Science and Transport Progress

7-16

Authors: S. S. Belymenko, V. O. Ishchenko

Purpose. Development of similarity criteria for different modes of operation of the solid-state heat accumulator working due to accumulation of heat in the volume of the heat storage material without phase transition, and the creation of systematic criteria of heat accumulator efficiency for determination the weight / size parameters and operating modes at the design stage. Methodology. To achieve the objectives of the study the theory of similarity and dimensional analysis were used as well as planning and carrying out techniques of physical experiments. Findings. Based on the theory of similarity and dimensional analysis similarity criteria operation of solid-state heat accumulators, under given basic parameters were obtained. These are performance criteria for charge, discharge and full criterion. Three theorems of similarity theory in application to the solution of engineering problems were used. The criterion of efficiency of the heat accumulator charge characterizes the effectiveness of achieving the specified value of the specific amount of heat in the material of heat accumulator under charge, under received materials, geometrical ratios, and heat flow of the heat input. The efficiency criterion characterizes the discharge efficiency of the heat accumulator, at the accepted materials; mass of heat-retainer and the total accumulated amount of heat when the value of the heat flow and the time of discharge. Full coefficient of the heat accumulator performance characterizes the efficiency of the heat accumulators for a full cycle. Originality. Accordingly to the analysis the implementation of any system of solid-state heat accumulator is possible on the basis of structural schemes of this type of device. The similarity criteria of the efficiency of the charge, the efficiency of discharge and the full criterion of solid-state heat accumulators’ efficiency based on the solid storage material without phase transition were obtained. Practical value. Criteria presented in this work are of a comparative nature. In accordance with the obtained criteria we can compare designed and existing heat accumulators that are similar to structures. Feasibility analysis indicates that the proposed assessment methodology of solid-state heat accumulators’ efficiency in different modes of operation is effective, technically feasible and allows determining the weight / size parameters and modes of operation of the solid-state heat accumulator at the design stage.

29-38

Authors: M. M. Biliaiev, A. V. Berlov, A. V. Shevchenko

Purpose. Development of the operational numerical model to compute contamination of the atmosphere over Pavlograd city in the case of solid rocket propellant ignition at the storage. Methodology. To simulate the toxic chemical dispersion (product of the solid rocket propellant firing) the equation of convective-diffusion transfer is used. This equation takes into account the toxic chemical dispersion in the atmosphere by wind and the atmosphere diffusion. To calculate the process of the indoor contamination in the case of the contaminated air infiltration a balance model is used. This model takes into account the ventilation flow rate, volume of the room, concentration of toxic chemical in the inlet air. To compute the ventilation flow rate the empirical model was used. The implicit change–triangle difference scheme was used for the numerical integration of the governing equation. FORTRAN language was used to develop code on the basis of the created numerical model. On the basis of the developed numeral model numerical experiment was carried out which allowed to estimate the level of atmosphere contamination in Pavlograd city. Findings. The operational model allows predicting quickly the hitting zone dimensions. The developed model was used to estimate risk of people toxic hitting in the residential districts of Pavlograd city. Originality. A numeral model allows to estimate the risk of toxic hitting of people in Pavlograd city in the case of an accident at the of solid rocket propellant storage. Practical value. The developed numeral model can be used for the quick estimation of risk for people in the city after toxic chemical release at the solid propellant storage. The developed numerical model solves the problem to assess the consequences for the population at ignition of solid rocket propellant in storage.

48-55

Authors: А. R. Мilianych

Purpose. Most of the freight traffic in Ukraine is made by railway transport. Government statistics of annual railway freight traffic (January-November) records the following data: 2011 - 468 million tons (108.2% to 2010); 2012 – 421.5 million tons (98.5% to 2011); 2013 – 441.8 million tons (96.6% by 2012). Despite the annual decrease of freight traffic volumes, a significant contribution during the freight traffic belongs to transportation in tanks. That is why the term of their service life extension is very topical today at the operation of tanks. Modern ideas about the accumulation of fatigue damages in the details of railway vehicles are based on models that assess the service life of metallic systems, depending on the load conditions. These models with sufficient accuracy let carry out an assessment of softening of metallic systems in high-cycle fatigue conditions and at the presence of elastic deformation. At the same time, peculiarities of counterbodies′ behavior these models do not take into account. The purpose of this paper is to construct a mathematical model to evaluate the durability of the operating tools, which are used in the purification of solidified organic cargo of tank cars. Methodology. With the use of modern approaches of deformed solid body mechanics the parameters impact of organic substances structure on the service life of heavy structural elements was analyzed. We present the interaction of damages ratio in this article. It relates mainly to those elements of the tool structure, which due to the influence of broadband Gaussian random loadings oscillate with their resonant or near-resonant frequencies. Findings. The influence of the fatigue loads features on the structure durability was studied. Thus, the obtained results suggest the increase of damages that are entered with low-amplitude cycles of strain, because of the nonlinear effect of the interaction between instrument operational elements with organic material. For the given example durability with fatigue which, according to an updated assessment, had been reduced by 10...15% was calculated. A decrease of 10% corresponds to the maximum amplitude of the voltage , and a decrease of 15% - the maximum amplitude . Originality. It is analytically shown that parameters of the metallic systems softening are connected with the kinetics of fatigue damages that accumulate in the metal structures under external loads. Practical value. Authors have proposed correlation that allows estimating the residual life of the part in conditions of a given sequence of multilevel cyclic loading.

65-73

Authors: D. O. Zabarylo

Purpose. Total mileage of Ukrainian electric railways is distributed approximately equally between the areas of direct and alternating current. A double system of electric rolling stock is used to pass jointing places of different current kinds without train’s stop. Therefore introduction of such rolling stock of a new concept that is using an asynchronous traction drive is prospective for Ukrainian railways. Apart from advantages a rolling stock of similar concept has significant disadvantages, it is pulse energy consumption from the power supply, and it can affect the reliability of track automatic devices, and consequently, the train traffic safety. In addition the specific power of traction transformer is considerably inferior to the power density of other traction elements. The promising schemes using an intermediary link of increased frequency, which consist of a transformer and inverter, have been proposed for disadvantages amendments. The main task for the further introduction of prospective circuit is to determine the operating frequency for high frequency link. Methodology. The method of thermal parameters calculation of semiconductor devices has been used for determination switching transistors of maximum operating frequency. To obtain analytical expressions curves of energy, released during the IGBT (insulated-gate bipolar transistor) switching from its current load approximation method is used. Findings. The permissible frequency of lowfrequency link is determinated by load current of intermediate transformer. Operating frequency range of a link depending on load current has been determined. A comparative analysis of the switching characteristics of 65 class IGBT production by companies Infineon and ABB has been performed. Originality. The further determination method of the maximum operating frequency of intermediate link for circuit with high-frequency transformer has been developed. Practical value. The established operating frequency range of the highlevel link will develop further research of tractive circuit with highfrequency transformer use for double feed electric rolling stock with asynchronous tractive drive. It will evaluate the introduction effectiveness of similar configuration circuits.

83-91

Authors: V. D. Petrenko, V. V. Kovalevych

Purpose. Defective places definition of road bed at ground penetrating radar is examined. Methodology. For achievement of this goal the experimental research on ground penetrating radar inspection of road bed defective places of the Donetsk Railway, which are caused by a complex of various reasons of geotechnical and constructive character, were conducted. Findings. According to these diagnostic results of road bed on the three districts of the Donetsk Railway is revealed the main causes which lead to the defects appearance, deformities and injuries in it, there is abuse of process parameters and modify its physic mechanical soil properties of natural and technology-related factors. As it is established, the use of ground penetrating radar of series “Losa” on the railways of Ukraine allows searching ballast tank in the body of road bed, defining damp places in soil road bed and foundations, to find arrangement of foreign matter in the soil road bed and work search heterogeneity and places weakening soil. In addition, the use of ground penetrating radar provides rapid detection of defects, deformation and damage of railway track, especially in areas the most dangerous for rolling stock that creates the high level security at the main and auxiliary lines of Ukrzaliznytsia. In conducting the research was justified the high level of reliability and performance with autonomous use of ground penetrating radar. Originality. In modern conditions of defects determination, deformations and damages by traditional methods with application of engineering-geological investigations, it is impossible in connection with their insufficient efficiency. Therefore the using of highly effective methodology of expeditious tool identification of defective places allows reducing significantly the periods of repair of a railway track which is very important for introduction of the highspeed movement on the Ukrainian Railways. Practical value. On the basis of the executed investigations the main actions for defects elimination, deformations and damages which consist in the device of counter dams, the draining sections, the augercast and augured piles are offered

101-108

Authors: I. P. Volchok, O. L. Skuibida, O. V. Liutova, N. V. Shyrokobokova

Purpose. As a rule secondary silumins are characterized by lower quality than their primary analogues. During manufacture of alloys a large quantity of intermetallides, first of all on the basis of iron, in their structure is ignored. To achieve the optimum level of properties it is necessary to search for ways to adapt refining-modifying, heat and laser treatments to peculiarities of the structure of secondary Al-Si alloys. Methodology. The research was carried out by using standard methods of metallographic analysis, determination of foundry, mechanical and service properties of alloys according to rotatable plans of multifactor experiments. Findings. It was established, that refining-modifying treatment is a required procedure during manufacture of secondary silumins as it permits to effectively influence the iron-containing phases' segregations by changing their morphology, size and distribution and to increase the effectiveness of further treatment in solid state. It was found that standard modes of heat treatment are not optimal for secondary silumins. Laser treatment has shown high effectiveness in increasing of strength, wear resistance, corrosion and cavitation resistance of secondary Al-Si alloys, and the increased iron content contributed to additional solid solution hardening. Originality. It was established, that after refining-modifying treatment the phase Al5SiFe, which crystallizes in the shape of long stretched plates transformed into phase Al15(FeMn)3Si2 in skeletal or polyhedral shape. The relationship between iron content in secondary silumins and holding time during heat treatment that ensures optimum of mechanical properties was obtained. It was proved that the presence of iron-containing intermetallides Al5SiFe results in the decrease of hardened layer's depth during laser treatment. It was established, that with increasing of iron concentration the corrosion rate of secondary silumins in 3 % NaCl + 0.1 % H2O2 and 10 % HCl environments increases. Practical value. The offered technical solutions are instrumental in upgrading second silumins to the level which allows to utilize them as raw material for making of alloys on the basis of aluminium.

119-125

Authors: S. R. Kolesnykov, M. R. Rомаniukha, I. Yu. Kebal

Purpose. Due to operation in complex loading conditions, the rolling stock wheelsets should provide high reliability, since the train traffic safety largely depends on them. Design and technical condition of wheelsets affect the smoothness, intensity of forces generated by the interaction between the car and track, and the motion resistance. Specificity of the axle operation consists in the fact that it undergoes the bending stresses under loading. These stresses are unevenly distributed along the cross-sectional area, reaching the highest values in the outer fibers and the minimal values in the internal ones. This aspect sets the problem of replacement of the uniform cross section with the hollow cross section. The disadvantages of hollow axle design, which are used at the present time, should include a significant manufacturing complexity of the variable section cavity. The purpose is to develop a modernized design of the wheelset axle. Methodology. A construction of the hollow axle having an inner longitudinal cylindrical through hole of the constant diameter throughout its length was proposed. The item is made of steel seamless tube. The inner surface of the tube is treated by mechanical means to remove the voltage concentrations in the internal longitudinal cylindrical through hole, which has a constant diameter along the entire length of the axle. Findings. Application of this design will facilitate manufacturing of the hollow axle and the machining of the inner longitudinal through hole, while retaining all the use advantages of the hollow axle in the rolling stock wheel pairs. Another use advantage of the hollow axle of this design is the absence of partial heterogeneity of the metal, which is inevitably, occurs during the solid axles blanking. Originality. A new design of the wheelset hollow axle of railway rolling stock was proposed. Practical value. Introduction of the new design simplifying the manufacture and mechanical treatment of the inner cavity of the wheel pair axle will bring significant economic benefits. According to preliminary calculations, the use of the axle with the uniform cross section cavity will reduce the metal consumption by 100-110 kg.

138-149

Authors: V. I. Bolshakov, М. O. Yelisieieva, S. А. Shcherbak

Purpose. Strengthening of fine concrete contact zone by mechanical processing of all components of the concrete mix in a mixer-activator and aggregate application with rough surface. Methodology. Rotary activator PC-06, developed by Scientific and Research Institute of Construction Technology, was used as a mixer-activator to achieve this purpose. Granulated blast furnace slag, having a more developed rough surface than sand, was used as fine aggregate. This apparatus provides intensive homogeneous mixing of concrete mix components, processing of raw materials (purification of their particles from contaminants), and mechanical destruction of granulated blast furnace slag surface layers and other components of the mix. Findings. During the preparation work, experimental research of new formations composition of fine concretes, using differential thermal and x-ray phase analysis methods, and physical-mechanical properties of fine concretes in accordance with the applicable standards of Ukraine, were carried out. It is established that the phase composition of new formations of fine concretes made from activated and non-activated mixes, is not changed. Their main difference is the size of generated effects and temperature intervals of occurrence of these peaks. Thus, in fine concretes made on the basis of the activated mixes, magnitude of effects is less, indicating a higher hydration degree of its components. Besides, TG curves of concrete specimens show that weight loss of gel calcium hydrosilicate of concrete from a mechanically activated mix is 0.5...0.7 % more than of concrete from a non-activated mix, which indicates a larger number of these formations in concrete from activated mixes. In general, concretes of different composition, made from a mix, processed in the mixer-activator, have higher mechanical strength. Originality. Ideas about the influence of mechanical activation of components of fine concrete mixes with forming humidity in a rotary mixer-activator on the value of the contact strength of cement and aggregates got further development. Practical value. Strengthening of contact area of fine concrete in the exercise of the combined machining of all concrete mix components in the mixer-activator is achieved owing to increment of hydration degree of raw concrete components; creation of conditions for solid-phase chemical reactions between its components; structure improvement of the received material. It promotes significant increase of mechanical strength of mechanoactivated fine concretes (around 5 times) in comparison with concretes, made from a non-activated mix, which makes it possible to decrease the cement consumption when manufacturing 1 m3 of concrete up to 59 %.

157-165

Authors: S. P. Panchenko

Purpose. The main goal of this paper is to develop the numerical model of viscoelastic material using finite element method (FEM). The model was applied to asphalt-aggregate mixtures. Additionally the obtained numerical results with use of different FEM software were compared with experimental data. Methodology. In order to perform the investigation, the numerical specimen was built within FEM software. Material of the specimen was assumed to be viscoelastic. Viscoelastic materials are characterized by a combination of elastic behavior, which stores energy during deformation, and viscous behavior, which dissipates energy during deformation. It was assumed that the behavior of the material corresponds to generalized Maxwell model. The model consists of a spring element in parallel with a number of spring and dashpot Maxwell elements. Generalized Maxwell model consisting of 5 elements was offered at . Mechanical properties of the material correspond to the properties of real asphaltic material. Findings. As the result of calculations the stress and strain state of the asphalt specimen were obtained. To compare mechanical characteristics of the model with experimental data the dynamic elastic modulus and phase angle values were calculated. Originality. Viscoelastic material model based on generalized Maxwell scheme was developed using ANSYS software. In order to compare the numerical model of the material with real asphalt-aggregate mix data, the values of dynamic modulus and phase angle were selected. Analyzing the results of calculations one can see good correspondence of numerical material model to experimental data. Moreover, the numerical data obtained with ANSYS and LS-DYNA software were compared. Practical value. It should be emphasized that FEM gives the possibility of determining stresses and strains for asphalt pavement non-elastic models what is of great importance using mechanistic design procedures.