High-speed Rolling Research Articles

Диагностика системы взаимодействия железнодорожного пути и подвижного состава по параметрам комфорта езды и эквивалентной конусности

Purpose: to identify the influence of the geometric parameters of wheel sets and rail track on the smoothness of the ride and the level of passenger comfort for an automated diagnostic system. Methods: statistical methods were used to conduct the research. Sampling and analysis of statistical observation data made it possible to identify existing approaches to assessing the levels of interaction of the wheel-rail system at different speeds. The track sections grouped into rows along pickets were assessed in terms of passenger ride comfort and equivalent conicity. Materials used in the public domain and official websites, as well as research by the authors. Results: a list of factors influencing the conditions of interaction between highspeed rolling stock and the railway track has been identified. Data were obtained for indicators of ride comfort and equivalent conicity for the St. Petersburg — Moscow line along pickets at actual realizable speeds. Practical importance: the possibility of using remote measurement diagnostics to determine the geometric parameters of wheelsets and rails and the geometric parameters of the rail track has been determined. Suggestions for improving the qualitative assessment of the interaction of the wheel-rail system are recommended.

Method of experimental determination of the effective area of a pneumatic spring of high-speed rolling stock

Method of experimental determination of the effective area of a pneumatic spring of high-speed rolling stock

Simulation of the Dynamic Impact of High-Speed Rolling Stock on Buried Structures of the Tunnel Type

Simulation of the Dynamic Impact of High-Speed Rolling Stock on Buried Structures of the Tunnel Type

Determining the effect of additional tank volume and air pressure in the spring on the dynamic indicators of a pneumatic system of spring suspension in high-speed railroad rolling stock

The object of this study is the pneumatic system in the spring suspension of rolling stock under conditions of high-speed movement from 170 to 250 km/h. Based on the thermodynamic model of the pneumatic spring suspension system, the influence of volume of the additional tank and the initial pressure in the pneumatic spring on the nature of change in the spring's dynamic stiffness, energy losses, and damping coefficient was studied. Based on the built "force-deformation" dependences for the pneumatic spring, it was established that the change in the volume of an additional tank has a slight effect on the deformation of the pneumatic spring at different speeds of the high-speed rolling stock. It was established that in the range of rolling stock speeds of 170–250 km/h, the diameter of the connecting pipeline is 30 mm, and the volume of the additional tank is from 30 to 60 l, the maximum change in the dynamic stiffness of the pneumatic spring up to 15.5 % occurs at the pressure in the spring of 6.5 bar. Dependences of energy loss and damping coefficient during the operating cycle of the pneumatic spring suspension system were derived. It was established that an increase in the volume of the additional tank and the initial pressure in the pneumatic spring leads to an increase in the energy loss during the operation cycle of the pneumatic system. The maximum values of the damping coefficient over the entire considered range of variable parameters are 1.16–1.29. It was established that with the volume of the additional tank in the range from 30 to 50 liters, the maximum values of the damping coefficient are observed at a diameter of the connecting pipeline of 25 mm and a speed of movement from 200 to 250 km/h. And with an additional tank volume of 60 liters – with a diameter of 30 mm and a speed of 170 to 250 km/h

AN EXPERIMENTAL STUDY OF THE EFFECT OF AN ADDITIONAL TANK ON THE DEFORMATION OF THE PNEUMATIC SPRING OF HIGH-SPEED RAILWAY ROLLING STOCK

The use of a pneumatic spring suspension system in the second stage of spring suspension of high-speed rolling stock is an integral component of ensuring its permissible dynamic indicators and traffic safety indicators. This work is aimed at researching the deformation characteristics of the rubber-cord shell of the pneumatic spring in the vertical and horizontal directions, taking into account manometric pressure, external load and an auxiliary reservoir. To achieve the goal, a methodology for experimental studies of pneumatic spring deformation was developed using a test rig with an assembled pneumatic spring suspension system, power and measuring equipment. Deformations of the rubber-cord sheath were measured by analog sensors of linear displacements using an analog-to-digital converter and special software. It was established that the effect of the auxiliary reservoir on the amount of vertical deformation of the lower part of the rubber-cord shell does not exceed 3.46 %, which allows us to conclude that the auxiliary reservoir of the pneumatic spring suspension system has a negligible effect on the vertical deformations of the lower part of the rubber-cord shell of the pneumatic spring. The dependences of the deformation of the rubber-cord shell of the pneumatic spring in the horizontal direction on the value of the manometric pressure when the auxiliary reservoir is connected and disconnected are obtained. It was established that in the range of manometric pressure changes of 1.0÷2.5 atm the presence or absence of an auxiliary reservoir has little effect on the amount of deformation of the rubber-cord sheath in the horizontal direction. However, at a pressure of more than 2.5 atm, closing the tap to the auxiliary reservoir leads to significantly greater deformation of the rubber cord shell compared to the deformation when the tap is open and the auxiliary reservoir is turned on. The obtained results regarding the deformation characteristics of the rubber-cord shell of the pneumatic spring will allow us to proceed to the study of the dynamic characteristics of the pneumatic spring, which are necessary when establishing safe conditions for the operation of modern high-speed rolling stock at the stage of its design.

Система комплексной диагностики элементов высокоскоростного подвижного состава и инфраструктуры: анализ и внедрение

Objective: to consider the issue of integrated diagnostics of the undercarriage equipment of high-speed rolling stock and track infrastructure, to analyze the impact of operational factors on the technical condition of rolling stock, to identify the main problems and propose possible solutions, to consider the prospects of domestic development in the field of integrated diagnostics of rolling stock and infrastructure. Methods: analysis of design features and impact on train operation safety, criteria and parameters of running stability and passenger comfort of the undercarriage equipment of the high-speed electric train “Sapsan”, description of prerequisites and stages of creation, testing and operation of the system of continuous monitoring of parameters of the dynamic system “undercarriage and track” of electric trains “Sapsan”, analysis of the impact of the main operational factors on the technical condition of the rolling stock undercarriage equipment. Results: the key role of the undercarriage equipment of the Sapsan electric train in ensuring operational safety and passenger comfort has been determined. The necessity of creating and implementing a system for continuous monitoring of dynamic reactions in the system “undercarriage equipment - track infrastructure” has been identified. The results of experimental operation of the prototype of the system in the Sapsan electric trains are considered on the example of research of track sections with increased impact on the rolling stock and problems of running stability of the electric train. It is revealed that vertical accelerations of axlebox units with significant amplitudes allow to reveal vertical irregularities of the track up to 3 m long, and constant registration of increased lateral accelerations of the bogie frame shows the necessity of solving the issues related to the geometry of wheel-rail contact at sinuous movement of rolling stock in terms of conicity. The current state and prospects of development of domestic systems of complex diagnostics are determined. Practical importance: the considered diagnostic system allows to carry out complex analysis of problems of technical condition of undercarriage equipment and infrastructure, to determine interdependence and level of influence of operational factors, which is the way to increase reliability and fault tolerance of rolling stock, operational safety and passenger comfort. Its integration into the digital platform will increase the efficiency of rolling stock maintenance planning and enterprise resource management.

Experimental Study of the Regularities of Deformation of the Rubber Cord Shell of a Pneumatic Spring of High-Speed Rolling Stock

Experimental Study of the Regularities of Deformation of the Rubber Cord Shell of a Pneumatic Spring of High-Speed Rolling Stock

Micropitting performance and friction behaviour of DLC coated bearing steel surfaces : On the influence of Glycerol-based lubricants

A better understanding about the rolling contact fatigue and micropitting performance of machine component surfaces lubricated with environmentally friendly lubricants is critical to designing and further formulating new lubricants intended to be used in rolling–sliding contacts such as those found in gear and bearing applications. In this work, the frictional behaviour and rolling contact fatigue (RCF) performance of DLC, Cr/a-WC:H/a-C:H and a-C:Cr coatings under glycerol-based lubrication in rolling sliding contact conditions have been investigated. Traction maps, Stribeck curves, and fatigue plots have been generated by using a micropitting test rig (MPR). The initiation and progression of micropitting was monitored by means of white light optical interferometry and scanning electron microscopy (SEM). Results indicated that glycerol-based lubricants exhibited a significant friction reduction as the hydrodynamic effect is enhanced at higher rolling-speeds. Under boundary lubrication the friction coefficient was significantly higher compared to the values obtained with a commercial mineral-based transmission oil. Compared to uncoated steel surfaces, DLC coatings effectively reduced the volume loss and micropitting progression. Irrespective of the coating thickness, DLC showed an excellent tribological behaviour when the base lubricant favours the onset of mild-wear, over micropitting. When the lubricant formulation favoured the onset of micropitting, the coatings tended to prematurely fail due to debonding from the substrate, and local micro-spallation. The experiments demonstrated that friction reduction does not necessarily correspond with a reduction of micropitting.

Wheelchair Badminton: A Narrative Review of Its Specificities

This narrative review aims to provide a comprehensive overview of the scientific literature on wheelchair badminton and its distinctive aspects, encompassing abilities and disabilities, propulsion technique, and the use of a racket. The relatively young history of wheelchair badminton is reflected in the scarcity of scientific studies within this domain, highlighting the need for further investigation. The review systematically covers existing articles on wheelchair badminton, offering a nearly exhaustive compilation of knowledge in this area. Findings suggest that athletes with abdominal capacities engage in more intense matches with a higher frequency of offensive shots compared to athletes with little or no abdominal capacities. Moreover, backward propulsion induces higher cardiorespiratory responses, overall intensity of effort, physiological stress, metabolic load, and rating of perceived exertion, particularly at high imposed rolling resistance or speeds, and makes it difficult to generate sufficient forces on the handrim, requiring adjustments in the kinematics of propulsion techniques, particularly at high rolling resistances or speeds, potentially leading to performance decrements. The use of a badminton racket further increases generated forces while decreasing the efficiency of propulsion and modifying the propulsion technique with shorter and quicker pushes, potentially impacting performance. Further research is imperative to explore additional perspectives, address existing gaps, and expand the scope of study within the wheelchair badminton domain. This narrative review serves as a foundation for future investigations, emphasizing the necessity of continued research to enhance our understanding of wheelchair badminton.

Использование численного моделирования при анализе аэроупругого взаимодействия подвижного состава с тоннельными сооружениями

Purpose of the work: study of the formation of a complex air structure under conditions of rolling stock movement along extended underground structures using numerical modeling methods. Methods: an analysis of the influence of aerodynamic factors on rolling stock, passengers and railway infrastructure was carried out based on the finite element and volume method. The reasons for the occurrence of a compacted air zone, which appears in front of the head car of the train and exerts significant resistance to the movement of the train using the “Frozen Rotor” method, have been investigated. The indicators of energy efficiency and safety of the process of freight and passenger transportation are analyzed, taking into account the processes of aerodynamic interaction of moving rolling stock and artificial tunnel-type structures. Results: using numerical modeling and the use of the “Frozen Rotor” method, it was possible to obtain a qualitative picture of the distribution of transverse vortex air flows resulting from the occurrence of viscous friction. Regularities were discovered in the changes in the dynamics of pressure and speed of air masses on the surface of the head fairing when a train enters a tunnel. The fact of the negative impact of zones of high and low pressure, as well as their sharp drop, on the locomotive crew and passengers has been established. Practical significance: the possibility of conducting research in the field of aerodynamics of railway transport using modern numerical modeling methods is shown. This topic is very relevant in the field of designing high-speed rolling stock.

Экспериментальные исследования динамической работы железнодорожных мостов при воздействии высокоскоростного подвижного состава

The issue of considering the dynamic interaction of the railway rolling stock and the structures of bridge structures is especially important when solving the tasks of increasing the speeds of trains on the existing railway lines, as well as when prescribing high-speed mode on designed bridges. Rational accounting of the parameters of dynamic interaction allows you to perform complete and reliable calculations of elements of bridge structures, which in turn has a beneficial effect on predicting the period and nature of the operation of structures and, because of the economic component of projects. The modern solution to the problem of dynamic interaction is reduced to determining the degree of influence of each component of the unified mechanical system of the bridge-travel. Objective: the purpose of this study is to determine the parameters of dynamic interaction through experimental measurements of stresses, accelerations, and displacements of structures of the bridge structure located on the existing railway line with an organized high-speed traffic movement. Methods: experimental measurement using high-frequency voltage sensors, accelerations and movements with subsequent statistical processing and analysis of the results. Results: graphs and tables displaying a change in the measured values of relative deformations, accelerations, and movements over time. Practical importance: The practical significance of this study is to assess the degree of influence of the components of the dynamic interaction of high-speed rolling composition and the bridge structure, which allows you to form a holistic picture of the nature of the process of dynamic interaction.

Dynamic precipitation and twinning-induced dynamic recrystallization in Mg–6Al–3Sn–1Zn alloy during multi-pass high-speed rolling

Ultrafine-grained microstructure was successfully obtained in Mg–6Al–3Sn–1Zn (ATZ631) alloy by multi-pass high-speed rolling (HSR) at a rolling speed of 1100 m/min and a rolling temperature of 400 °C. The grain refinement mechanism of ATZ631 alloy during HSR was investigated, which is attributed to mechanically fragmented grains and twinning-induced dynamic recrystallization (TDRX). During the initial stages of rolling, the initial coarse grains are refined by the intersection of twins. With increasing strain, the grain refinement mechanism is the typical dynamic recovery and TDRX. In general, twins are filled with a high density of dislocations and nano-sized precipitates at the dislocations, which can accelerate DRX by increasing the driving force or particle-stimulated nucleation (PSN) within the twins. Subsequently, the coarse grains are refined by forming fine DRXed grains via dislocation entanglement, dislocation rearrangement, and dislocation absorption. As the process proceeds, grain boundaries (GBs) migration is suppressed by the precipitates at the GBs of new DRXed grains. Thus, the growth of the DRXed grains can be inhibited. Finally, ultrafine-grained microstructure with an average size of ∼116 nm is obtained. Moreover, the new grains formed by TDRX exhibit random orientation during this process, indicating that the basal texture gets effectively weakened by increasing the fraction of DRXed grains. These findings bring forward the microstructural evolution during dynamic precipitation and DRX, thus providing a novel notion for improving microstructures and grain refinement in Mg alloys.

High-speed rolling bearing lubrication reliability analysis based on probability box model

An efficient and high-precision method is proposed for the analysis and evaluation of high-speed rolling bearing lubrication reliability based on a probability box (p-box) model. This method expands the application of mixed aleatory and epistemic uncertainties analysis within the realm of bearing lubrication reliability. Initially, the method establishes a reliability model for high-speed rolling bearing lubrication, taking into account the shear thermal effect through the analytical solution of a Γубин-type entrance zone. Subsequently, the uncertainty surrounding lubrication parameters under high-speed conditions is examined, with its mixed aleatory and epistemic uncertainties accurately depicted by using the p-box model. Furthermore, an effective and precise method for analyzing the reliability of rolling bearing lubrication is introduced based on the p-box model, in which the optimization model involved is efficiently solved using a decoupling method. Finally, lubrication reliability analysis and sensitivity analysis of parameter uncertainty levels are conducted for high-speed rolling bearings in this study. The research results demonstrate that the proposed method achieves higher accuracy and efficiency.

Development of Mg–6Al–4Sn–1Zn alloy sheets with ultra-high strength by combining extrusion and high-speed rolling

Achievement of ultra-high yield strength of above 400 MPa for rare-earth-free magnesium (Mg) alloys is quite difficult via traditional thermal-mechanical processing. In this study, Mg–6Al–4Sn–1Zn alloy (ATZ641) sheet with the yield strength of 410 MPa, ultimate tensile strength of 442 MPa, and elongation of 5.1 %, was fabricated by combining extrusion and high-speed rolling (HSR). The results showed significant refinement in the grains of high-speed rolled ATZ641 alloy due to dynamic recrystallization (DRX) effectively promoted by particle-stimulated nucleation (PSN) of pre-existing relatively coarse Mg17Al12 precipitates uniformly distributed along grain boundaries, formed during extrusion prior to HSR. Meanwhile, the Mg17Al12 nano-precipitates with high number density, mainly due to dynamic precipitation during HSR and submicron Mg2Sn precipitates formed during both extrusion and HSR, suppress DRX and thus promote the formation of a certain amount of subgrains via particle pinning. The excellent mechanical properties are mainly attributed to fine-grain strengthening, high density residual dislocations and presence of numerous hybrid particles such as bimodal size (micron and nanometer) Mg17Al12 precipitates and submicron Mg2Sn precipitates as well as a large amount of subgrains. This study offers an important notion for developing rare-earth-free Mg alloys with ultra-high strength.

Design and Testing of a Measurement Device for High-Speed Bearing Evaluation

The submitted article focuses on the proposal of a testing device for researching alternative methods of lubricating technical systems, specifically high-speed rolling bearings using lubricants containing nanoparticles. The aim of this research is to verify the functionality of the proposed technical device, whose main task is to ensure the measurement of the functional and operational characteristics of high-speed rolling bearings. The proposed technical device allows us to carry out a series of measurements, primarily for the purpose of selecting specific bearings and secondarily for the purpose of conducting technical diagnostic measurements. The results of these measurements are significant in the selection of suitable nano-particle additives for the lubrication of the tested bearings. The tests was carried out using speeds reaching 110,000 rpm. Methods of monitoring vibrational and acoustic diagnostics were chosen for the analysis of the operational processes of loaded technical systems.

Моделирование технического обслуживания и ремонта высокоскоростных электропоездов с использованием данных бортовых систем диагностики

Purpose: High–speed railway lines (HSRL) are the most promising direction of railway transport development in the 21st century, increasing the mobility of the population at a distance of up to 1000 km, contributing to the development of urban conglomerations. Reliable rolling stock is necessary for the functioning of the HSRL. The article describes the performed mathematical simulation of the operation and maintenance and repair system (MRS) of high-speed electric trains in relation to the St. Petersburg — Moscow landfill. The purpose of the simulation is to substantiate the requirements for MRS, including when using on-board automated systems for technical diagnostics. Methods: It is based on the principles of passenger traffic organization, technical requirements for domestic high-speed rolling stock, queue theory methods, as well as probabilistic mathematical modeling methods in MS Excel in the algorithmic language Visual Basic for Applications (VBA). The corresponding software has been developed. Results: A mathematical model and software have been developed, multifactor modeling has been performed, the degree of failure impact on the required fleet of high-speed electric trains has been determined. Methods of optimization of maintenance to reduce the required fleet are proposed. The requirements for the mathematical model itself are defined. A factor analysis of operation and maintenance has been performed by mathematical modeling. Practical significance: The guarantee of safe and reliable high-speed traffic is the creation of a modern system of maintenance and repair of rolling stock. The study of the interaction of operation and maintenance is very important in preparation for the launch of domestic high-speed traffic.

DETERMINATION OF CHARACTERISTICS OF FATIGUE CRACKS GROWTH IN THE AXLES OF RAILWAY CARRIAGES

Providing damage resistance is the most important requirement presented to railway axles. This paper provides a detailed review of the characteristics of resistance to fatigue crack growth in axles made of EA4T steel (25CrMo4). This steel is typical for axles of high-speed rolling stock. Resistance to fatigue crack growth is defined by the nature of the Paris-Erdogan curve da/dN=CKm, the parameters of which are the coefficient C and the exponent m. Determination of these parameters is based on the results of fatigue tests with the samples or with full-scale axles having cracks. The analysis of numerous scientific papers has shown that for the specified steel there is a significant scatter in the values of these parameters. This scatter is caused by a number of factors, the main of which are: the difference in test objects (from small samples of the SE(B) type to full-scale rolling axles 190 mm in diameter); the difference in loading methods (tension-compression, flat bending, circular bending); the variation of mechanical properties of EA4T steel. In the paper the models of surface fatigue crack geometry are analyzed and semi-elliptical shape of crack front line is selected as the most acceptable. The significant scatter in the values of the parameters m and C prevents to establish reliably the residual life of axles with cracks, which is an important characteristic for practical forecasting of axle survivability. The technique for parameters m and C optimization in view of semi-elliptical shape of the crack front line has been developed. The relationship linking the parameters m and C has been established. The method for determining the residual life of the axle by the criterion of non-destruction is proposed. The dependence between the residual life and the value of the parameters of the Paris-Erdogan equation in the development of fatigue failure is established. The procedure for axles monitoring timeframes setting to prevent their fatigue failure is discussed. Keywords: parameters of Paris-Erdogan equation, fatigue crack, residual life of axle.

INFLUENCE OF ROLLING SPEED ON THE TEMPERATURE FIELD DURING COLD ROLLING OF ALUMINIUM SHEETS

One of the effects of plastic deformation is an increase in the temperature of the formed metal. The rolling pressure, friction stress, and contact state show different characteristics in different zones along the deformation zone, which causes the heat generation and transfer states to be different, so the strip temperature is subject to a complex change process. The paper presents the results of experimental temperature measurements at several points on the width of the rolled strip and on the surface of the working rolls depending on the rolling speed in the range of 0.5-4.0 m/s. The results obtained showed a clear dependence of both the strip temperature and the working roll temperature on the rolling speed, with the increase in strip temperature being more intense. At very high rolling speeds, the temperature of the rolled sheet may even exceed 1000C, which is unfavourable due to the possibility of the formation of deposits on the surface of the rollers.

Fault diagnosis of high-speed rolling bearing in the whole life cycle based on improved grey wolf optimizer-least squares support vector machines

Under the high-speed condition, the fault diagnosis of rolling bearing is difficult due to parameter limitation and local optimization. To solve these problems, a fault diagnosis method of the whole life cycle based on wavelet thresholding denoising, genetic algorithm-variational mode decomposition (GA-VMD) and improved grey wolf optimizer-least squares support vector machines (IGWO-LSSVM) is proposed. The nonlinear convergence factor is adopted to improve the global search ability of GWO, and then LSSVM is optimized by IGWO, which is used to improve the fault identification accuracy. Based on the high-speed rolling bearing test rig, this method is applied to fault diagnosis of high-speed rolling bearing in the whole life cycle. The kurtosis and approximate entropy indexes are adopted as the basis for the stage division in the degradation process. The fault diagnosis of rolling bearing in the whole life cycle is completed from the five aspects of data acquisition, stage division, data preprocessing, fault feature extraction and fault feature identification. The results show that the maximum identification accuracy of this method can reach 97 %.

Recent research advances on high-speed railway noise

Around 42,000 km high-speed railways are in operation in China at speeds up to 350 km/h. 400 km/h trains are also under development. Huge resources have been put into research on high-speed railway noise. This paper outlines advances achieved in several key projects by covering the following aspects: measurement results showing typical characteristics of high-speed railway noise; analyses on source contribution to pass-by noise based microphone array data; modelling of high-speed rolling, aerodynamic and viaduct bridge noise; prediction of the vibro-acoustic behaviour of car-body with poro-elastic media; and finally, analyses of vibration transmission in the suspension/bogie system.