BASIC PRINCIPLES OF MODELING OF THE SOFTWARE COMPLEX "UNIVERSAL MECHANISM" RAILWAY TRACK

ABSTRACT

The article presents a simulation of a railway track in the "Universal Mechanism" software package. Automation of the processes of studying mechanical objects, such as a system of elastic, as well as rigid bodies that are connected by kinetic and power elements, such as a wagon, an electric locomotive and a diesel locomotive, can be calculated using software systems, one of which is the Universal Mechanism software package.

АННОТАЦИЯ

В статье приводится моделирование железнодорожного пути в программном комплексе «Универсальный механизм». Автоматизация процессов исследования механических объектов, таких как система упругих, а также твердых тел, которые связаны кинетическими и силовыми элементами, такими как вагон, электровоз и тепловоз, возможно, рассчитать с помощью программных систем, одной из которых является программный комплекс «Универсальный механизм».

Keywords: modeling, railway track, software package, track width, longitudinal profile of the track.

Ключевые слова: моделирование, железнодорожный путь, программный комплекс, ширина колеи, продольный профиль пути.

Operating conditions on different railways may have significant differences. This applies, in particular, to the plan and profile of the track, axial loads and weight of trains, track width, climate, geological characteristics, traffic structure and their intensity. Any of these factors can have a noticeable impact on the choice of structural solutions for the wheel-rail system and strategies for the maintenance of the track and rolling stock. In order to avoid conflict situations when choosing technical means and strategies and to make this choice conscious, it is necessary to have a deep understanding of the basic mechanisms of interaction in the wheel-rail and rolling stock-track systems [1, 2].

It should be noted that a mechanical system in its structure can be flat or spatial, whereas for complex systems, the analysis of equations, summing up, as well as the representation of the structure of the object itself is complex.

In order to simplify the above process, the method of subsystems "Universal Mechanism", which includes several types of subsystems, is used in the analysis of the technical system. Thus, the components of the rolling stock can be divided into certain subsystems, after which one of the same subsystems is selected, which will later be described in order to save and avoid a large number of errors in the calculation.

The "Universal Mechanism" software package allows the use of modern computer graphics methods for graphically-animated description of the motion process in the process of numerical solution of the problem and in processing the results obtained [3, 4]. In Russia, the Universal Mechanism (UM) software package has become the most popular for studying the dynamic interaction of complex systems [5, 6]. Currently, interest in the program is also manifested outside of Russia [7, 8].

The equations of motion of an object are output by a special program module in symbolic or numerical form.

Object modeling requires data entry and description of key interacting calculation systems, one of which is a railway track and rolling stock.

In the "Universal Mechanism" software package, the railway track is qualified by the following parameters given in [9]:

•  macrogeometry of the path (plan and longitudinal profile of the path);
•  microgeometry of rail threads (nervousness of rail threads in vertical and horizontal planes);
• elastic-dissipative and inertial properties of the path.

The geometry of the path includes the following components:

•  the geometry of rails in a perfect straight line (track width, slope, profiles);
•  macrogeometry of curves and switches;
• irregularities of rail threads [9].

The geometry of rails in an ideal curve includes the following components:

• Rail profiles;
• distance between the centers of the rail heads;
• rail canting.

Figure 1. Rail profile coordinate system

Figure 1 shows a special rail coordinate system (TFR) set in the rail profile in the "Universal Mechanism" software package. The beginning of the TFR is located on the central axis of the rail section, on its surface (that is, the profile curve passes through the origin). The abscissa (y) axis is perpendicular to the cross-section axis of the rail and is directed into the track. The ordinate (z) axis is directed upwards. The profile is set in mm [9].

The position of the rail in the transverse direction in an ideal straight line in the "Universal Mechanism" is set (Figure 2) by the gauge widening parameter in a straight line, for the calculation of which the formula (1) is used.

Figure 2. Widening of the track in a straight line

,                                                                    (1)

where L_r - distance between the centers of the rail heads;

L – the distance between the wheelset riding circles.

In other words, the widening of the track in a straight line is the transverse distance from the bottom point on the wheel's rolling circle to the central point of the rail head at their ideal position.

To calculate the exact value of the track width, the formula (2) can also be used:

,                                                             (2)

where S – track width;

h_r – rail head width.

The default value is set to Δy = 0,003 m.

Rail canting a_r0 – the angle between the axis of symmetry of the rail section and the vertical in a perfect straight line. The angle is measured in radians. The angle value is positive when the rails are inclined into the track [9]. The default value is set to a_r0 = 0,05 rad.

References:

1. Begmatov N.I., Ergashev U.E. MODELING OF THE FORCE IMPACT FROM ROLLING STOCK ON THE RAILWAY TRACK // Universum: технические науки: электрон. научн. журн. 2022. 11(104). URL: https://7universum.com/ru/tech/archive/item/14617
2. Begmatov N.I., Muhammadiyev N.R. Eksperimentаlnoe opredelenie jestkosti relsovoy niti [Experimental determination of the stiffness of the rail thread] // TSTU. 2021. №1. [in Russian]. URL: https://cyberleninka.ru/article/n/eksperi-mentalnoe-opredelenie-zhestkosti-relsovoy-niti.
3. Dmitry Pogorelov, Alexander Rodikov, Roman Kovalev. Parallel computations and co-simulation in Universal Mechanism software. Part 1: Algorithms and implementation Transport problems. 2019. Volume 14, Issue 3. DOI: 10.20858/tp.2019.14.3.15. [in English].
4. Dmitry Pogorelov, Alexander Rodikov, Roman Kovalev. Parallel computations and co-simulation in Universal Mechanism software. Part II: examples Transport problems. 2019 Volume 14 Issue 4. DOI: 10.20858/tp.2019.14.4.3. [in English].
5. Dmitry Pogorelov et al. Train 3D: the technique for inclusion of three-dimensional models in longitudinal train dy-namics and its application in derailment studies and train simulators / Vehicle System Dynamics, Published online: 11 Jan 2017 DOI: 10.1080/00423114.2016.1273532. [in English].
6. Universal mechanism // Моделирование взаимодействия железнодорожных экипажей и пути [Modeling the in-teraction of railway crews and tracks]. / Rukovodstva polzovatelya. – 2021. – 21 pp. [in Russian].
7. Ying Song, Lei Liang, Yanliang Du, Baochen Sun. Railway Polygonized Wheel Detection Based on Numerical Time-Frequency Analysis of Axle-Box Acceleration / Applied sciences. - 2020. - Vol. 10. - Iss. 5. DOI: 10.3390/app10051613 [in English].
8. Iman Hazrati Ashtiani. Optimization of secondary suspension of three-piece bogie with bevelled friction wedge geometry / International Journal of Rail Transportation.
9. Universal mechanism // Моделирование динамики железнодорожных экипажей [Modeling the dynamics of railway carriages]. / Rukovodstva polzovatelya.  – 2021. – 268 pp. [in Russian].