ANALYSIS OF THE STRESSED STATE OF THE AXLE OF A WHEEL PAIR OF A PASSENGER CAR

The paper considers the results of calculations of the axle of the wheel pair of apassenger car for strength and durability from fatigue. The loads acting on the axle of a passengercar during movement at the maximum permissible speed are determined.To solve the problems of studying the stress state of the axle of the passenger car at the firststage, a three-dimensional geometric model of the axis RU1 was developed. The most unfavorableload combination was taken into account in the calculation. The horizontal load was up to 10 kN.The load was applied to the axle necks, respectively, in the vertical and horizontal directions.The calculated model of the car axle RU1 is developed, on the basis of which the finiteelementmodel is created and the stress state of the wheel pair under the action of the main types ofload is investigated. The size of the finite element grid was chosen using a graphoanalytical methodand refined to a size of 2 mm. This feature of the finite element grid allowed to calculate thestresses in the calculated cross sections with greater accuracy and to determine the nature of thestress distribution.It is established that the maximum stresses arising in the axle of the passenger car under the most unfavorable work conditions that are concentrated in the filler in the zone oftransition from the neck to the pre-axle part.The axle was calculated for fatigue. Fatigue tests are usually performed at a uniaxial stressstate, so it is necessary to convert the multiaxial stress state to one scalar value to determine thenumber of cycles to failure at a given voltage amplitude. The load can occur with a constantamplitude.The number of load cycles that the car axle can withstand under operating loads isdetermined. According to the results of the research, restrictions on the service life of the axles ofwheel pairs of passenger cars are proposed.

Monitoring the technical condition of the railway track using the method of continuous recording of dynamic processes occurring due to the interaction between rolling stock and railway track

Objective: To develop the method to monitor the technical condition of the railway track. Me-thods: A strain-gauge wheel pair is used for continuous recording of vertical and lateral interaction forces in a dynamic wheel–rail system. Results: Stability margin factors of a wagon relative to de-railment have been determined and the defective (prone to derailment) sections of a railway track have been identified with the exact identification of their location (GPS coordinates) on the map using navigation devices. Practical importance: The developed monitoring method makes it possi-ble to promptly re¬gister and eliminate railway track defects

Comparison of Stress-Strain States of Rail-Wheel Pair Made of Steel and MoNiCa

Contact interaction in a wheel-rail pair and its corresponding stress-strain state for various combinations of materials of this pair and the weights of passenger and freight cars were considered. The materials under study were steel and high-strength cast iron based structural material MoNiCa with strength and wear-fatigue characteristics close to steel ones.The load on each wheel was: 53.9 and 294.3 kN for an empty and loaded freight car, 146.8 kN and 230.5 kN for an empty and loaded passenger car. The bottom surface of the rail was rigidly fixed.Young's modules were adopted as follows: 200 GPa for steel and 165 for MoNiCa. The results of finite element calculations of the three-dimensional stress-strain state showed that the largest von Mises stresses of 613.08 MPa occur in the wheel (steel)-rail (steel) pair of the loaded freight car. For all types of loading, the lowest stresses (15.8 % – 16.7 % less than in the steel-steel pair) are observed in the wheel (MoNiCa)-rail (MoNiCa) pair. This indicates the appropriateness of using MoNiCa for the manufacturing elements of the wheel-rail system.

Development of technological equipment for restoration of rolled wheeled pairs of railway wagons

Introduction. The problem of the shortage of energy-efficient restoration technologies makes it a priority to develop new technological equipment for the restoration of the rolling surfaces of railway wheels using highly concentrated energy sources. Currently, in the practice of repair DPO, discarded non-bonded wheels are increasingly replaced with new ones, but their resource potential is high during the operation. This approach is not technically and economically feasible.Materials and methods. This article presents the results of the strength calculation of the main moments of forces and dynamic loads per wheel pair. The problem of repair equipment related to the lack of the independent mobile complexes that ensure prompt arrival at the work site and high quality restoration of the design geometry of the wheel surface is formulated.Results. To solve this problem, a mobile complex was designed and developed, which allows to restore the design geometry and modify the high physical and mechanical properties of the riding surface with optimal stresses in the phase structure of the wheel base.Discussion and conclusion. It is recommended to use the results of the research carried out for the design, creation and production of high-tech repair equipment.

EFFICIENCY ASSESSMENT OF BRAKING EQUIPMENT OPERATION IN INNOVATION FREIGHT CARS

The object of researches is brake systems of innovation freight cars. The work purpose consists in the assessment of braking system effectiveness in innovation freight cars and in standard ones at different operation modes. The scientific novelty consists in the definition of the dependence of a slide block depth on the length of wheel pair skidding motion and braking distance dependence upon car speed. During the work there was carried out a retrospective analysis of cases with traffic safety violation connected with the formation of excessive sliders in freight cars in organized trains because of the violation of braking equipment normal operation. By means of the least-squares method there was obtained a linear equation defining the dependence of slider depth upon the skidding length of a wheel pair. As a result of the work there were defined parameters of defect formation on freight car wheels at their skidding, the calculations of braking system efficiency in different freight cars were carried out. In the course of the analysis of freight car braking efficiency there are obtained equations of braking length in the accepted range of speeds at the beginning of braking for empty and loaded states. Minimum values of the design factor of braking block pressing in translation to a train length of 200 shafts in the empty state were 0.2256 for a speed of 40km/h, in the loaded one – 0.1781 for a speed of 120 km/h at the standard values 0.22 and 0.14 respectively. By means of calculations and experiments it is proved that composite braking block pressing force on a shaft exceeds 4tf/shaft, and that of cast-iron – 10tf. Accordingly, a car with the shaft load of 25 tf/shaft and accepted parameters of a braking system may be operated up to the speeds of 120 km/h inclusive without limitations.

PROBLEMS IN DEVELOPMENT OF ENERGY-SAVING TRACTION DRIVE

The problems of traction properties increase in locomotives are considered. The necessity in devices for instantaneous control of a friction coefficient of wheels and rails based on the impact of electric current or a magnetic field upon a wheel/rail contact area. There are defined basic fields of researches essential for the actual realization of such devices. It is defined that devices based on electric current impact require the introduction of considerable changes in the units of a crew part for wheel pair insulation and searches of problem solution in the separation of traction current and control one and the prevention of control current impact upon alarm systems. It is offered to consider magnetic amplifiers of adhesion as a solution of a short-term outlook which can be introduced in an existing locomotive fleet and those using current impact as a solution of newly-developed promising machines. There is offered a design of an individual traction drive simplifying a problem in the arrangement of devices for instantaneous control of a friction coefficient.

MATTERS OF LOAD DECREASE IN TRACTION DRIVE UNITS AT BOXING

The purpose of this work consists in the development of constructive solutions decreasing loads in the units of the electric locomotive traction drive at boxing. The investigations carried out in the field of electric locomotive operation on domestic railways have shown that one of the basic directions in the decrease of non-sprung masses consists in the introduction of an elastic tie between a wheel pair and a drive motor armature. The improvement mentioned results in the considerable load increase in the traction drive at friction self-oscillations arising in the mode of wheel slip on a rail. The analysis, carried out in the work, of methods to reduce similar dynamic loads has shown that approaches efficient enough are: - shock vibro-damping of wheel pair self-oscillations, - limitation of wheel slip rate on a rail with the control of friction factor by means of the impact upon a contact area of electric and magnetic fields, - changes of elastic-dissipative properties of dynamic systems in an electric locomotive running gear to control self-oscillation fashions. To realize measures described there are offered constructive solutions limiting self-oscillation amplitudes in a boxing mode. In particular the system of instantaneous control with clutch amplifies based on the application of magnetic inductor in the form of a mounted unit upon a crew section of an electric locomotive. For realization of the method for the process control of the competition of self-oscillation fashions there is offered a design of the device changing forcibly a fashion of growing self-oscillations at the expense of the control of elastic-dissipative properties of dynamic system links in the traction drive. The innovation solutions developed are protected with the patent for invention, two patents for utility model.

Building an information model in wheel-rail tribosystem control tasks

The issues of filling the information model with data on the state of the wheel-rail tribosystem are considered. The “Program for modeling the transverse position of a wheelset in a track” is used, and the main modules of the program are described. The geometrical parameters of the contact of the wheel profile with the rail profile are obtained. The values of the nominal contact of the wheel with the rail for the extreme and intermediate positions of the wheel pair in the rail track are calculated. The displacement of the wheelset in the rail track, its slope, and the width of the contact of the wheel with the rail, the gap between the wheel crest and the inner face of the rail are determined. The obtained data are compared with the results of the experiment.

Qualitative Analysis of the Dynamics of a Trailed Wheeled Vehicle with Periodic Excitation

This article examines the dynamics of the movement of a wheeled vehicle consisting of two links (trolleys). The trolleys are articulated by a frame. One wheel pair is fixed on each link. Periodic excitation is created in the system due to the movement of a pair of masses along the axis of the first trolley. The center of mass of the second link coincides with the geometric center of the wheelset. The center of mass of the first link can be shifted along the axis relative to the geometric center of the wheelset. The movement of point masses does not change the center of mass of the trolley itself. Based on the joint solution of the Lagrange equations of motion with undetermined multipliers and time derivatives of nonholonomic coupling equations, a reduced system of differential equations is obtained, which is generally nonautonomous. A qualitative analysis of the dynamics of the system is carried out in the absence of periodic excitation and in the presence of periodic excitation. The article proves the boundedness of the solutions of the system under study, which gives the boundedness of the linear and angular velocities of the driving link of the articulated wheeled vehicle. Based on the numerical solution of the equations of motion, graphs of the desired mechanical parameters and the trajectory of motion are constructed. In the case of an unbiased center of mass, the solutions of the system can be periodic, quasi-periodic and asymptotic. In the case of a displaced center of mass, the system has asymptotic dynamics and the mobile transport system goes into rectilinear uniform motion.