bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the reliability of the plates of complex shapes for the cams of automatic half-hose machines by the criterion of fatigue strength
Authors: Berezin L , Rubanka M , Savchenko K , Polishchuk O 
Published: July 2021

Abstract
The purpose of the work is to develop the algorithm for calculation of the probability of failure-free operation of flexible plates of complex shapes for the cams, using the criterion of fatigue strength, to make decisions on minimization of their sizes with the subsequent evaluation of the implemented measures. The studies are performed on the example of a plate for the cam, the configuration of which provides both beam and double console deformations at the same time. The comprehensive approach is presented, which includes dynamic analysis of the needle impact on the cam surface, computer simulation of geometric parameters of the plate by the finite element method (FEM) according to the condition of strength, and classical principles of mathematical statistics and Theory of Probability. The finite-element model with a volumetric 8-node element is used, which allows, with ease of calculations, to obtain the results with a high accuracy when determining the stress-deformed state of the study object. The computer simulation is performed using Code_Aster software with free access. Also, in the calculation of reliability, the random nature of the multifactorial influence on the value of the plate fatigue limit and the loading variations of the cam are considered. When determining the equivalent forces, taking into account the cyclical operation of the machine, the forces that affect the cams during the production of one product are taken as a loading. The numbers of cycles corresponding to these loadings are calculated by the formulas, which are made as a result of the analysis of trajectories of needles motion concerning the cams when knitting different sections of the product. When calculating equivalent stresses, only stresses that influence the accumulation of fatigue failures are used, that is, the values greater than the half of the detail fatigue limit.
The proposed computational approach can be used to generate the cams with flexible work plates of different configurations, including under the equal stress condition.
The influence of time on the bearing capacity of piles in water-saturated clay soils
Authors: Novskiy A , Bichev I , Novskiy V , Yeresko E 
Published: July 2021

Abstract
The change in the bearing capacity of piles over time is an established fact that is carefully studied by many researchers. Depending on the type of soils and their condition, there is both a decrease (in sandy) and an increase (in clay) in the bearing capacity of piles over time. The most effective increase in bearing capacity occurs in water-saturated, clayey soils with the property of thixotropy. The results of experimental studies of soils with piles in natural conditions, carried out with different periods of their rest, are of considerable value in the study of this phenomenon. During the construction of a multi-storey residential complex in Odessa, which began in 2019, it became necessary to increase the load on the pile foundation made of prismatic piles with a length of 16 m and a cross-section of 350×350 mm. According to research in 2019, the bearing capacity of the piles was 1500 kN. In February 2021, static soil tests were carried out with the existing piles from under the grillage of the building, which was installed by 90%, while the bearing capacity of the piles was 1800 kN. Thus, for the period from July 2019 to February 2021, the bearing capacity of C160.35-11 piles at the construction site in water-saturated soils in Odessa increased from 1500 kN to 1800 kN, which is 20%.
Reliability assessment of cylindrical joints with tensioned roll band of the rolling mill
Authors: Checheneva O N , Pashkov A N , Balakhnina E E , Sizova E I , Devyatiarova V V 
Published: July 2021

Abstract
The work addresses to the problem of ensuring the operability of a composite roll made in the form of a cylindrical joint with the tension of a carbide band and a steel axis. When considering the wear processes, all the characteristics related to the surface microgeometry are combined by a dimensionless complex roughness parameter, which, along with the roughness class, includes the features of the surface treatment technology. To determine the contact pressure associated with the tension, the Lame formula for calculating thick-walled cylinders is used. When a hard-alloy bandage is placed on a steel roll with the tension between the contacting surfaces, a plastic unsaturated or saturated contact is performed, for which a method for calculating the tension values shall be proposed. Formulas are given for determining the maximum permissible torque that does not cause a change in the strength of the joint with tension under conditions of plastic saturated and unsaturated contact. In order to test the strength of the connection elements with tension, the theory of the greatest tangential stresses is applied for two dangerous points located on the inner surfaces of the covered and the covering parts: a formula is obtained for determining the maximum permissible calculated value of tension from the strength condition of the covered part. An example of fitting with the tension of a band made of hard alloy VK8 on a working roll made of improved steel 45 with a diameter of d = 100 mm is considered. The band is installed using a press with an H7/p6 fit to transmit a torque of M = 5 kNm. The minimum tension value is obtained from the condition of fixing the contact surfaces without their relative slippage, and the maximum tension value is obtained from the condition of the strength of the steel axis. As a result of the calculations, it was found that the minimum tolerance for this attachment does not provide the transmission of the specified torque since its value is less than the minimum allowable tension. Therefore, to ensure reliable operation of the connection with tension, it is recommended to use the H7/s6 fit, which provides the transmission of the specified torque without the strength of the connection elements.
Study of metal changes in form during forging of on-off valves
Authors: Chukhlib V , Duvanskii O , Biba N , Ashkelianets A , Gubskii S , Okun A 
Published: July 2021

Abstract
An overview of the existing technological scheme for the production of on-off valves is given. The analysis of the existing shape of the on-off valves was carried out with its classification by the output hole. Depending on the shape of the on-off valve output hole, a new technological process is proposed for obtaining on-off valve with a tapered part of the output hole using free forging. To develop the main forging technological scheme, an analysis of the part of the workpiece that is directly exposed to the technological tool was performed by determining the displaced bulks. For this, the entire bulk of the metal under the influence of the deforming tool was divided into characteristic zones, both before deformation and after its implementation. The analysis of the shape change showed the dependence of the metal flow parameters relates to the main geometric and technological parameters, and for this, the main graphic changes were built. On the basis of these studies, a new technological forging process of on-off valve forged pieces with the maximum approximate shape to the finished product can be developed.
Investigation of the surface properties of quartz-based dispersed materials
Authors: Danchenko Yu , Andronov V , Vazhynskyi S , Khmyrov I , Khmyrova A 
Published: July 2021

Abstract
Researched quartz disperses materials (Ukraine): mineral - quartzite of the Ovruch deposit and quartz sand of the Novovodolazsky deposit and products of processing of quartz minerals - dinas and marshalite. The mineral composition, surface morphology, dispersion and specific surface area were experimentally studied. The structure of the hydroxyl-hydrate surface layer was studied by thermogravimetric (TG) analysis and differential thermal analysis (DTA). The number and acid-base characteristics of surfaces active centers were investigated by the methods of pK-metric and pH-metric. It is established that the mechanisms of physical and chemical adsorption of water molecules on the surface of all quartz dispersed materials are identical and do not depend on the mineral nature of impurities. It is shown that the thickness of the surface hydroxyl-hydrate layer of quartz dispersed materials is determined by the amount of chemically adsorbed water, i.e. the thickness of the hydroxyl layer and depends on the nature of the associated minerals. It is established that the acid-base surface characteristic of quartz materials significantly depends on the chemical nature of the accompanying minerals and does not depend on the thickness of the surface hydroxyl-hydrate layer.
Efficient technologies for making gypsum binders
Authors: Gabitov A I , Salov A S , Ryazanova V A , Timofeev A A , Timofeev V A 
Published: July 2021

Abstract
A number of various proposed options and flow charts applied for the production of gypsum binders are considered herein. Large volumes of inorganic waste amount to millions of tons therefore the phosphogypsum utilization to get effective gypsum binders is an urgent issue. The production of phosphogypsum binders both in our country and abroad is indicated to go in three main directions - burnt, autoclaved and anhydrite (hard-burnt) binders.
Influence of technological factors on the properties of building materials on the basis of expanded alunitized high-silica mountain rocks
Authors: Gots V I , Palchik P P , Palchik S P , Berdnik O Y 
Published: July 2021

Abstract
The influence of technological factors in the production of building materials on the basis of expanded alunitized high-silica rocks on their physical-mechanical and thermal-technical characteristics is determined. It is determined that the production of wall materials with high physical and mechanical and thermophysical characteristics, as well as the ability to obtain products with certain predetermined geometric dimensions, are determined by a set of initial indicators, both properties of raw materials and processes, as well as a certain sequence of individual elemental operations. It is shown that the production of wall materials with high physical and mechanical and thermal characteristics can be achieved by reproducing in the volume of the material of a porous system of closed type with homogeneous, evenly distributed throughout the material pores. The influence of the nature of pores and their textural characteristics of alunitized highly siliceous rocks on the performance properties of building materials has been studied. It is shown that the extension of the service life of these materials without reducing their basic physical and mechanical, thermal and thermal-technical indicators directly depends on the porosity coefficient, the values of their textural values and the nature of the pores. The influence of technological factors on the process of pore formation of alunitized highly siliceous rocks, their textural characteristics and stability of parameters during operation under the influence of aggressive environmental factors are considered. It is determined that the increase in the operating temperature of materials created in compliance with these principles is determined by the morphology and structural characteristics of the source materials by their chemical and mineralogical composition, as well as the influence of process parameters.
Calculation of coast-protecting structure from wave influence
Authors: Grishin A 
Published: July 2021

Abstract
A coupled system consisting of a shore protection structure, a soil base and an aquatic environment is considered. The influence of the aquatic environment on the oscillations of the structure was taken into account. The wave processes arising in the system from the action of surfing and breaking waves were investigated. The developed methodology and software package allow the calculation of various structures interacting with a deformable soil environment from the action of static and dynamic loads, taking into account the real properties of their materials, such as elasticity, viscosity and plasticity. The theory of plastic flow was used. Discretization of the computational area was performed by the finite element method. Studies were carried out on the basis of the obtained schemes of plastic zones, diagrams of stresses and oscillations at various points of the structure.
Research of the process of water absorption by thermally modified wood
Authors: Tsapko Y , Bondarenko O , Horbachova O , Mazurchuk S 
Published: July 2021

AbstractThe analysis of the process of thermal modification of wood, which was obtained by a controlled process of pyrolysis of wood heating (> 180 °C), which causes some chemical changes in the structures of cell wall components (lignin, cellulose and hemicellulose), to increase its durability. It is proved that in the process of thermal modification there is a decomposition of hemicelluloses and amorphous part of cellulose, reduction of water absorption, and also the quantity of substances which are the environment for development of fungi decreases. In addition lignin and psevdolihnin formed by the process of polymerization and redistribution in cell volume and cell walls provide higher density, hardness, increase the hydrophobicity (water repelling), thereby reducing their ability to absorb moisture and swell. Polymerised lignin fills the inside of the cell – formed closed porous structure with low ability to bind water. It was established that the most effective option to reduce such substances are temperature and exposure time. The results of water absorption, dependence on which the calculated diffusion coefficient in the water absorption. Thermal modification of wood reduces water absorption by more than 10 times within 6 hours, which allows it to be used on objects with high humidity.
Some features of oscillations and stability of reinforced cylindrical shells under action of movable inertial loading
Authors: Klyushnyk D , Demianenko A , Zelensky A 
Published: July 2021

Abstract
This paper describes some features of the mathematical models for the elastic shell with movable load and for the elastic elements of changeable length. In these systems two forms of eigenoscillations - the eigen component and the accompanying one, displaced in phase to the right angle correspond to every frequency of the system. The accompanying component is caused by the mobile inertia load or by the changeable length and they are non-trivial when those factors are present. As well as for objects with time-varying length, these problems lie in outside of the scope of the classical problems of mathematical physics due to that the eigenfrequencies and eigenforms will be presented as time-nondependent functions. This non-classical section of the mathematical physics is waiting for its development, new researches and generalizations. The main attention of this work is paid to the elastic systems with the mobile inertia load. The problem of oscillations and stability of thin cylindrical envelope with regular stringer set is being considered under assumption that they are regularly placed with a small step from one to another. Also, we assume that there is unsymmetrical stream of mobile inertia load. There is a wide variety of problems in area of jet engine, cooling systems, flying, and floating vehicle framework’s design, which boil down to such computational schemes. The linear theory of structural-orthotropical envelopes with equilibrium equations and geometrical Donnel-Mushtary relations are being used to obtain of the discussed problem formulation. We assume that ribs of the shell are considered as Kirchhoff-Klebsh bars. The accurate solution of the problem is obtained by using of two-waves representation for motion and it has been applied for research on influence of geometry, elastic and structural parameters on the oscillation and stability properties of the shell.
Laboratory tests of the steel fiber concrete road slab model
Authors: Surianinov M , Neutov S , Korneieva I , Kirichenko D 
Published: July 2021

Abstract
The results of experimental studies of bearing capacity and cracking resistance of road slab models made of steel-fiber concrete according to the span loading scheme are presented. The bearing capacity of the models has been fixed at 27.96 kN, which is 2 times higher than the load corresponding to the beginning of cracking (14.8 kN). At the moment of bearing capacity loss, the height of compressed zone was 1 cm, which is one third of its original size. The relative strains before the first crack appeared were 0.1175×10-4 and 0.235×10-4 in the compressed and stretched zones, respectively, and similar limiting relative strains reached values of 3.715×10-4 and 9.235×10-4. The maximum crack opening width was substantially less than in the same tests of the slabs without dispersion reinforcement and was 0.3 mm, which is explained by the more ductile properties of steel fiber concrete, which prevent crack opening. The final deflection in the middle of the plate model span was 10.4 mm, which is 5.5 times greater than the deflection before cracking began (1.9 mm).
Study of deformation properties of alkali activated concretes using active aggregates
Authors: Kovalchuk O , Zozulynets V 
Published: July 2021

Abstract
Results of study of deformation properties of fine-grain concrete are shown using slag alkali activated cement and active aggregate. It had been shown that expansion deformations of specimens, supplying process of alkaline corrosion of aggregate in concrete, directly combined with component composition and conditions of hardening of material. It was shown that using alkaline component in the state of dry salt shrinkage deformations are varying in the shorter ranges comparing to concrete with the soluble glass. Introduction of active mineral admixture leads to the decreasing of deformations comparing to the compositions without admixture. Different conditions of hardening of the specimens are also influence well on the development of shrinkage deformations. It is shown that drying of specimens with active process of alkaline corrosion of concrete makes it possible to stop development of expansion deformations in concrete. Hydrophobization of the dried specimens make it possible to store linear characteristics of specimens. Hydrophobization of without drying leads to the intensification of structure formation processes and higher rates of development of deformations. Traditional method of protection of concrete constructions (covering by painting materials) is not able to prevent, but also possible to activate development of destructive processes of alkaline corrosion of concrete.
Influence of boundary forces on the strength of a thin-walled cylindrical tank
Authors: Dziuba L , Lishchynska K , Chmyr O , Tomenko V 
Published: July 2021

Abstract
The strength of a thin-walled cylindrical large-capacity tank was evaluated. The walls of the tank and the bottom are simultaneously exposed to hydrostatic pressure of the liquid and additionally gas pressure-loaded. The stress at the bottom of the tank was determined taking into account the boundary forces under the combined action of hydraulic and gas pressures. The dependences for determining the boundary forces were obtained by solving the equation of deformations compatibility of a thin-walled cylindrical shell and a round plate resting on a solid surface. The influence of gas pressure increase on the magnitude of stresses was investigated.
Investigation of the Stability Conditions of an Automated Control System for a Centrifugal CVT of Automotive Special Equipment
Authors: Lytovchenko V. , Pidhornyy M. , Bondarenko M. , Fedyuk I. , Shapovalov O. 
Published: July 2021

Abstract
Modern continuously variable mechanical transmissions (CVT) with V-belt variators change the gear ratio due to tangential forces. In most cases, both the input and the initial links are geometrically similar wedge disks that move in a linear mode along their axis of rotation, while the process of controlling the transformation of the gear ratio is realized individually for each of the proposed solutions. The authors suggest employing direct action forces, the centrifugal force of the CVT working elements and the variator for transformation, instead of the traditionally used tangential forces. The use of the methods specified above allows reducing power loss by means of mechanical self-regulation of the continuously variable transmission.
Scientifically grounded approach to the prescription of additives for obtaining complex-modified concretes
Authors: Adylkhodzhaev A I , Makhamataliev I M , Tsoy V M , Kondrashchenko V I 
Published: July 2021

Annotation
The results of theoretical and experimental studies on the development of a scientifically grounded method of prescribing plasticizing chemical additives and mineral fillers in the selection of the compositions of complex-modified concretes (CMB) at the design stage are presented. The classification of plasticizing additives according to the degree of decrease in the surface tension of water upon their introduction and the activity of mineral additives according to the indicator of the reduced hydration activity, allowing to obtain highly economical MPC with the required properties.
Modelling of wind impacts on silos and silo parks
Authors: Makhinko A , Makhinko N 
Published: July 2021

Abstract
This paper devoted computer modelling of wind impacts on the silos for grain storage in order to obtain their aerodynamic characteristics. This modelling was made in the system of computer analysis Ansys Workbench for various wind conditions and different layouts of silos: separately located silo and silo parks by varying their sizes and mutual arrangement at various angles of the wind pressure. Within the numerical experiment it was obtained not only a huge array of data about the aerodynamic resistance of the silos, but also developed a special technique of the mathematical modelling of the wind effects on the selected class of constructions. This technique is a single software module for the platform Ansys Workbench, which automatically forms an optimal calculation area, makes an estimation of the wind loads on the silo and exports obtained loads in the software package SCAD for calculating the strength and deformability. To achieve this goal it was made the calculation of the same tasks on meshes of different dimensions, set the dimensions of the mesh in different places of the calculation area and installed the minimum required time of computer simulations.