Stress-deformed State Research Articles

STRENGHENING OF RC BEAMS BY FRC AND FRP SYSTEMS – A REVIEW

The article examines studies on the reinforcement of reinforced concrete elements of cement -based fibro -based fibro systems (FRC) and polymers reinforcement fibro (FRP). Nowadays, the world economy, and with it, the construction industry is developing at a rapid pace. New materials, mechanization, construction equipment are emerging on the market. Due to this, modern structures impress with their shapes, scale and complexity of structures. The state of construction production in the country can be judged on the state of the economy of this country as a whole. Now the urgent issue in the world is the use of new composite materials in the strengthening of building structures. Such materials include non -metallic fittings, laminates, nets and canvases based on high -strength fibers. In this case, the own weight of fiber materials is slightly small. Only units of the above researchers performed enhancement of experimental samples under load, so the influence of the initial stress-deformed state on the work of the structure after amplification was practically not studied.

INFORMATION MODEL FOR SELECTING THE OPTIMAL SPATIAL FORM OF PARTS

A complex of interrelated methods and means of analysis, clustering, segmentation and classification of objects on images obtained by sensors of different physical nature (with the help of modern methods of radiography, computer and magnetic resonance imaging) is proposed, which will allow modeling the optimal form of a bone substitute with functional properties by CAD/CAM/CAE design methods, depending on the anatomical data, the nature and localization of the cavity bone defect, its size, load conditions and patterns of bone tissue neoplasm. Methods for making multi-criteria decisions have been developed, which will allow for their implementation for a wide range of optimization tasks of researching the correlation of the shape and size of porosity with indicators of the stress-deformed state of bone substitutes in order to maintain the structural integrity of the biomaterial in the process of regeneration of hard tissue.

Оценка рисков реактивации разломов при бурении горизонтальной скважины по результатам одномерного геомеханического моделирования

The article presents main factors affecting the fault stability. Concepts of critically stressed faults and critical pore pressure are discussed. The methodologies for evaluation of stressed-deformed state of rocks in the vicinity of fault zones during reservoir depletion and injection, well drilling are analyzed. 1D geomechanical models of fishbone sidetracks and main borehole of the well N are constructed. The fault stability evaluation is made using Mohr – Coulomb failurecriterion from data of insitustresses and near-wellborestressescalculated from Kirsch wellbore solution. Optimal mud weight ranges are determined for safe drilling of fishbone boreholes accounting fault reactivation risks. Basic recommendations for optimal drilling through the interval of unstable shales are made.

Analysis of the stress-deformed state of the structure of road clothing depending on the location of the load relative to the edges of the combined slab

Abstract. Problem. Cement-concrete coatings are characterized by the complexity of repair work, therefore, for their repair or new construction, it is advisable to use asphalt-concrete coating. This constructive solution during the repair of cement concrete slabs helps to improve their technical and operational condition since the asphalt concrete layer performs the function of a protective or wearresistant layer on cement concrete slabs. The operating conditions of asphalt concrete layers on cement concrete slabs are significantly different from those typical for other structural solutions. The existing methods of calculating the strength of asphalt concrete coatings for hard road wear are not accurate enough, because they take into account only certain criteria of the strength of the asphalt concrete layer. The specifics of the stress-strain state of the asphalt concrete layer on cement concrete slabs under different load conditions, such as the middle of the slab, the edge of the slab, and the corner of the slab, are not taken into account. Given the complex stressstrain state of the asphalt concrete layer on a rigid base, the analysis of the stress-strain state is particularly relevant, aimed at determining the most dangerous variant of the location of the transport load to ensure the strength of the asphalt concrete layer. Goal. The purpose of this article is to determine the stress-deformed state of an asphalt concrete layer on a rigid base with various options for applying a transport load, which will allow the establishment of the most dangerous option for the location of the load. Methodology. General methods of solving problems of the mechanics of a deformed solid body were used to develop a calculation scheme and select a material model. Simulation of the stress-strain state of the road surface was carried out using the finite element method using the ANSYS software complex, investigating three options for placing the transport load: in the center of the slab, on its edge, and in the corner. Results. According to the results of the simulation of the stress-strain state of a combined slab made of an asphalt concrete layer on a rigid base, it was established that the edge of the slab is the most unsafe both in terms of tensile and shear stresses for a cement concrete slab. For the asphalt concrete layer, placing the load in the corner of the slab is the most dangerous both in terms of tangential shear stresses and Mises stresses. Originality. According to the results of the simulation of the stress-strain state of a combined slab made of an asphalt concrete layer on a rigid base, it was established that the edge of the slab is the most unsafe both in terms of tensile and shear stresses for a cement concrete slab. Practical value. Based on the results of modeling the stress-strain state of a combined slab made of an asphalt concrete layer on a rigid base, it was established that the edge of the slab is the most dangerous both in terms of tensile and shear stresses for a cement concrete slab. For the asphalt concrete layer, placing the load in the corner of the slab is the most dangerous both in terms of tangential shear stresses and Mises stresses

Simulation of the stress-deformed state of the structure of road clothing taking into account the combined action of vertical pressure and horizontal force from vehicles

Abstract. Problem. This study was carried out with the aim of determining the stress-strain state of various structures of pavement consisting of asphalt concrete pavement on a cement concrete slab from the action of the transport load and analysis of the results. The article analyzes the literature data regarding the advantages of using hard pavement compared to non-rigid, in the conditions of a constant increase in traffic intensity and load from vehicles.Determination of the stress-strain state of asphalt concrete layers on cement concrete slabs under the influence of vertical pressure from vehicles and horizontal force from traction or braking of vehicles is carried out using the finite element method. In the simulation, three-layer models were used, consisting of an asphalt concrete layer, a cement concrete slab, and an elastic foundation. On the surface of the model, a vertical load (0,8 MPa) and a horizontal force (from 5 kN to 40 kN) are applied, which simulates the pulling force or the braking forces of vehicles. The diameter of the stamp print is 34,5 cm. The location of the load, relative to the edges of the cement concrete slab limited by temperature seams, is taken in the middle of the cement concrete plate. To confirm the correctness of the simulation results, we compared the stress values obtained by the finite element method and the stresses obtained by strict analytical solutions V. P. Plevako, which are recognized as correct, tested and reliable. Relative error in the voltage values determined by analytical solutions prof. V. P. Plevako and determined as a result of numerical simulation using the finite element method does not exceed 6 %. Analysis of the simulation results made it possible to establish the influence of the elastic modulus of structural layers, layer thicknesses and vehicle motion conditions (horizontal forces) on the patterns of change in the stress-strain state of an asphalt concrete layer on a cement concrete slab. Main goal. The purpose of the research is to determine and analyze the stress-strain state of the asphalt concrete layer on the cement-concrete slab due to the action of transport loading. Methodology. General methods of solving problems of the mechanics of a deformed solid body were used to develop a calculation scheme and select a material model. Simulation of the stress-strain state of the road surface was carried out using the finite element method using the ANSYS software complex. Results. The analysis of the simulation results made it possible to establish that with changes in the modulus of elasticity of the asphalt concrete layer, the stresses change linearly. The verification of the given dependence was performed for the range of modulus of elasticity of asphalt concrete from 400 MPa to 5000 MPa at horizontal force values from 5 kN to 40 kN. Therefore, in the future, it is possible to carry out linear interpolation of stress values according to the elastic moduli of neighboring values. Practical value. According to the results of simulation of the stressstrain state of a combined slab made of an asphalt concrete layer on a rigid base, it was established that the edge of the slab is the most unsafe both in terms of tensile and shear stresses for a cement concrete slab.

STRESS-DEFORMED STATE OF THE ACROMIOCLAVICULAR JOINT IN CASE OF DAMAGE TO THE UPPER ACROMIOCLAVICULAR LIGAMENT SUPERIOR AND VARIOUS METHODS OF FIXATION

During the operative stabilization of the acromial end of the clavicle (AEC) for its dislocation, there are two ways: clavicle – beaklike process, clavicle – acromial process. Fixation of the AEC to the acromial process of the scapula is a priority. Competing metal structures are the hook plate and the Weber method. The significant disadvantages of using the Weber method of fixation are the migration of the tips and the violation of their integrity andthe wire. Objective. To conduct a comparative analysis of the fixation of the acromial end of the clavicle according to Weber, hook plate and the proposed construction, by studying the stressed-deformed state of the clavicular-acromial joint in case of damage to the lig. acromioclavicular superior and various methods of fixation. Methods. A finite-element model of the clavicular-acromial joint was constructed. Damage to the ligaments was modeled. claviculo-acoacromiale superior, as well as fixation of AEC in three ways: according to Weber, hook plate and the proposed construction. Results. The best results, from the point of view of reducing the level of stresses in intact ligaments, are provided by fixation of the AEC according to Weber, but its use leadsto an increase in the level of stresses on the AEC and the acromial process of the scapula, which can cause destruction of the latter. The hinge-type fixator provides the best stress distribution, both in the bony elements of the model and in intact ligaments. The hook plate holder occupies an average position,both in terms of the level of stress and the magnitude of the relative deformations in the ligaments. Conclusions. Weber fixation provides the best results for reducing the level of stresses and relative strains in the intact ligaments, but leads to a several-fold increase in the level of stresses on the AEC and acromial process of the scapula. The hook plate holder occupies an average position, both in terms of the stress level and the magnitude of the relativedeformations in the ligaments. The proposed design provides the best stress distribution, both in the bony elements of the model and in the intact ligaments.

The use of planar and three-dimensional calculation models for the numerical modeling of retaining walls in conditions of dense urban construction

In modern realities, the construction of multi-story buildings increasingly has to be carried out in the conditions of dense urban development. Since high-rise buildings are characterized by the presence of deep pits, there is a need to select the parameters of the enclosing structures (retaining walls) and take into account the influence of the pit arrangement and enclosing structures on the existing building. Numerical simulation of the stress-strain state (SSS) of the elements "soil base - existing structures - pit enclosure" was performed to assess the impact of choosing the dimensions of the calculation scheme when designing a deep pit and assessing its impact on existing buildings and selecting effective parameters of enclosing structures. with different dimension options (flat two-dimensional and spatial three-dimensional) calculation scheme. Modeling was performed using the finite element method using a nonlinear model of soil deformation in the Plaxis software package. Since the soil conditions within the construction site are complex (the presence of a significant layer of plastic and flowing clay soils and powerful aquifers), the level of groundwater within the construction site was taken into account in the modeling and the effect of water lowering during the development of the pit was modeled accordingly for a more correct assessment of the stress-strained state of pit enclosure elements and the impact on existing structures. Numerical calculations of retaining walls provide for taking into account the technological sequence of the construction of retaining walls and modeling of the step-by-step development of the pit. Studies have shown that the use of a spatial finite-element model of the system "soil base - existing structures - pit enclosure" provides an opportunity to more correctly and effectively assess the stress-deformed state of system elements due to taking into account the spatial rigidity of the elements of the pit enclosure and the foundations of existing structures. The values of the displacements of the retaining walls obtained by the calculation of the spatial finite element model (FEM) are 20% smaller than the values obtained using the plane FEM. The values of the bending moments obtained by the calculation of the spatial FEM are 10% smaller than the values obtained using the plane FEM.

ПРОГРАМНЕ ЗАБЕЗПЕЧЕННЯ ПРОЄКТУВАННЯ ДЕТАЛЕЙ АВТОМОБІЛІВ

The informative and programmatic providing of processes of проєктування details of cars is the application of computer-aided design considered on an example for automation of works of industrial enterprise on the stages of designer and technological preproduction of SolidWorks and her addition of SolidWorks Simulation for possibility of replacement of expensive and scarce steel of 18HGT for making of cog-wheel of billow of back bridge of car UAZ-31512 on more cheap and more accessible in repair shops steel 45. After reassignmentof material to the cog-wheel of billow conducted her fixing and appendix of loading. Conducted dividing of model of cog-wheel of billow the repeated calculations into eventual elements; resulting forces and moments defined; built the matrix of inflexibility, carried out the synthesis of certainly-element model taking into account the terms of her fixing in key points and untied the got system of equalizations of algebra; components of the stress-deformation state of model defined.

Визначення власних частот та форм коливань лопатки турбіни, виготовленої зі сплаву на основі алюмініду титану

This paper investigates the possibility of manufacturing the working blade of the 2nd stage of the free turbine from an experimental alloy based on titanium aluminide of the Ti-28Al-7Nb-2Mo-0.3 (Y, Re, B) system. Alloys of this class are important structural materials with a unique set of physical and mechanical characteristics. Alloys based on aluminide are characterized by low density, high heat strength, and heat resistance and have a high potential to replace nickel-based alloys designed for operation at temperatures no higher than 850°C. However, the use of a new alloy for the manufacture of a turbine blade involves calculations of the strength and oscillations of the blades. The purpose of the calculations is to determine the possibility of using an aluminide-based alloy of the Ti-28Al-7Nb-2Mo-0.3 (Y, Re, B) system instead of the VZHL12E-VI alloy for the selected working blade. The research was carried out by performing a modal analysis, determining the stress-deformed state, and checking the strength and mass characteristics. The physical properties of the materials were used as the initial data for the calculation. The geometry and temperature distribution of the blade and its fixing remained constant for the two options. A three-dimensional model of the experimental vane was built using the Unigraphics NX system, and a finite element model was developed using the Ansys software complex. It was established that when an experimental alloy is used, the mass of one blade is reduced by almost 40%. Using the finite element method, the natural frequencies and forms of blade oscillations were calculated, and Campbell’s diagrams were constructed for the original and experimental blades for the nominal operation of the engine. When using an experimental alloy, the frequencies of the blades’ natural oscillations are further from the resonant frequency. The distribution of equivalent stresses was determined, and it was shown that the maximum stresses act in the root section of the blade feather. When using the experimental alloy based on titanium aluminide, the equivalent stresses are reduced by 35% compared with the initial values. It is shown that the safety margin of the proposed material is not less than that of the VZHL12E-VI alloy.

Stability Analysis of the Exploitation System with Room and Pillar by Analytical Methods

The mining method that is still often used in salt deposits is the room-and-pillar mining method, in which the dimensioning of the most requested element in the system is followed. The pillars are the elements subjected to the greatest loads. Knowing the size and distribution mode of the secondary state of stress—deformation—is a necessity that can lead to the design and realization of stable, reliable underground excavations. This paper proposes an analytical assessment model of the secondary stress state in the pillars between the operating rooms, as well as in the whole system room–pillar–floor, based on the results obtained from laboratory research through modeling and in situ research. For this purpose, the evaluation of the secondary stress state was carried out considering the following methods: (1) the dimensioning method based on the theory of limit equilibrium, taking into account the effective stress in the pillars; and (2) the mechanics of the continuous environment based on the design of some analytical models for evaluating the secondary stress-deformation state in the pillar and floor. The exploitation of one of the largest salt deposits in Romania is used as a case study, and the stability of the exploitation system with rooms and pillars is evaluated by analytical methods. The secondary state of tension was calculated at different points on the height of the pillar. Through the proposed algorithm, the value of the axial component of the secondary stress state at different points along the axis of a pillar located at a depth of 100 m varies between 1.498 and 1.657 MPa, compared to the value obtained by the finite element method and in situ measurements, which was 1.64 MPa. The comparison revealed a high degree of agreement between the results obtained for the depth of 100 m using both the FEM and laboratory and in situ measurements. This suggests that the proposed algorithm is a reliable method for predicting the secondary stress state. The presented algorithm can be extended in the field of mining deposits, where mining methods with rooms and pillars are used.

Horizontal tank strength analysis considering nozzle loads and horizontal deviations

When assessing the reliable and safe operation of technological equipment, and in particular, capacitive-type equipment, a fairly diverse number of methods are used. However, all current procedures do not sufficiently take into account the impact of certain factors on the forming stressed-deformed state of the object. Usually, when assessing the actual technical condition of an object, the level of defect of the object is determined, and appropriate calculations are carried out according to the criterion of the dominant damage mechanism. A significant impact on the stressed-deformed state of the shell structure can be exerted by the level of loads on process nozzles from the connection of process pipelines, as well as possible deviations during installation work. One of these deviations may be a deviation from the horizontal of the housing when installing supports on the foundation. Moreover, the combination of the action of the above factors can have a determining negative effect on the strength, and, accordingly, the operational reliability of the technical device. In the modern world, technological progress does not stand still and the consequence of this is the development of a fairly extensive number of software products that allow you to simulate possible individual scenarios for the development of unfavorable processes and predict the behavior of the object under the conditions under consideration. In this work, studies are carried out on the strength analysis of the horizontal tank, taking into account various values of loads on the nozzle of the body diameter, as well as taking into account the deviation of the tank body from horizontal.

Stress in the tank case at mounting displacements and loads on nozzles

In the practice of operating capacitive equipment, production moments often arise due to technical re-equipment and changes in the operating parameters of tanks to meet specific requirements for equipment design in the technological process. Common reconstruction activities involve modifying process nozzles in technical device housings to align with process piping project specifications. Consequently, the stressed-deformed state in vessel bodies before and after reconstruction can vary significantly. During manufacturing or repair tasks, permissible installation displacements, such as the shifting of edges in joined cylindrical shell housings, may occur within regulatory limits. This study focuses on analyzing stress variations and stress distribution zones, considering the combined effects of these factors.

Zalety materiałów kompozytowych stosowanych w otworowych narzędziach skrawających

One of the important reserves for the growth of oil and gas production is the acceleration of emergency recovery work in production and exploration wells at minimal cost. A significant amount of work in downhole conditions is performed using downhole destructive and cutting tools. Each oil and gas producing country annually uses more than 100 standard sizes, thousands of cutting tool sets: downhole, annular, combined, pilot, internal and external pipe cutters, as well as reamers for cutting side “windows” in production strings. Therefore, the need for them is growing significantly every year. The conducted experiments show that during the operation of cutting tools, the working abrasive-cutting part of the tool wears out and collapses, but the body, other elements and the connecting thread remain suitable for further operation. Therefore, the restoration of working bodies, consisting of crushed particles of used borehole cutting tools, is an urgent scientific and technical task for the oil and gas industry. When repairing oil and gas wells, as well as eliminating the most complex accidents, more than a hundred standard sizes of downhole cutting and destructive tools are used. Currently, an acute shortage of this equipment in oilfield facilities makes it necessary to reconsider the technologies for restoring downhole cutting and destructive tools and introduce them into production. The conducted studies show that there is not enough information about the thickness and height of the layers of the material applied to the damaged area of the cutting and destructive tool, as well as the information necessary for the optimal mode of its operation and its effectiveness after restoration. Composite materials are widely used in the preparation of cutting-chopping and destructive elements of oil-field tools and equipment used in the drilling, operation and repair of wells. In order to increase the cutting capacity of the cutting part of the tool, it is necessary to investigate the advantages of tungsten-carbide (TC) type composite materials compared to other materials and ensure their resistance to high temperatures. As a result of theoretical studies, the stress-deformation state of the contact areas of the composite elements, where the working areas of the cutting and destructive tools are reinforced, and the dependence of the productivity of the composite materials on the speed of transition to metal and the sizes of the composite grains were determined by using the finite element method (two-dimensional simplex elements).

Geoecological and economic consequences of creation, drainage and possible variants of restoration the Kakhovsky reservoir

In the article, in the aspect of engineering and geological safety of structures and communications, the long-term hydrogeological consequences of the support and drainage effects at coastal areas of destroyed Kakhovsky hydro node reservoir as a leading eco-forming component of a giant natural and man-made geosystem are considered. In particular, it included Zaporizhia NPP, the largest in Europe, and the largest irrigation systems in Ukraine. The consequences of the hydrodynamic disaster due to explosion of Kakhovskaya HPP, the dynamics and current state of drainage of the bed of its reservoir are briefly described, according to the data of GIS analysis of space images. And also – the state of hydrogeological and engineering-geological conditions in the reservoir support zone at the time of disaster and in retrospect. A calculated assessment of changes in hydrogeological conditions for the next 10-15 years has been carried out. Long-term natural and man-made threats that arose as a result of such changes in hydrogeological (geofiltration and geodynamic) conditions are named. The set of socio-economic threats that arose due to the negative consequences of Kakhovsky reservoir existence and draining is described. It is emphasized that the restoration of hydrotechnical and water management parameters of the reservoir in the previous values (according to the conservative version) will lead to secondary geospatial water saturation of subsiding loess-loamy silty-clay floatingable rocks that have already undergone deformations due to a decrease in geotechnical stability during the initial flooding and subsequent drainage. This will start a new stage in the formation of dangerous violations of stress-deformed state of coastal slopes, of Zaporizhzhya NPP responsible structures foundation and in nearby cities and towns. A socially and ecologically favorable option for the rehabilitation of affected region is possible only on the modern European ideological and technological basis of taking into account the maximum permissible changes in the hydrological network, i.e. by means of: creating a cascade of low support channel reservoirs with locks and small hydroelectric power stations, reconstruction of riverside ponds and water supply systems, transfer of domestic water supply to underground sources, irrigated lands – for drip irrigation, ecological reclamation and afforestation of drained lands.

Innovative stress analysis and machine learning forecasting for semi-trailer truck body durability

This article presents an in-depth analysis of the stress-deformation state (SDS) in the bottom structure of a semi-trailer truck body. Engineering analysis was conducted utilizing the SolidWorks software, focusing on a comprehensive CAD model of the semi-trailer truck body. The study explored variations in SDS parameters resulting from alterations in the geometric parameters of the body bottom elements. The research investigated alterations in static stress and displacement relative to changes in the proportions of the cross-section of the channel while maintaining fixed geometric dimensions of the workpiece, thickness of the workpiece, and the material of the body bottom. Graphical representations were generated to illustrate the variations in static stress, displacement, and safety margin concerning the thickness of the shelf and channel. Additionally, dependencies were derived that correlate static stresses in the channel with the thickness of the channel wall and the thickness of the body bottom sheet. The study results were compiled and summarized, offering valuable insights into the stress-deformation state of the semi-trailer truck body's bottom. Furthermore, machine learning techniques, specifically the RandomForest algorithm, were implemented in a Python environment to predict changes in static stress based on various factors. The model's predictions were validated by comparing predicted static stress values with actual values on a test sample. These findings facilitate efficient selection of appropriately sized elements by predicting static stress values, employing the RandomForest machine learning algorithm.

INFLUENCE OF ANNUAL GROWTH RING STRUCTURE REGULARITIES AND NATURAL DEFECTS ON PHYSICAL AND MECHANICAL PROPERTIES OF CARPATHIAN SPRUCE

In the process of technical inspection of buildings and structures constructed with the use of both solid logs and Carpathian spruce lumber massively observed processes of deplanation of the wall fence, exit from functional state of constructive elements of inter-storey floors and rafter systems. During inspection calculations of existing construction elements, which are in exploitation for all types of stress-deformed state, there are often questions to the accepted constructive solutions of cross-sections and nodal joints of building structures made of solid wood. This fact can only be due to the discrepancy between the strength and deformation properties of Carpathian spruce and the declared characteristics in normative documents. The presence of natural defects and structural features of the Carpathian spruce structure indicate that the unequal physical and mechanical properties of the two coniferous species that grow in the northern latitudes and the Carpathian region of Ukraine are not entirely true. The distribution of the ratio of latewood to earlywood has a direct influence on the physical and mechanical properties of wood. This fact is caused by rather cellular structure of wood with large annual growth of early and late wood. Such characteristics can have both positive and negative effects on the properties of Carpathian spruce as a building material. This type of wood with a high degree of natural moisture content and cellular structure requires a special pre-drying procedure for the production of building structures. To establish the factual physic-mechanical properties of Carpathian spruce, the current normative documents were analysed and the existing scientific research on this issue was studied. In the process of conducting a comparative analysis of the results of comprehensive studies of standard samples of Carpathian spruce for compression along the fibres and control samples made from the base species - pine, the fact of partial inconsistency of physical and mechanical parameters of the two varieties of conifers was established. In general view, recommendations are made for changes to the current norms for the construction of solid timber structures. Keywords: : physic-mechanical properties, bulk weight, wood defects, temporary resistance.

Numerical Determination of the Life of Steel Exposed To Low Cycle Fatigue

In the paper, based on the results of the experimental research of high-strength low-alloy steel (HSLA), Nionicral 70 (NN-70), under conditions of low-cycle fatigue (LCF), a numerical analysis of stress and determination of the life of steel samples was performed. Experimental testing of the behavior of the samples were performed with controlled and fully reversible strain (/2 = const, R = min/max = -1), according to the standard ISO 12106:2003 (E). For computational analyses, the following were used: the method of least squares and the method of finite elements (FEM). On the basis of the analysis of the results of the stress-deformation state and the determination of the life span through the isolines of the life span and comparison with the results of experimental tests, a graphic representation is given. The analysis justified the effort to numerically solve the estimation of the lifespan of steel under low cycle fatigue (LCF).

Numerical analysis of wood beam bending with verification of breaking force

The work represents the continuation of the research of the maximum bending stress force of a wooden beam up to the moment of failure, which is defined experimentally and with a corresponding mathematical model. The goal was to confirm the accuracy of the mathematical model of the breaking force using numerical simulation and the Solid Works software. Five different types of wood and five different beam thicknesses were used as input parameters whose influence was monitored trough the simulation. The stress deformation state and deflection for the calculated fracture forces were analysed separately for each variant. The breaking force model, which is defined depending on the density of the wood and the thickness of the board, proved to be adequate for defining the maximum stresses and deflections when bending beams.

SUBSTANTIATING THE CONCEPTS OF COMPONENTS COMPOSITION AND METHOD OF OBTAINING SOIL-CEMENT ELEMENT FOR REINFORCEMENT OF EMBANKMENTS

Purpose. Substantiating of the choice of components of materials and methods of obtaining a soil-cement element for strengthening the ground bases in Ukraine, taking into account the European experience. Methodology. The concepts of embankment reinforcement developed and implemented in Ukraine and the European union using horizontal reinforcement (geosynthetic materials), vertical reinforcement (vertical piles or micropiles) and a combination of geosynthetic materials with piles are analyzed. Advantages and disadvantages of physic-chemical and mechanical strengthening methods are considered. Findings. The substantiation of the material and constituent components of soil-cement elements and methods of their creation for strengthening the embankment of railways was carried out. One of the effective directions for obtaining vertical reinforcing elements and reducing the cost of work on strengthening and strengthening the embankment is the use of a mixture of soil with the addition of cement, obtained by drilling mixing technology. To modify the structure of soil cement and minimize cement consumption, it is suggested to use fiber fibers, chemical additives and finely dispersed industrial waste in the form of ash or ground slag as reinforcing components. A study was conducted to establish the basic parameters of the soil-cement composition for further modification of the structure of the element under the specific situational conditions of the embankment. Originality. The originality of the work is that, for the first time, based on the strengthening experience, the justification of the directions of strengthening the ground bases with vertical soil-cement elements at different stress-deformation conditions of the soil foundations and the composition of vertical elements in Ukraine and the European union was performed. Practical value. The practical value of the presented research is that when choosing one or another method of strengthening soil bases, the appropriate composition of the strengthening material is selected, that is, its efficiency and rationality can be determined during implementation in the specific conditions of operation of the railway, the embankment of which needs to be strengthened or rearranged for a combined or European track.

Determination of the stress-deformed state of the grinding circle adjustment pencil

Using the Ery stress function in a linear formulation, using the methods of the classical theory of elasticity, an algorithm for analytically determining the stress-strain state of the working part of the abrasive wheel straightening tool as a two-layer composite material was developed. The algorithm allows considering arbitrarily distributed normal and tangential loads of the working surface of the abrasive grain of the tool. It considers the mandrel's limitation of deformations of the grain and the material that attaches it to it, the compatibility of the deformation of the grain and the material of its attachment to the mandrel, and their mechanical properties.
 Calculations performed according to the obtained algorithm allowed the following to be established. The maximum standard stresses on the working face of the grain exceed the corresponding stresses on the opposite face due to their more uniform distribution. The tangential stresses are almost uniformly distributed along the specified face. The material connecting the grain to the tool mandrel deforms almost uniformly due to its lower modulus of elasticity and smaller thickness than the abrasive grain's modulus of elasticity and thickness. Determining the stress-deformed state of the executive part of the pencil for correcting the working surfaces of grinding wheels for abrasive processing of materials makes it possible to specify the known mechanism of their interaction and increase the efficiency of the technological process of restoring the working surfaces of the tool for abrasive processing of metals.
 Taking into account the simultaneous deformation of the abrasive grain and the material that attaches it to the pencil mandrel, determining their stress-strain states using the methods of the classical theory of elasticity allows us to consider the results obtained by the given algorithm as sufficiently reliable within the limits of linear deformation. It is advisable to direct further research to determine the durability of the "abrasive grain-bond" system under variable cyclic loads.