At the present stage of development of the railway industry it is necessary to introduce new innovative solutions during the design of the flat wagons of articulated type for their structural design. ...To reduce the material consumption of flat wagons, in article was proposed to produce bearing elements of their structures from pipes of a circular cross section. Flat wagon of articulated type was designed on the basis of the developed construction in order to improve the operational efficiency of the wagon. The innovation design of a flat wagon of articulated type from round pipes are presented. The mathematical model of the bearing structure dynamic load of the flat wagon from round pipes in the main operational modes are made. Accelerations which act on the bearing structure of articulated flat wagon under I rated conditions (tension – jump) are presented.
The transport of goods on the Brazilian railway networks has been growing over the last decades, reflecting growth in industries in this segment, including those related to the design of railway ...wagons. The general objective of this paper is to propose a method for designing railway wagons capable of developing the usual wagon models and meeting specific design demands, which can be applied in industrial environments and education. The proposed method combines practices identified in the literature on the design of railway wagons with traditional product development methods. It was structured in three phases: Informational Design, Conceptual Design, and Detail Design. The proposed method was evaluated by wagon manufacturers in Brazil and applied in teaching environments, demonstrating its feasibility. The method proposed for the design of railway wagons presented in this work has a high affinity with the practices adopted by the industry and is easy to apply in the academic environment, helping both in the training of human resources and in the execution of new wagon design projects.
Railway transportation plays an important role in many disaster relief and other emergency supply chains. Based on the analysis of several recent disaster rescue operations in China, the paper ...proposes a mathematical model for emergency railway wagon scheduling, which considers multiple target stations requiring relief supplies, source stations for providing supplies, and central stations for allocating railway wagons. Under the emergency environment, the aim of the problem is to minimize the weighted time for delivering all the required supplies to the targets. For efficiently solving the problem, we develop a new hybrid biogeography-based optimization (BBO) algorithm, which uses a local ring topology of population to avoid premature convergence, includes the differential evolution (DE) mutation operator to perform effective exploration, and takes some problem-specific mechanisms for fine-tuning the search process and handling the constraints. Computational experiments show that our algorithm is robust and scalable, and outperforms some state-of-the-art heuristic algorithms on a set of problem instances.
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•Failure analysis of parabolic spring belonging to a railway wagon.•The failure occurred in the contact zones between the leaf springs.•Finite element analyses were performed taking into account the ...service conditions.•The Goodman's criterion shows a safety factor of approximately 1, not enough to prevent the fatigue failuren.
This paper describes the study of three fractured parabolic springs belonging to a two-axle wagon suspension system. In order to determine the causes of the failures, a material analysis was performed, followed by a detailed study of the fracture’s surface both visually and using optical and scanning electron microscopy. The observations of fracture surfaces of the three springs revealed that the fractures began in the contact zones between the leaf springs, suggesting a fretting fatigue mechanism. The mechanism of failure of the springs fracture was a fatigue process. The propagation of fatigue cracks is more pronounced and extensive in one of the leaf springs. Finite element analyses were also performed taking into account the service conditions in order to determine the stress and strain distribution along the leaf springs. From the numerical simulations it can be concluded that the maximum stresses occur in two different zones: in the central section of the leaf spring and along the distance to the central section, in the sections where the relationship between the thickness reduction of the leaf spring and the resulting bending moment is most unfavourable. The Goodman's criterion shows a safety factor of approximately 1 and it can be concluded that this value is not enough to prevent the fatigue failure.
Railway tank wagons are widely used for the transportation of liquid cargo as petroleum products, acids, alcohol etc. During the last years only tank wagons with bogies were manufactured (four axles ...wagons). The prototype of each wagon’s series is tested according with international standards in purpose to validate the design (the project). This paper present the static and dynamic test performed at the body of a four axles tank wagon.
A wheel flat is a common fault in railway vehicles that may develop after incorrect brake application, or localised wheel-rail adhesion reduction. Operators detect wheel flats using wayside systems ...that are not capable of delivering real-time alarms. A wheel flat defect was modelled and introduced to a railway wagon multibody dynamic simulation to study the vehicle dynamic behaviour triggered by such wheel tread defect. Bogie-based and car body-based wheel flat detection was evaluated to determine eventual hardware robustness and signal processing requirements for on-board wheel flat detection devices. Various vehicle operating conditionds and wheel flat defects were simulated to analyse the wheel flat impact propagation throughout the railway vehicle bodies. Wheel defect detectability was assessed using detectability indicators (DIs) based on envelope power spectrum analysis, crest factor and RMS. It was found that bogie and car body-based wheel flat detectability is highly dependent on the track characteristics. The wheel flat signature was reduced in the wheelset-bogie and bogie-car body interfaces, indicating that advanced signal processing techniques are required for bogie-based and car body-based wheel flat detection systems. The DIs showed clear differences between healthy and faulty wheelset and bogie frame acceleration signals, which is promising for eventual on-board wheel flat detection systems.
•The evolution laws of WDD and tread wear are analyzed based on the tracking measured data.•A freight wagons model considering Non-Hertz wheel-rail contact is developed for numical simulation.•The ...influence of WDD with the new profile and worn profiles on tread wear are studied.•The correlation analysis of wheel tread wear and the WDD is conducted based on the field test data.
Wheel wear is a fundamental problem for railway vehicles. The unequal wear rate of the two wheels of a wheelset results in the wheel diameter difference (WDD). The WDD and wheel wear not only affect the dynamic performances of rail vehicles, but also increase the maintenance cost. This paper presents an investigation of the effect of the WDD on tread wear for freight wagons based on extensive field measurements and numerical simulations. The evolution laws of the WDD and tread wear of 4 freight wagons are first analyzed based on the monitoring data in an operation period of 200,000 km. A freight wagon dynamics model considering wheel-rail non-Hertzian contact is then established to study the influence of the WDD on the wheel tread wear of a freight wagon. The correlation analysis of wheel tread wear and the WDD is conducted based on the field test data. The results show that the initial WDD significantly affects the shapes and stress distributions of wheel-rail contact patches. The WDD can lead to the asymmetric wear of the two wheels of a wheelset, which conversely aggravates the WDD in return.
This article presents an efficient methodology for the calibration and validation of a numerical model of a freight wagon based on a dynamic test under real operation conditions. The dynamic test ...takes place during a regular journey of the train and involved the installation of on-board accelerometers and LVDTs, whose number and location was conditioned by the space occupied by the goods and constraints associated with loading and unloading the wagon. The data derived from the dynamic test was used for the identification of carbody's modal parameters, namely the frequencies, mode shapes and damping coefficients and to extract accelerations and displacements time-histories. A three-dimensional (3D) FE numerical model of the freight wagon was developed and calibrated using a genetic algorithm. The methodology proves efficiency and robustness in precisely estimating three numerical parameters, besides a significant upgrade in relation to the model before calibration. Model validation involved the comparison between numerically simulated results, based on a vehicle-track dynamic interaction analysis, and the experimental observations. An excellent agreement between experimental and numerical after updating time-histories was obtained, especially for the carbody responses, whose behaviour is governed by lower frequencies (below 3.5 Hz), in which the calibration process was focused.
•A diagnostic method for freight wagons hunting performance is proposed.•An evaluation indicator HC is utilized to describe the hunting stability.•The detection principle and performance validation ...through simulations and experiments.•The proposed method has been applied on practical railway engineering.
Vehicle hunting instability can cause a great threat to the operational safety of freight wagons, which urgently requires condition monitoring. To address this challenge, an innovative diagnostic method is proposed by employing an indicator called Hunting Coefficient (HC) applied on a wayside hunting detection system (WHDS). Firstly, a diagnostic index HC is defined according to the vehicle hunting characteristics, specifically related to the wheelset lateral amplitude A and frequency f. Subsequently, an in-depth analysis on hunting stability is conducted and a mapping relationship between HC and the vehicle hunting state is established, validated through a rig test. Furthermore, building on the detection principle, a case analysis is performed to verify the feasibility of the proposed method applied on WHDS. This approach provides a means to conduct condition monitoring for freight wagons hunting instability, offering a crucial foundation for condition-based maintenance.
•The predictive maintenance and train scheduling are formulated as a MILP problem.•Hierarchical solution for the maintenance and train scheduling is proposed.•Hierarchical solution using a dual ...decomposition and mechanism design is developed.•The optimality of the solution of hierarchical optimization is investigated.
While the progress of predictive maintenance has been rising in various application fields and several feasibility studies and prototypes have been developed, the operational implementation of predictive maintenance requires a more flexible and adaptive scheduling of the predicted maintenance interventions. Contrary to the traditional preventive maintenance tasks that are typically known long in advance, predictive maintenance may require very short-term schedule changes which are also affecting the operation. Railway rolling stock has some special requirements in terms of time table adherence and vehicle scheduling and routing that make the operational implementation of predictive maintenance particularly challenging. In this paper, we propose a hierarchical multi-agent framework for the predictive maintenance scheduling of passenger railway wagons. Besides fulfilling the requirement of scheduling the maintenance of a wagon before it fails (and potentially causes delays), also the passenger demand must be satisfied and the trains must be accordingly assigned to different routes following the time table. We propose a hierarchical distributed learning algorithm using dual decomposition and mechanism design approach. The proposed framework enables to preserve local preferences and particularities and to avoid high computational cost. In the proposed method, first, we decompose the centralized problem using the dual decomposition method, and handle the passenger demand fulfillment constraints by Lagrange multiplier (“shadow price”). Furthermore, the wagons with the private information on the system health need to perform the maintenance before their failure time (with a predicted remaining useful lifetime (RUL) and the corresponding uncertainty). To achieve this aim, we propose a mechanism design approach to align the wagons’ objective function to the aim of the central system using an incentive signal. The incentive signal creates a non-cooperative game among the wagons. We prove that the Nash Equilibrium (NE) of this game is the optimal solution of the predictive maintenance scheduling. The effectiveness of the proposed method is demonstrated on a case study of a small railway network.
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