Introduction. The selected research topic urgency is due to the need for a quick assessment of the condition and reliability of materials used in various designs. The work objective was to study parameters of the influence of the defect on the response of the surface of the medium to the shock effect. The solution to the inverse problem of restoring the radius of a defect is based on the combination of a computational approach and the use of artificial neural networks (ANN). The authors have developed a technique for restoring the parameters of a defect based on the computational modeling and ANN.

Materials and Methods. The problem is solved in the flat setting through the finite element method (FEM). In this paper, we used the linear equations of the elasticity theory with allowance for energy dissipation. The finite element method implemented in the ANSYS package was used as a method for solving the boundary value problem. MATLAB complex was used as a simulation of the application process (ANN). Results. A finite element model of a layered structure has been developed in a flat formulation of the problem in the ANSYS package. The problem of determining unsteady vibrations under pulsed loading for different radius variations of the defect is solved. Positional scanning of the research object is applied. Graphical dependences of the vibration amplitudes of points on the surface on the defect radius are plotted.

Discussion and Conclusions. As a result of studying the dependences of vibration responses on the defect radius, the authors have developed an approach to restore this parameter in a flat structure based on a combination of the FEM and ANN. The research has shown that the amount of data used is sufficient for successful training of the constructed ANN model and identification of a hidden defect in the structure.

Introduction. The use of probabilistic analysis is important when the input data are random, that leads to stochastic results. This paper describes the integration of a probabilistic design strategy of the solid and hollow stems implanted in a proximal femur in order to compare their advantages. The used hollow stem is called “Improved Austin-Moore” (IAM) model.

Materials and Methods. Probabilistic methods allow variations in factors which control the biomechanical effects of the implanted femur to be taken into account while determining its performance. Different material properties were generated randomly using Monte Carlo simulation (MCS). Monte Carlo sampling techniques were applied, and different von Mises stresses of the layers (bone and metal) were chosen as a performance indicator.

Results. A simple 2D implant-bone study of solid and IAM stem design was carried out with a high level of confidence, 99.87%, which corresponds to a target reliability index with regard to statistical uncertainties. The probabilistic design results show that the input and output parameters for the IAM stem are highly correlated relative to those for the solid stem.

Discussion and Conclusions. The sensitivity analysis shows that the input parameters for the IAM stem play a much larger part in the output parameters relative to the solid stem. The IAM stem is much more advantageous than the solid stem which causes an increase in the performance of the hip prosthesis.

Introduction. Microdefects and zones with stress concentration in welded joints cause fatigue macrocracks. Such damage is potentially dangerous, especially if the fatigue life of the structure is almost exhausted. In this case, the crack size is close to the critical value, and it is crucial to determine its length. The paper considers the development of an engineering analytical model for assessing the critical crack length and endurance limit of welded joints with the formed grain in the structure of ferrite-pearlitic steels after welding.

Materials and Methods. The theory and methods of fracture mechanics at the mesoscale are used. A simple analytical dependence is obtained, which provides determining the critical dimensions of a macrocrack for ferrite-pearlite steels without using the Griffiths formula. . The calculation results of the critical crack lengths of various steels depending on their yield strength are presented. An analytical dependence of the endurance limit calculation for the most dangerous symmetric loading cycle, according to the standard set of mechanical characteristics and the average grain diameter of ferrite-pearlite steel, is presented.

Results. Structural deformation analysis of the crack propagation process has been performed. On its basis, an engineering technique for assessing the endurance limit is developed. A mathematical model that enables to calculate the endurance limit and the critical crack length in the components of welded assemblies of large-sized facilities, considering periodic loads of a symmetrical cycle, is developed. Using this model, it is possible to estimate the degree of metal sensitivity to the original characteristics (yield stress, Poisson's ratio, grain diameter, relative constriction, Young's modulus, power-law hardening coefficient, etc.).

Discussion and Conclusion. Under stresses corresponding to the steel endurance limit, the critical crack opening rates of the tip and edges approach each other. Energetically, this moment approximately corresponds to the transition of the crack to an unstable state. The accumulation of one-sided plastic deformations causes the limiting state of plasticity of the region adjacent to the crack tip and its avalanche-like or sharply accelerated motion. This critical area is interrelated with the grain diameter of the material, the characteristic of critical plasticity and the critical opening at the crack tip at the fatigue limit. The proposed analytical dependences can be used to assess the residual life and the fatigue limit of welded structures, the influence of various factors on the fatigue limit of welded joints of ferrite-pearlitic steels used in mechanical engineering, shipbuilding, pipeline transport, etc

Introduction. The study results of the abrasive processing of parts made of polymer-composite materials are presented. The features of processing polymer composites and the technology of preforming through waterjet cutting are described. The stages of preparation of a part made of polymer-composite material for the “glueing” operation are investigated.

Materials and Methods. Dependences for determining the surface roughness under waterjet cutting of polymercomposite material are considered. Research is carried out to achieve the required surface roughness under adhesive bonding of workpieces. The dependence is given that describes the roughness that is required for a reliable adhesive bond.

Results. The theoretical and experimental studies of the waterjet cutting process are resulted. Their implementation technique, the tool and equipment used are described. The results of theoretical and experimental studies are compared. Their high convergence is established. The results of experimental studies on the preparation of parts made of polymercomposite materials for glueing are shown. The abrasive tools and processing modes are selected.

Discussions and Conclusions. The process design procedure of abrasive treatment of workpieces from polymercomposite materials is proposed.

Introduction. The paper considers the creation and application of digital twins at various stages of the life cycle of mobile transport and transshipment rope complexes (mobile ropeways), the equipment of which is mounted on the basis of wheeled or tracked chassis of high load capacity. The work objective is to improve safety in using such transport systems based on real-time forecasting of potential failures. This will prevent the occurrence of emergencies in a timely manner.

Materials and Methods. The structure of the digital twin of the mobile transport and transshipment rope complex is proposed. Approaches to the analysis of ongoing work processes in order to prevent accidents have been developed. They are based on simulation modeling of the system dynamics using new complex mathematical models built through the system approach.

Results. The developed method was tested on a large-scale layout of a mobile transport and transshipment rope complex created by 3D printing methods. A mathematical model of this system was developed; it was used to construct a digital double of the experimental model. The possibility of predicting failures in the layout is shown experimentally through the example of a rope slipping case. To do this, the actual value of the load suspension point coordinate obtained through the video stream processing method was compared to the predicted value calculated using a digital twin.

Discussion and Conclusions. The research results provide the creation of an industrial digital twin of a mobile transport and transshipment rope complex mounted on cross-country wheeled chassis.

Introduction. Improving the quality and operational reliability of welded structures of power equipment is an urgent task of welding production. Its solution is possible on the basis of the development or selection of advanced methods and technologies of electroslag welding (ESW), which eliminate the causes of the formation of tempering cracks (TC) in thick-plate welds. This paper considers a comparative assessment and recommendations on the selection of such advanced ESW methods. The work objectives are to solve the problem of forming a fine-grained, uniform, crack-resistant metal structure of a welded joint with high mechanical characteristics and to reduce the negative impact of the ESW thermal cycle on the base metal. The solution to this problem is possible on the basis of a reasonable choice of methods and technologies for ESW with regulated (controlled) thermal cycle.

Materials and Methods. A comparative analysis of advanced methods and technologies of ESW with a controlled thermal cycle is carried out; a comparison of their pros and cons is provided; practical recommendations on the selection of advanced methods for controlling the thermal cycle parameters are offered.

Results. It is shown that moderate heat input at high-speed ESW in a narrow gap provides a single pass to form a welded joint with a finer-grained structure and high mechanical properties compared to the in-house technologies of ESW and automatic submerged-arc welding. Recommendations for practical use of the method in welding production are given.

Discussion and Conclusions. The results obtained are recommended to be used in the development of ESW technology for thick-sheet welded structures of nuclear and thermal power equipment that enables to abandon postwelding heat treatment (normalization and high tempering).

Introduction. The weld formation under the submerged-arc welding of bridge metal structures is investigated. The work objective is to study possibilities to increase the welding performance during the arc welding of fillet seams.

Materials and Methods. Methods of computer analysis are used to optimize the technology. With their help, a physicomathematical model of fillet weld formation under the submerged-arc welding has been developed. It is based on a system of equations for thermal conductivity and equilibrium of the weld pool surface. In this system, the formation of an arc cavern is determined through the flux boiling isotherm under the action of the arc column radiation; heat transfer by the flux vapor inside the arc cavern and the influence of the spatial position on the formation of the weld pool are taken into account.

Results. New mathematical relationships that describe physical phenomena under the submerged-arc welding of fillet welds are proposed. The key feature of the proposed model is in the fundamental difference between the submerged-arc welding and the gas-shielded arc welding, i.e., during submerged-arc welding, the arc burns in a gas-vapor cavern that appears due to the melting and evaporation of flux. Numerical simulation of the temperature distribution during production of the fillet welds in 1F and 2F positions is carried out. The process constraints under the single-run welding of the fillet welds are specified. It was determined that the single-run submerged-arc welding of fillet welds in 1F position exhibits high-quality formation of welds for almost the entire range of metal sheet thicknesses. During production of fillet welds in 2F position, high-quality formation is provided only for sheet thicknesses up to 8 mm. At heavy thicknesses, the formation of the seam is disrupted due to the melt flow from the vertical wall. In this case, the leg length decreases; a typical undercut is formed; so the weld will be asymmetric and less strong.

Discussion and Conclusions. Comparison of the numerical analysis results with actual data on welding modes under the production of bridge metal structures shows that the existing fillet welding technologies have already reached their maximum efficiency rate. Further productivity gain is possible by forming oversized legs only with multiarc or multielectrode welding methods.

Introduction. The main work objective is systematization and analysis of structural defects of vacuum ion-plasma coatings; on this basis, their classification principles are developed and given in the paper. Another important part of the work is the experimental study on one of the specific defects of coatings, which the authors propose to call “defect of substructural origin”.

Materials and Methods. PVD coatings of various nitride and metal systems 1.5-9.0 μm thick were used as an object of the research. Coatings were applied in vacuum installations using arc and magnetron evaporators. The research results were obtained by high resolution electron microscopy, energy dispersive analysis and indentation.

Results. Various types of defects in ion-vacuum coatings are presented as the research results. They include discontinuities, deformation of crystallites, and structural inhomogeneity. The principles of their systematization are validated. It is proposed to classify defects into droplet, substructural, and growth defects (depending on the causes of their nucleation), as well as regular and stochastic ones (depending on their distribution in the coating volume). The study of “substructural defects”, classified by the authors as stochastic, is given special consideration. These micrometric defects are shaped like a cylinder with a conical “head”. Their main axle is oriented perpendicular to the surface of the coating. They can be “extruded” (tore away) by the coating. The paper validates the dislocation mechanism of their nucleation and the helicoid growth principle.

Conclusions. The inference is summarized that the proposed systematization of defects in ion-plasma coatings has the character of an intermediate result of research in this scientific area. At this, the “substructural defects” do not have a fatal effect on the structure and properties of the coating due to a small size.

Introduction. Obtaining high-quality thin metal films is important for advances in the technologies of applying antifriction and wear-resistant coatings on cutting tools or parts of friction couples. Various techniques of physical film deposition are applied using technologies of cathode (ion), magnetron and ion beam assisted sputtering. The work objective is to analyze, compare and determine the feasibility of techniques for the physical deposition of thin metal films when applying antifriction and wear-resistant coatings on cutting tools or parts of friction couples.

Materials and Methods. Technologies of cathode (ionic), magnetron and ion-beam sputtering are considered. Schematic diagrams, conditions and parameters of the considered processes are presented.

Results. An advanced technology for the deposition of thin films, alloying and hardening of the surfaces of metal parts is magnetron sputtering. Continuous wave (cw) magnetrons are used to apply coatings of complex composition or multilayer coatings on flat substrates. Ion beam sputtering is considered a slow sputtering of the target surface by bombardment with a high-energy ion beam and deposition on the substrate surface. Under the ion implantation, the surface of metals is doped with recoil atoms, which receive high energy from accelerated ions and move a few nanometers deeper. This enables to obtain ultra-thin doped layers. Low temperature of ion implantation, the possibility of sufficiently accurate control of the depth and the impurity distribution profile, create the prerequisites for the process automation. Wear tracks are more acidified under the same wear conditions on implanted steel compared to non-implanted steel. The nonequilibrium process under ion implantation causes the formation of such alloys in the surface layers that cannot be obtained under normal conditions due to diffusion of components or limited solubility. Ion implantation makes it possible to obtain alloys of a certain composition in the surface layer. Surface properties can be optimized without reference to the bulk properties of the material. Implantation is possible at low temperatures without a noticeable change in the size of the product.

Discussion and Conclusion. Cathode (ion), magnetron and ion-beam sputtering have common advantages: due to the relatively low temperature, the substrate does not overheat; it is possible to obtain uniform coatings; the chemical composition of the deposited coatings is accurately reproduced. The rest of the advantages and disadvantages of the considered methods are individual. The results can be used to create thin films through alternating magnetron and then ionbeam deposition processes, which enables to obtain films uniformly modified in depth. This is important in the production of parts of friction couples and cutting tools to improve their quality.

Introduction. The paper considers an actual issue of the development and application of a non-destructive method for controlling the quality of surfaces of steel products (Kelvin probe method). The work objective is to establish the magnitude of the contact potential difference (CPD) of steel 107WCR5 after heat treatment.

Materials and Methods. The object of study is alloy tool steel 107WCR5. The chemical composition of the samples was refined through the optical emission analysis method. To carry out the statistical processing, there were three samples in three series. We chose different heat treatment modes for each series, i.e., quenching with low tempering, strengthening and normalization. The end surfaces of the samples were polished and then one of them was treated with a solution of nitric acid. Further, the measurement of the contact potential difference and statistical data processing were carried out.

Results. The data obtained show that the CPD value of steel 107WCR5 samples changes after heat treatment. With an increase in tempering temperature, the contact potential difference of the polished surface and the hardness, decrease almost linearly. Exposure to acid causes a significant decrease and equalization of the contact potential difference for all structures. The contact potential difference of steels 107WCR5 and CT105 is compared. Alloying steel by the elements with the work function values of the electron higher than that of iron causes a decrease in the CPD between the standard and the sample. The CPD behavior under a change in the composition of the steel depends strongly on the presence of alloying elements. The dependence of CPD on the dispersion of the structure is seen in both cases; however, it is more pronounced for 107WCR5 steel. The electron work function of the martensite, troostite, and sorbitol structures obtained as a result of heat treatment of steels 107WCR5 and CT105 is calculated.

Discussion and Conclusions. The dependence of the contact potential difference on the structure, chemical and phase composition was experimentally established; the electron work function of steels 107WCR5 and CT105 was calculated. This technique is more sensitive to alloy steel samples than to carbon steel. It seems possible to conclude that the measurement of the contact potential difference can be used to control surfaces exposed to active media or elevated temperatures as a non-destructive express diagnostic method.

Introduction. The development of a mathematical model of one-parameter shaping of a toothed product is considered. As an example, shaping of the side surface of the teeth of the Novikov gearing is studied; the mode and magnitude of the change in the shaping error heightwise the wheel tooth are shown. The work objective was to develop a mathematical model of the surface of the product teeth as a generating surface envelope of the tool. A computational and experimental study is carried out. The mathematical models obtained can be used in devices with copiers when shaping the side surface of the teeth of the Novikov gear. As an example, we consider the deviation behavior of the teeth profile of the Novikov gear with the original profile of DLZ 0.7-0.15

Materials and Methods. When building the model and studying its characteristics, the mathematical tools of the gearing theory, calculation procedure for cylindrical gears (A.A. Silich’s author development) were used. The paper proposes new mathematical models of the equations of the lateral surface of the gear teeth formed with a tool whose axial profile coincides with the original one. In the model under consideration, the tool moves along the axis of the product while the latter rotates on its axis. In the course of the study, numerical modeling was carried out to determine the error value in shaping the product profile using the tool.

Results. New mathematical models and software have been developed for numerical simulation of the shaping of a toothed product using a tool with one independent motion parameter. An algorithm has also been developed to determine the deviation error of the real profile from the nominal one for the tooth of the Novikov gear. Solutions to accurately reproduce the tooth profile are provided.

Discussion and Conclusions. The parametric method of analytical description of the surface used in the work simplifies the calculation of the cutting tool displacements in the problems of numerical control. Solving the problem of synthesizing the technology of workpiece surface treatment on metal-cutting machines provides the development of a description of the entire shaping process and requires the representation of the workpiece surface in the form of a mathematical model. The results obtained can be used under creating finishing methods for processing teeth when improving the quality of gear wheels and gear drives, as well as production efficiency.

Introduction. The creation of new types of bucket working bodies of excavators through synthesizing technical solutions to improve the transporting functions of the bottom is considered. These solutions are based on reducing the resistance and energy consumption under digging-in and scooping due to the transition from sliding friction to rolling friction during the movement of the rock mass along the bottom of the bucket.

Materials and Methods. Analysis of the bulk materials handling processes using existing loading appliances identified design flaws that affect the efficiency of their operation. Advanced design diagrams of loading bodies were searched on the basis of the accumulated experience and the study of the morphological features of the existing equipment. Combinatorial analysis of possible combinations of elements with their various qualitative compositions, mutual arrangement, imposed links, and synthesis of new technical solutions for loading and transportation modules are carried out.

Results. The results of the morphological synthesis implementation were the systematization and development of designs of bucket working bodies with a bottom in the form of a roller surface and a closed belt, as well as with a conveyor-type drive mechanism. The application of rollers as a supporting surface of a loaded rock mass causes a decrease in friction forces and in the power capacity of the work process. In addition, rotating rollers provide uniform abrasion of the working surface, which increases significantly the time to the equipment breakdown and increases the process efficiency. Working bodies with a drive mechanism make it possible to activate the interaction of the conveyor bottom in the form of a closed belt with the rock mass and, as a result, to accelerate the process of filling the bucket container.

Discussion and Conclusions. The bucket working bodies described in the paper compare favorably with existing analogues in that they provide a reduction in the time to digging-in, scooping and unloading, a decrease in specific energy consumption, an increase in bucket filling, which ultimately contributes to an increase in productivity. A slight increase in the structural complexity and cost of the working body causes additional capital costs, which are paid back within two to four months.

Introduction. The structure of the transport logistics system for the transportation of container transformers in an urbanized environment to optimize production costs with elements of intelligent urban mobility, as well as the simulation software for modeling and testing the developed system, are described. The basic principles of the interaction between elements of the system are presented through the behavioral modeling of containers and carriers.Software is created to simulate the operation of the logistics infrastructure for transformer containers using wireless technology and the Internet of Things; and services for the rapid information exchange between participants (objects and subjects) of this process are implemented.

Materials and Methods. A general method of organizing a network with a web server and a mobile client, as well as the basic principle of interaction between the server and the client, is described. The basics of developing a simulator designed to simulate all possible states of a container transformer are specified.

Results. A common system architecture and a simulator are created for the software debugging and testing under the organization of a single space to monitor and optimize cargo transportation using “smart” container transformers while providing transport services to the population and legal entities in an urban environment.

Discussion and Conclusions. The developed simulator as part of the information system provides speeding up the creation, debugging and testing of the software for solving logistics problems in the transport sector.

Introduction. The paper considers problems of creating information support for solving the task of assessing the maturity level of an organization. It is proposed to use intelligent information systems, i.e. expert systems. Substantive aspects of various stages of creating such systems are briefly described; the expert system architecture, which is based on using a fuzzy expert knowledge base, is given. The work objective was to create new software to solve the problem of assessing the maturity level of an organization.

Materials and Methods. Previously performed modeling of the subject domain under consideration allowed us to create a knowledge base in the form of production memory, which is the basis of the fuzzy inference mechanism. The software is written in PHP and is suitable for embedding in complex web applications. The software system is a web application written primarily in PHP and JavaScript. The software works in all modern web browsers, which accelerates significantly the implementation and deployment based on both the parent-enterprise and its subsidiaries.

Results. New software has been created to automate the processing of questionnaires during the organization’s selfassessment based on key indicators, as well as considering 6 main groups of the quality management system indicators. Application of the program will significantly speed up the process of input and processing of expert information required for self-assessment. The program provides organizations to get an adequate idea of the opportunities and prospects for improving the organization’s quality management system. Some fragments of the software system interface are given.

Discussion and Conclusions. The proposed software can be used to determine the level of maturity of an organization. The application of Web-technologies improves usability, reduces software support costs. The software can be both deployed in the existing network infrastructure of a customer and used by all the functionality through connecting to a remote server. The software is optimized for various screen resolutions, which allows you to use it not only at the central office, but also when analyzing the quality management system of corporate customers. The traffic generated by the web application is optimized for working with mobile devices with a low-speed Internet connection. Application of the program will significantly reduce the time for users to enter and process expert information required for the problem solving and to eliminate duplication of information.

Introduction. Various algorithms for solving fuzzy vehicle routing problems are considered. The work objective was to study modern methods for the optimal solution to fuzzy, random and rough vehicle routing problems.

Materials and Methods. The paper reviews fuzzy vehicle routing problems, existing methods and approaches to their solution. The most effective features of some approaches to solving fuzzy vehicle routing problems considering their specificity, are highlighted.

Results. The Fuzzy Vehicle Routing Problem (FVRP) occurs whenever the routing data is vague, unclear, or ambiguous. In many cases, these fuzzy elements can better reflect reality. However, it is very difficult to use Vehicle Routing Problem (VRP) solving algorithms to solve FVRP since several fundamental properties of deterministic problems are no longer fulfilled in FVRP. Therefore, it is required to introduce new models and algorithms of fuzzy programming to solve such problems. Thus, the use of methods of the theory of fuzzy sets will provide successful simulation of the problems containing elements of uncertainty and subjectivity.

Discussion and conclusions. As a result of reviewing various methods and approaches to solving vehicle routing problems, it is concluded that the development and study of new solutions come into sharp focus of researchers nowadays, but the degree of elaboration of various options varies. Methods for the optimal solution of FVRP are limited, in general, to some single fuzzy variable. There is a very limited number of papers that consider a large number of fuzzy variables.

Introduction. Modeling serves as a methodological basis for modern science and a tool for cognitive activity. It can be considered as a thinking activity mediated and optimized through information models. In this case, logical operations of cognition and simulation techniques are applied to the information.

Materials and Methods. The scientific research results on how knowledge is formed, stored and processed in a person's memory, how they interact with information representations are studied and summarized. Information models used in various subject domains are analyzed. The provisions on rational ways of presenting information under modeling are formulated, and computer tools for constructing such representations are indicated.

Results. Methods and techniques for visualizing information on the object under study are specified. Software tools and services providing visualizations and research modeling procedures are given.

Discussion and Conclusions. The results obtained can be used to optimize modeling procedures. Images, structures, relationships and connections of the object under study are visualized in special programs with the help of the described methods and techniques. They, in turn, mediate the process of mental modeling and broaden the basis for its implementation.