“Naukovi Notatki” is a peer-reviewed, open-access journal (Category B) that publishes review articles and the results of original fundamental and applied research in the field of “Mechanical Engineering and Machine Building.” Scientific papers are published in the following specialties: G8 Materials Science; G9 Applied Mechanics; G11 Mechanical Engineering (by specialization)
Луцький національний технічний університет
RESEARCH ON THE MECHANICAL PROPERTIES AND HEAT RESISTANCE OF PLASTICIZED EPOXY COMPOSITES WITH MICROADDITIONALS
The article investigates the influence of microfillers on the mechanical and thermophysical properties of epoxy composites based on plasticized resin DER 331. As microfillers, chromium oxide Cr₂O₃ powders (20 μm) andsilicon carbide SiC (40 μm) were used with a content of 5 to 20 wt%. Mechanical properties were investigated: fracture stress and modulus of elasticity during bending, impact strength. Additionally, heat resistance tests of the developed materials were conducted. Comparative analysis of the effect of microfillers confirms the advantage of using chromium oxide compared to silicon carbide for improving the properties of epoxy composites. At a concentration of 10 wt.% chromium oxide provides 6.4% higher strength of materials (85.2 MPa vs. 80.1 MPa) and 17.6% higher modulus of elasticity (4 GPa vs. 3.4 GPa) compared to composites filled with silicon carbide. This advantage is due to better adhesion to the matrix and the ability to form physical, covalent and ionic bonds at the interface. The best results are characteristic of the material with chromium oxide, which at a content of 15 wt.% provides the formation of CM with values of tensile strength (88.3 MPa), elastic modulus (4.2 GPa) and heat resistance (364 K). The mechanism of improving the properties is that microdispersed particles form a structural framework that creates barriers to crack propagation (i.e., cohesive strengthening of the material occurs). For composites with Cr₂O₃, the formation of additional physicochemical bonds with the matrix is also key, which ensures the thermal stability of new materials.
mechanical and thermophysical properties
SYNTHESIS MODES OF CONVERSION PLASMA-ELECTROLYTIC COATINGS ON ZIRCONIUM BASIS AND THEIR CORROSION PROPERTIES
The aim of the work was to conduct a spectral analysis of electrolytic plasma. It was established that the plasma temperature in which the high-temperature oxide is formed is 8000 500 K. The influence of the electrolyte composition and the ratio of current densities on the electrophysical parameters of plasma-electrolytic oxidation was investigated. During the research, a study of corrosion resistance in such an aggressive environment as 10% HCl was conducted. As a result of the experiments, it was found that the obtained oxide-ceramic coatings are characterized by high microhardness and corrosion resistance.
INVESTIGATION OF DEFECTS AND DAMAGE IN TIMBER TRUSSES
The identification of defects and their timely remediation in structures in service constitute a key factor in ensuring the durability and reliability of buildings and civil engineering structures. This study presents the results of investigations of timber trusses that have been in long-term service. The most common defects and damage affecting truss members during operation are analysed. The research is based on the examination of ten different structures incorporating timber trusses with various geometric configurations. A statistical analysis of the frequency of occurrence of the identified defects and damage was carried out. The detected defects were compared with the defect classifications specified in relevant regulatory documents. The results indicate that almost all defect types listed in the regulatory literature are observed in structures employing timber trusses. In addition to the defects identified in the standards, additional types of damage were detected, including contamination of timber structural elements with bird droppings. Furthermore, a significant deficiency of timber trusses in service is the lack of documentation and the absence of systematic application of protective treatments. Of the defects identified, prolonged and repeated moisture exposure was found to have the most adverse impact on timber truss members, promoting fungal activity and subsequent wood decay. Decay of timber, especially in joint regions, results in a substantial reduction in the service life of timber trusses. The results of the study indicate that the most prevalent defects in timber truss members are longitudinal cracking due to wood shrinkage and corrosion of metal components in joint connections. The next most prevalent defect observed in timber trusses is the lack of information regarding treatment with protective agents (antiseptics and fire retardants). Given the frequent occurrence of timber infestation by wood-boring insects, as well as the necessity to comply with fire safety requirements, maintaining systematic and documented treatment of timber elements with protective substances is of critical importance.
FORMATION OF A MODEL FOR DETERMINING STRESSES IN METAL STRUCTURES UNDER THE INFLUENCE OF HYDROGEN CONCENTRATION
In modern industrial conditions, the issue of accurately predicting the operational resources of metal systems, in particular their durability and reliability, is becoming particularly acute. This is due to the complex combination of material corrosion degradation and constant mechanical stress. To date, the mechanisms of the relationship between hydrogen saturation and stress redistribution in metals have been studied fragmentarily. The process of hydrogen absorption causes deformation of the body structure, which manifests itself in a change in its linear parameters and total volume. Under appropriate conditions, such volumetric transformations become a source of internal forces. This paper considers a model in which the mutual influence of hydrogen atoms is considered negligible. The key objective of the study is to determine the parameters of the stress-strain state of an object resulting from the diffusion and accumulation of hydrogen in its structure.
COMPARATIVE ANALYSIS OF MACHINE LEARNING MODELS FOR PREDICTING CONCRETE COMPRESSIVE STRENGTH
This paper addresses the problem of predicting concrete compressive strength based on mixture composition using machine learning methods. A comparative analysis of linear regression, polynomial regression, artificial neural networks, and ensemble learning techniques was conducted using the publicly available Concrete Compressive Strength dataset. The results show that simple linear models are unable to adequately capture the complex non-linear physicochemical processes of cement hydration, while ensemble-based approaches provide a superior balance between accuracy and robustness. The best stable performance was achieved by the Random Forest algorithm, with a mean absolute error of 3.73 MPa. In addition, an empirical power-law formula was derived through linearization of a multiplicative model, enabling approximate strength estimation without computational resources. The findings confirm the effectiveness of ensemble and hybrid modeling approaches for practical engineering applications in construction materials science.
DETERMINATION OF THE IMPACT OF CLOSED-TYPE IMPELLER DESIGN ON THE EFFICIENCY OF INDUSTRIAL HEMP SEED SHELLING
The article presents the results of a study on the efficiency of the centrifugal dehulling method for industrial hemp seeds using a device equipped with a closed-sector impeller with four profiled radial channels. At an impeller rotational speed of 6000±200 rpm, the kernel yield in the first three cycles was 9.27%, 12.75%, and 7.86%, respectively, whereas the fourth and fifth cycles produced only 3.54% and 1.39%. The decrease in yield at later stages is explained by the increased strength of the seed hulls remaining after the previous cycles. The share of unhulled seeds gradually decreased from 71.24% after the first cycle to 1.90% after the fifth. The results indicate that limiting the number of dehulling cycles to three is advisable, as it significantly reduces operating costs without reducing kernel yield. The geometry of the radial channels (20×20 mm, 44 mm long), combined with a rotational speed of 6000 rpm, provided sufficient centrifugal acceleration for effective dehulling. Within the tested design, the configuration with four channels was recognized as a technically justified solution for the basic setup.
DEVELOPMENT OF AN ADAPTIVE UAV CONTROL METHOD BASED ON DEEP REINFORCEMENT LEARNING AND DOMAIN RANDOMIZATION
The paper addresses the problem of creating an adaptive control system for an unmanned aerial vehicle (UAV) to operate under conditions of stochastic uncertainty. An approach based on the Proximal Policy Optimization (PPO) algorithm using a domain randomization strategy for environmental parameters is proposed. A neural network structure and a reward function have been developed to ensure a balance between navigation accuracy and energy efficiency. The developed controller demonstrated the ability to adapt to payload mass changes (up to 20%) and external wind disturbances without the need for manual coefficient retuning. Comparative simulation results confirm the advantage of the proposed method over a classical PID controller: stabilization time is reduced by 1.5 times, and maximum deviation during disturbances is reduced by 40%.
STUDY OF MECHANICAL PROPERTIES AND STRUCTURE OF BIOMPOSITS FILLED WITH COFFEE GROUNDS
В статті досліджено міцність на стискання біокомпозитних матеріалів на основі глютинової матриці та кавової гущі залежно від вмісту наповнювача та ступеня підсушування композиції. Визначено міцність на стискання біокомпозитів залежно від концентрації біополімерної матриці, вмісту композиції в прес-формі, температури основної термічної обробки та додаткової термічної обробки. Досліджено, що максимальну міцність на стискання 79,6 МПа мають біокомпозитні матеріали із ступенем підсушування 20%. Також досліджено мікроструктуру біокомпозитів оптимального складу (вміст кавової гущі в кількості 200 мас. ч.) зі ступенем підсушування композиції 20%.
THE INFLUENCE OF METAKAOLIN COMPOSITION ON THE PROPERTIES OF THERMOPERLITE-BASED GEOPOLYMER COMPOSITES
Geopolymers are promising modern building materials, serving as an alternative to Portland cement-based concretes. Optimizing the chemical and granulometric composition of geopolymer components, particularly metakaolin, allows for controlling the hardening rate, increasing durability and mechanical properties, and adapting geopolymers to specific application conditions. This study analyzes metakaolin MK 40 and highly active metakaolin HAM, their chemical composition and particle distribution, as well as the influence of these factors on the properties of geopolymers.
REGULARITIES OF FORMING CUTTING PRESSURE ON THE AXIS OF THE ASSISTING GAS JET DURING GAS LASER CUTTING
The results of theoretical and experimental studies of the cutting pressure of the assist gas formed by subsonic and supersonic jets when they are decelerated on the surface of a part during gas laser cutting are presented. The patterns of influence of the gas type (air/oxygen), pressure at the nozzle inlet, gap between the nozzle and the part on the gas jet structure, and the efficiency of melt removal have been established. The obtained accurate quantitative data are in good agreement with the basic features of gas dynamics of supersonic jets. The high accuracy of the proposed numerical model has been experimentally confirmed. A high level of correlation between the quality of the cut and the nature of the cutting pressure fluctuations on the jet axis has been demonstrated.
ANALYTICAL METHOD FOR CALCULATING BENDING OF BEAMS OF VARIABLESTIFFNESS ON A NON-UNIFORM ELASTIC FOUNDATION
An analytical method for calculating beams of arbitrary continuous variable stiffness supported on a non-uniform continuous elastic Winkler foundation has been developed. The classical problem of calculating the bending of beams of constant stiffness supported on a constant elastic Winkler foundation is well studied. However, the assumption of the homogeneity of the foundation is far from reality and for more qualitative studies it is necessary to take into account the heterogeneity (variability) of the foundation. In this case, the bed coefficient will be variable along the beam axis, which significantly complicates the solution of the corresponding differential equation. The problem becomes even more complicated when not only the bed coefficient, but also the stiffness of the beam is variable. This is the case that this article is devoted to. The heterogeneity of the foundation is characterized by a variable linear bed coefficient, which can be any continuous function. The method is based on the exact solution of the corresponding differential equation with variable coefficients. In closed form, calculation formulas for the parameters of the stress-strain state of the beam are given. The calculation for the bending of a concrete beam in the form of a truncated wedge resting on an exponentially varying elastic base is given.
STATISTICAL ANALYSIS OF THE IMPACT OF ARCHITECTURAL DESIGN ON USERS’ PSYCHOLOGICAL STATE
This paper presents a statistical analysis of the impact of architectural design on users’ psychological well-being using A/B testing, a methodological approach introduced by the author. The study relies on synthetic datasets generated in Python and informed by empirical patterns reported in contemporary literature on A/B testing and environmental psychology. Three architectural parameters—color schemes, lighting type, and spatial configuration—were examined to determine their influence on stress, emotional comfort, and cognitive performance. Statistical techniques including t-tests, ANOVA, and regression modelling were applied. The results show that cool colors, natural lighting, and open layouts positively affect psychological well-being. These findings demonstrate the importance of incorporating evidence-based statistical methods into architectural design practice.
DEVELOPMENT OF A MULTI-STAGE INNOVATIVE TECHNOLOGY FOR COMBINED CLEANING OF MINIATURE AND PRECISION BALL BEARINGS
The article presents the development of a multi-stage technology for combined cleaning of miniature and precision rolling bearings, which was developed based on the results of comprehensive experimental studies of miniature and precision ball bearings with an outer diameter of up to 30 mm (classes P4/P2). Such bearings are critical elements of high-tech mechanical systems, which is especially relevant in the aviation, space and special high-precision industries. For miniature rolling bearings, the need to achieve the 12th class of cleanliness according to ISO 16232, where the remaining particles of contaminants with a size of ≥ 5 μm do not exceed 60 pieces, has been established as a critical condition for ensuring operational characteristics. It has been experimentally established that when developing a cleaning technology, the optimal cleaning angle should be 30o–45o, and the rotation speed should be 500 rpm. During the development, technological parameters were optimized, including: magnetic separation (0.5 T), dual-frequency ultrasonic cleaning in a turbulent flow of solvent D-60, final washing with Heptane using vacuum drying. The confirmed cleaning efficiency η ≈ 96.7% ensures the preservation of vibroacoustic parameters and economic feasibility by avoiding expensive operational failures.
RESULTS OF RESEARCH ON THE MATHEMATICAL MODEL OF AN AXIAL-PISTON HYDRAULIC MACHINE WITH A DEFECT IN THE PISTON PART
The paper presents research on a mathematical model of an axial piston hydraulic machine with a defect in the piston part with specified defect dimensions.
PROSPECTS OF PRE-HARVEST MONITORING OF FLAX CROPS USING UNMANNED AERIAL VEHICLES
Modern agricultural monitoring approaches require increased efficiency and accuracy in assessing crop conditions during the pre-harvest period. This paper presents an algorithm for comprehensive assessment of the flax crop stand condition prior to harvesting, based on the integration of data obtained using unmanned aerial vehicles and results from traditional field and laboratory measurements. A mathematical model of an integrated indicator describing the flax crop stand condition is developed, incorporating key agronomic, technological, and biological parameters. Furthermore, an approach for generating digital field maps with mapped values of the integrated crop stand condition index is proposed, enabling visualization of the quality of the flax crop stand within fields. The resulting information enables well-founded decisions on optimal harvesting dates, selection of appropriate harvesting technologies, and optimization of harvesting machinery settings. The proposed methodology is applicable to both fiber flax and oilseed flax and contributes to improving harvesting efficiency and overall crop management.
MODELING THE PLASTIC BEHAVIOR OF A POROUS MATERIAL WITH AN INVERSE OPAL STRUCTURE AT LARGE DEFORMATION
By means of finite element modeling on a representative cell, the process of irreversible plastic deformation of a porous material with an inverse opal structure was investigated up to the moment when the pore structure becomes almost completely closed. This is important for predicting the preservation of the adsorption and chemical-catalytic functional properties of inverse opal materials during operation and pressure treatment. It was found that the structure of inverse opal retains permeable porous structure even under fairly large deformations. A significant discrepancy was found between the engineering yield criterion of 0.2% residual strain and the physical yield point.
АUTOMATED DESIGN OF ELECTRICAL SYSTEMS IN THE FOOD INDUSTRY: SOLIDWORKS ELECTRICAL, EPLAN ELECTRIC P8 AND AUTOCAD ELECTRICAL
This article provides a comparative analysis of modern ECAD systems used for automated design of electrical circuits in the food industry. It examines the architecture and functionality of SolidWorks Electrical, EPLAN Electric P8, and AutoCAD Electrical, and provides practical examples of their use in manufacturing processes and educational institutions. SolidWorks Electrical provides ECAD/MCAD integration, EPLAN Electric P8 is characterized by a high level of standardization and automation, and AutoCAD Electrical is accessible and efficient for local control systems. The development prospects for ECAD solutions in the context of Industry 4.0 are identified, including integration with cloud services, IoT, and digital twins.
FUNCTIONAL ROLE OF DIVIDERS IN HARVESTING LODGED FLAX
Lodged flax remains one of the most critical challenges in mechanized harvesting due to stem interlocking, ground-level deformation, and the high elasticity of flax stems. While the functional role of crop dividers in fiber flax pulling systems is well described in classical literature, little attention has been paid to their applicability in harvesting modern oilseed flax, whose increasing plant height and density lead to stem-flow behaviour similar to lodged fiber flax. This paper presents an analytical evaluation of divider designs, synthesizing findings from recent engineering studies and technical documentation. The mechanisms of stem separation, lifting forces, and controlled pre-bending are examined to clarify how divider affect feeding stability and harvesting quality. Particular emphasis is placed on comparing rigid and spring-loaded dividers and identifying their performance under varying lodging conditions. The analysis demonstrates that dividers significantly improve the completeness of stem capture, reduce bending-induced damage, and stabilize crop flow not only in fiber flax pulling but also in cutting-based oilseed flax systems. Design implications are formulated to guide the integration of divider into modern flax harvesters, including adjustable height settings, flexible mounting, optimized nose curvature, and low-friction surfaces. The findings highlight that crop dividers should be considered a functional component for both flax categories, with direct impact on harvesting efficiency, ribbon uniformity, and material preservation.
SOME ASPECTS OF THE THEORY OF DEFECT ANNEALING IN IRRADIATED CdSb CRYSTALS
The processes of formation and rearrangement of radiation defects during irradiation and annealing can be considered as a set of quasichemical reactions of different orders. Some of them are difficult to reduce to a form that would allow analyzing the time dependence of the defect concentration during annealing. An important parameter that determines the kinetics of defect annealing is the annealing activation energy. There are many methods for determining this energy. We used the cross-section method, which is based on the analysis of Arrhenius curves at different annealing temperatures. To determine the thermal stability region of radiation defects, the isochronal annealing method was used.
CHECKING THE COMPATIBILITY OF THE PRINCIPLES OF THE SPECIAL THEORY OF RELATIVITY
The apparatus of the special theory of relativity (SR) is the basis for the study of both micro- and mega-world [1]. Astronomical observations and calculations, including the ΛCDM-model of the Universe [2], have revealed new types of matter - dark matter, which have no means of description in space-time. By means of precision measurements of the anisotropy of the cosmic microwave background (CMB), J. Smoot [3] reliably registered an unobservable directly distinguished direction in the Galaxy [4] . Additional study requires the violation of the principle of equivalence of by A. Einstein of the mass and energy particles in SR. Based on the results of these studies, one can assume the redundancy (or a broader interpretation) of some of the postulates of the SR, the re-verification of which is the purpose of this work. The paper [5] presents a comparison between the SR apparatus and test theories (including the Robertson and Mansouri-Sext theories), which are an extended Lorentz transformation [1] with additional parameters. It turned out that the theories used did not in any way dispute the SR. With the help of relativistic wave mechanics, P. Dirac showed [6] that the 4 momentum space of particles is adequate to relativistic mechanics. In [7], the approach proposed by P. Dirac was extended to another method for checking SR – in Euclidean 4 space, in which directly unobservable particles can also be described. It is shown that the reason for the discrepancy between the SR apparatus and the equivalence principle is the low dimension of the momentum space. Restrictions imposed by the law of conservation of energy on the principle of superposition of particle momentum are revealed, and the indeterminacy of particle interaction is pointed out. The uniqueness in relativistic mechanics of the selected reference system and the properties of dark particles of matter and energy is taken into account. It is shown that the use of the principle of general covariance leads to a different course of time in different frames of reference. The concept of a non-planar dissipative interaction node is introduced, without which it is impossible to build a dynamic apparatus in Euclidean space.
DETERMINATION OF THE CAPACITY OF A COMBINED COMPENSATOR BY THE OPERATION OF THE SOLUTION ACCUMULATION OF A SINGLE-PISTON HYDRAULIC MORTAR PUMP
Analysis of modern pumps indicates the search for ways to simplify their designs and improve the basic scheme of single-piston mortar pumps while minimizing pulsations in the pipeline during the transportation of building mortars. Reducing pressure pulsations in modern single-piston mortar pumps is ensured by the use of pressure compensators in the form of air caps of various volumes. But air compensators, while performing their function along with advantages, have significant disadvantages, namely: the volume of compressed air that is in direct contact with the pumped solution is intensively removed from the compensator during the operation of the mortar pump. Especially the intensity of air removal increases at the pressure of the solution supply (above 1.5 MPa). In this case, the useful volume of the compensator decreases, the efficiency of the solution accumulation of the compensator significantly decreases, and the degree of solution pulsations increases proportionally. The article analyzes the work and mathematically substantiates the determination of the useful volume based on the rules of gas behavior in the isothermal process of a new design of a combined compensator of increased efficiency in reducing the degree of pressure pulsations during pumping of mortars of different mobility by a hydraulically driven single-piston mortar pump.
BUILDING A FASHION BRAND BASED ON SUSTAINABLE DEVELOPMENT PRINCIPLES
The article examines the theoretical and practical foundations of building a fashion brand on the principles of sustainable development. It analyzes contemporary approaches to sustainable branding, including the concepts of slow fashion, the circular economy, and international environmental certification standards. The study summarizes behavioral factors that influence consumer loyalty to sustainable brands and identifies the key barriers to implementing sustainable practices in the fashion industry. Particular attention is paid to the characteristics of textile materials in terms of their environmental impact and recyclability. A comparative analysis of the recyclability of major fiber groups is presented, and design principles for sustainable garments are systematized, including modularity, repairability, zero-waste design, mono-materiality, and durability. Based on these principles, a men’s clothing collection was developed, demonstrating the practical application of eco-design solutions. The results show that integrating eco-friendly materials, responsible technologies, and carefully considered construction can improve functionality, reduce resource intensity, and extend the product life cycle. The study highlights the necessity of a holistic approach to sustainable branding that encompasses not only the product and materials, but also communication, production processes, consumer behavior, and business models.
SUBSTITUTION OF THE LIMIT STATE CRITERIUM OF GAS PIPELINE STEEL DURING THEIR REPROFILING FOR HYDROGEN
Long-term operation of natural gas transmission pipelines causes a significant decrease in the initial mechanical characteristics of pipeline steels. The influence of operating conditions of hydrogen uptake by natural gas pipeline steels on their degradation in terms of resistance to brittle fracture is analyzed. The criterion for achieving a limit state of steels in terms of crack growth resistance considering the operational degradation, hydrogen charging conditions, gas pressure in the pipe and the presence of crack-like defects is substantiated. The obtained results can be used for assessment the serviceability of gas transit pipeline steels reprofiling for gaseous hydrogen transportation.
FE SIMULATIONS OF THE STATIC DEFORMED STATE OF ATHEROSCLEROTIC VESSELS BASED ON OCT IMAGE DATA
This study focuses on the biomechanical modeling of atherosclerotic vessels to predict the risk of plaque rupture, a primary cause of acute cardiovascular events. A methodology integrating clinical Optical Coherence Tomography (OCT) imaging with Finite Element Analysis (FEA) is proposed. An automated Python-based algorithm was developed to reconstruct patient-specific geometries of vessel layers (intima, media, adventitia) and plaque components directly from OCT images. Numerical simulations were conducted for three different plaques cases under physiological pressure. The results revealed that maximum stresses are consistently localized at the plaque shoulders. The proposed approach provides a quantitative tool for assessing plaque vulnerability beyond geometric analysis.
RESEARCH OF THE STRUCTURE OF EPOXY COMPOSITES BY OPTICAL MICROSCOPY AND IR-SPECTRAL ANALYSIS
For the formation of polymer materials, the epoxy dian oligomer ED-20 was used, and its polymerization was performed using the amine hardener polyethylenepolyamine PEPA. The properties of epoxy composites were improved by using a mixture of discrete fibers based on polyester, viscose, and elastane, the content of which was varied within q = 0.25…2.00 wt.%. In this work, the nature of surface destruction in epoxy composites was investigated using optical microscopy, which enabled us to determine the interaction features between ingredients and the resistance of the developed materials to shock loads. Additionally, the interfacial interaction of the composite ingredients was investigated using the IR spectral analysis method. A change in the intensity parameters (T, %), relative peak area (S, %), as well as insignificant shifts in wave numbers (Δν, cm-1) was established, which corresponds to vibrations of the groups: -NН-, О-Н (ν = 3408 cm-1), С-Н, (ν = 2922…2848 cm–1), С=О (ν = 2019 cm–1), polyester component (ν = 1700 cm–1), С–О–С (ν = 1112…914 cm–1) and indicates structural transformations during polymerization of the composite ingredients.
STRETCHING OF A PLATE WITH A HOLE AND A RADIAL CRACK, THE CONTINUATION OF WHICH FORMED PLASTIC ZONES USING TRESCA-SAINT-VENANT PLASTICITY CONDITION
The work presents a solution to the problem of the stretching of an infinite isotropic plate with a circular hole and a radial through straight crack. It was assumed that under the action of an external load at infinity, on the crack extension the plastic zones are formed, modeled using Tresca-Saint-Venant plasticity conditions. The solution of the problem is built using the method of the theory of functions of a complex variable and complex potentials and is reduced to a system of singular integral equations, which is numerically solved using the method of mechanical quadrature. A numerical analysis of the problem is conducted and graphic dependencies of the length of the plastic zones and applied external loads were constructed
PROBABILISTIC MODELS FOR THE ANALYSIS AND PREDITION OF THE DURABILITY OF ARCHITECTURAL STRUCTURES
This paper examines the application of probabilistic models for the analysis and prediction of the durability of architectural structures under uncertainty in material properties and operational conditions. The research methodology is based on reliability theory and time-to-failure analysis, with particular emphasis on the Weibull and lognormal distributions, which are widely used to describe degradation processes in building materials and structural systems. The study employs synthetic datasets generated on the basis of empirical results reported in previous investigations of the durability of concrete and structural materials. Structural reliability methods and Monte Carlo simulation are applied to estimate failure probabilities and to predict the service life of architectural objects. The results demonstrate the effectiveness of the probabilistic approach for quantitative assessment of degradation risks and enable the estimation of expected service life while accounting for the variability of influencing factors. The proposed methodology can be used as a decision-support tool in the design process and in the reliability assessment of architectural structures.
STRUCTURE OF HIGH-ENTROPY AlNiCrTiB ALLOY AFTER HIGH-SPEED ELECTRON-BEAM HEAT TREATMENT
In this study, the structure and phase composition of lightweight high-entropy AlNiCrTiB alloy produced by mechanical alloying followed by electron-beam treatment were investigated. The in-situ formation of TiB and Cr2B3 boride phases during high-temperature exposure was confirmed. It was shown that remelting of the surface layer leads to the formation of a metallic matrix containing large, , edged boride inclusions, whereas more uniform heating at lower temperatures promotes the growth of finely dispersed TiB particles through the interaction of titanium with boron. A thin TiB-enriched transition layer forms between the remelted surface and the inner regions, facilitating the development of a homogeneous composite structure composed of a metallic matrix reinforced with dispersed boride inclusions.
ВПЛИВ ВМІСТУ ВОЛЬФАРМУ НА ЗАКОНОМІРНОСТІ ФОРМУВАННЯ МІКРОСТРУКТУРИ ТА ФАЗОВОГО СКЛАДУ ПОРОШКІВ СПЛАВУ WXFECONI ПІД ЧАС МЕХАНІЧНОГО ЛЕГУВАННЯ
This work investigates the synthesis of heavy high-entropy alloys WₓFeCoNi (x = 1, 1.5, 2) produced by mechanical alloying in a gasoline medium. It is shown that the equiatomic alloy WFeCoNi forms a dual-phase BCC/FCC structure without intermetallic compounds, whereas increasing the tungsten content to x = 1.5 reduces the configurational mixing entropy and enhances phase segregation. For the composition x = 2, the formation of tungsten carbide (WC) is established, resulting from the exceeded carbon solubility limit and the diffusion activation occurring during milling. The obtained results highlight the importance of controlling the W concentration and mechanical alloying conditions to tailor the microstructure and phase stability of heavy HEAs, which is promising for applications in high-temperature and highly loaded components.
ANALYSIS OF THERMOMECHANICAL COMPATIBILITY OF PHASES IN MULTILAYER MOSI2–MEB2–(TI, MO) COATINGS
This work presents a finite element study of the thermomechanical compatibility of multilayer gradient coatings MoSi₂–MeB₂–(Mo, Ti) on an Inconel 718 substrate. The stress and deformation fields in the coatings were analyzed during cooling from 1000 °C to 20 °C. Coatings with Mo as the buffer layer showed high stability at elevated temperatures, while Ti as a buffer improved plastic accommodation but increased residual stresses in some layers. Among the studied compositions, MoSi₂–ZrB₂–10 SiC–Mo demonstrated the lowest stress levels (~100 MPa) and the highest thermomechanical stability under cyclic thermal loading. The results highlight the importance of selecting appropriate barrier and buffer layers to minimize thermal stresses and ensure coating integrity in high-temperature applications.