Mathematical model of the formation and development of wave-shaped rail wear when an electric locomotive operates in the traction mode in tangent sections of the track

The problem of wave-shaped rail wear is highly relevant for rail transport. The paper presents a mathematical model of the formation and development of wave-shaped rail wear. The task of estimating vertical wear of the rail head under the axles of electric locomotives passing in the traction mode is considered. A technique has been developed that allows building chain of calculations that determine the formation and development of a wave-shaped rail head wear. A specific calculation example is given, illustrating the process of propagation of a wave-shaped wear from the source of its formation in the direction of train motion. An example of the calculation allows drawing the following conclusions:

1. Wave-shaped wear primarily occurs when the shock interaction of the wheel of an electric locomotive moving in the traction mode and a rail thread having imperfections of the rolling surface. Such imperfections, among others, may be a joint with a significant gap or a “step down” in the direction of the locomotive, as well as a welded joint with defect 46.3-4.

2. Wavelength of the wave-shaped rail wear, its configuration and amplitude of the fundamental tone are determined mainly by joint oscillations of the wheel-motor unit of the locomotive and the track infrastructure in the field of high-frequency oscillations (120 – 180 Hz).

3. Multivariate calculations showed that in steady state, the distribution speed of wave-shaped rail wear in the direction of train motion (as a function of the number of axles of electric locomotives passed in traction mode) is directly proportional to the vertical load at the wheel and rail contact in the slip zone, is inversely proportional to wear resistance C and significantly depends on the parameters of the undercarriage of the electric train and the track superstructure.

Criteria for predicting the initiation of rolling contact fatigue damage in the railway wheels and rails 

The development of the methods for modeling the processes of accumulation of the rolling contact fatigue damage and wear of the wheels of the railway rolling stock and the rails is particularly relevant due to the increase in the number of damage in the recent times. The work is underway to improve the chemical composition and the technology of production of the wheel and rail steels in order to improve their mechanical properties and ability to resist the action of the cyclic loads. The methods of modeling allow predict the possibility of initiation of the fatigue cracks during operation with the sufficient accuracy in the short time. The selection of the contact fatigue criterion and the mathematical apparatus for calculating the stresses at points in the area adjacent to the contact patch to obtain the numerical values of the criterion components is the most important task in the development of modeling methods. The article focuses on the approaches based on the Dang Van criterion and the shakedown diagram for a material undergoing to the action of cyclic loads, which are widely used to assess the rolling contact fatigue of the wheels and rails. The assumptions that are used in the development of the algorithms concerning the models of the contacting bodies, the shape of the contact patch, the distribution of the contact pressures and the tangential forces are considered. The approach using the criterion — the amplitude value of the maximal shear stress is also considered. The example of modeling the process of accumulation of the rolling contact fatigue damage in the wheel of the freight car is given. The results of modeling are presented in the form of the isolines of the criterion values and the accumulated damage in the area adjacent to the contact patch.

Motion stability of railway cars on bogies 18-100

Stability of the rolling stock in a rail track is determined by the nature of the motion of the wheelsets under the influence of processes in the “wheel — rail” system and connections with the bogie and the carriage body. Factors affecting the motion of wheelsets are the irregularities of rail threads and the interaction forces

in the “wheel — rail” system, which cause fluctuations in carriage hunting oscillation even in the absence of external disturbances. Parametric excitation of oscillations in the “carriage — track” system is caused by the difference in the radii of the rolling surfaces of the bevel gears with the transverse displacement of the wheelset in the track. This excitation is damped by the forces of resistance to rotation and displacement on the contact surface, the magnitude of which is inversely proportional to the rolling speed of the wheel. Therefore, with an increase in the speed of motion, the magnitude of resistance forces decreases and the intensity of processes determining hunting oscillations in the “wheel — rail” system increases. The excitatory factors on each of the wheelset of the bogie are of random nature and are not interconnected, therefore their vibrations are limited to the designs of the bogie and its connections with car body, which combine all the elements into a single system. Increasing the connectivity of the wheelsets and sidewalls of the bogie among themselves and with the carriage is the most appropriate solution for reducing hunting intensity. To do this, three-element bogies should reduce wear in the spring suspension, prohibiting the raising of the wedge above the plane of the supports of the bolster. To reduce the rotation of the bogie when hunting, bolster should be equipped with elastic contact bearings.

Numerical modeling of the dynamics of the clutch couplers

One of the priorities of the program “Strategy for the development of railway transport in the Russian Federation until 2030” is the introduction and development of heavy haul traffic, allowing to ensure the increasing volume of freight traffic and significantly improve the efficiency of railways. Main challenges for scientific research and design development to ensure the creation of freight cars for heavy haul traffic, along with an increase in longterm load and decrease in tare weight, include the issue of increasing the load from the wheelset to the rails to 27 tons for heavy haul cars SA-3T and couplers SA-3. It is shown that increasing the load from the wheelset to the rails up to 27 tons while maintaining the dynamic running load within the normalized values can be achieved by increasing calculated deflection of the spring suspension of the truck, which in turn leads to an increase in the possible height difference between the couplings of adjacent cars. Authors explain necessity of putting into operation a coupler for heavy haul cars SA-3T, providing an increase in the vertical coupler contour line up to 210 mm. Regulatory documents governing the provisions of automatic coupling devices in freight cars were analyzed. Dynamic computational models have been developed that describe the behavior of automatic couplings in the process of coupling cars, taking into account the inertial characteristics of all parts included in the assembly, the geometric nonlinearity associated with their contact interaction, and the elastic-damping properties of the absorbing device. Verification of calculated dynamic model has been carried out. Numerical experiments simulating the coupling of the considered automatic coupling devices with the most unfavorable possible combinations of horizontal deviations and rotation angles were performed. It is confirmed that the developed design of the coupler CA-3T provides grip when there is a possible difference between the lower surfaces of the locks of adjacent coupler up to 210 mm both between themselves and with the typical coupler CA-3.

Methodological approach to estimation of the structure of load bearing  insulation materials of buildings and constructions of railway transport

The article considers the question of the development of a new methodological approach to the creation of a heat-insulating constructional building material for external enclosing structures of buildings and constructions of railway transport. As the strength of cellular concrete is directly proportional to the average density, and the thermal properties are inversely proportional, solution to the problem of optimizing macrostructure of material in order to simultaneously improve its strength and thermal properties is much more complicated. In addition, when optimizing the properties of cellular concrete, it is necessary to vary the components that form it. Thus, optimization, ultimately, is reduced to solving a multifunctional problem with variable multicomponent parameters. Solving the problem of optimizing macrostructure of cellular concrete on the basis of an experiment using the “trial and error” method is very expensive. Moreover, even an experiment based on some technological approach does not guarantee a positive result for the values of average density taken in a reasonably wide range. Given that the thermal properties of cellular concrete are closely related not only to its average density and, consequently, to average porosity, but also to the pore size distribution and structure features in general, the method of estimating pore structure of the material in a simple and accessible way is of particular interest. A numerical experiment was performed in which the structure of cellular concrete was modeled to conditions close to real samples. To do this, using a random number generator for a given range of sizes of spherical pores and a given percentage of porosity, the structure of cellular concrete was modeled. The modeling results were analyzed on the basis of the constructed histograms for a given percentage of pores in the entire considered range (from 10 to 90 %). Results of model calculations were approximated by Gauss curves (normal law of probability distribution) and Cauchy – Lorentz curves. Thus, the new methodological approach to estimating structure of cellular concrete, based on the use of the modern approach from the standpoint of information technology, is quite accurate in defining and in its practical implementation much simpler than classical research methods.

Maintenance service technology and analysis of operation results of electronic equipment of AC electric locomotives on the railways of the Eastern operational area

The article presents the relevance of the topic associated with the introduction of technical diagnostics tools and the service system of electronic equipment for AC electric locomotives. Results of operating a microprocessor control system and diagnostics of AC electric locomotives on the Eastern operational area are presented in the form of failure statistics of elements of microprocessor technology. Structure of the technological process of servicing AC electric locomotives on the railways of the Eastern operational area is shown. Authors revealed features of building a system of locomotive maintenance points (LMP), which carry out repair and maintenance of electronic equipment for AC electric locomotives of various series. Functional scheme of the system for servicing electronic equipment for AC electric locomotives has been developed. Bench and technological equipment of the service area for the maintenance of electronic equipment is shown. The article describes development of an automated workplace (AWP) for optimization and repair of a microprocessor control system (MCS) for an electric locomotive, which was not previously in the locomotive sector. Examples of performing technological processes of repairing cassettes of MCS using AWP are given. The following conclusions were made: 1. Statistics of MCS failures and malfunctions of their cells on AC electric locomotives at the Eastern operational area for the period from 2016 to 2018 (LMP of station Tayshet and Karymskaya) shows that the number of failures of MCS decreased by 30 % and the number of malfunctioning MCS cells, received for repair, decreased by 45 %. 2. Automated workplaces created in the JSC “DTsV of the Krasnoyarskaya Railway” for optimizing and repairing the local government of AC electric locomotive made it possible to optimize repairs and create an automated process for the maintenance and repair of electronic equipment for electric locomotives. 3. Developed by specialists of the JSC “DTsV of the Krasnoyarskaya Railway” together with the employees of the LLC “Lokotech-Service” technological model of full service maintenance and repair of electronic equipment for AC electric locomotives on the railways of the Eastern operational area was implemented and well proved itself in the work of the LMP.

Improving the efficiency of the “wheel — rail” friction system

Relevance of the topic of increasing the efficiency of the “wheel — rail” friction system is considered. It is shown that the main condition for a significant  optimization of the interaction processes in the “wheel — rail” system is the use of scientifically based technologies and technical means for lubrication of a dynamically loaded open friction pair. Basic requirements for the characteristics of lubricants is used in the open “wheel — rail” friction system. Authors named lubricants that meet the stated requirements. The main disadvantages of the remote method of supplying liquid and/or plastic lubricants in the “wheel — rail” system are presented as argument. Examples are given. The article describes technology of contact rota-print rod lubricating system “GRS — RAPS” and its advantages over analogues, as well as the experience of industrial implementation and operation of this technology. Based on the experience of using the “GRS — RAPS” technology in various climatic zones and operating modes, work was carried out on its adaptation and development, in particular, the tribological properties of rod lubricants were improved, the volumes of one-time refueling were increased, the drive of lubricating rods was optimized. All this allows increasing the effectiveness of this technology in 5 – 7 times. Equipment for freight locomotives is provided with metal-plating systems for working surfaces of wheelsets. Total traction capacity of freight locomotives, if all other things being equal, increases by 15 – 20 %, while protecting wheel flanges of locomotives from wear and improves the braking characteristics of the train. A new concept of building a system for the lubrication of the “wheel — rail”contact zone on the basis of a modernized and improved “GRS — RAPS” technology and technology for modifying (metal-plating) working surfaces has been proposed. Potential economic effect from the comprehensive implementation of the proposed technology is estimated taking into account the existing economic conditions.

Service life evaluation of ballastless track construction

The article presents method for calculating service life of ballastless track structure using the track oscillation model as a structure containing three infinitely long beams, the lower of which lies on the modified Winkler base, and the upper and middle are based on elastic layers, mainly having the characteristics of Winkler. The use of this model is due to the need to carry out calculation for bearing concrete slab, the destruction of which is the main reason for the failure of the ballastless track structure. First part of the article presents model for calculating service life of a ballastless structure. When calculating the damage index, which takes the stresses in the bearing concrete slab, to estimate the vertical dynamic forces acting on the track, it is proposed to use a frequency response that determines the dynamic system with input on the track unevenness and output on the dynamic force at the wheel and rail contact in the model oscillations of the track as a three-layer beam. Second part presents estimates of the service life of ballastless structure for various operating conditions and their comparison with the results obtained using the practice method with the single-beam model. Graphs were plotted for the service life of the ballastless track structure on axle loads, the speed of the carriages and the load capacity on the line. Results show the applicability of the single-layer beam model for estimating the service  life of the ballastless track structure in the current operating conditions; however, for the promising conditions of high-speed and heavy traffic, it is advisable to use a three-layer model.

The use of liquefied natural gas in the combined power unit of autonomous refrigerated car

A specific feature of the market for the transport of perishable goods is the length of the routes. As part of the implementation of new technical solutions for  isothermal rolling stock, research is being conducted on the development of autonomous power supply complexes. The article discusses combined power supply system of an autonomous refrigerated car (ARC), which includes a diesel generator set and a carriage generator. Possibility of using liquefied natural gas as a motor fuel for a diesel generator set, as well as generator and drive units with a car generator is being evaluated. Taking into account the operating experience of power plants of cars in the mode of unmanned technologies, the advantages of using liquefied gas as fuel are described. Comparative calculation of the costs of various types of fuel by the ARC power plant is given. The advantages of using the utilization of the heat of vaporization of liquefied natural gas (LNG) to increase the cooling capacity of a regular refrigeration unit are substantiated. Article gives comparative calculated economic assessment of fuel costs when using different options for power supply systems on routes when driving at high speed and accelerated refrigerated trains, which allows determining the required onboard fuel supply for different options. The use of LNG as a motor fuel and an additional source of cold for ARC is promising. Autonomy of the car on existing fuel reserves is increased by reducing the operating time of refrigeration and power plants. Reducing operating costs is achieved through savings on the purchase of fuel, since the price of an equivalent amount of LNG is lower than that of gasoline or diesel fuel. Operational advantages of LNG are to protect the fuel system from corrosion and contamination. The use of a generator-drive unit with a car generator will save from 30 to 70 % of the fuel used (LNG or diesel), depending on the speed of the freight train on routes of considerable length.