Introduction. The actual technical condition of Ukraine’s critical transport infrastructure facilities is a retrospective indicator of the problem of maintenance and operation. The primary task during the restoration of transport infrastructure facilities is to compile a defect list for each facility in order to further develop design solutions and prepare design and cost documentation. The rate of degradation and its patterns directly affect the final cost of restoring transport structures. Determining the technical condition of transport structures, accompanied by an analysis of the condition of structural elements and operating conditions, makes it possible to effectively select technological solutions and construction materials for repair works, taking into account the study of degradation patterns to ensure acceptable reliability and durability, which is a global scientific issue of today. The application of numerical modeling to determine the load-carrying capacity of a bridge is an urgent prerequisite for clarifying its operational condition, as well as for predicting its reliability and durability as a function of time. Problem Statement. It has been established that there is a substantiated need to carry out numerical modeling of the bridge’s load-carrying capacity, taking into account corrosion processes, in order to assess its residual service life. Objectives. The aim of this research is to calculate the load-carrying capacity of the bridge using the finite element method based on the results of a special detailed inspection of the bridge over the Guiva River on Lomonosova Street in Andrushivka, Zhytomyr Region. Results. The study established a pattern of loss of load-carrying capacity of a steel–reinforced concrete road bridge, taking into account the weakening of truss elements due to corrosion processes. Furthermore, based on the results obtained, the technical condition of the structure was determined; an assessment of the loss of load-carrying capacity in accordance with the identified defects and operational condition was carried out; the residual service life was evaluated; proposals for eliminating defects and damages were provided; and a conclusion regarding the feasibility of new construction was formulated. Conclusions. The study presents numerical modeling of the bridge’s load-carrying capacity, taking into account corrosion processes, based on the results of a special detailed inspection.

Local High-Pressure Torsion (L-HPT) is a recently developed technological process that induces severe plastic deformation (SPD) within a boundary layer (BL) beneath a slowly rotating punch pressed against a metallic plate. In contrast to conventional high-pressure torsion (HPT), where the severe plastic deformation zone extends through the entire thickness of the processed metallic disk, the depth of such a zone and its microstructure after L-HPT are not known in advance and have not been previously investigated. Such novel results, obtained using scanning electron microscopy and nanoindentation, are presented in this work for an AA5083 aluminum alloy as a model system. Unlike conventional dry friction conditions, where BL thickness typically does not exceed 10 μm, electron backscatter diffraction (EBSD) measurements have revealed that the BL with an ultrafine-grained (UFG) structure that develops near the contact interface between an AA5083 aluminum alloy sample and a rotating punch can reach the thickness of up to 500 μm, starting from about 2 mm distance from the rotation center. A gradient microstructure is observed in this region, with an average grain size of about 100–200 nm in the layer immediately adjacent to the punch surface with a thickness of about 50 μm. Within this layer, a Mackenzie-type random misorientation distribution is identified, associated with extreme shear strain and saturation flow stress. This is accompanied by a slightly noticeable trend toward an increase in nanohardness in the vicinity of the contact surface. The discussion of the experimental results encompasses analytical description and finite element simulation.

In the light of recent developments in the design of structural materials, micro-architected heterogenous-structure metals are considered among most structurally efficient. In this work, a new technique for Local High Pressure Torsion (L-HPT) enabling the creation of heterogeneous structures through localised deformation processing in sheet metals by impeding a rotating punch is proposed. Using AA5083 aluminium alloy as an example, we show experimentally that the rotation of the punch sets adjacent material layers in motion. This results in more than two-fold increase in material hardness over initial level in the workpiece bulk with rather sharp gradients in hardness level transition. The maximum hardness is observed at the peripheral edge of a punch tip. Finite-element modelling of the L-HPT process confirmed that the rotational flow of workpiece material leads to the accumulation of shear strain. The level of accumulated strain increases with an increase in friction at the contact surface. Further analysis based on dimensionality theory revealed that for such an L-HPT configuration the level of equivalent strain is directly proportional to the ratio of rotation-to-translation speeds at the punch.

The study examines the impact of the technical condition of asphalt-concrete pavement on the stress-strain state of the bridge superstructure. It compares theoretical design loads with the actual movement of heavy vehicles. It is noted that, while the technical condition of the road surface is understandably not considered for design loads, it significantly influences the forces generated by actual heavy vehicles. The state of the asphalt-concrete pavement plays a crucial role in the bridge's response to real traffic conditions.

Problem. Today, the initial project of the bridge may not meet the existing conditions of operation of the structure due to socio-economic and socio-technical developments, which will require the need to increase the level of maintenance of the bridge. Goal. The goal is technical and economic substantiation of the new construction of a bridge across the Chornoguzka River, Golyshiv - Korshovets, in the Lutsk district, Volyn region. Methodology. Calculation of classes of consequences was carried out, engineering and geological surveys were performed. Results. Technical solutions have been developed on the basis of the conducted research. Originality. The work offers both traditional approaches to solving the given problem using modern reinforced concrete structures and the use of progressive technologies using metal corrugated structures. Practical value. The work considers the most rational solutions of the given task with the analysis of the positive and negative sides of the selected ones, which makes it possible to analyze the most appropriate solution.

Abstract. The parameters of a car wheel and its pneumatic tire, in particular, significantly affect both the dynamics of the vehicle and the nature of its interaction with the road surface. This is explained by the fact that the pneumatic tire of a car wheel is the final element of the car structure which directly interacts with the road surface and transfers all forces and moments (acting in the contact patch with the bearing surface) to its suspension and steering. So, on the one hand, the parameters of the interaction of the car wheel with the bearing surface largely determine the controllability and stability of the car, the passability and smoothness of the ride, the fuel economy and the efficiency of the vehicle use in general, etc.; on the other hand, the level of negative impact of the vehicle on the road surface. Accordingly, the parameters of the car wheel and its interaction with the bearing surface are necessary both in the study of the movement of motor vehicles and in the calculation of road wear. This article presents the results of experimental studies on the determination of the radial stiffness of the pneumatic tire 175/70 R 13 82 T (internal pressure 0.2 MPa) and the size of its contact spot with the support surface at different values of the vertical load on the car wheel. The presented research was carried out within the framework of the project "Development of a load model based on the actual parameters of heavy-duty rolling stock to determine the load-carrying capacity of road bridges during their restoration and operation in the war and post-war periods" under the competition "Science for the reconstruction of Ukraine in the war and post-war periods" the grant support account of the National Research Fund of Ukraine. Keywords: car wheel, pneumatic tire, tire radial stiffness, contact patch between the tire and the supporting surface, road surface, bridge crossing.

The article discusses the durability and reliability of a separate element – bridge approach slab, which is justified by the need to maintain a satisfactory technical condition of Ukrainian bridges in general and traffic safety on public roads with limited funding during martial law. The scope of the research is forecasting the residual service life of bridge elements (on the example of approach slabs) using probabilistic methods. Approach slabs are designed to smoothly and safely connect the road approach embankment with the bridge to gradually equalize the elastic modulus of the carriageway from a less rigid asphalt pavement on an elastic base to a more rigid one on a reinforced concrete slab. The main defects in the destruction of approach slabs are: changes in the longitudinal profile of the road due to the collapse and subsidence of the soil under the approach slabs; longitudinal and transverse cracks in the asphalt concrete pavement on the bridge approaches; and potholes that lead to an increase in the additional dynamic load on the bridge deck.

The mechanism of structural evolution of a three-layer Cu-Mo-Cu laminate under high-pressure torsion (HPT) was studied using scanning and transmission electron microscopy, atom probe tomography, and nanoindentation, complemented with finite element calculations. The results demonstrate a gradual refinement of the structure of the Mo component; a greater degree of refinement is observed in the peripheral part of the disk-shaped HPT specimen, although some heterogeneity of the structure remains even at a gigantic degree of shear deformation accumulated therein. The elemental distribution calculated from STEM-EDX mapping as well as 3D reconstruction of atom probe tomography results shows a significant degree of mixing of the sample components at the atomic level, the concentration of copper in molybdenum and molybdenum in copper reaching ∼4.3 at. % and ∼6 at. %., respectively. These observations correlate with nanoindentation results showing an increase in the hardness of both phases due to strain hardening and solid solution strengthening, as well as grain refinement. Numerical simulations made it possible to provide a detailed description of the stages of the structure fragmentation, including its self-organizing nature, to show the formation of rupture forerunners in the hard Mo layer, and the deformation of harder fragments in a softer matrix. The experimental results are supported by a model assuming a fractal self-organization of a self-similar structure during HPT processing.

This article presents a study aimed at identifying typical deformations of the road surface and determining their geometric parameters. These deformations not only affect the nature of the movement of motor vehicles, but also cause excessive dynamic loads on road bridges. Various methods are used in the research process, including measurement of vehicle movement parameters, diagnosis of bridge deck defects. Special attention is paid to the study of the impact of these defects on the traffic mode of vehicles and their impact on load-bearing bridge structures. The results obtained in the article are based on the combination and analysis of information received from specialists in the fields of road construction and automobile manufacturing. These results are the basis for mathematical modeling of the movement of heavy vehicles on bridges with damaged road surfaces.

The article presents a theoretical study of the regimes of high-pressure torsion (HPT) for which slippage of the deforming material on the interfaces with anvils is possible. The approach taken is a generalisation of the currently accepted view of the HPT process. It enables a rational explanation of its salient features and the effects observed experimentally. These include a lag in the rotation angle of the specimen behind that of the anvils, an outflow of the material from the deformation zone, enhancement in gripping the specimen with anvils with increasing axial pressure, etc. A generalised condition for gripping the specimen with anvils, providing a basis for an analytical investigation of the HPT deformation at a qualitative level, is established. The results of the analytical modelling are supported by finite-element calculations. It is shown that for friction stress below the shear stress of the specimen material (i.e., for the friction factor m < 1), plastic deformation is furnished by non-shear flows, which expands the range of possible process regimes. The potential of these flow modes is impressive, which is reflected in the second meaning of the word “gripping” in the title of the article. Non-shear flows manifest themselves in the spreading of the material over the anvil surfaces whose cessation signifies the end of deformation and the beginning of slippage of the specimen as a whole. The model shows that for m < 1 such a finale is inevitable at any axial pressure. It predicts, however, that the highest achievable strain is increased when the axial pressure is raised in the course of the HPT process. Unlimited deformation of the specimen is only possible for m = 1, when slippage of the deforming material relative to the anvils is suppressed.

The article conducts a study to identify typical pavement defects and their geometric parameters that affect the nature of vehicle traffic and lead to excessive dynamic loads on road bridges not provided for by the design. Various research methods are used, including measurement of vehicle movement parameters, vehicle movement theory, diagnostics of bridge deck defects, and analysis of the impact of defects on automotive equipment. Accordingly, the results obtained in the article are based on the combination and analysis of information from specialists in road construction and automotive engineering. The results obtained can be used in mathematical modeling of the movement of vehicles over road bridges with defects and damage to the road surface.

Бейгельзімер Я. Ю., Кулагін Р. Ю., Естрін Ю. З., Давиденко О. А., Дмитренко В. Ю. Литоподібні архітектури, сформовані методами інтенсивної пластичної деформації Одна з найбільш ефективних концепцій сучасного матеріалознавства - матеріали з внутрішньою архітектурою (architectured materials), полягає в максимально можливому використанні тих резервів, які надає структура матеріалу по формуванню його властивостей. У статті описаний новий підхід до створення таких матеріалів, заснований на тому, що композиції з різних металів піддають великому зсуву під високим тиском. Для цього використовують добре розвинені в даний час методи інтенсивної пластичної деформації (ІПД): кручення під високим тиском, рівноканальне кутове пресування, гвинтова екструзія тощо. Дослідниками показано, що ІПД-обробка призводить до міцного з'єднання компонентів композиції між собою та контрольованого формування в ній мультімасштабних структур. На нижньому масштабному рівні створюються наноструктури, головним елементом яких є нерівноважні висококутові границі зерен, товщиною близько 1 нм. На проміжних масштабних рівнях, з характерним розміром елементів порядку 1-100 мкм, формуються мезоструктури, подібні до тих, що спостерігаються в літосфері землі: складки, будини, вихрові структури, кінк-бенди, смуги зсуву та ін. Звідси і назва нового підходу - літоміметіка. Є підстави вважати, що на цьому шляху можуть бути створені нові матеріали з високою в'язкістю руйнування і з властивостями, які зазвичай разом непоєднувані, наприклад: високою міцністю, високою пластичністю, низьким модулем Юнга, малою густиною, гарною біосумісністю та ін.

The plastic deformation of Al-3.8 at.% Li polycrystals processed by the equal-channel angular hydroextrusion (ECAH) were investigated during tension in the temperature range of 4.2-400 K. The evolution of the microstructure during loading was studied by the electron backscatter diffraction (EBSD) method, including the orientation and kernel average misorientation (KAM) mappings. In as-prepared state the microstructure characterized by grains with small misorientation angles and a high density of dislocations. The deformation of a sample at 120 K leads to increase in the density of deformation defects while at 290 K to their decrease. The strong temperature sensitivity of the yield strength indicates the thermally activated nature of the plastic deformation. An increase in the plasticity and strength of polycrystals with decreasing temperature is explained by a decrease in the dislocation annihilation due to a decrease in the mobility of atoms, resulting in increase in the strain hardening rate. A nonmonotonic dependence of the activation volume Va(T) with a maximum at 180 K was established from stress relaxation data. The analysis of stress-strain curves and microstructure evolution indicate a dominance of thermally activated mechanism of intersection of the forest dislocations below 180 K and an increase in the activity of recovery processes at moderate temperatures.

The problem of water drainage from the carriageway and from the base layers of road pavement of the highway remains relevant worldwide. Gravel or sand layers, as well as geotextile and geocomposite layers are mainly used. Selection of parameters of tubular drainage structures of shallow laying is mainly carried out by an analytical method. This is explained by the difficulty of creating numerical models for predicting the stress-strain state of the road structure, taking into account the physical and mechanical properties of the subgrade elements saturated with water. The lack of a methodology for modelling a road structure with shallow drainage in software complexes based on the finite element method makes it difficult to obtain and analyse the stress-strain state of the structure and the subsequent selection of parameters of shallow tubular drainage. Keywords: road pavement, shallow drainage, subgrade, stress-strain state, numerical model.

The plastic deformation of Al-3.8 at.% Li polycrystals prepared by the equal-channel angular hydroextrusion ECAH were investigated during tension in the temperature range of 4.2-400 K. The evolution of the microstructure was studied by the electron backscatter diffraction (EBSD) method, including the orientation and kernel average misorientation (KAM) mappings. It has been established that such treatment forms a microstructure characterized by grain with small misorientation angles and a high density of dislocations. The elongation of the grains and texture features indicate the incompleteness of the grain structure fragmentation processes after 6 passes of ECAH. It was shown that the deformation of a sample at 120 K leads to increasing the density of deformation defects and to their decreasing at 290 K. The average grain size decreases with deformation induced by proceeding, and this effect stronger at lower deformation temperature. The strong temperature sensitivity of the yield strength indicates the thermally activated nature of the plastic deformation. An increase in the plasticity and strength of polycrystals with decreasing temperature is explained by a decrease in the dislocation annihilation due to a decrease in the mobility of atoms, resulting in increase in the strain hardening rate. A nonmonotonic dependence of the activation volume Va(T) with a maximum at 180 K was established from stress relaxation data. The results of the mechanical tests and microstructure analysis indicate a dominance of thermally activated mechanism of intersection of the forest dislocations below 180 K and an increase in the activity of recovery processes at moderate temperatures.

The article is devoted to the pressing problem of managing the reliability and durability of transport constructions. Modern scientific approaches to assessing the technical condition of transport facilities based on an analysis of element degradation during the life cycle of operation considered. The article presents the advantages and disadvantages of the most common prediction models of the technical condition of building structures. Each model uses a characteristic criterion for degradation of building structures: load and unload cycles, rejection number of chlorides, intensity coefficient, a geometric parameter (parameters) of the crack in the material, reliability, etc. The problem of choosing the control parameter of the lifecycle model of the bridge elements is analyzed. The theoretical basis for the Markov phenomenological model of damage accumulation and the model of degradation based on the physical and mechanical characteristics of the material formulated. Depending on the stage of the life cycle, it is proposed to select the type of prediction model.

The processes forming the humidity mode of the drainage layer of a road structure under the action of excess load have been investigated. The stressed-strained state was determined based on a numerical experiment using the software-calculation suite SCAD Office. The numerical modeling of the examined structure involved the static load of the А2 group for a road of category II. A series of numerical experiments were performed, which included an increase in the rated load by 10–50 % when overwetting the drainage layer and the earth bed. The distribution of the isofields and isolines of normal stresses and deformations in the volumetric elements was derived, which made it possible to determine the thickness of the soil layer of the earth bed, 0.67 m, from which water is squeezed out under the influence of excess loading. Based on the approach for determining the parameters of soil subsidence at its drying or freezing, the dependences were established for the relative subsidence of soil, the coefficients of linear subsidence and compaction of soil under the influence of excess load. The proposed dependences integrate such indicators as the deformation below a drainage layer, the depth of stress spread, at which water is not squeezed out from soil, the optimum humidity, and the full moisture content of the soil. Based on the results of numerical experiments and soil subsidence parameters, the amount of water squeezed out from a layer of soil under the influence of excess load has been determined, which is 5.4 liters per m2. The results obtained make it possible to adjust the value of the total specific excess water flowing into a drainage structure. Taking into consideration the squeezing out of water from an earth bed from a soil layer under the influence of excess load from a wheel of 86.25 kN, the general specific excess could vary in the range from 35.4 to 22.4 liters per 1 m2. Increasing it by 18–32 % would change the humidity mode of the road bed and reduce the overall elasticity module

УкраїнаМета роботи полягала у побудові відсутньої на сьогодні фізико-механічної моделі процесу циклічної гідроекструзії.Представлена модель створена на підґрунті сучасних уявлень механіки і фізики металів про принципи й закономірності росту та релаксації напружень у вершинах концентраторів, не тільки завжди присутніх всередині

The stress-strain state of a road structure with shallow tubular drainage, which is arranged on waterlogged sections of public highways, has been investigated. Three-dimensional models of the road structure with pipes made of various materials were built using the finite element method. Experimental studies on models were carried out for cases of normative and over-norm load on the basis of the SCAD Office software and calculation complex. The distribution of normal stresses, deformation values in the road structure and directly in the body of the tubular drain is obtained. The working conditions were determined and the expediency of using PVC pipes and concrete pipes on the road of III category was substantiated. Subject of research: stress-strain state of a road structure with shallow transverse tubular drainage. Investigated problem: determination of deformations in a road structure with tubular drains based on the distribution of normal stresses. Main scientific results: distribution of isopoles and isolines of normal stresses, deformation values in road structures with shallow transverse tubular drainage. The expediency of using the type of drainage pipes on waterlogged sections of roads under conditions of excess load has been determined. The area of practical use of the research result: design institutions and enterprises specializing in the road transport industry. An innovative technology product: stress and strain distribution in atypical road structures with tubular holes. Scope of application of the innovative technological product: for the design of atypical road structures with tubular holes on waterlogged road sections.