Rail Vehicles Research Articles

Reduction of distortion during laser beam welding by applying an in situ alloyed LTT effect and considering influencing factors

In rail vehicle construction, austenitic stainless steels are used to achieve lightweight design concepts, as the higher specific strength of the material allows the thickness of parts to be reduced. However, when these are welded to create complex structures, increased welding distortion occurs even with low-heat joining processes such as laser beam welding.In order to reduce distortion, an in situ low transformation temperature (LTT) effect has been achieved using commercially available materials rather than specially manufactured LTT alloys. The LTT effect introduces compressive stresses into the weld seam, which counteract the formation of welding distortion due to tensile stresses. However, in the case of complex structures, several other factors influence the formation of distortion. The influence of the LTT effect and other factors such as tack welding, clamping and cooling conditions were analysed by distortion measurements and a maximum distortion reduction was determined.

Rigorous investigation into the identification of malfunctions in the air conditioning and refrigeration systems of urban rail vehicles

Rigorous investigation into the identification of malfunctions in the air conditioning and refrigeration systems of urban rail vehicles

Otimização da tripulação em sistemas ferroviários urbanos: estudo de caso do VLT do Rio de Janeiro

ABSTRACT: This study aims to develop a mathematical model for crew optimization in urban rail systems. In this sense, the proposed model offers a solution that considers the number of operators distributed daily in each working day, as well as providing the distribution of the workforce in work schedules, to minimize the total number of operators needed, but without any penalty to contractual work restrictions, legal restrictions and practical specificities presented by the operational context of the system. Another relevant aspect of the proposed model is the joint optimization of both the shifts and work schedule problem, without the need to use the timetable as an initial parameter for the model. Also in this work, the application of the model in a light rail vehicle (VLT) operator in the city of Rio de Janeiro is presented, while allowing the practical evaluation of the capacity to optimize the workforce after to use of the model, by the comparison between the generated computational results and the currently solution from the operator. In the end, some alternative work schedules in Brazilian labor legislation are tested and their direct gains in the reduction of the workforce obtained by optimizing the model are presented, as well as the guarantee of a more evenly fair work schedule, avoiding any work overload for operator or deviations from current labor legislation.

Fatigue Behaviour of Cord Rubber Composite Materials in Air Spring Bellows of Rail Vehicles

Bogies of rail vehicles for passenger coaches and traction units commonly contain air spring systems as secondary spring stages. In the development and design of spring stages, it is necessary to ensure precise knowledge about the material properties and fatigue behaviour of the air spring bellows.The aim of this work is to systematically investigate the damage mechanisms evaluated at air spring bellows on sample level and to analyse the fatigue strength of the base material under different load conditions. The specially developed small-scale sample is biaxially loaded and different layups are examined at varying load levels. In the tests with different parameters, an increase in the mean value of the longitudinal displacement by 20 % has proved to act as a suitable failure criterion. In addition to the purely optical damage analysis, micro computed tomography analysis was carried out.In this study, four layered samples with a fibre angle of ±15, ±25 and ±35 degrees in respect to the longitudinal direction are examined. A global evaluation of the service life tests reveals that under comparable load conditions, the fibre angle exhibits a clear influence on the fatigue strength. The increase of 10 degree in fibre angle roughly results in a 15 % reduction of the tolerable lateral displacement amplitude at a number of fifty thousand load-cycles which commonly acts as design lifetime. In a second step, a local analysis based on an analytical approach is presented. With the help of the fibre strain amplitude calculated, all fatigue test data points can be unified to a master S/N-curve leading to an elaborated design model of cord rubber composite materials used in air spring bellows of rail vehicles.With the help of the presented methodology utilizing the developed representative small-scale sample testing procedure and evaluation approach, a time- and cost-efficient fatigue design is facilitated.

Theoretical investigation of the rail vehicle suspension system using different optimised controllers by harmony search algorithm incorporating magnetorheological dampers

Theoretical investigation of the rail vehicle suspension system using different optimised controllers by harmony search algorithm incorporating magnetorheological dampers

Issues for the Introduction of Hydrogen-Powered Rail Vehicles on Hungarian Regional Railway Lines Through an Example from Germany

The research provides an answer for the introduction of a hydrogen rail system in Hungary, based on an ongoing project in Germany. The research will provide a solution for a more sustainable replacement of the rail branch line services, which currently generates significant emissions. The research also takes into account the important issues of energy trade, i.e. the unpredictable wind and solar energy storage in the summer months. The novelty of the research lies in the fact that it describes the situation of the Hungarian branch line railway infrastructure on the one hand and the problem of storage and use of renewable and surplus seasonal energy in Hungary on the other hand. The study compares the CO2 emissions of three selected regional railway areas in Hungary with the amount of hydrogen consumption on the same line. The current level of hydrogen production in Hungary at the national level and in the regions under study was determined.

Development and validation of test rig for experimental analysis of contact behavior between rail wheel-rail and rubber tire-rail in road cum rail vehicles

Development and validation of test rig for experimental analysis of contact behavior between rail wheel-rail and rubber tire-rail in road cum rail vehicles

Dynamics Response of Rail Vehicle Induced by Incorporating Electric-Dominated Transmission Component

Abstract As an important component of train speed regulation, traction transmission system is the power source and the main transmission component of traction force. Its dynamic characteristics can affect the dynamic performance of vehicle system to a certain extent. With the rapid development of rail train transportation in China, the running speed of the train continues to improve, the dynamic characteristics of the vehicle is becoming more complex, and the influence of the electrical part of the traction transmission system gradually appears. The motor and gearbox are crucial components of the train power bogie to complete the conversion and transmission of electric energy to mechanical energy, with their dynamic characteristics are most directly affected by the electrical characteristics of the traction system. In this work, a vehicle electro-mechanical coupling mathematical model based on multi-body dynamics was established by explicitly incorporating the electric-induced traction into the transmission system, to study the influence of traction system vibration on vehicle dynamics. The dynamics responses of the lateral and longitudinal vibration on vehicle motor and gearbox were quantitatively analysed from the traction drive system. Compared with the line test, it was observed that 12-times of the fundamental frequency of the rotor has a great influence on the motor and gearbox.

Design and Control of Hybrid Electric Light Rail Vehicles With Open Ended Winding Machines

Design and Control of Hybrid Electric Light Rail Vehicles With Open Ended Winding Machines

Deep Learning-Based Segment Trend Removal Approach for Prognostics and Health Management Signals of Rail Vehicles

Deep Learning-Based Segment Trend Removal Approach for Prognostics and Health Management Signals of Rail Vehicles

Data-Driven ToMFIR-Based Incipient Fault Detection and Estimation for High-Speed Rail Vehicle Suspension Systems

Data-Driven ToMFIR-Based Incipient Fault Detection and Estimation for High-Speed Rail Vehicle Suspension Systems

Energy efficiency in rail vehicles: analysis of contemporary technologies in reducing energy consumption

The article focuses on the problem of energy intensity in rail vehicles and analyzes current technologies aimed at reducing it. The author discusses innovations and strategies aimed at increasing energy efficiency in rail transportation. He also outlines the challenges of reducing energy consumption in this sector and future development prospects. The main focus of the article is on the problem of energy demand in rail vehicles, with a special emphasis on railroads. The author analyzes the current challenges of high energy consumption in rail transportation and presents various technologies that have been introduced to minimize this consumption. The article includes descriptions of technological innovations such as advanced energy management systems, efficient braking systems that recover energy, and the use of low aerodynamic drag materials. The author also discusses strategies to improve the energy efficiency of rail vehicles, including both existing ones and those planned for market introduction. One of the key points of the article is also a presentation of the challenges of reducing energy consumption in the rail sector. These include the need to adapt existing infrastructure, the financial aspects of introducing new technologies, and acceptance by consumers and operators, among others.

The Strength of Rail Vehicles Transported by a Ferry Considering the Influence of Sea Waves on Its Hull.

The article presents the results of a determination of the load attributed to rail vehicles transported by a ferry, considering the influence of sea waves on its hull. A mathematic model describing the displacements of a train ferry, which transported rail vehicles on its decks during rolling oscillations, was created. Calculated accelerations were used to identify the load of components from a dynamics point of view and they were subsequently applied as an input to the analysis of the strength of the open wagon main-bearing structure in a standard scheme of interaction with a train ferry deck. The calculated maximal equivalent stresses in the structure of the fastening units exceeded the valid permissible values. To confirm the theoretical results, experimental studies focused on the strength analysis of the open wagon placed on the railway ferry deck, which was performed in real operational conditions. Electrical voltage sensors were used to determine stress distribution in the areas where the body was attached to the deck. In this case, sensors of the strain gauges, i.e., tensiometers, were used. The base of 25 mm is a dimensional parameter and the resistance, 124 Ohms, is the tensiometer parameter. Verification has been performed and, based on the obtained experimental results, it has been established that the hypothesis' adequacy is not rejected. The authors developed some measures for adaption of the lashing devices for rail cars on train ferries, which can ensure their safe transportation by sea. The strength calculation demonstrated that, in the new scheme of securing the transported railway vehicles on the railway train ferry, the stresses in its structure do not exceed the permissible values. The article also includes information about the results of the strength calculation of a container placed on a roll trailer transported by a train ferry. This research will contribute to the development of measures regarding the safety of railway vehicle transportation by sea ferry and better efficiency of train ferry transportation.

An experimental methodology to support development of yaw damper prototypes based on a hardware-in-the-loop test bench

Research and development of innovative suspension components for rail vehicles have involved huge investments in recent years. Research efforts have focussed on designing and optimising suspension systems to deal with the new challenges introduced in railway dynamics by the continuous increase in vehicle speed. In particular, yaw dampers have been a relevant research topic due to their influence on vehicle stability. In this context, this paper aims to propose a Hardware-In-the-Loop (HIL) methodology for testing yaw dampers under experimental conditions close to real operating scenarios, comparing the influence of different prototypes on the stability of high-speed rail vehicles. A reduced vehicle model is proposed for real-time integration in HIL tests. This model provides a reference stroke to be imposed on the prototype tested, considering the actual damping force provided by the device being analysed. Two yaw damper prototypes are introduced to validate the proposed methodology by means of comparative analysis at different vehicle speeds. The experimental results provided by the HIL test bench are then compared with corresponding analysis done using Multi-Body (MB) simulations. The proposed HIL methodology has proved to be able to test physical prototypes and define guidelines to assist damper manufacturers developing and optimising yaw damper components.

Entrapment and extraction of wheelchairs at flange gaps with and without flange gap fillers at pedestrian railway crossings

Purpose Where pedestrian crossings meet rail tracks, a flange gap allows the train wheel flanges to pass. This gap can be hazardous for wheelchair users as castor wheels may become trapped. While compressible gap fillers can eliminate the flange gap, fillers are subject to wear, pose a derailment hazard to light rail vehicles and can strip grease from passing wheels. These issues could be mitigated by partially filling the flange gap with a compressible filler. The aim was to investigate the risk of entrapment and ease of extraction of wheelchair castors from flange gaps fully and partially filled with compressible fillers, and assess ride quality. Materials and methods Entrapment risk and ease of extraction for four wheelchairs were tested at various crossing angles with flange gap fillers. Twelve wheelchair users tested ease of extraction and ride quality for partially and fully filled flange gaps. Results It was found that risk of entrapment is low if a standards-compliant crossing with open flange gaps is traversed in a straight line. However, castors can become trapped if the user alters direction to avoid an obstacle or if the crossing surface is uneven. Once trapped, castors are extremely difficult to remove without external assistance. Conclusions Flange gap fillers that reduce the gap to 10 mm or less eliminate entrapment while retaining acceptable ride quality. Filling flange gaps or leaving a residual gap depth of less than 10 mm is the best option to eliminate risk of entrapment and ensure good ride quality for wheelchair users. IMPLICATIONS FOR REHABILITATION Rail crossings flange gaps pose an entrapment hazard for wheelchair users Partial or complete flange gap fillers may reduce entrapment but require research Rehabilitation professionals need to educate wheelchair users on techniques to cross flange gaps safely Consumers and health professionals can consult rail operators to partially fill flange gaps

Multi-body dynamic modelling and simulations for train crashworthiness design analysis

ABSTRACT One of the most important issues for rail passenger vehicles is on occupant safety through vehicle crashworthiness. Crashworthiness, in terms of rail vehicle designs, is the capability to dissipate the crash energy in such a controlled fashion that the overall damage is inconsequential to passenger space. A case study on a popular city passenger train has been conducted using a multi-body formulation of a three-dimensional, non-linear rigid body dynamic train model. The simulated crash scenario details a one to eight vehicle train in a front-on collision onto a fixed block. The crashworthiness is measured in terms of the degree of impact energy absorption, vehicle deceleration, and passenger injury criteria. The results showed that in a single vehicle, the crash energy management systems (CEMS) adequately compensated for the effects of impact at a crash speed of 44.5 km/h and below. At higher speeds, it is projected that the energy crush zones will need significant structural increases in both its crush length and crush force. An increase in the crush length is normally preferred over the crush force so as to maintain the longitudinal deceleration gradient within a tolerable range to ensure passenger safety. The benefits of computational modelling and simulations should not be underestimated as it allows for a thorough appreciation of a sound appreciation of the crashworthy structures and energy absorbers within any rail vehicle during the initial periods of the design process.

Improvements in Urban Rapid Transit Boarding and Alighting Safety during System Modernization

Urban rail transport has advantages that determine its particular usefulness. However, despite decades of technical development, it is still difficult to speak about satisfactory solutions. Safe, independent access to this transport and public infrastructure for passengers with reduced mobility (PRM) is an essential element of civil rights and an interesting subject of scientific research. In relation to that, the interface between rail vehicle and platform, despite multiple efforts aiming at improving this situation, is one of the hardest problems to overcome. This paper presents a summary and analyses of distinctive features of selected transit systems that are interesting from the viewpoint of finding various solutions to improve the safety of passengers on platforms. This analysis led to preparation of a new, improved standard of the vehicle–platform interface, illustrated with an example of the city of Wrocław, as discussed further in this paper. Some of the main conclusions of this paper are that insufficient progress has been made with developing the vehicle–platform interface, there are a multitude of systems and ways of (more or less effectively) ensuring independent access for PRM, and further research and development work is needed to optimize engineering solutions in this domain so they are both sustainable and economical.

Selection of tramcars for sustainable urban transportation by using the modified WASPAS approach based on Heronian operators

The wrong design of rail system vehicle fleets is one of the most critical problems in terms of urban transportation. Light rail system fleets in many large cities, including Istanbul, consist of various types and feature vehicles. It creates significant problems in integrating each rail system vehicle into the system. In addition, while it is necessary to keep an inventory of spare parts for each different type of vehicle, it requires different qualifications for professionals involved in processes such as maintenance and repair, leading to extra costs. In this context, the study's primary purpose is to determine the most suitable light rail vehicles for urban transportation systems and create vehicle fleets accordingly. In that regard, the study aims to provide a reliable and practical decision-making model that can be used as a roadmap for decision-makers when choosing tramcars to solve these problems. The present work proposes a hybrid procedure integrating the Best and Worst Method (BWM) and Power-Heronian Weighted Aggregated Sum Product Assessment (WASPAS'PH) approaches. The most critical implication of the work indicated that the acquisition cost per tramcar set (0.148) is still the most influential factor. The economic lifespan of tramcars (0.037), the number of seats in a vehicle set (0.041), and energy consumption (0.072) have followed the most significant criterion, respectively. Besides, it highlighted that the A14 Brand CR (0.7819) is the most appropriate option for well-structuring the urban light rail system fleet. An extensive validation test to check the suggested model's robustness confirmed the procedure's stability and consistency.

Experimental and simulation study on bonded repaired low-velocity impact of carbon fiber reinforced plastic laminates for rail vehicles

In this study, a high-strength carbon fiber reinforced composite laminate for rail vehicles was machined as a perforated sample and repaired by bonding a patch of the same material. The mechanical response of the repaired laminate to a low-velocity impact with energies of 25J and 30J was investigated through experiments and simulations with variations in patch thickness, size radius, and off-axis angle. The finite element simulation model was established in Abaqus/Explicit. The model integrated the progressive damage model based on the 3D-Hashin failure criterion, which can simulate the intralaminar damage of the fiber and the matrix. The cohesive zone model was used to simulate the delamination damage. According to the finite element analysis results, the mechanism and process of impact damage of the repaired laminates were analyzed. Based on the validated finite element model, the effect of patch size, thickness and off-axis angle on impact response was investigated. Patch radius reduced to 15 mm or thickness reduced to 2.1 mm can still resist low-velocity impacts with an energy of 30 J. Although the off-axis angle of the patch had little effect on the impact response of the repaired laminate, an off-axis angle of 90° was effective in suppressing delamination damage within the patch.

A Service-Driven Routing Algorithm for Ad Hoc Networks in Urban Rail Transit

Due to increased traffic pressure, traditional urban rail vehicle–ground communication systems are no longer able to meet the increasing communication requirements. In this paper, ad hoc networks are applied to urban rail transit vehicle–ground communication systems to improve link reliability and reduce transmission delay. In the proposed network, a service-driven routing algorithm is proposed, which considers the distance factor for cluster head selection and optimizes the routing transmission delay by service priority and congestion level. An auxiliary node-based routing maintenance mechanism is also proposed to avoid the problem of frequent breakage of communication links due to the high-speed movement of trains. Through the simulation, the proposed algorithm can effectively reduce the packet loss rate, end-to-end delay, and routing overhead of vehicle–ground communication compared with the traditional routing algorithm, which is more conducive to meeting the next generation of urban rail transit vehicle–ground communication requirements.