits for tracks were derived from these conicity maps. This approach enabled the open point ‘equivalent conicity’ in the TSI: Locomotives and Passenger Rolling Stock and TSI: Infrastructure to be closed.

This paper outlines the historical development of the wheel and rail profiles currently used on railway vehicles. It also presents the key damage mechanisms involved in wheel-rail contact and summarises the methods that have recently been developed by railway engineers to predict the level of wheel and rail damage from these mechanisms. Tools for predicting the key damage modes of wear and rolling contact fatigue (RCF) are explained. Methods of optimising the wheel and rail profiles to reduce the overall damage and therefore improve the efficiency of the railway system are discussed and a case study from the UK of an ‘anti-RCF’ wheel profile is presented. Finally a novel method using a genetic algorithm is discussed which uses a penalty index to optimise the wheel profile for good running, low track forces and rail stress, low wear and RCF.

Railway wheel and rail head profiles development based on the geometric characteristics shapes