Кафедра "Рухомий склад та колії"

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ENG: Department of Rolling Stock and Track

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Application of Computational Mechanics Approaches for Increasing of Tribosystem Operational Parameters by using Plasma Hardening Method
(Czestochowa University of Technology, Poland, 2021) Kopylov, Viacheslav; Kuzin, Oleg A.; Kuzin, Nickolai O.
EN: On the basis of the mathematical model of the continual description of functionalgradient metal systems, taking into account their structure, a computational computer scheme has been developed that makes it possible to assess the stress-strain state of local volumes of parts taking into account their spatial inhomogeneity. With the use of modern software components of computational mechanics – FEniCS finite element analysis package and its implementation in Python, the optimal structural characteristics of wheelsets of railway locomotive tires after plasma treatment have been established. It is shown that, depending on the value of the load, hardening of products must be carried out to a depth of 4.5 mm; with a further increase in thickness, the parameters of operational strength do not change.
Application of the Models of Mechanics for the Evaluation of the Microstructural Parameters of Alloys with Elevated Wear Resistance
(Springer, US, 2009) Kuzin, Oleg A.; Yatsyuk, Rostislav A.; Kuzin, Mykola O.
EN: We show the possibility of application of the approaches of mechanics to the determination of the relative fractions and sizes of phases in antifriction alloys with elevated wear resistance. It is demonstrated that the wear resistance of B16 babbitt increases if its microstructure contains an Sn Sb hardening phase whose size is equal to 53 μm.
Common Crossing Condition Monitoring with on-Board Inertial Measurements
(Czech Technical University, Prague, 2019) Sysyn, Mykola; Nabochenko, Olga; Gerber, Ulf; Kovalchuk, Vitalii V.; Petrenko, Oleksiy
EN: A railway turnout is an element of the railway infrastructure that influences the reliability of a railway traffic operation the most. The growing necessity for the reliability and availability in the railway transportation promotes a wide use of condition monitoring systems. These systems are typically based on the measurement of the dynamic response during operation. The inertial dynamic response measurement with on-board systems is the simplest and reliable way of monitoring the railway infrastructure. However, the new possibilities of condition monitoring are faced with new challenges of the measured information utilization. The paper deals with the condition monitoring of the most critical part of turnouts - the common crossing. The application of an on-board inertial measurement system ESAH-F for a crossing condition monitoring is presented and explained. The inertial measurements are characterized with the low correlation of maximal vertical accelerations to the lifetime. The data mining approach is used to recover the latent relations in the measurement’s information. An additional time domain and spectral feature sets are extracted from axle-box acceleration signals. The popular spectral kurtosis features are used additionally to the wavelet ones. The feature monotonicity ranking is carried out to select the most suited features for the condition indicator. The most significant features are fused in a one condition indicator with a principal component analysis. The proposed condition indicator delivers an almost two-time higher correlation to the lifetime as the maximal vertical accelerations. The regression analysis of the indicator to the lifetime with an exponential fit proves its good applicability for the crossing residual useful life prognosis.
Common Crossing Fault Prediction with Track Based Inertial Measurements: Statistical vs. Mechanical Approach
(Akadémiai Kiadó, Hungary, 2019) Sysyn, Mykola; Gerber, Ulf; Nabochenko, Olga; Kovalchuk, Vitalii V.
EN: The analysis of track based inertial measurements for common crossing fault detection and prediction is presented in the paper. The measurement of spatial acceleration in common crossing spike and impact position during overall lifecycle are studied regarding to rolling surface fatigue degradation. Two approaches for retrieving the relation of inertial parameters to common crossing lifetime are proposed. The first one is based on the statistical learning method - t-SNE algorithm that helps to find out similarities in measured dataset. The second one is a mechanical approach that handles the data with a fatigue and contact models. Both approaches allow the significant improvement of the common crossing fault detection as well as its early prediction.
Common Crossing Structural Health Analysis with Track-Side Monitoring
(EDIS, University of Zilina, Slovakia, 2019) Sysyn, Mykola P.; Nabochenko, Olga S.; Kluge, Franziska; Kovalchuk, Vitalii V.; Pentsak, Andriy
EN: Track-side inertial measurements on common crossings are the object of the present study. The paper deals with the problem of mea- surement's interpretation for the estimation of the crossing structural health. The problem is manifested by the weak relation of measured acceleration components and impact lateral distribution to the lifecycle of common crossing rolling surface. The popular signal processing and machine learning methods are explored to solve the problem. The Hilbert-Huang Transform (HHT) method is used to extract the time-frequency features of acceleration components. The method is based on Ensemble Empirical Mode Decomposition (EEMD) that is advantageous to the conventional spectral analysis methods with higher frequency resolution and managing nonstationary nonlinear signals. Linear regression and Gaussian Process Regression are used to fuse the extracted features in one structural health (SH) indicator and study its relation to the crossing lifetime. The results have shown the significant relation of the derived with GPR indicator to the lifetime.
Comparative Study of the Mechanical and Tribological Characteristics of Fe–Cu–Ni–Sn Composites with Different CrB2 Content under Dry and Wet Friction
(Springer Nature Switzerland AG, 2021) Mechnik, V. A.; Bondarenko, N. A.; Kolodnitskyi, V. M.; Zakiev, V. I.; Zakiev, I. M.; Gevorkyan, E. S.; Kuzin, Nickolai O.; Yakushenko, O. S.; Semak, I. V.
EN: The structure, phase composition, hardness, and elasticity modulus of sintered Fe–Cu–Ni–Sn–CrB2 composites and their tribological properties under dry and wet friction have been studied by X-ray diffraction, scanning electron microscopy, microindentation, and tribological testing. The obtained results have demonstrated that the microstructure and mechanical and tribological properties of these composites depend on the CrB2 additive content. The Fe–Cu–Ni–Sn–CrB2 composites incorporate the α-Fe, γ-Fe, and Cu phases and a certain fraction of the crystalline Cu9NiSn3, NiSn3, and CrB2 phases. The hardness and elasticity modulus of these composites are almost independent of the friction medium (dry or wet), and the friction force and the wear rate are variable. The Fe–Cu–Ni–Sn–CrB2 composites are superior to the Fe–Cu–Ni–Sn composites in their mechanical and tribological properties. The addition of 2 wt % of CrB2 to the 51Fe–32Cu–9Ni–8Sn composite has decreased the friction force from 220 to 170 mN and the wear rate from 7.41 × 10–2 to 3.41 × 10–2 mm3/(N m) under dry friction and, respectively, from 200 to 140 mN and from 8.19 × 10–2 to 4.10 × 10–2 mm3/(N m) under wet friction. A further growth in the CrB2 content in the composites leads to an increase in the wear rate. The mechanism of increase in the wear resistance of the composite containing 2 wt % of CrB2 as compared to the initial composite implies the formation of a more fine-grained structure with an optimal combination of the hardness and elasticity modulus. The Fe–Cu–Ni–Sn–CrB2 composites can be used as a material for the matrix of composite diamond-containing materials subjected to strong wear.
Comparison of Motor Coach Exhaust Emissions in Real Operating Conditions for Different Testing Procedures
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Gallas, Dawid; Merkisz, Jerzy; Andrzejewski, Maciej; Tomaszewski, Sylwin; Strzemkowski, Jan; Kinter, Stepan O.
EN: Abstract. The article discusses the results of applying real driving emissions (RDE) testing methods in measuring the exhaust emissions of a passenger rail vehicle. Portable Emissions Measuring Systems (PEMS) were used to measure the exhaust emissions from a motor coach in real operation, performed on a test track for selected drive cycle parameters. The road emission values of exhaust components have been calculated and compared to road vehicles and road exhaust emission limits based on the legal norms. The assessment was concluded with a comparison of the environmental cost, in terms of exhaust emissions, of transporting passengers using the tested rail vehicle relative to alternative road transport, based on measurements in real operating conditions.
Comparison of the Effects and Efficiency of Vertical and Side Tamping Methods for Ballasted Railway Tracks
(Elsevier Ltd, 2022) Przybyłowicz, Michał; Sysyn, Mykola; Gerber, Ulf; Kovalchuk, Vitalii V.; Fischer, Szabolcs
EN: The relatively high maintenance costs of the ballast track are related to the short lifecycle of the ballast layer. The current vertical ballast tamping technology (e.g., Plasser & Theurer, Matisa, etc.) causes high ballast destruction and is neither applicable for unconventional sleepers’ designs nor slab tracks. The side tamping method presents an alternative, ballast saving, and sleeper form independent ballast tamping technology. This paper compares the ballast layer compaction and its resistance to permanent settlements accumulation after the vertical and the side tamping methodologies. Scaled models of ballast layer and tamping units and scaled simulation with discrete element method (DEM) were applied for the comparison. In the laboratory tests, the ballast compaction along the sleeper was estimated using the measurements of elastic wave propagation. The settlements resistance for both tamping methods was estimated under the vibration loading. The tests’ results show 5–7% higher compactness of the ballast layer under the sleeper ends for the side tamping method. The settlement intensity of the ballast layer after the vertical tamping is higher than for the side tamping method. In discrete element modeling, the performed laboratory tests were simulated. The compactness of the ballast bed, as well as the residual stresses, were determined in MATLAB. The side tamping technology provided five times higher residual stresses in the ballast layer below the sleeper than in the case of vertical tamping, which can be explained by the more stable and dense layer resulting from the side tamping ensures higher interlocking between the grains. The simulation of the wave propagation shows an influence of the residual stresses on the wave propagation velocities. The simulated wave propagation velocity was more than two times higher for the side tamping than for the vertical one.
The Complex Phenomenological Model for Prediction of Inhomogeneous Deformations of Railway Ballast Layer after Tamping Works
(Warsaw University of Technology, Poland, 2018) Sysyn, Mykola P.; Gerber, Ulf; Kovalchuk, Vitalii V.; Nabochenko, Olga S.
EN: The given article considers the method of calculating the track geometry deformation with respect to uneven accumulation of residual deformations along the track. The technique proposes two significant changes in existing approaches to calculating the efficiency of the ballast layer. The transition from the approach of allowable stresses design in the ballast layer to the deformative approach of accumulations of track geometry deformations allows us to draw conclusions regarding the intervals of track tamping and the duration of ballast layer life cycle. The transition from the determinative to probabilistic approaches makes it possible to draw conclusions not only from the average unevenness, but also with regard to all possible facts of unevenness. The method is based on the mechanism of sudden and gradual deformations occurrence, which depends on a number of key factors: dynamic stresses on the ballast, non-uniformity of track elasticity, performance of current maintenance work. Based on the experimental studies results, the dependencies of sudden deformations and the intensity of gradual deformations on the level of stress on the ballast layer were established. The experimental results of the influence of the sub-ballast base elasticity on the intensity of accumulation of residual deformations are shown. On the basis of the developed method, the prediction of track geometry deterioration for a given structure of the track, the rolling stock and the permissible level of geometric deviations for track maintenance is presented.
A Comprehensive Procedure for Estimating the Stressedstrained State of a Reinforced Concrete Bridge Under the Action of Variable Environmental Temperatures
(РС ТЕСHNOLOGY СЕNTЕR, Kharkiv, Ukraine, 2021) Kovalchuk, Vitalii V.; Onyshchenko, Artur; Fedorenko, Olexander; Habrel, Mykola; Parneta, Bogdan Z.; Voznyak, Oleh M.; Markul, Ruslan V.; Parneta, Mariana; Rybak, Roman
ENG: This paper reports the full-scale experimental measurements of temperature distribution over the surfaces of bridges’ steel-concrete beams under the influence of positive and negative ambient temperatures. It has been established that the temperature is distributed unevenly along the vertical direction of a bridge’s steel-concrete beam. It was found that the metal beam accepted higher temperature values. The maximum registered temperature difference between a metal beam and a reinforced concrete slab at positive ambient temperatures was +9.0 °C, and the minimum temperature difference was −2.1 °C. The mathematical models for calculating a temperature field and a thermally strained state of bridges’ steel-concrete beams under the influence of variable climatic temperature changes in the environment have been improved, taking into consideration the uneven temperature distribution across a bridge’s reinforced concrete beam. The possibility has been established to consider a one-dimensional problem or to apply the three-dimensional estimated problem schemes as the estimation schemes for determining the thermoelastic state of reinforced concrete bridges. The temperature field and the stressed state of bridges’ reinforced concrete beams were determined. It was found that the maximum stresses arise at the place where a metal beam meets a reinforced concrete slab. These stresses amount to 73.4 MPa at positive ambient temperatures, and 69.3 MPa at negative ambient temperatures. The amount of stresses is up to 35 % of the permissible stress values. The overall stressed-strained state of a bridge’s reinforced concrete beams should be assessed at the joint action of temperature-in- duced climatic influences and loads from moving vehicles.
Cracks Interaction in the Elastic Composite under Action of the Harmonic Loading Field
(Tbilisi State University, Georgia, 2018) Stankevych, Volodymyr Z.; Butrak, I. O.; Kovalchuk, Vitalii V.
EN: A three-layer composite with penny-shaped cracks in the field of harmonic torsional loading is considered. The solutions are chosen in the form of Helmholtz potentials with densities that characterize unknown crack opening functions. The problem is reduced to the solution of the system of two-dimensional boundary integral equations (BIFs). The influence of the frequency of the applied load, the ratio of the elastic constant parameters of the composite on the dynamic stress intensity factors in the defect vicinity is investigated.
Degradating Concrete and Reinforced Concrete Building Structures and Long-Term Structures
(Одеська державна академія будівництва та архітектури, 2022) Luchko, Joseph; Nazarevich, B.; Kovalchuk, Vitalii V.
ENG: In the work on the basis of the performed field researches the problems of degradation of concrete and reinforced concrete constructions of buildings and constructions of long operation are formulated and its urgency is noted. The authors analyzed a number of works on this problem. In particular, the results of technical diagnostics of many buildings and structures, both newly built and long-term operation, are described. The necessity of periodic technical diagnostics is noted. Based on these studies, the main factors that significantly affect the reduction of load-bearing capacity of reinforced concrete structures of buildings and structures are summarized and found that they are as follows: design errors, defects and shortcomings of construction and operational shortcomings of buildings and structures. Also, using modern technologies and materials, the authors identified the benefits of their use for repair and restoration of concrete and reinforced concrete structures at a number of long-term facilities. Relevant conclusions have been formulated on research and repair works. It is established that to prevent loss of load-bearing capacity of structures for long-term operation it is necessary to study the degradation and residual life of load-bearing capacity of structures, their reliability and durability, which were exposed to aggressive air, soil and water. It is established that the reason for the decrease in the strength of concrete beams, which were operated in an aggressive environment, was the error in the design of corrosion protection of structures. Reinforcement and injection filling of dry cracks, crevices and hidden cavities and stratifications and other corrosion damage of beams and slabs with the use of fluid polyurethane compositions, which allowed to extend the service life of structures. It is established that the use of the Polymer Cement Concrete system with the use of glued composite materials ensured the further normal operation of the monolithic reinforced concrete floor of the technical floor of the residential building. Recommendations for the sequence of operations in the repair of reinforced concrete structures of buildings and structures of long-term operation.
Determination of Integrated Indicator for Analysis of the Traffic Safety Condition for Traction Rolling Stock
(Kaunas University of Technology, Kaunas, Lithuania, 2018) Bodnar, Borys Ye.; Bolzhelarskyi, Yaroslav V.; Ochkasov, Oleksandr B.; Hryshechkina, Tatyana S.
ENG: Traffic safety is a major priority in railway transport operation. Locomotive facility is one of the responsible units in general system of railways. A complex and cumbersome system of indicators is used in locomotive facilities to analyze the operation. The existing system makes it difficult to analyze the general level of work organization in the locomotive facilities. Purpose of the study is to determine the methodology of forming a certain dimensionless indicator (or group of indicators) that will reflect the general level of safety in the locomotive facilities. As the research methodology it was chosen principal component analysis as the corresponding mathematical apparatus, which makes it possible to analyze the existing indicators characterizing the performed work and the traffic safety condition with the necessary degree of informativity. As a result, the main components and the degree of their influence on the general level of traffic safety in the locomotive facilities are set. The indicators that have the most influence on the technical and safety components of the integrated indicator of traffic safety condition are determined. Originality of the work is that it for the first time proposes the concept of index of traffic safety condition and the method of its determination using the principal component analysis. Practical value of the work lies in the fact that the ranking of technical and safety components according to the degree of their influence on the general traffic safety index has been performed. Also, the locomotive units which have the greatest influence on the traffic safety condition and reliability were determined.
Determination of the Optimal Parameters of the Structure of Functional Gradient Materials using Mathematical Modelling Approaches
(International OCSCO World Press, Poland, 2019) Lyashenko, B. A.; Stotsko, Z. A.; Kuzin, Oleg A.; Kuzin, Mykola O.; Mikosianchyk, Oksana
EN: Abstract. Purpose: Functioning of mechanical friction systems largely depends on the characteristics of the structure of their surface layers. By controlling these parameters, it is possible to significantly adjust the reliability and durability of parts under the conditions of contact interaction. Design/methodology/approach: he proposed approach, which is based on the principle of nonlocality of the operational properties of materials, allows determining the optimal microhardness values of the surface layers and the gradient of this parameter, at which the contact durability of friction pair elements significantly increases. Findings: It is established that by adjusting the ratios of the surface strength of materials and its gradient, it is possible to achieve a significant increase in the operational parameters of friction units. Practical implications: The engineering relationship considered in the work allows to establish functional distributions of microhardness in the structure of surface layers, at which their wear reaches minimum values. Originality/value: Mathematical approaches are proposed, which allow determining the parameters of the structure of the surface layers of parts to increase their durability under conditions of friction contact loads.
Determining Patterns in the Stressed-Deformed State of the Railroad Track Subgrade Reinforced with Tubular Drains
(РС ТЕСHNOLOGY СЕNTЕR, Kharkiv, Ukraine, 2020) Luchko, Josyp; Kovalchuk, Vitalii V.; Kravets, Ivan B.; Gajda, Oleksiy; Onyshchenko, Artur
EN: The technical condition of the railroad track subgrade has been analyzed, as well as the issues related to ensuring its strength and stability when exposed to floodwaters and when the track's sections are overmoistened during operation. As a result, it has been established that it is necessary to develop methods aimed at improving the subgrade's carrying capacity. The georadar research has explored the problematic areas of the railroad track subgrade, based on which the distribution of subgrade heterogeneity in the vertical plane, as well as the boundaries of its location, were established. Therefore, georadar research makes it possible to detect hidden defective sites in the subgrade without disrupting its strength characteristics. A technique has been proposed to improve the carrying capacity of the failed subgrade of a railroad track using the combined arrangement of drainage pipes in the vertical and horizontal directions in the railroad embankment. The special feature of this technique is the possibility to drain water at the different levels of surface water, which provides for an increase in the carrying capacity of the failed subgrade. The strained-deformed state of the subgrade reinforced with tubular drainage has been investigated. The result has proven the effectiveness of the use of tubular drainages to improve the carrying capacity of the railroad track overmoistened subgrade exposed to constant and temporary loads. This study findings have established that the deformity of the subgrade increases when using tubular drainage, though this occurs only in the initial period of its arrangement, in further operation, when it removes water from the subgrade body, the carrying capacity of the subgrade, on the contrary, will improve due to the enhanced physical and mechanical properties of soils.
Determining the Causes of Rolling Stock Derailment From the Track Using Modern Research Methods
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Kuzyshyn, Andriy; Batig, Andriy V.; Sobolevska, Julia H.; Kostritsa, Sergei A.; Ursulyak, Lyudmila V.; Dovhaniuk, Stepan S.
EN: Abstract. The analysis of cases of rolling stock derailment from the track at PJSC «Ukrzaliznytsia» over the past 5 years has been carried out and their main types are given. It is noted that the rapid development and improvement of computer technology allows the use of computer and mathematical modelling in the study of cases of rolling stock derailment from the rail track, which makes it possible to take into account a combination of factors that have the main influence on the behavior of rolling stock when moving along the track. It has been established that the first step is the construction of a mathematical model of an object using a selected type of mathematical description: algebraic, differential, integral equations, discrete mathematics, set theory, and others. And the second step is the choice of a method for solving these models. The simulation methods are given, which, depending on the programming style, are divided into: procedural-oriented, object-oriented, logical-oriented, rule-oriented, and oriented to constraints. An objectoriented programming of a freight car has been developed, which will make it possible to evaluate its main dynamic indicators, in particular, indicators of stability from derailment. This in turn will facilitate the establishment of the main causes of rolling stock derailment from the rail track.
Development of a Promising System for Diagnosing the Frogs of Railroad Switches Using the Transverse Profile Measurement Method
(PC "Technology Center", Ukrainian State University of Railway Transport, Kharkov, 2018) Kovalchuk, Vitalii V.; Sysyn, Mykola P.; Hnativ, Yuriy M.; Bal, Olena M.; Parneta, Bohdan Z.; Pentsak, Andrii Ya.
EN: We have developed a system for diagnosing the frogs of railroad switches, based on the application of modern microcontrollers of the type ESP with high technical characteristics and the simultaneous use of the information technology IoT (Internet of Things). The proposed system has advantages over mechanical systems in terms of the accuracy of data, their operational processing and submission to user in order to analyze technical condition of frogs at railroad switches. The results of measuring the transverse profile of frogs at railroad switches make it possible to take scientifically-substantiated decisions regarding the need for recovery repair of frogs by the method of surfacing and for control over gradual decrease in their carrying capacity, for establishing their actual technical condition and residual resource. We carried out experimental-theoretical research into longitudinal profile of frogs at railroad switches laid on the reinforced concrete bars. It was established as a result that after passing 50–65 million tons of cargo (that corresponds to the medium degree of wear) the trajectory takes the shape of a bump. We observe sharp hollows on the reinforced concrete base in the zone where a wheel rolls from a rail wing onto the core, characterized by significant total inclination. Subsequently, when the passed cargo increases, the number of sinusoidal irregularities grows. At wear close to maximal (80–95 million tons passed), the percentage of unfavorable trajectories (sinusoidal and hollows) grows; at low wear, they make up 49.8 %, at a wear of 5−6 mm and larger – 88.3 %. Sometimes there is a transformation of the sinusoidal irregularities into the wave-shaped ones. We have established characteristic motion trajectories of the center of mass of the wheel over the frog depending on the wear of rail wings and the core of a frog and the passed cargo. A mathematical model was constructed for predicting the wear of frog profile depending on the total weight of passed cargo.
Development of an Algorithm for Investigation of Technical State of Wagons’ Running Gears During Their Derailment
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Batig, Andriy V.; Hrytsyshyn, Petro; Kuzyshyn, Andriy; Milyanych, Andriy R.; Voznyak, Oleh M.; Tereshchak, Yuriy V.
EN: Abstract. A freight wagon is a collection of a large number of parts and assemblies that form a single structure. During wagon operation, there are gradual changes in the characteristics and parameters of its structural elements. That is, the parameters of its constituent elements change – their numerical values increase or decrease that result in a change of the unit’s technical state, and, in turn, affects the totality of its performance. Gradually accumulating, the changes in the parameters of the structural elements of a wagon reach such a level that radical, sometimes abrupt qualitative change occurs. A malfunction that has not been repaired timely may lead to a failure of a wagon structural element, which, in turn, may result in rolling stock derailment. It has been established that the loss of stability of freight wagons during their movement is most often due to their unsatisfactory dynamic properties, which can be explained by design features and technical state of running gears. In this regard, the authors of the article have developed an algorithm for investigation technical state of running gears of freight wagons and determined the effect of their parameters’ deviation on rolling stock operation with possible further derailment.
Device for Measuring and Evaluation Stress-Strain State Transport Facilities at Variable Load and Temperature
(Dolnośląskie Wydawnictwo Edukacyjne, Wroclaw, 2015) Luchko, Józef; Kovalchuk, Vladimir; Wozniak, Oleg
EN: In this work the scientific principles of a new device for the measurement and evaluation of the stress-strain state of transportation facilities under changing temperatures and loads. The technical problem which is solved by this work is to adopt the monitored transport facilities evidence-based decisions about the need for renewal of an element, controlling gradual reduction of the bearing capacity of the structural elements, establishing their actual technical condition and residual life. At the heart of the new device is measuring strain using analog-to-digital converter (ADC) and analog measuring bridge-tensometer. The advantage of the proposed device is that the accuracy of measurements made with the help does not depend on the length of the connecting conductors and supply voltage. He can help you evaluate and consider the deformation caused by too, and temperature effects on transport facilities.
Devising a Procedure for Assessing the Subgrade Compaction Degree Based on the Propagation Rate of Elastic Waves
(РС Тесhnology Сеntеr, Kharkiv, Ukraine, 2021) Kovalchuk, Vitalii V.; Kravets, Ivan B.; Nabochenko, Olga S.; Onyshchenko, Artur; Fedorenko, Olexander; Pentsak, Andriy; Petrenko, Oleksiy V.; Hembara, Nataliya
EN: This paper reports the analysis of the methods for estimating the technical condition of the subgrade underneath a constructed railroad track or road during its operation. The study results have proven that the issue related to monitoring and controlling high-quality compac-tion of a heterogeneous subgrade remains relevant and requires the construction of reliable experi-mental methods for assessing the subgrade degree of compaction.A procedure for determining the compaction of subgrade in the laboratory has been devised, based on inertial microcomputer technologies, which makes it pos-sible to assess the degree of com-paction of subgrade soils depend-ing on the propagation rate of an impact's elastic waves.An experimental study has been performed into the propaga-tion rate of elastic waves across a homogeneous subgrade made of coarse-grained sand and a hetero-geneous subgrade made of coarse sand with a layer of clay in the middle of the prism. The study results established that the propa-gation rate of an elastic wave in a heterogeneous subgrade accepts a lower value than the rate of wave propagation in a homogeneous subgrade.Through the dynamic inter-pretation, by using a discriminant statistical analysis, the character-istic features have been defined in the distribution of accelerations in the body of the homogeneous and heterogeneous subgrade, depend-ing on the degree of compaction, which would make it possible to monitor the state of the subgrade during operation. As the degree of the subgrade soil compaction affects the technical condition of roads.
Devising a Procedure to Calculate and Analyze Parameters for Passing the Flood and Breakthrough Wave Taking into Consideration the Topographical and Hydraulic Riverbed Irregularities
(РС Тесhnology Сеntеr, Kharkiv, Ukraine, 2022) Onyshchenko, Artur; Ostroverkh, Вorys; Potapenko, Liudmila; Kovalchuk, Vitalii V.; Tokin, Оleksndr; Harkusha, Mykola; Bashkevych, Іryna; Koretskyi, Andrii; Khvoshchynska, Nadiia; Rolinska, Iryna
ENG: It has been established that the most likely period of breakthrough wave occurrence is the time of spring flooding or heavy rain when water-head facilities are subjected to significant loads that lead to the collapse of their individual elements or the entire structure. In addition, the possibility of man-made accidents that can occur at any time cannot be ruled out. It has been proven that breakthrough wave formation depends on the nature of the destruction or the overflow through a water-head facility. For the study reported in this paper, a model of the kinematics of riverbed and breakthrough flows was used, which is based on the equations of flow, washout, and transport of sediments that are averaged for the depths of the stream. The differential equations describing the nonstationary flow averaged for depth are solved using the numerical grid system FST2DH (2D Depth-averaged Flow and Sediment Transport Model), which implements a finite-element method on the plan of a riverbed's topographic region. These tools are publicly available, which allows their wide application to specific loads and boundary conditions of mathematical models. The construction of an estimation grid involving the setting of boundary conditions and the use of geoinformation system tools makes it possible to simulate the destruction of a culvert of the pressure circuit and obtain results for a specific case of an actual riverbed and a water-head facility. It has been established that there is a decrease in the speed of wave propagation along the profile, from 3 m/s to 1 m/s. The impact of bottom irregularities, the effect of floodplains, and the variety of bottom roughness have also been assessed, compared to the results of their calculation based on one-dimensional models given in the regulatory documents. Hydraulic calculations were carried out taking into consideration the related properties of the main layer of the floodplain, which consists of peat accumulations, and the heterogeneity of the depths and roughness of floodplain surfaces of soils. It has been established that there is almost no erosion of supports in the floodplain zone in this case. It was found that as the distance between the flow and breakthrough intersection increases, there is a decrease in the height of the head from 2.1 m to 1.25 m.
Effect of CrB2 on the Microstructure, Properties, and Wear Resistance of Sintered Composite and the Diamond Retention in Fe–Cu–Ni–Sn Matrix
(Allerton Press Inc., USA, 2021) Mechnik, V. A.; Bondarenko, N. A.; Kolodnitskyi, V. M.; Zakiev, V. I.; Zakiev, I. M.; Gevorkyan, E. S.; Chishkala, V. A.; Kuzin, Nickolai O.
EN: Using the method of powder metallurgy, we studied the effect of CrB2 additives (0–8 wt %) on the formation of the structure of the diamond–matrix transition zone and the matrix material, microhardness, elastic modulus, and fixation of diamond grains in a Fe–Cu–Ni–Sn matrix and determined the wear resistance of sintered composite diamond-containing materials (DCMs). Micromechanical and tribological tests were carried out using composite samples 10 mm in diameter and 5 mm thick. The transition zone structure depends significantly on the concentration of CrB2 in the composite and has a different nature than the structure of the matrix material. The structure of the DCM transition zone based on the 51Fe–32Cu–9Ni–8Sn matrix consists of Cu, α-Fe, and Ni3Sn phases with graphite inclusions, and with the addition of CrB2, it consists of the α-Fe phase and Fe3C, Cr7C3, and Cr3C2 carbide layers without graphite inclusions. The hardness and elastic modulus of the matrix material of the sintered composites linearly increase with an increase in the concentration of CrB2 in their composition, while the wear rate decreases. The addition of 2 wt % of CrB2 to the 51Fe– 32Cu–9Ni–8Sn composite increases hardness from 4.475 to 7.896 GPa and an elastic modulus from 86.6 to 107.5 GPa and decreases the wear rate from 21.61 × 10–6 to 10.04 × 10–6 mm3 N–1 m–1. The mechanism for improving the mechanical properties and decreasing the wear resistance of DCM samples containing CrB2 additive consists in grain refining of the matrix phases of iron and copper from 5–40 to 2–10 μm and in binding carbon released during graphitization of diamond grains into nanosized carbides Fe3C, Cr7C3, and Cr3C2. This, in turn, increases the ability of the matrix material to keep diamond grains from falling out during the operation of DCMs. The coarse-grained structure and the formation of graphite inclusions in the diamond–matrix transition zone explain poor mechanical and tribological properties of the initial (51Fe–32Cu–9Ni–8Sn) composite, causing its premature destruction and falling out of diamond grains from the DCM matrix.
Effect of Vanadium Nitride Additive on the Structure and Strength Characteristics of Diamond-Containing Composites Based on the Fe–Cu–Ni–Sn Matrix, Formed by Cold Pressing Followed by Vacuum Hot Pressing
(Springer Link, 2021) Ratov, B. T.; Mechnik, V. A.; Bondarenko, N. A.; Kolodnitskyi, V. M.; Kuzin, Nickolai O.; Gevorkyan, E. S.; Chishkala, V. A.
ENG: We prepared samples of composite diamond-containing materials 10 mm in diameter and 8 mm in thickness, based on the 51Fe–32Cu–9Ni–8Sn matrix (wt %) with different (0–10 wt %) concentrations of vanadium nitride (VN), the physical the mechanical characteristics of which depend on the composition of the iron matrix. The optimal (cVN = 4%) concentration of vanadium nitride in the matrix of composites sintered in the temperature range of 20–1000°C at a pressure of 30 MPa for 5 min ensures the highest indices of the physicomechanical properties of the composites (Rbm = 1110 MPa and Rcm = 1410 MPa) due to the dispersion mechanism of strengthening and modification of the structure, that is, a decrease in the average grain size, the disappearance of pores, the formation of clusters of the inhibitor phase at the interphase boundaries, and the phase composition of the composites. All sintered samples containing VN powder additives in the charge are characterized by a more uniform distribution of phases and a more dispersed structure compared to a sample without VN additives. The structure of composites containing a VN additive consists of a solid solution of nitrogen and vanadium in α-iron and a mixture of Fe, Cu, Ni, and Sn phases and primary and secondary dispersed phases of vanadium nitride.
Estimation of Carrying Capacity of Metallic Corrugated Structures of the Type Multiplate MP 150 During Interaction with Backfill Soil
(PC "Technology Center", Ukrainian State University of Railway Transport, Kharkov, 2018) Kovalchuk, Vitalii V.; Kovalchuk, Yuri; Sysyn, Mykola P.; Stankevych, Volodymyr Z.; Petrenko, Oleksiy V.
EN: We estimated the stressed state of a railroad structure with a large cross section spanning more than 6 m, which is made from metallic corrugated sheets of the type Multiplate MP 150. The stressed-strained state of the corrugated structure was estimated depending on the residual deformation of vertical diameter of the pipe, the modulus of elasticity of backfill soil, and the degree of compaction. The study conducted has demonstrated that maximum stresses occur on the horizontal sides of a metallic pipe, and maximum deformations ‒ in the pipe vault. It was established that an increase in the degree of compaction of backfill soil leads to a decrease in the stresses in a metallic pipe by almost half. The stresses grow much faster with an increase in irregularity on the railroad track. Numerical calculations have shown that the equivalent stresses exceed the permissible magnitude of 235 MPa when the degree of compaction of backfill soil is below 90 % and an operational irregularity on the track develops beyond the permissible magnitude. Operational observations have shown that the pipe is most vulnerable, in terms of resistance against the formation of a plastic hinge, in the initial period of operation when the backfill soil has not yet reached the standard compaction. At the initial stage of operation of a metallic corrugated pipe it is necessary to improve the level of technological control in order to timely detect railroad track's irregularities that exceed the standards, and to eliminate them. Under normal operational conditions, a metallic corrugated structure has a rather large reserve of carrying capacity, which amounts to 80 %. However, these structures, despite their high initial strength margin, are very sensitive to an increase in external dynamic loads due to the occurrence of irregularity on the railroad track.
Estimation of Strength Properties of Functionally Graded Structures with Elliptical Stress Concentrators
(International OCSCO World Press, Poland, 2022) Stotsko, Zinoviy A.; Kuzin, Oleg A.; Kuzin, Mykola O.; Mechnik, V. A.
ENG: Purpose: The purpose of this paper is to elaborate new calculation schemes for evaluating the strength parameters of railway rolling stock parts with non-local properties of surface layers in the presence of elliptical stress concentrators. Design/methodology/approach: Using the proposed approaches of developed mathematical modelling and open software for calculating FEniCS, it were established the most dangerous angles of stress concentrator orientation and the required thickness of the hardened zones of parts, which ensures their minimum softening during operation. Findings: It is shown that for an elliptical stress concentrator with any orientation angle, there is a certain key size of surface hardening thickness, the exceeding the value of which does not have influence on the operational strength of the parts, but rise the price of technological operations. Research limitations/implications: In this paper proposes a method for computation the impact of the orientation of the surface elliptical stress concentrators on the contact strength of parts under conditions of dominate friction power loads. Practical implications: The obtained results were used to set the modes of plasma hardening, which increase the contact strength of railway parts with elliptical stress concentrators. Originality/value: Using the approaches of contact mechanics, mathematical and computer modelling, methods of controlling the contact strength of the parts with the surface elliptical stress concentrators were proposed for the first time.
Evaluation Deflected Mode of Point Frogs Mark 1/11 Finite Element Method
(НВП ПП «Технологічний Центр», Харків, 2017) Kovalchuk, Vitalii V.; Bolzhelarskyi, Yaroslav V.; Parneta, Bogdan Z.; Pentsak, Andriy; Petrenko, Oleksiy V.; Mudryy, Ihor B.
EN: We carried out evaluation of the stressed-strained state of crossings of turnouts by the finite element method in the Ansys programming complex. It was established that under conditions of three-axial compression, at large stresses of vertical compression, the cracks of multi-cycle metal fatigue of the crossing develop. It was found that the development of defects by the code DS 14.1-14.2 on the rolling surface of the cast part of a wing rail and the crossing’s core occurs due to high contact stresses near the edge of the working face of a wing rail and the crossing’s core. They occur in this region in the form of cyclically repeated and sign-alternating normal and tangential stresses from cyclically recurring power impacts from the wheels of rolling stock of railroad transport. It was established that for the normal stresses, values that are maximal by absolute magnitude correspond to the moment when a wheel passes the estiamted cross section of the crossing. For the tangential stresses, on the contrary, at the moment when the wheel is over the estimated cross section, their magnitude is close to zero. The obtained results of the stressed-strained state of crossings are necessary for the optimal design of transverse and longitudinal profiles of the crossing. This will make it possible to extend operation life cycle of the crossings of turnouts and save state budget resources for their current maintenance and repair.
Evaluation of RailWay Ballast Layer Consolidation After Maintenance Works
(Czech Technical University, Prague, 2019) Sysyn, Mykola P.; Nabochenko, Olga S.; Kovalchuk, Vitalii V.; Gerber, Ulf
EN: Abstract. The results of the study of the ballast layer consolidation after the work of ballast-tamping machines of different types are given in the article. The existing methods of determining the degree of consolidation of the ballast layer are analysed. The seismic method was improved by means of a complex dynamic and kinematic interpretation of the impulse response. For the dynamic interpretation with the use of statistical analysis, the features are selected so that they correspond to the degree of consolidation of the ballast layer. On the basis of researches, a device and software were developed that allow an automated evaluation of the ballast layer consolidation based on the kinematic and dynamic analysis of the measured impulse response. The measurements of the degree of the ballast layer consolidation after an operation of ballast-consolidation machines in different sequences allowed establishing the efficiency of the consolidation and the feasibility of the machines’ application.
Evaluation of the Stressed-Strained State of Crossings of the 1/11 Type Turnouts by the Finite Element Method
(ПП "Технологічний центр", Український державний університет залізничного транспорту, 2017) Kovalchuk, Vitalii V.; Bolzhelarskyi, Yaroslav V.; Parneta, Bohdan Z.; Pentsak, Andrii Ya.; Petrenko, Oleksii V.; Mudryy, Ihor B.
EN: We carried out evaluation of the stressed-strained state of cross-ings of turnouts by the finite element method in the Ansys program-ming complex. It was established that under conditions of three-axial compression, at large stresses of vertical compression, the cracks of multi-cycle metal fatigue of the crossing develop. It was found that the development of defects by the code DS 14.1-14.2 on the rolling surface of the cast part of a wing rail and the crossing’s core occurs due to high contact stresses near the edge of the working face of a wing rail and the crossing’s core. They occur in this region in the form of cyclically repeated and sign-alternating normal and tangential stresses from cyclically recurring power im-pacts from the wheels of rolling stock of railroad transport. It was established that for the normal stresses, values that are maximal by absolute magnitude correspond to the moment when a wheel passes the estiamted cross section of the crossing. For the tangential stresses, on the contrary, at the moment when the wheel is over the estimated cross section, their magnitude is close to zero. The obtained results of the stressed-strained state of crossings are necessary for the optimal design of transverse and longitudinal profiles of the crossing. This will make it possible to extend operation life cycle of the crossings of turnouts and save state budget resources for their current maintenance and repair.
Experimental and Theoretical Evaluation of Side Tamping Method for Ballasted Railway Track Maintenance
(Silesian University of Technology, 2020) Przybylowicz, Michal; Sysyn, Mykola P.; Kovalchuk, Vitalii V.; Nabochenko, Olga S.
EN: Ballast layer is the most weak element of railway track that causes track geometry deterioration. At the same time, it is subjected to intensive particle breakage during the corrective tamping. This causes high maintenance costs of ballasted track. The present paper is devoted to the study of tamping methods. The present machine tamping methods are considered and compared. The possible influence of the tamping technology on the ballast-related maintenance costs is analyzed. The side tamping technology is studied in detail with theoretical and experimental methods. The process of material transport during the side tamping is studied using a scale model of ballast layer and photogrammetric measurements. A theoretical finite element model (FEM) is validated to the experimental results. The study shows that the side tamping is a promising method for the development of a universal, superstructure independent tamping technology.
Experimental Investigation of The Dynamic Behavior of Railway Track with Sleeper Voids
(Springer-Verlag, 2020) Sysyn, Mykola P.; Nabochenko, Olga S.; Kovalchuk, Vitalii V.
EN: The deterioration of the sleeper support on the bal-lasted track begins with the accumulation of sleeper voids. Theincreased dynamic loading in the voided zone and the ballastcontact conditions cause the accelerated growth of the settle-ments in the voided zones, which results in the appearance oflocal instabilities like ballast breakdown, white spots, subgradedefects, etc. The recent detection and quantiﬁcation of thesleeper voids with track-side and onboard monitoring can helpto avoid or delay the development of local instabilities. Thepresent paper is devoted to the study of the dynamic behavior ofrailway track with sleeper voids in the ballast breakdown zone.The result of the experimental track-side measurements of railacceleration and deﬂection is presented. The analysis shows theexistence of the dynamic impact during wheel entry in thevoided zone. However, the measured dynamic impact is sub-jected to the bias of the track-side measurement method. Boththe mechanism of the impact and the measurement aspects areexplained by using the one-beam model on viscoelastic foun-dation. The void features in the dynamic behavior are analyzedfor the purpose of track-side and onboard monitoring. A prac-tical method of the void parameter quantiﬁcation is proposed.
Experimental Investigation of the Influence of Train Velocity and Travel Direction on the Dynamic Behavior of Stiff Common Crossings
(University of Niš, Serbia, 2019) Kovalchuk, Vitalii V.; Sysyn, Mykola P.; Gerber, Ulf; Nabochenko, Olga S.; Zarour, Jandab; Dehne, Stefan
EN: Abstract. Common crossing rails are subjected to a rapid deterioration of the rolling surface due to a dynamic loading of trains. The present study is devoted to an experimental study of the displacement and rail strain measurements in the common crossing. The experimental measurements were carried out for two stiff common crossings under the dynamic loading of high-speed train for the velocity range of 54-254 km/h. The results showed 2.5 times increase of the maximal displacements within the velocity range. The absence of the difference in the displacements between the trailing and the facing travel direction is explained with the relative displacement measurements between the rail and the sleeper and the different dynamic impact loading for the wing rail. The proposed model-based analysis of the absolute measurement of rail strain enables us to estimate the dynamic factor under the impact loading. The wing rail for trailing direction is almost twice as highly loaded as the frog rail for the facing direction. The maximal dynamic factor for the trailing direction shows almost no change for the velocities of more than 200 km/h.
Experimental Study of Railway Ballast Consolidation Inhomogeneity under Vibration Loading
(Akadémiai Kiadó, Hungary, 2020) Sysyn, Mykola P.; Kovalchuk, Vitalii V.; Gerber, Ulf; Nabochenko, Olga S.; Pentsak, Andriy Ya.
EN: Railway ballast tamping is one of the cost-expensive renewal and maintenance works of railway superstructure. The quality of ballast consolidation influences its resistance to residual deformations and long-term deterioration of track geometry. The process of ballast compaction along the sleeper under the vibration loading is complex and depends on many factors. The ballast flow processes under the vibration loading can produce both consolidation and un-consolidation of ballast material. The present study is devoted to the experimental investigation of ballast consolidation inhomogeneity. The method of ballast local consolidation measurement is proposed. The method is based on the velocity of impact wave propagation that is measured with device. The application of modern microcontroller and sensor techniques provided simple and reliable multi-point velocity measurements in a ballast layer. That enables well enough spatial resolution of ballast consolidation inhomogeneity. The measurement analysis has shown more than 4 times higher consolidation under the sleeper center than for unconsolidated ballast.
Experimental Study of Railway Trackred Pressure Distribution under Dynamic Loading
(Riga Technical University, Latvia, 2019) Sysyn, Mykola P.; Kovalchuk, Vitalii V.; Nabochenko, Olga S.; Kovalchuk, Yuri; Voznyak, Oleg M.
EN: Abstract. Reliable and durable operation of the railway track under the dynamic load of the rolling stock depends considerably on the ability of the ballast layer to get the load from the sleepers and distribute it to the subgrade. In this paper, the experimental study of the distribution properties of the ballast layer under the impact of dynamic loading depending on the density of the ballast layer is carried out. The ballast behaviour during load cycles is estimated by pressure measurements at the ballast prism base along the axis of a sleeper with simultaneous video observation of the ballast particles movement through transparent sidewalls of the box with crushed stone. Measurements of pressure distribution are carried out with the developed microcontroller system of measurements and developed load cells. The system allows performing multi-point measurements of stress in combination with measurements of acceleration and photogrammetry. The results of measurements showed a significant effect of the ballast layer consolidation on the distribution of stresses under the sleeper. The performed research opens up opportunities for practical improvement of the existing types of track structures and the technology of the ballast layer tamping in terms to provide the optimal conditions for the ballast layer operation.
Fractographic Analysis of the Destroyed Side Frame of the Truck of a Wreight Wagon
(ПОСВІТ, Дрогобич, 2020) Vakulenko, Ihor O.; Kuzin, Nickolai O.; Vakulenko, Leonid I.
EN: The initial inspection of damaged frame in fracture revealed two sections with characteristic structural features. The area with traces of slight corrosion, representing a smooth surface, corresponds to the gradual movement of fatigue crack. The rest of fracture surface with signs of a dynamic destroy has a qualitatively different structure. The fatigue part occupies approximately 30% of the total cross-sectional area. The propagation front of fatigue crack, after reaching the outer and inner surfaces of vertical wall from the side of wheel, reaches half the length lower horizontal wall. The focus of origin fatigue crack, located in lower inner corner, when moving from vertical wall to horizontal part of the side frame, is difficult obtain access when visually inspecting the frame trolley.
Identification of Sleeper Support Conditions Using Mechanical Model Supported Data-Driven Approach
(MDPI, 2021) Sysyn, Mykola; Przybylowicz, Michal; Nabochenko, Olga; Kou, Lei
EN: The ballasted track superstructure is characterized by a relative quick deterioration of track geometry due to ballast settlements and the accumulation of sleeper voids. The track zones with the sleeper voids differ from the geometrical irregularities with increased dynamic loading, high vibration, and unfavorable ballast-bed and sleeper contact conditions. This causes the accelerated growth of the inhomogeneous settlements, resulting in maintenance-expensive local instabilities that influence transportation reliability and availability. The recent identification and evaluation of the sleeper support conditions using track-side and on-board monitoring methods can help planning prevention activities to avoid or delay the development of local instabilities such as ballast breakdown, white spots, subgrade defects, etc. The paper presents theoretical and experimental studies that are directed at the development of the methods for sleeper support identification. The distinctive features of the dynamic behavior in the void zone compared to the equivalent geometrical irregularity are identified by numeric simulation using a three-beam dynamic model, taking into account superstructure and rolling stock dynamic interaction. The spectral features in time domain in scalograms and scattergrams are analyzed. Additionally, the theoretical research enabled to determine the similarities and differences of the dynamic interaction from the viewpoint of track-side and on-board measurements. The method of experimental investigation is presented by multipoint track-side measurements of rail-dynamic displacements using high-speed video records and digital imaging correlation (DIC) methods. The method is used to collect the statistical information from different-extent voided zones and the corresponding reference zones without voids. The applied machine learning methods enable the exact recent void identification using the wavelet scattering feature extraction from track-side measurements. A case study of the method application for an on-board measurement shows the moderate results of the recent void identification as well as the potential ways of its improvement. View Full-Text
Improvement of Inspection System for Common Crossings by Track Side Monitoring and Prognostics
(Techno-Press, South Korea, 2020) Sysyn, Mykola; Nabochenko, Olga; Kovalchuk, Vitalii V.; Gruen, Dimitri; Pentsak, Andriy
EN: Scheduled inspections of common crossings are one of the main cost drivers of railway maintenance. Prognostics and health management (PHM) approach and modern monitoring means offer many possibilities in the optimization of inspections and maintenance. The present paper deals with data driven prognosis of the common crossing remaining useful life (RUL) that is based on an inertial monitoring system. The problem of scheduled inspections system for common crossings is outlined and analysed. The proposed analysis of inertial signals with the maximal overlap discrete wavelet packet transform (MODWPT) and Shannon entropy (SE) estimates enable to extract the spectral features. The relevant features for the acceleration components are selected with application of Lasso (Least absolute shrinkage and selection operator) regularization. The features are fused with time domain information about the longitudinal position of wheels impact and train velocities by multivariate regression. The fused structural health (SH) indicator has a significant correlation to the lifetime of crossing. The RUL prognosis is performed on the linear degradation stochastic model with recursive Bayesian update. Prognosis testing metrics show the promising results for common crossing inspection scheduling improvement.
Improving a Methodology of Theoretical Determination of the Frame and Directing Forсes in Modern Diesel Trains
(PC "Technology Center", Ukrainian State University of Railway Transport, Kharkov, 2018) Kovalchuk, Vitalii V.; Kuzyshyn, Andrii Ya.; Kostritsa, Sergey A.; Sobolevska, Yuliia H.; Batig, Andriy V.; Dovhaniuk, Stepan S.
EN: The method for determining the directing force was improved, taking into consideration the effect of transverse creep forces and the angle of the directing force inclination to the vertical axis. It was established that when determining the directing force, it is necessary to check the gap between the wheel flange and the rail head which is difficult to realize without computer simulation. When determining the frame force on the axle of the wheel set, a comprehensive approach was adopted taking into account geometric irregularities of the track path, both in vertical and horizontal planes; longitudinal and transverse creep forces at the point of the wheel-rail contact and influence of adjacent wheel sets of the diesel train car. Dependences of the frame and directing forces on speed of the carriage movement and the value of amplitude of the horizontal irregularity of the rail track were obtained. It was established that when moving in the straight section of the track, an increase in speed from 0 m/s to 50 m/s results in a rise in the value of the frame force: up to 8.3 kN for the first wheel set and 19.37 kN for the second wheel set and the directing force up to 31.38 kN for the first wheel set and up to 46.83 kN for the second wheel set. The increase in amplitude of the horizontal irregularity of the track, which is one of the primary causes of occurrence of forced oscillations of the carriage section above the springs also leads to an increase in numerical values of the forces of interaction of the rolling stock with the rail track. All this can bring about an increased power influence of the wheel set on the track and a negative impact on the basic criteria of traffic safety. Influence of the carriage movement speed on the value of transverse creep forces was studied. It has been established that with an increase in the carriage speed from 0 m/s to 50 m/s, these forces grow from 0 to 15.75 kN for the 1st wheel set and from 0 to 29.22 kN for the 2nd wheel set. This indicates impermissibility of neglecting the transverse creep forces when determining the directing force. Comparison of numerical values of the directing force determined by different methodologies was performed. It has been established that the methodology used in conducting forensic examination of railroad accidents may result in underestimation of fulfillment of the derailing condition. At the same time, calculations according to the formula improved in this study give an opportunity to obtain the results most approximate to the real operation conditions. Comparison of the experimental and theoretical calculated values of the frame force acting on the first wheel set of the diesel train car was made and their practical coincidence was shown. Discrepancy of the compared values of the frame force was within 7.2 %.
Improving Contact Durability of Polycrystalline Systems by Controlling the Parameters of Large-Angle Grain Boundaries
(НВП ПП «Технологічний Центр», Харьків, 2019) Kopylov, Vyacheslav; Kuzin, Oleg A.; Kuzin, Nickolai O.
EN: ABSTRACT: Polycrystalline metal systems in the samples made of steel 40X with different morphology and parameters of the distribution of large-angle grains boundaries for energy have been examined. The effect of the structural-energy state of grains boundaries on the operational reliability of improved steel 40X has been established. Based on the hierarchical modeling of polycrystals structure, new approaches have been proposed and algorithms have been developed for defining relationships between the structure that is formed in the technological processing of materials and stages in the life cycle of parts. It has been revealed that it is advisable to use, as a digital prototype of the structure of polycrystalline alloys that describes their performance under conditions of contact loads, the matrix representation of a system model that would incorporate the quantitative characteristics of grains. By using the devised procedures, the ways to execute technological control over the energy state of grain boundaries in the structural components have been defined in order to improve durability of parts exposed under contact loads. An estimation-experimental method has been developed to assess the effect of quantitative characteristics of the structure on the parameters of strength of the grains boundaries and their ability to form intragrain damage under external loads. The energy level of grains boundaries and triple joints between the groups of small and large grains is higher than that between grains of the same size. The boundary surfaces with a high level of energy are places where damage occurs at technological processing and under external loads on structural materials. This points to the crucial role of large-angle boundaries placed between triple joints with a high energy gradient in the process of forming microstructurally short cracks and intragrain destruction of polycrystalline systems. The use of hierarchical modeling methods and computational materials science makes it possible to improve the operational reliability of articles by choosing the optimal parameters for internal boundary surfaces. The lower cost of the parts' life cycle is achieved by thermal treatment regimes, which alter the quantitative characteristics of the steel structure.
Improving the Energy Efficiency of Operation of Elements of the Structures of the Rolling Stock by Means of Surface Engineering
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Kopylov, Vyacheslav; Kuzin, Oleg A.; Kuzin, Mykola O.
EN: Abstract. The manufacture of rolling stock components with a given life cycle based on the computerization of all design and production stages is the most promising way to increase the energy efficiency of its operation. The implementation of this approach requires the expansion of the use of technologies that provide parts with a high level of mechanical and operational properties. The state of the surface layers is important in the formation of the reliability parameters of high-loaded parts. The principles of using system approaches for the physical justification of the choice of the optimal modes of engineering grain boundaries depending on the operating conditions of products are presented. New approaches and algorithms have been created that allow quantitative and qualitative studies of the effect of technological treatments and the chemical composition of polycrystals on the strength of grain boundaries and the processes of softening of the boundary zones. Using the developed techniques, the ways to control the energy state of the internal interfaces by doping, microalloying and heat treatment were determined to increase the resistance to brittle fracture and wear of the steels used in the manufacture and repair of rolling stock.
Improving the Performance Parameters of Railway Wheels with the Help of Optimal Design Technologies of their Electric Pulse Processing
(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Vakulenko, Igor A.; Kuzin, Nickolai O.; Vakulenko, Leonid I.; Raksha, Sergey V.; Proidak, Svetlana V.
ENG: Abstract. The processing by pulses of electric current (PEC) of a fragment of the rim of a railway wheel was carried out on the DS10D equipment. When the density of the electric current is from 3 to 17 A/mm2, the processing cycle consisted of the action of a pulse with a duration of 2.5-3 s and a pause between pulses of 4 s. After 150 cycles of PEC, the hardness of cold-formed metal was reduced from 10 to 20%. Studies of the parameters of the metal structure of the wheels have determined that the processing of PEC leads to a decrease in the number of defects in the internal structure, which are accumulated as a result of cold deformation of the rim along the rolling surface of the railway wheel. It has been established that, according to the nature of the influence on the hardness distribution of carbon steel, the PEC treatment corresponds to changes during tempering in the average temperature range and allows to significantly increase the operating parameters of the wheels of railway equipment.