Purpose of research. At present, it is found that the process of corrosion-mechanical destruction proceeds in several stages. However, as practice and analysis of numerous destructions of structural elements made of high-strength materials in the construction and engineering industries show, very often in real structures there are already technological defects such as cracks. In such cases, the process of corrosion-mechanical destruction begins directly with crack growth, bypassing the preparatory stages – the incubation time and the formation of a stress concentrator. The goal of this paper is to study the influence of scale factor and surface condition on the sensitivity of 20GS2 steel to hydrogen cracking.

Methods. Reinforcing steel of 20GS2 grade (four melts) was chosen to determine the influence of surface condition and scale factor on the long-term corrosion strength in the environment causing hydrogen cracking. Full-scale specimens (l = 300.400 mm) of different diameters (10, 12 and 14 m) with smooth-rolled and die-rolled sections were tested. Also, from 10, 12 and 14 mm diameter full-scale rods (smooth-rolled and with die-rolled sections) there were turned samples with a diameter of the working part from 6 to 10 mm every 1 mm with surface condition of Ra2,5. The long-term corrosion strength was estimated through time preceding failure by testing four samples at each point of the graph. To create the experimental conditions as close as possible to the operational ones, the tests were carried out in an aqueous solution of sulfuric acid with the addition of ammonium rhodanide at room temperature with cathodic polarization and different levels of tensile stresses.

Results. It has been experimentally found that full-scale specimens of 20GS2 reinforcing steel in comparison with turned ones have less sensitivity to hydrogen cracking. This circumstance is due to the fact that after mechanical processing by cutting in turned samples, the value of residual tensile stresses is much higher than in full-scale specimens. It has been shown that full-scale specimens of 20GS2 reinforcing steel  with a die-rolled section have less resistance to hydrogen cracking, as compared with full-scale smooth-rolled samples. The lower resistance to hydrogen cracking of die-rolled section reinforcement is due to the presence of ribs on its surface which play the role of natural stress concentrators.  The experimental results obtained allow us to recommend full-scale specimensto to be tested for corrosion and mechanical destruction in environments that cause hydrogenation of full-scale specimens, since their use makes it possible to approximate the experimental conditions to the actual conditions of operation of products.

Conclusion. The results obtained can be used in the creation of resource-saving processes for processing metal alloys and composite materials.

Purpose of research. The study is aimed at improving the accuracy of shaping the surface layer of mechanical engineering products by additive methods.

Methods. Shaping of parts surfaces by additive methods is characterized by high values of shaping error (approximation.)To reduce this error it is necessary to ensure the orientation of the surface at which the normal at the point of the surface being shaped will coincide with the axis of the final link of the shape-generating system. To ensure the orientation of the surface being shaped, the use of equipment for additive shaping with a hybrid design is proposed.

Results.The model of shape-generating system of the equipment for additive shaping with hybrid design has been developed. The problem of parametric synthesis of hybrid design technological equipment for additive shaping has been solved, as a result of which the necessary shaping capabilities of the equipment have been provided. The calculation method of kinematic error of additive shaping has been developed, which allows you to choose such engine and driver of additive equipment that wiil make it possible to obtain the necessary accuracy of shaping.

Conclusion.The developed technique allows us to solve the problem of parametric synthesis of hybrid design technological equipment based on the condition of providing a given value of the kinematic component of additive shaping error.

Purpose of research. The purpose of this work is to develop a method for calculating parameters of volumetric zones of plasticity in powder and cast steels, occurring in the vicinity of pores under external tensile stress and internal gas pressure.

Methods. The problem was solved on the basis of the analysis of the distribution of stress tensor components in the vicinity of discontinuities (pores) of different shapes. A sample under tensile stresses (σ), containing a single stress raiser - a spherical pore with radius "a", and a pore in the form of a biconvex lens, was studied stepwise. The choice of pores morphology was determined by their experimental observation in the structure of real commercial steels, and the presence of a solution for estimating the stress field near the spherical pore, performed by L. D. Landau and E. M. Lifshitz. In comparison with such stress raisers as a tight crack or a pore in the form of a biconvex lens, the stress concentration near a spherical pore is weaker. However, for the processes of diffusion of atoms through the zone of increased stress, not only the intensity of stress is important, but also the size of the zone itself. Near the spherical cavity, the size of the overstressed zone is the largest, so the analysis of its morphology was taken as a basis. In this paper, we used the modeling of functions describing the stress distribution around the pores similarly to the velocity field of an ideal fluid.

Results. As a volume object, the described zones of plasticity are the surfaces of a spheroid and an ellipsoid surrounding spherical and lenticular pores. It is obvious that the smaller the ratio h/l for the pore is, the further in the transverse direction the plasticity zone (more than p_max-l) spreads, becoming tighter and tighter (z₁ is approximately proportional to h). The following geometric parameters of the plasticity zones near the lenticular pore were determined as characteristic ones: its greatest length in the radial direction from the apex; the characteristic thickness of the zone (ρ_max– l)l/a; the area of the lens; the volume of the zone and its share of the volume of the lens. The development of plasticity zones near pores of different morphologies in steels under stress-corrosion conditions stimulates the change (increase) of the kinetic characteristics of the metal and the creation of favorable conditions for accelerated diffusion (decarburization). In the area of plasticity zones in the vicinity of pores under external and internal (gas pressure) stresses, the creation of channels of facilitated diffusion forms places of nucleation of submicrocracks at points D, B and C. Juvenile free surfaces formed in radial directions create zones of realized accommodation opportunities of the medium - zones of plasticity. Along with the growth of radial cracks to their tops from the pore under high pressure, gases diffuse rapidly.

Conclusion. The stress distribution analysis algorithm proposed in this paper allows predicting the intensity of plasticity zones (crack formation) development depending on the ratio of parameters β (β = σT/ σ) and s (s = p/σ), that is, on the ratio of external stress values, steel yield stress and gas pressure in the pore. The calculation made it possible to clarify the place of nucleation, the shape and scale of the development of zones of plasticity (cracking) in the vicinity of pores of different morphology depending on the ratio of external stress and gas pressure in the pores.

Purpose of research. The main technological problem of tooling backup of machining operations by turning the surfaces of parts of various structural complexities is the choice of the rational design of a changeable indexable insert for equipping straight-turning tool. Known technical solutions are associated with the selection of the shape of the changeable insert and the rational geometric parameters of its cutting element to the closest possible desired option. However, in the current engineering industry it is impossible, and it is economically unprofitable to have a large number of standard cutting inserts with step-by-step gradation of geometric parameters.  It should be noted that the operation of turning structurally complex surfaces of parts of the class 71-Body of rotation is characterized by the multivariance of tooling backup, concerning both the selection of the optimal tool design and the rational grade of its cutting part. The most time-consuming part of the task is related to the fulfillment of the multiple requirements for the grade of tool material, namely: maintaining the necessary resistance in the conditions of interrupted cutting, within the boundaries of a given batch of parts, while ensuring the productivity, accuracy and roughness of the machined surfaces of complex profiles established by the production task.

Methods. To solve this problem, methods of system analysis were used, which made it possible to establish a functional relationship between the structural complexity of surfaces machined by cutting of complex profile and the design of changeable indexable insert of straight turning tool.

Results. It has been shown that the composite10 is potentially the best grade of tool material, for clean turning of structurally complex surfaces. The characteristics of tool materials are presented that allow, by alternative choice of a rational grade of changeable indexable insert, to confirm the adequacy of the decisions made.

Conclusion Recommendations have been developed on choosing the structural form and grade of tool material of changeable indexable inserts for clean turning operations on surfaces of complex profiles of parts of the class 71-Body of rotation. It is shown that the use of a rational shape of the cutting element is capable, under intermittent cutting, to provide predetermined performance indicators, accuracy and processing quality. 

Purpose of research of this research is to study wear resistance characteristics of additive products made from electroerosive cobalt-chromium powders.

Methods. Wastes of cobalt-chromium "CELLIT" alloy were used for the research [27]. Butyl alcohol was used as a working  fluid.  A unit  for  layer-by-layer  application  of powder  materials  with plasma  was used for  experimental samples  production.  The  intensity  and  wear  rate  of  the  sample  surface  and  counterface  were  measured  on Tribometer automated friction machine, CSM Instruments. The sample was mounted in a holder. A rod was fixed perpendicular to the surface of a sample. A 6 mm diameter ball made of Stainless Steel AISI 420 (Vickers hardness 5000-8000 HV) was at the end of the rod. Radius of wear curvature was selected by adjusting the displacement sensor. Another sensor compensated the friction force and allowed to set the friction coefficient value at a certain time. The condition of friction surfaces was studied with the help of optical inverted microscope Olympus GX 51 equipped with "SIMAGIS Photolab" automated image analysis system and Quanta 200 3D electron ion scanning microscope.

Results. According to the performed analysis of wear resistance characteristics of additive products made from electroerosive cobalt-chromium powders friction coefficient varies from 0.144 to 0.602. An average friction coefficient is 0.526. A wear factor of the sample is two times higher than the wear factor of counterface.

Conclusion. Performed research allows expanding the information about properties of additive products made from electroerosive cobalt-chromium powders and reducing production cost.

Purpose of research. The purpose of the paper is to find new solutions for equiaxial-contour (EC) holes machining and milling cutter modeling with the use of radial constructional feed.

Methods. The results of the determination of the original contour of the milling cutter surface using the basics of the geometric theory are provided in the paper. Theoretical considerations were based on the use of the basics of the vector algebra, analytical and differential geometry, theory of material cutting. The results of the milling cutter design modeling with the application of software COMPAS 3D are presented in the paper.

Results. The analysis of the existing methods for EC holes machining is provided. To improve the efficiency of EC internal surface machining there was proposed a method for milling with a miller cutter with radial constructional feed. The results of the determination of the original cutter surface are provided, the models of its cutting edges and front and flank surfaces were developed. The result of the modeling of the front and flank surface of the cutter teeth with R_f = 24 mm, and cutter width of 50 mm with the front rake angle of 5°, back angle of 10° and 16 teeth are presented. There are also provided the results of the milling cutter modeling by means of 3D modeling which in the future will make it possible to manufacture tool equipment for the proposed method and to conduct an experiment research to determine optimum technological parameters.

Conclusion. On the basis of the developed models it’s becoming possible to perform the modeling of the milling process of EC shaped holes in order to determine milling rational values and specifications. The research findings can  be  used  for  design-engineering   documentation   development   during  the  preparation  of  shaped  holes manufacturing in order to ensure specified item characteristics.

Purpose of research. Analysis of residential buildings’ condition after the total renovation.

Methods. Inspection of buildings and structures – is an important part of the construction industry, which allows to analyze and identify defects and damage to building structures, both by visual and instrumental methods of research. Comparative analysis of design documentation and inspection materials of previous years reveal the dynamics of building structures’ condition and moments of poor quality work of contractors at different stages of production.

Results. The revealed discrepancies in the process of inspection of buildings of Kursk housing stock have been presented in the article. First of all, it is a disregard for the requirements of existing regulations to the thermal characteristics of enclosing structures. Violations of technology of plastering of walls made of silicate bricks have been also revealed. The following negative moments are the low quality of the materials applied for roof repair, decrease in a grade of wood in comparison with design requirments, violation of the requirement and rules of fire safety. Moreover, it has been established that the strengthening offered by results of the previous inspections wasn't carried out during total renovation.

Conclusion. When carrying out works on total renovation it is necessary to pay great attention to each apartment building, its features and damages. At the same time, the project documentation must comply with the instructions of modern rules and regulations. Materials and procedure of works must meet the requirements of the project documentation. To reduce the risk of nonconformities during total renovation, it is necessary to perform acceptance of works after each completed stage of construction.

Purpose of research. The purpose of the research is to develop a simplified approach for the further algorithmization of a hot-water  supply solar collector calculation for seasonal operation of an individual residential building and designation of the main predicted values.

Methods. To achieve objectives, the approximate values of the main solar system of hot-water supply characteristics was determined, affecting the technical and economic indicators of the system and determining the mode of system operation, its comfort in use and maintenance - the efficiency of the solar installation, the total cost of water heating in the alternate heater, the temperature of the water in the storage tank according to the estimated number of operation days in months of solar system of hot-water supply maintenance. As a criterion for the system effectiveness, the replacement coefficient for the solar system of hot-water supply was adopted, i.e. the share of the hot-water supply heat load satisfied by the absorbed solar energy during the operation of the facility.

Results. A variant of the problem statement is proposed for developing an algorithm for calculating a solar water collector for hot-water supply in an individual residential building for operating conditions with a relatively low level of solar radiation intensity and the presence of low temperatures in winter, which creates significant difficulties during the year-round operation of the system and determines the seasonality of its operation. The developed method allows to calculate: the course of the water temperature in the storage tank, the total amount of heat used to prepare hot water due to the energy of solar radiation; the replacement and efficiency coefficients for the solar system of hot-water supply.

Conclusion. A universal equation is obtained that allows you to determine the main predicted parameters of the solar system for any mode of operation for solar system of hot-water supply.

Purpose of research.   To meet the requirements of Federal Law No. 384 “Technical Regulation on the Safety of Buildings and Structures”, a deeper study of the stability of frame-rod structural systems in the event of an emergency associated with subsidence of the base of one of the supports, and the development of a methodology for assessing the resource of resistance of building elements located in difficult engineering and geological conditions.

Methods. As a stability criterion, the sign of the work of the end moments and transverse forces is adopted. A negative value of this work is a sign of "active" loss of stability of the rod, a positive - "passive". In the event of an emergency related to the subsidence of one of the frame supports, the work of the longitudinal force ceases to contribute to the bifurcation of the rod. Therefore, at a certain strain value Ssl, a separate rack can go from active loss of stability to passive, changing the critical stability parameters of the entire system as a whole. The formula for determining the critical drawdown S_cr is given.

Results. A two-span frame is considered, in which the central strut is loaded with the force P_kr, the extreme - with the forces αP_kr. The type of rod bifurcation is determined. Using the above equations, critical parameters and forms of buckling of the structural system under consideration were found before and after the emergency in question. An assessment is given of the influence of the draft of the base of the supports of the frame racks on the character of the bifurcation of the rods of the structural system as a whole. The analysis of the dependence of the critical drawdown value S_{sl, cr}. on the loading scheme of the frame under consideration is performed. It is shown that when the coefficient of load application is α = 0.6, at the first stage, when the system in question is stable, the first rack loses stability passively, the rest actively. When the base of the second pillar sags by 21 mm or more, a change in the type of its bifurcation occurs, while the critical stability parameters of the remaining elements do not change significantly. In the event of a similar emergency with the base of the right frame pillar, the critical drawdown value is 140 mm. Moreover, a change in the type of bifurcation of the third pillar leads to the transition of the first pillar to active bifurcation, as a result of which the critical parameters of the entire system as a whole change significantly.

Conclusion. An analysis of the calculation results showed that with a certain drawdown value, the emergency in question will lead to a change in the nature of the bifurcation of both individual elements and the entire structural system  as  a  whole.  The  proposed  stability  criterion  for  frame-rod  structural  systems,  the  basis  of  which  are subsidence soils, makes it possible to relatively easily identify elements with low resistance to buckling in difficult engineering and geological conditions.

Purpose of research. The estimation problem of the influence of the systemic effect on the performance of the antagonistic games of several participants, who play the game, acting in various ways, is considered. It is assumed, that players play games, match through independent, incompatible actions, or through concerted, joint actions.

Methods. It is obvious that joint actions provide greater efficiency, but such a qualitative estimation is often not enough. For informed decision making, as a rule, quantitative estimations are required.

Results. The analytical and computer solutions of the well-known equations describing the state of dynamic systems in which random Markov processes occur are used to obtain quantitative  estimates. The result of incompatible actions of the players is considered as the result of many independent events, while the process due to the combined actions of the players appears to be the result of the functioning of some dynamic system. The increase in the productivity of joint actions of players compared with incompatible actions is considered to be a consequence of the organization of several players as a dynamic system, and is called the system effect. Analytical solutions of the “dynamics  of  averages”  equations  obtained  earlier  by  Russian  and  foreign  mathematicians  are  used  for  a quantitative, approximate estimation of the influence of the systemic effect. The exact Kolmogorov equations describing changes in the probabilities of the state of dynamical systems with random processes were solved by computer methods using MATLAB.  These decisions made  it possible to obtain  estimates of the numerical values of the coefficient  of systemicity, which characterizes the effectiveness of joint actions compared to incompatible ones.

Conclusion. The results obtained in the article can be used to estimate the performance of the various training methods of participants in antagonistic games, athletes, and in educational institutions. 

Рurpose of research. Operation speed increase of fuzzy parallel-conveyor  device based on a new method of thermal element controlling.

Methods. Cutting tool and part's surface are heated in the process of device handling using NC-machining technique. Thermal deformations reduce the surface of workpiece treatment quality. Various methods are used to compensate temperature deformations: spraying of lubricating-cooling liquid, cooling by compressed air. The device is proposed to be used for cooling control which is implemented on Peltier thermo element and FPLD Spartan 3E. Constant control is necessary to control thermal errors and control systems are built on artificial intellect models. As input parameters are indeterminate, fuzzy logic is used to describe the connection between input and output parameters.

Results. A fuzzy mathematical model has been developed to calculate current intensity. The intensity depends on the change of input parameters. Tests conducted at 50 MHz showed that 380 ns are necessary to calculate current intensity according to the developed mathematical model. Fuzzy mathematical model is implemented on the basis of FPLD Spartan 3E for faster operation. A universal formula for current-voltage transformation was developed. Test results showed that the voltage calculation is carried out in 190 ns. It was stated that thermo element control device produces a control signal within 570 ns.

Conclusion. The article describes a device for temperature controlling conditions in the product processing area. In this device thermal element controlling is done by a current generator implemented on an operational amplifier and on a bipolar transit generator. A device for current-voltage transformation is implemented on FPLD. It was developed to receive a pressure signal for NC-machining technique actuators to receive a pressure signal.  A fuzzy MISO model has been  developed  to calculate  current  magnitude  that  depends  on temperature  change  in the cutting  zone. Conducted tests showed that the speed of this device is several times higher than present analogues.

Purpose  of research. Thе tаsk оf соmрiling арlаn fоr lоаding рrосеssоrs in multiрrосеssоr  systеms оf сitiсаl рurроsе (trасking, оbsеrvаtiоn, аiming, аtоmiсаnd finаnсiаl systеms) is disсussеd. Mоdеrn аlgоrithms imрlеmеnt thерrоblеm mаinly рrоgrаmmаtiсаlly аnd аrе unассерtаblе fоr thесоnsidеrеd сlаss оf systеms bесаusеоf thе lоng sоlutiоn timе, whiсh lеаds tоа dесrеаsе in its аvаilаbility аnd асоrrеsроnding dесrеаsе in реrfоrmаnсе. Existing аррrосhеs, аs а rulе, shоrt-tеrm рlаnning аrеоftеn fосusеd оn thе rарid rеsроnsеоf оngоing рrосеssеs, whiсh аlsо dоеs nоt аllаw tоасhiеvе thе rеquirеd реrfоrmаnсе. Аs а result, thеаrtiсlерrороsеs аn аlgоrithm fоr sсhеduling thе lоаding оf рrосеssоrs in multiрrосеssоr systеms, fосusеd оn hаrdwаrе imрlеmеntаtiоn, using thеаdditiоnаlly intrоduсеd mаtriсеs оf timе, оrdеr аnd оrdеr.

Methods. Thеаrtiсlерrороsеs е blосk diаgrаm аnd а funсtiоnаl diаgrаm оf а sресiаlizеd dеviсу fоr рlаnning thе lоаding оf рrосеssоrs оf о multiрrосеssоr systеm. А distinсtivе fеаturе is thе usеоf thе dеvеlороd dоviсеаs аn аdditiоnаl ассеlеrеtоr соnnесtеd tо thераrаllеl роrt оf thесоmрutеr. Thерrороsоd dеviсе in this саsереrfоrms аll thесаlсulаtеd funсtiоns оf thерrороsеd аlgаrithm, thеrеby rеduсing thе mаin lоаd оn thесоmрuting systеm, thеrеby rеduсing thе tоtаl lоаd. А struсturаl аnd funсtiоnаl diаgrаm оf thе dеviсе fоr sсhеduling а lоаding sсhеdulе is givеn, whiсh аllоws thесоnstruсtiоn оf соrrеsроnding timе diаgrаms оf tеmроrаry аnd hаrdwаrесоmрlеxity.

Rеsults. Frоm thеаnаlysis оf thе grарhs оf thе dереndеnсеоf thе inсrеаsе in thе hаrdwаrесоmрlеxity оf thе dеviсеоn thе numbеr оf рrосеssоrs, аn еxроnеntiаl inсrеаsе in thеореrаting timеоf thе dеviсе, dуруnding оn thе numbеr оf рrосуssоrs, fоllоws. Duе tо thееxроnеntiаl grоwth in thе numbеr оf рrосеssоr lоаding орtiоns, thе hаrdwаrе imрlеmеntаtiоn оf thе sсhеduling аlgоrithm shоws аn аdvаntаgе.

Conсlusiоn. With thу hуlроf thерrороsуd аlgоrithm аnd dуviсе fоr рlаnning рrосеssоr lоаding, it is роssiblе tо inсrеаsе thе sрееd оf lоаd соmрilаtiоn, dесrеаsе thе tоtаl аmоunt оf соmmuniсаtiоn dоlааy аnd inсrеаsе thе tоtаl реrfоrmаnсеоf multiрrосеssоr systеms.

Purpose of research.   The process of controlling and decision making in any area is directly connected with the ability to process a large amount of data quickly and accuracy of the obtained formation.

Modeling of different objects or processes as a result of data processing becomes more difficult for users with the high level of modern computer technologies development. And the ability to visualize the results can give more visible information to the decision-maker. The use of Surfer program for geological data processing is described in the article. This application is suitable for processing a large amount of data, surface analysis, landscape visualization, and mapping. Examples of specific tasks solution with the help of Surfer program are described.

Methods. Theoretical basis of the study is a set of scientific provisions of native scientists in the field of geological modeling. Practical methods of analysis are based on an experiment of contour geological map creation of nickel distribution, empirical (geochemical data processing), statistical (accumulation of obtained data and their processing with Surfer program) analysis.

Results. The process of geological data processing using Surfer program are discussed in the article. A contour geological map of nickel distribution was developed.

Conclusion. The paper proposed the possibility of using Surfer program for geological data. The use of this task-solving application in student training will help future geologists in necessary practical skills acquiring for geological data processing, reducing task-solving time, acquiring the ability to evaluate the results of development in projects and improving the level of information technology and professional competence.

Purpose  of  research.  The  article  contains  mathematic  simulation  and  research  of  movement  of  a  portable underwater robot designed to monitor pollution of hydrosphere objects. Modern methods of environmental monitoring suggest the presence of stationary sites. The task of mobile controlled monitoring remains unresolved currently. One of the ways to solve this problem is the transition to control systems that provide a given movement of the water system both on the surface and under water. Therefore, the purpose of this article is to study and set the basic laws and algorithms based on mathematical models that describe the controlled movement of portable underwater systems.

Methods. When developing the motion control algorithm for PUS, a mathematical model was used to determine the spati-temporal location of PUS with a variable thrust vector. The basic mathematical expressions that determine the movement of PUS in a predetermined path are obtained. Particular attention is paid to that part of the algorithm that ensures the movement of PUS in a predetermined path in underwater mode if there is no contact with the global navigation system, taking into accounts the underwater GPS and the distance to the bottom and obstacles. As the main criterion of quality of control system we have used the deviation of the actual position of PUS from the position datum.

Results. To select the direction of movement when monitoring water, a method of planning the trajectory, built on piecewise linear sections, has been developed that allows probing the space of water in such a way as to ensure maximum efficiency of the monitoring process with a minimum number of sampling points. For this, each new segment of the trajectory and sampling points are planned taking into account information on the concentration of pollutants at the previous stage, as well as the coastline and the depth of water.

Conclusion The article discusses the method for monitoring water bodies using a portable unmanned underwater system. The kinematic and dynamic models of the PUS movement are developed. It is proposed a method of planning a trajectory of motion based on piecewise linear segments. We have developed an algorithm of controlling the autonomous movement of the underwater vehicle.