Andrey Kurkin

This study experimentally investigates the effect of oxide film thickness on the amplitude of laser-induced stress waves in AISI W1-7 carbon steel. Oxide layers of approximately 0.045 μm (straw-yellow) and 0.07 μm (blue) were synthesized via controlled heating using a free-running YAG:Nd3+ laser. The work used a Q-switched ruby laser (λ = 0.69 μm; FWHM = 25–30 ns; E up to 1.5 J) to generate intense stress waves. The displacement of the sample’s free surface was recorded using a Michelson interferometer with a probing He–Ne laser (λ = 0.6328 μm), which was used to construct the “pressure–time” relationship. It has been established that oxide films with thicknesses of 0.045 and 0.07 μm increase the wave amplitude by 1.15 and 1.4 times, respectively, relative to pure steel, which is associated with enhanced optical absorption and thin-film interference at the laser pump wavelength. Furthermore, the quasi-linear dependence of the stress wave amplitude on the laser pulse energy (0.7–1.5 J) indicates the absence of plasma shielding within this energy range. These findings suggest that controlled thermal oxidation can serve as an effective, clean absorptive coating to optimize laser shock peening (LSP) processes.

Two methods of accounting for the motion of the bodies—the deforming mesh method and the method of overlapping meshes (or overset mesh method)—are compared using problems with floating bodies, which are typical for the shipbuilding industry. Three problems are considered: oscillation of the cylinder on the water surface, movement of the box under the influence of waves, and heaving and pitching of the ship model in head waves. Numerical computations are carried out in the LOGOS software package, the simulation methodology used is based on the solution of a system of Reynolds-averaged Navier-Stokes equations, and the Volume of fluid (VOF) method to take into account the free surface. In all problems, the characteristics of the movement of bodies are evaluated; the resistance force of the ship model is also determined in the third problem; control values obtained using two methods of accounting for moving bodies are compared with the available experimental data. The results of numerical simulation have shown that both methods predict body movement parameters well; the accuracy in determining the resistance force in the task of streamlining the ship’s hull is also comparable: the difference between the maximum deviations of the resistance coefficient in the computations with deformation and overlapping computation meshes is 0.5%. In the case of computations of the three-dimensional problem, the time spent when using the mesh-deformation method turned out to be 10% more; therefore, the method of overlapping meshes can be considered more optimal when solving such shipbuilding tasks as self-propelled tests and streamlining the ship’s hull with and without wind and wave loads.

In the context of the digital transformation of industrial production, the need for intelligent maintenance and repair systems capable of ensuring reliable operation of machine-tool equipment without operator involvement is growing. This present study reviews the current state and future development of diagnostic and condition-monitoring systems for metalworking machine tools. A review of international standards and existing solutions from domestic and international vendors in vibration diagnostics has been conducted. Particular attention is paid to non-intrusive vibration diagnostics, digital twins, multiparametric analysis methods, and neural network approaches to failure prediction. The architecture of the developed system is presented. The concept of the system is developed in full compliance with Russian and international standards of vibration diagnostics. At its core, the comprehensive digital twin relies on machine learning methods. The proposed architecture is a predictive-maintenance system built on interconnected digital twin realizations: the dynamic machine passport of a unit, operational data, and a comprehensive digital twin of the machine-tool equipment. The potential of neuromorphic computing on a hardware platform is being considered as a promising element for local-condition classification and emergency protection. At the current development stage, the operating principle has been demonstrated along with the integration into the control loop. The system is now at the beginning of laboratory testing. It demonstrates capabilities for comprehensive assessment of the equipment’s technical condition based on multiparametric data, short-term vibration trend forecasting using a Long Short-Term Memory network, and state classification using a Multilayer Perceptron model. The results of the system’s testing on a turning machining center have been analyzed.

Under cyclic loading, almost immediately after its onset, a surface layer forms where hardening and softening processes occur. The interaction of plastic deformation traces with each other, and with other structural elements, leads to the formation of a characteristic microstructure on the surface of a component subjected to cyclic loading. The set of factors (conditions) acting during cyclic loading determines the nature of slip band accumulation, the integral structurally sensitive fatigue parameter, expressed as the slope of the left side of the fatigue curve linearized in logarithmic coordinates, and the location of the breaking point on the fatigue curve in the high-cycle region. A combined review of numerous data on the fatigue of metals, obtained under various combinations of factors, and the generalization of these results through a normalization procedure for obtaining the relative (recalculated) parameters of fatigue, allows us to derive a universal method for “S-N” curve prediction. However, extensive generalization decreases the prediction accuracy for specific cases; therefore, it is proposed to form limited generalized dependencies corresponding to specific operating conditions. This paper evaluates the accuracy of fatigue limit prediction using generalized and limited-generalized relationships of fatigue recalculated parameters for various fatigue curves obtained from independent experimental data.

Overhead power lines (OHPLs) represent the backbone of electric power systems and connect generation sources with consumers. The power supply reliability and maintenance costs of power grids largely depend on accurate fault location on OHPLs, as this significantly affects the speed of power supply restoration and reduces equipment downtime. This article proposes a new approach to fault location which includes the division of the OHPL bypass (inspection) zone into sections with subsequent implementation of a faulted section location procedure. This article substantiates the application of sequential multi-hypothesis analysis, which allows us to adapt the decision-making process regarding the OHPL faulted section to the peculiarities of emergency event oscillogram distortion and the conditions for estimating their parameters. According to the results of our calculations, it is noted that the application of sequential analysis practically does not affect the speed of OHPL fault location but does ensure unambiguity in decision making regarding the faulted section under the influence of random factors.

Modern software systems have implemented calculation techniques that allow numerical modeling of the icing of various aerodynamic objects and show themselves well when modeling the icing of objects at subsonic speeds. This paper describes a technique that is used to solve the problem of icing the profile of a NASA SC (2)-0714 airfoil streamlined by a supersonic gas stream. A feature of modeling this class of problems is the consideration of factors that arise when moving at high speeds: at supersonic flight speed, aerodynamic heating of the surface above 0 °C is observed, which is accompanied by a high intensity of impinging supercooled water droplets on this surface. The results of the numerical solution of the NASA SC (2)-0714 airfoil icing problem showed that even at a positive airfoil surface temperature, ice shapes can grow at the leading edge due to intense deposition of supercooled droplets.

This article presents the results of a study on the possibility of using a single-speed multiphase model with free surface allowance for simulating boiling and condensation processes. The simulation is based on the VOF method, which allows the position of the interphase boundary to be tracked. To increase the stability of the iterative procedure for numerically solving volume fraction transfer equations using a finite volume discretization method on arbitrary unstructured grids, the basic VOF method is been modified by writing these equations in a semi-divergent form. The models of Tanasawa, Lee, and Rohsenow are considered models of interphase mass transfer, in which the evaporated or condensed mass linearly depends on the difference between the local temperature and the saturation temperature with accuracy in empirical parameters. This paper calibrates these empirical parameters for each mass transfer model. The results of our study of the influence of the values of the empirical parameters of models on the intensity of boiling and evaporation, as well as on the dynamics of the interphase boundary, are presented. This research is based on Stefan’s problem of the movement of the interphase boundary due to the evaporation of a liquid and the problem of condensation of vapor bubbles water columns. As a result of a series of numerical experiments, it is shown that the average error in the position of the interfacial boundary for the Tanasawa and Lee models does not exceed 3–6%. For the Rohsenow model, the result is somewhat worse, since the interfacial boundary moves faster than it should move according to calculations based on analytical formulas. To investigate the possibility of condensation modeling, the results of a numerical solution of the problem of an emerging condensing vapor bubble are considered. A numerical assessment of its position in space and the shape and dynamics of changes in its diameter over time is carried out using the VOF method, taking into account the free surface. It is shown herein that the Tanasawa model has the highest accuracy for modeling the condensation process using a VOF method taking into account the free surface, while the Rohsenow model is most unstable and prone to deformation of the bubble shape. At the same time, the dynamics of bubble ascent are modeled by all three models. The results obtained confirm the fundamental possibility of using a VOF method to simulate the processes of boiling and condensation and taking into account the dynamics of the free surface. At the same time, the problem of the studied models of phase transitions is revealed, which consists of the need for individual selection of optimal values of empirical parameters for each specific task.

Electric vehicles (EVs) are the fastest-growing type of transport. Battery packs are a key component in EVs. Modern lithium-ion battery cells are characterized by low self-discharge current, high power density, and durability. At the same time, the battery management system (BMS) plays a pivotal role in ensuring high efficiency and durability of battery cells and packs. The BMS monitors and controls the battery charge and discharge to ensure EV safety and optimum operation. This paper is devoted to analyzing BMS circuitry configurations and algorithms. The analysis includes circuit solutions and algorithms for implementing the main BMS functions, such as parameter monitoring, protection, cell balancing, state estimation, charging and discharging management, communication, and data logging. The paper provides insights into the recent research literature on BMS, and the advantages and disadvantages of methods for implementing BMS functions are compared. The paper also discusses the application of artificial intelligence technologies and aspects of further work on next-generation BMS technologies.

In this paper numerical simulation of tsunami waves is carried out using data from the earthquake off the coast of Mindanao Island in the Philippine Sea on 23 December 2023 in the western part of the Pacific Ocean. The paper considers two scenarios of seismic source localization with different dynamics of the Earth's crust displacement in the seismic source region during the earthquake process. Consideration of two scenarios with different location of keyboard blocks, into which the earthquake source is segmented, allows one to study the influence of source geometry on the characteristics of generated tsunami waves. In the course of simulation, during dynamic displacement of keyboard blocks in the earthquake source, tsunami source formation, tsunami waves and their propagation in the Pacific Ocean water area take place. The wave characteristics of the process along the mainland and island zones in the considered water area were obtained. The results of simulation for the two scenarios are compared with observational data, which makes it possible to identify which type of block arrangement provides better similarity with the recorded tsunami characteristics and, therefore, better describes the real dynamics of the earthquake source.

The computational and experimental study results of swirling single-phase coolant motion and heat transfer for the standard operation parameters of a nuclear power plant are presented. The experimental model is a vertical heat exchanger of a “pipe in a pipe” type with the countercurrent movement of coolants. Six different swirlers (three with a constant twist pitch and three with a variable pitch) were considered. The heat exchanger temperature field was measured at various combinations of coolant flow rates, and a channel pressure drop for each swirl was determined. Computational studies were performed using the Omega-based Reynolds stress model and SST model with a correction for curvature streamlines. A good agreement between numerical and experimental data was obtained. Based on the velocity and temperature fields, swirling flow motion features in channels with a variable swirl pitch were discovered. For each intensifier, the effectiveness criterion in comparison with a pipe channel was determined.