Indicators of the force interaction of the track and rolling stock when a freight car runs on long irregularities, taking into account the action of longitudinal forces

Authors describe formation mechanism of long irregularities of the railway track and the importance of their elimination for the track facilities. Based on the results of freight train operation modeling on long irregularities in the traction mode, an analysis of the processes occurring during the motion of heavy trains along a track with such deviations was carried out, modeling was carried out on the basis of the “Universal Mechanism” software package. Based on the results of the calculation, interaction between the track and the rolling stock in the vertical plane was assessed in terms of the magnitude of the vertical force and coeffcients: dynamics, stability margin, Nadal, unloading (in percent) of axle springs of freight car springs. Article analizes the nature of the infuence of the irregularity slope on the decrease in the vertical force transmitted from the wheel to the rail and the change in the traction force on the dynamics of freight cars in the train and passing on long irregularities of the longitudinal profle through the indicators of the vertical force.

Structural analysis of freight car lever transmission with parallel shoe releasing devices taking into account the edge contact of the shoe and wheel

The article deals with the issues of modeling the stress-strain state of the attachment points of the cab of a wheeled chassis of high load capacity. The main design loads are determined. Geometric and computational finite element models are constructed, taking into account the features of the metal structure. The technique of gluing elements of the grid model is applied. The contact interaction of the parts is taken into account. Based on the calculations performed, conclusions are drawn about the compliance of the developed structure with the strength requirements.

Defining patterns in the dynamic load and strength of the bearing structure of a covered freight car with a filler in the girder beam

This paper reports a study into determining the dynamic load and strength of the bearing structure of a covered freight car under operational modes. A feature of the freight car's bearing structure is that the girder beam has a closed cross-section. To reduce the dynamic load of the frame, the girder beam is filled with a material with viscoelastic properties. Such a solution could contribute to the transformation of the kinetic energy of impact (due to jerk, stretching, compression) into work of viscoelastic friction forces, and, consequently, to reducing the load on the bearing structure. To substantiate the proposed improvement, the dynamic load on the bearing structure of a covered freight car was mathematically modeled. The calculation was performed for the case of joint impacts at shunting. The study was carried out in a flat coordinate system. It was established that the maximum accelerations acting on the bearing structure of a covered freight car were about 37 m/s2. The calculated acceleration value is 3.2 % lower than that obtained for the bearing structure of a covered freight car without filler. The results of calculating the strength of the load-bearing structure of a covered freight car are given. In this case, a finite-element method was applied. The maximum equivalent stresses occur in the zones of interaction between the girder beam and the pivot beams, and amount to 319.5 MPa, which is 8 % lower than permissible. The calculation was also performed regarding other operational modes of loading the freight car's bearing structure. The model of the dynamic load on the bearing structure of a covered freight car was verified according to the F-criterion. The research reported here could contribute to designing innovative rolling stock structures, thereby improving the efficiency of their operation.

Improvement of the tribological properties of heavy-loaded friction units “Centre block-footstep bearing” of a freight car

Various problems and different approaches of solution of such a problematic unit as “centre block-footstep bearing” of freight cars are discussed in the paper. The methods of improving the tribological properties of this friction unit by means of material modification of friction surfaces and perfection of physical, chemical and tribological properties of the used lubricants were studied. Grease lubricants common for friction units of railway machinery were used after being modified with inorganic polymers based on double metaphosphates. Bench and operational tests of the developed additive of the polymeric double metaphosphates were carried out. This additive reduces wear and increases the service life of the friction unit, due to the better adhesion properties of this additive. The variants with a change in the geometry of the contact surface of the disk between the bolster and the “centre block-footstep bearing” arrangement of the car are considered. Simulation of the parameters of movement in curved sections is proposed.

Calculation model for the evaluation of tired defect development in the freight wagon side frame

The reliability and safe operation of mechanical elements of rail transport is an important and relevant scientific and technical issue since high-loaded units and elements of its chassis are exposed to prolonged operation and their failure can lead to damage with catastrophic consequences. To prevent the possible failure of such objects, there is a necessity for a reliable estimation of their residual life. Among the cast parts of the freight car trolley, the side frames are one of the most loaded elements, which take on dynamic loads that cause vibrations of the unsprung parts of the freight car. The side frame of the 18-100 trolley, as a typical representative of a number of trolleys of freight cars, does not have a sufficient margin of resistance to fatigue and survivability, so it is sensitive to some deviations and defects (different wall thickness, sinks, and pores, residual stresses) that are detected during the operation process. Based on the energy approach of the mechanics of materials fatigue failure, the calculation models for estimating the dynamics of the development of crack-like defects under the action of operational load are developed in this work. The calculation models constructed using modern information technologies, and the software developed for their numerical implementation allow predicting the impact of irregular cyclic loading and complex stress on the growth of surface fatigue crack in the side frame of the carriage, which significantly brings the problem closer to real operating conditions. Numerical calculations were performed using a computer program of our own development in the Python programming language. At the first stage of the program functioning the spectrum of amplitudes of irregular cyclic loading is built, at the second - the program module of numerical solution construction for systems of usual differential equations of the proposed mathematical model of fatigue defect development is started. Calculations of the fatigue crack growth dynamics taking into account the action of shear stresses in the section with the crack of the side frame showed a slight effect of shear stresses on the residual durability of the frame. It is demonstrated that the dynamics of surface crack development significantly depend on its initial geometry. The proposed calculation method for determining the initial shape of the surface crack with a minimum period to critical growth can be effectively used to predict the residual durability during the technical diagnosis of the running gear parts of railway rolling stock. Keywords: wagon side frame; fatigue crack; probability distribution function; load amplitude spectrum; numerical method.

From Coarse to Fine: An Augmented Reality Based Dynamic Inspection Method for Visualized Railway Routing of Freight Cars

It is a challenge for the dynamic inspection of railway route for freight car transporting cargo that out-of-gauge. One possible way is using the inspection frame installed in the inspection train to simulate the whole procedure for cargo transportation, which costs a lot of manpower and material resources as well as time. To overcome the above problem, this paper proposes an augmented reality (AR) based dynamic inspection method for visualized railway routing of freight car with out-of-gauge. First, the envelope model of the dynamic moving train with out-of-gauge cargo is generated by using the orbital spectrum of the railway, and the envelope model is matched with a piece of homemade calibration equipment located on the position of the railway that needs to be inspected. Then, the structure from motion (SFM) algorithm is used to reconstruct the environment where the virtual envelope model occludes the buildings or equipment along the railway. Finally, the distance function is adopted to calculate the distance between the obstacle and the envelope of the freight car with out-of-gauge, determining whether the freight car can pass a certain line. The experimental results show that the proposed method performs well for the route selection of out-of-gauge cargo transportation with low cost, high precision, and high efficiency. Moreover, the digital data of the environments along the railway and the envelope of the freight car can be reused, which will increase the digitalization and intelligence for route selection of out-of-gauge cargo transportation.

Methodology for estimating the resource of the friction vibration damper of a freight car trolley

The concept of digitalization of railway transport and the introduction of digital technologies provides for the creation of a “Digital Railway” based on a “Digital Twin”, including a “Digital Twin” of a car, which implements a number of information and organizational measures aimed at assessing the current technical condition of a real car during its operation; reducing the cost of the life cycle of the car; increasing the reliability of assemblies and parts (increasing the overhaul life); reduced maintenance costs; creation of a service maintenance system for freight cars throughout the life cycle. However, the wear of vibration damper parts is the most important parameter that determines the turnaround time, the volume of repairs and the dynamic qualities of the car, which requires more detailed and reliable scientific substantiation. The assessment of the wear of vibration damper parts (friction bar, friction wedge, bolster) is carried out in two ways - by direct examination of them in operation (in this case, wear is estimated by changing the linear dimensions, i.e., in mm over the service life) and according to the results of bench tests of models of vibration damper or testing samples on friction machines (in this case, wear is estimated by the mass of the worn-out material). The proposed method for predicting the wear of parts of frictional vibration dampers implements the Archard friction model, takes into account the variability of loads acting on the working surfaces, for which a method for determining the friction path under various driving conditions has been developed. The developed methodology makes it possible to evaluate their service interval at the design stage of the car’s running gears.

SIMPLIFIED APPROACH OF DETERMINATION OF THE MEASURE TO INCREASE THE EFFICIENCY OF RAILWAY TRANSPORT OF THE METALLURGICAL PLANT

The article proposes the approach for determining the measure to increase the efficiency of railway transport of the metallurgical plant. The analysis of scientific and normative works on the efficiency of railway transport at industrial enterprises showed that this issue is not fully covered and requires more detailed study. The work of the railway shop of the metallurgical enterprise is considered, namely, the turnover off right cars of different owners and the time of their stay on the factory tracks are determined. An analysis of statistical data was made, which showed that the time difference between the standard set at the enterprise and the actual time of stay of the freight car at the planthas a large discrepancy. This requires spending additional funds for the use of cars of different owners. For this purpose, a model for determining measures to minimize costs at the metallurgical enterprise was developed. The algorithm for its solution involves five stages of calculations. It is based on the model of managements science, which is presented as the approach of linear programming to determine the optimal means of allocating scarce resources in the presence of competing needs. Calculations were made, thanks to which the first stage of development of the model for determining the measure to improve the performance of railway transport was performed and the indicators that characterize it were determined. The total time of rolling stock at the enterprise is determined. Based on this, it is established that it is necessary to separate from the total time the time spent at each station according to the operations performed with the cars. Costs are determined operationally due to the received analysis of the stay and turnover of the freight car at the metallurgical enterprise. Installed stations, which are the most time-consuming freight cars, is there is an excess of payment for the down time of cars at these stations. Based on this, it was decided that it is necessary to study in more detail the operations performed with cars at theses stations and to identify "weaknesses" in the turnover of the freight car at the metallurgical enterprise.

Increasing the life of the center plate-center bowl friction unit of a freight car by applying a combined coating formed by electrospark alloying

An increase in the operational reliability of friction units of railway transport by applying antifriction combined coatings formed by electrospark alloying, which ensures their greater strength and adhesion to metal, is considered. Keywords: electrospark alloying combined antifriction coating, strength, adhesion. [email protected]

Development of a refined methodology for calculating the balance of wheelsets and assessment of the need for wheels and axles for the wagon fleet of the Republic of Uzbekistan

Objective: To develop a refined methodology for calculating the balance of wheelsets for a freight car fleet, apply it to determine the need for wheels and car axles for the freight car fleet in the Republic of Uzbekistan. Methods: Methods of combinatorial and statistical analyzes of the initial data were employed. Results: Methods for calculating the need for wheels and car axles are proposed, which makes it possible to determine the number of required wheel disks and finished axles for freight cars, depending on the forecast of the volume of freight turnover per year. Practical importance: The presented method for calculating the need for wheelsets can be used for a general analysis and assessment of the state of the production base in terms of shortcomings or excess of wheel disks and finished axles.