Bulletin of Lviv National Environmental University. Series Agroengineering Research

Analysis of transient processes in a power transmission line with lightning protection cables during controlled switching

V. Levoniuk — 2024-01-19

The article analyzes scientific publications related to the study of transient processes in the elements of electrotechnical systems of energy transmission during controlled commutations by electric and gas switches. The analysis shows that the issue of researching transient processes during controlled switching is relevant, but insufficiently explored with respect to transient processes in lightning protection cables.

The author has developed a mathematical model of a fragment of an electrotechnical energy transmission system with the key element of which is a long power transmission line with lightning protection cables of ultra-high voltage, taking into account the parameters distribution. The developed mathematical model is based on the equation of a long line with partial derivatives of the second order. Neumann and Poincaré boundary conditions are proposed to solve the mentioned equation. Equations of a long line with second-order partial equations are solved by the method of straight lines using the concept of the central derivative. The search for voltages in fictitious nodes of the power transmission line was carried out and their appearance was presented for the phase wires at the end of the power transmission line and lightning protection cables at the beginning and end of the power transmission line. Based on the developed mathematical model, a program code was written in the algorithmic programming language Visual Fortran, with the help of which two numerical experiments were carried out. In the first experiment, transient processes in the power transmission line were studied without considering the controlled switching, and in the second – with it. The results of the computer simulation of transient electromagnetic processes in the phase wires of the line and lightning protection cables are presented in the form of drawings that are analyzed. Functional dependences marked in yellow on the oscillograms refer to phase A, green to phase B, and red to phase C.

Investigating voltage deviations in the enterprise’s power supply network during the electrical equipment operation

D. Hrechyn — 2024-01-19

The article focuses on the issue of voltage levels at consumers' buildings and the acceptable limits of voltage fluctuations. Any deviation from the nominal voltage can negatively affect the electricity supply for consumers, including lighting, electrical engines, and other electrotechnical equipment. One of the primary reasons for voltage drop is the loss of voltage in the power supply network. Research has shown that analyzing power supply networks is crucial to ensure better technical and economic performance. Nowadays, research is conducted through modeling, and the main goal is to build a structural-mathematical model of the power supply system of the enterprise using MATLAB/Simulink and analyze voltage drops in the network. The purpose of this work is to investigate voltage drops in the network using the constructed model. In this work, the authors built a structural-mathematical model of the power supply network of the enterprise. The researchers conducted a study of the 10kV line's operation on voltage drops in the line and also studied three 0.4kV cable lines alternately for voltage drops. The KL2 line had a voltage drop of more than 5%, so the cross-section was increased and the experiment was conducted again. This time, the voltage drop was less than 5%. The authors of the study also experimented with the simultaneous operation of three feeders with nominal loads. The analysis showed that, as in previous experiments, the voltage loss was within the allowable losses, and in the KL2 line, the losses exceeded the allowable ones, but changing the cable cross-section solved this problem. First, the authors analyzed the KL1 line, studying it at nominal mode from 0 to 1.2Sn. It was found that the voltage losses in this line were within the limits of permissible losses, specifically 274.5 V. Subsequently, voltage drops on the KL2 line, which were also analyzed at the nominal mode from 0 to 1.2 Sn, were observed. The voltage deviation exceeded the permissible norms, so a cable with a larger section was selected, and the voltage deviation was within the permissible limits from -5% to +5%. The researchers then tested the KL3 line and found that the voltage losses were within the allowable loss limits, particularly 5%. The line also operated at the nominal mode. In the KL4 line, the voltage losses were minimal, and the line at the nominal mode from 0 to 1.2 Sn was monitored. In the fifth experiment, the entire load was connected to the KL2 - KL4 cable lines at the same time. The analysis showed that the voltage losses in the KL3 and KL4 lines were within the permissible limits, and in the KL2 line, as mentioned earlier, the losses exceeded the permissible ones, but changing the cable cross-section solved this problem.

Operation of the technological equipment of vibration type in an electrostatic field

P. Koruniak — 2024-01-19

Increase of production efficiency and production output, improvement of its quality while reducing labor costs, upgrade of the forms of organization and production management are the basic elements of mechanical engineering development. This is ensured by the improvement of the existing and introduction of new types of equipment, technological processes and means of their mechanization and automation, creation of new technological complexes where all these issues are interconnected and comprehensively solved.

Means of transportation ensure the continuity and rhythm of work of all structural units of flow production, starting from warehouse operations, supply of a technological object, and the work process of processing to the output of finished products. In terms of automation, the most time-consuming technological operations are those that are associated with the necessary orientation of products.

The most common and effective means of technological object orienting are vibration feeders with an electromagnetic drive. In these devices, the process of orientation of the object (product) is carried out with vibrational movement both on the path of the bowl and on any part of its movement to the working position. The ease of operation and the perfect design of this type of equipment have provided it with a leading place in automated production.

In addition to automation, vibration technology has been widely used in various technological processes, in particular during separation. The orientation of the mixture components referring to the sieve openings significantly increases the screening efficiency. One of the ways to implement this task is to combine vibration processes with the electrical properties of the mixture components in a high-voltage electric field. Сontinuous mode of vibration transportation of the working mixture and the required electric field strength improve the conditions for the working process of vibration separation.

According to the results of the research, it is found that ensuring the appropriate operating parameters of the technological equipment can significantly intensify the process of sifting the mixture components through the sieve openings and thereby reduce its working area.

Combining the considered effects can be applied not only during the interoperational transportation of products but also in the operation of devices for their group cassette and stacking, storage magazines for automatic orientation and positioning for gripping devices of manipulators and industrial robots, and automatic loading devices for technological equipment. These devices must be widely used in production processes associated with products with small mass-geometric parameters.

Developing the technological equipment for the T1/N1 traction transport machine used in the agro-industrial complex

H. Khudaverdian — 2024-01-19

The article introduces a modified model for the movement of universal all-wheel drive traction vehicles of the Mercedes-Benz Unimog type on a deformable surface (according to the WES methodology of the US Army). The model is created in the MATLAB Simulink software environment, namely a software module for determining the maximum traction force that can be implemented on any support surface. By investigating the influence of design parameters and operating conditions on traction properties, this model helps in selecting appropriate equipment for technological operations, and a trailer for transportation purposes. The researchers also explore ways to increase the traction properties of a wheeled vehicle and reduce the negative impact on soil fertility. Through this simulation model, the researchers obtained the value of the free traction force of a universal wheeled vehicle of the Mercedes-Benz Unimog type (based on the project of the Open Joint Stock Company “Ukravtobusprom” – TUR VT-041 “Avtotrak”), determined its traction class according to the classification, and selected the appropriate technological equipment and a trailer. The adequacy of the elaborated methodology is assessed by comparing the results of experimental data of the wheeled tractor T-150K and the results of the corresponding simulation model, i.e. calculation by applying the above-mentioned module. The article highlights the problem of insufficient access to low-tonnage wheeled vehicles for small farms and utility companies. Importing such equipment often becomes an expensive and complicated process. To address this issue, it is expedient to study the expertise of the Western European countries after the Second World War and the current situation and to develop a concept of a universal wheeled vehicle of the N1/T1 category of the Avtotrak/Unimog type. This concept aims to create a vehicle that can perform various tasks in the conditions of small farms and utility companies by combining the functions of a small tractor with high traction and an all-wheel drive truck that can move on and off-road.

Mathematical modeling of grain cooling in bunker systems with radial air distribution

B. Kotov — 2024-01-19

The need to create or improve the existing grain cooling systems after drying, which operate separately from grain dryers (portable grain coolers), is currently caused by the requirements to increase the efficiency of dryers on farms (by using cooling chambers as drying units) and the emergence of integrated grain dryers with solid fuel furnaces that operate with periodic loading. One way to address the challenges of creating portable grain coolers after drying is to utilize ventilated bunkers with radial distribution of external atmospheric air for grain cooling. To ensure their effective operation and to align the productivity of the cooler with that of the dryer, it is essential to study the patterns of heat exchange in non-steady-state conditions and determine optimal structural and operational parameters. Such research is best conducted by developing mathematical models of non-steady-state thermal processes during the cooling of heated and dried grain. The present work proposes a developed mathematical model of the grain cooling process in bunker systems with radial air distribution based on a two-level hierarchy: microkinetics and macrokinetics of grain cooling.

At the microkinetics level, the equation of non-steady-state heat conduction for a grain particle (or a grain layer element) with a negative heat source is employed, along with the boundary conditions for convective heat exchange. At the second level, the grain cooling model is represented by a differential equation for heat exchange of a ring-shaped grain element with radially moving cooling air. The solution to this equation is implemented in the Mathematica computer environment for two airflow scenarios: from the center of the bunker to the outer surface and in the opposite direction. The results of the calculations are graphically illustrated. It has been determined that the temperature non-uniformity of grain along the radial coordinate of the layer during the final stage of the process, with air filtration from the external cylinder to the central one, is 20-30 % lower than when air filtration is carried out in the reverse direction.

Methods of researching hydro-gas-dynamic processes in closed bypass channels of different cross-sections

S. Baranovych — 2024-01-19

The article considers different methods of researching the hydro-gas-dynamic processes in closed bypass channels with different cross-sections. One of the used methods involved an analytical approach, which was distinguished by the complexity of mathematical calculations and the subsequent visualization of hydro-gas-dynamic processes using the MATLAB system. This method facilitated a detailed analysis of the channel’s features and reproduction of the phenomena of a laminar mode of the flow of liquids and gases in it, providing a deeper understanding of their nature.

Another technique involved simulation computer modeling of the processes of laminar flow of liquid and gas through channels of different cross-sections in the SOLIDWORKS Flow Simulation environment. To apply this technique, the input parameters and conditions were specified, and the obtained results were analyzed and interpreted in detail. This approach was used to create realistic computer models of hydro-gas-dynamic phenomena, allowing researchers to deeply study their behavior and interaction in the conditions of different cross-sections of channels.

A comparison of the results obtained using both methods indicated the adequacy of their reproduction of hydro-gas-dynamic processes in closed bypass channels with different cross-sections. The obtained data not only confirmed the accuracy of the chosen methods of analysis but also expanded the understanding of the flow of liquid and gas under the conditions of their laminar movement. This research opens up new horizons for further scientific studies in the field of hydro-gas-dynamic phenomena and can be applied in important engineering design calculations where high accuracy and reliability of hydro-gas-dynamic process calculations are required.

Efficiency of differential pressure regulation in tires under conditions of off-road passability and mobility

V. Khoma — 2024-01-19

The article discusses the problem of increasing the efficiency of full-drive high-passability vehicles by optimizing the air pressure in tires. The tire pressure control system provides "adaptation" of the wheels to the different physical and mechanical properties of the supporting surface, which reduces the depth of the track and increases the contact surface area with the ground. However, using systems that set the same air pressure values in the tires of all wheels does not allow for optimizing the pressure depending on the physical and mechanical properties of the supporting surface and the load on the wheels. Therefore, the author proposes to use the systems that allow for separately regulating the air pressure in the tires of each wheel, which will increase the efficiency of wheeled vehicles. The impact of this factor on the load-carrying capacity is examined and its significance is indicated. It is noted that with a change in tire pressure and each new pass of the wheel over the supporting surface, the physical and mechanical characteristics of the ground change. The question of forming a unified complete methodology for evaluating the passability of wheeled vehicles and selecting the main design parameters remains relevant. Approaches to modeling the process of vehicle movement on a deformed supporting surface with consideration of the changes in the physical and mechanical characteristics of the soil are considered. The research found that reducing tire pressure can improve the load-carrying capacity parameters on a deformed surface, but the results depend on the type of soil, the size of the vehicle, and the normal average pressures. Using a MATLAB Simulink-based off-road vehicle simulation model, the author obtained values for the maximum possible off-road speeds, which demonstrate sufficient adequacy with experimental studies on high-passability vehicles, but require additional experimental research and adequacy assessment. The obtained results serve as the basis for the parametric optimization of the tire pressure distribution system in full-drive vehicles.

Methodology of determining the basic parameters of all-terrain hybrid vehicles

L. Krainyk — 2024-01-19

The hybrid drive is becoming increasingly popular and is now being used in most of the new model generation of military vehicles (MV) in NATO countries. However, the drive schemes and basic parameters of the drive units for off-road conditions are significantly different from those used in serial hybrid drives for passenger cars and all-wheel drive general-purpose crossovers designed for paved roads.

The analysis of known MV constructions with hybrid drives confirms the dominance of the so-called serial or mix-hybrid drive schemes. There is a lack of methodology for determining the necessary basic parameters of the main units of such construction for off-road conditions in available sources of information. Therefore, it is proposed to determine the required power values of the traction electric motor and the "internal combustion engine-generator" system, the battery capacity for electric traction range, and the necessary transmission range for driving off-road and on paved roads.

The gear ratios of the main gear and the low gears of the transfer case (all-wheel drive scheme) or the gearbox (in the case of a single-drive rear engine layout) are formed to ensure the realization of the maximum power of the traction electric motor at a speed of more than 120 km/h when driving on an asphalt road and at speeds of 40-60 km/h on a typical wet all-terrain (restriction due to the conditions of extreme vibrational loads).

The studied schemes of hybrid drive off-road vehicles also allow using the "internal combustion engine-generator" system as a source of autonomous power supply, which is especially relevant in field conditions with problematic access to stationary power networks. The mixed drive scheme also provides the possibility of vehicle movement, albeit limited, in the situation of the failure of either the internal combustion engine or the traction electric motor, which is important for MV.

Justification of the method of controlling the manipulator installations of trucks

O. Sukach — 2024-01-19

Transportation often requires loading and unloading cargo in areas beyond fixed warehouses, such as the field. To meet these needs, trucks equipped with manipulators are typically utilized. Hydraulic drives are commonly used in these manipulators, as they provide sufficient power and performance and can be easily integrated into a car's standard hydraulic system.

To substantiate the effective control system of the manipulator's hydraulic drive, a model of the truck's side was developed, consisting of an on-board platform; rotary module, power part (arrow, beam), hydraulic drive, electrical part (drive, control), and cargo lifter with servo drive.

A rational model of the electronic hydraulic drive control system of a manipulator crane for use in universal crane-manipulator installations on an automobile, self-propelled, and trailer chassis is proposed. This helps to increase the efficiency of loading and unloading operations while reducing the number of equipment and workers involved in cargo handling outside warehouses.

The authors propose an architecture of control of manipulator installations with a low cost of its implementation and a simple, understandable setting. The use of the proposed technology and electronic control scheme provides control of a complex system of drives, and allows for flexible settings according to the user's needs, e.g. to control the manipulator crane remotely via a radio channel or limit the amount of movement in certain directions.

To control the executive mechanisms of the manipulator crane, a hardware-computing platform with an Ardiuno microcontroller was used with the Processing/Wiring software development environment in the programming language, which is a subset of C/C++ and ensures: uninterrupted operation of the mechanisms during operation; their start and braking; informativeness, accuracy, and efficiency of mechanisms; minimal static and dynamic loads with reduced inertial action during cargo movement.

Analysis of modern sensors and the feasibility of automated monitoring of feed consumption by pigs on farms

A. Tryhuba — 2024-01-19

An analysis was conducted on the process of automated monitoring of feed consumption by pigs on different farms to establish the peculiarities of the feed consumption process. Effective feeding management and optimal animal growth are based on these peculiarities. The feasibility of using modern sensors for automated monitoring of feed consumption by pigs was substantiated. The authors suggest using different types of sensors, including weight, movement, volume, and individual feed consumption sensors. The study established that image analysis methodology is preferred when using motion sensors to monitor feed consumption. Radio frequency identification (RFID) technology is recommended for monitoring individual feed consumption by pigs. RFID technology uses radio waves to read and capture information stored on a tag attached to the object. Each type of sensor has its advantages and disadvantages in terms of accuracy, reliability, cost, and ease of installation. Despite the shortcomings of existing sensors for automated monitoring of pig feed intake, they have significant advantages over manual feeding monitoring, including real-time data collection, increased accuracy, and reduced labor costs. The study defines the tasks that should be solved during the automated monitoring of fodder. Solving the main tasks can increase the accuracy of data collection and, accordingly, the efficiency of animal feeding. The study concludes that the use of modern sensors for automated monitoring of feed consumption has great potential for increasing the efficiency and profitability of pig farming. The choice of sensors for automated feed consumption monitoring systems significantly affects the efficiency and reliability of the systems and is a direction for further research.

Analysis of the state of occupational injury as a prerequisite for managing the processes of dangerous events formation

I. Horodetskyi — 2024-01-19

The article provides characteristics of the problem of accidents and injuries at work in Ukraine and the world. According to the State Statistics Service of Ukraine, the total number of injured people has been increasing annually in recent years: 4,040 in 2018, 4,394 in 2019, 6,646 in 2020, and 12,315 in 2021. Moreover, according to statistical data, the number of severe injuries with fatal consequences is similarly increasing: 275 in 2018, 410 in 2019, 393 in 2020, and 537 in 2021. According to the International Labor Organization, Cuba (25), Burundi (13.8), Egypt (10.7), Costa Rica (9.7), and the Philippines (9.6) are among the leaders in the number of fatal accidents/injuries. The state of research on industrial injuries in certain branches of supervision is analyzed, particularly in agriculture, mechanical engineering, power engineering, and road transport. The peculiarities of the terminology of traumatism in normative acts and forms of the State Statistics Service are characterized. Based on the information from the State Statistics Service of Ukraine, the State Labor Service of Ukraine, and the Social Insurance Fund of Ukraine, the state of injuries for 2018-21 was analyzed in the branches according to the specialties trained at the Faculty. The features of dangerous and harmful production factors of the analyzed areas and their role in the formation of traumatic situations are emphasized. The dynamics of industrial injuries in recent years in the studied industries were established: electricity supply 143 in 2018, 162 in 2019, 150 in 2020, 149 in 2021; agriculture and forestry, respectively 272, 337, 243, 250; transport, warehousing 391, 404, 395, 386, processing industry 1112, 1014, 813, 875, respectively. Groups of causes of the insurance accidents were established: organizational – 66.8 % of accidents; psychophysiological – 18.4 %, technical – 11.9 %; technogenic, natural, ecological, and social – 0.7 %; others (do not belong to any of the specified groups) – 2.2 %. Emphasis is placed on the role of the employer in managing the processes of formation of traumatic events and improving the civil safety management functions: planning, organization, motivation, and control of measures to prevent dangerous situations and accidents.

Adaptive value approach to managing the projects of community and regional development

A. Tryhuba — 2024-01-19

After analyzing the current state of community and regional development projects, it has been determined that there are both advantages and disadvantages in current methodologies and approaches to project and portfolio management. To eliminate existing shortcomings, it is necessary to develop an adaptive value approach that takes into account the specific features and current realities of the communities involved.

This adaptive value approach will consider uncertainties and risks inherent in community development projects while ensuring that goals are met and the maximum value is created for stakeholders. To achieve this, a 14-step algorithm for managing community and regional development projects has been developed. This algorithm reflects the processes involved in managing projects and their specific features, while also considering the interrelationships between stages and changes in the project environment.

As a result of this research, project ideas and alternatives for portfolios of community development projects have been formed. Various configurations of community development projects were proposed, and using the adaptive value approach, the feasibility of including projects in a community development portfolio was determined for each option. Based on this approach, a portfolio of development projects was formed for a specific community, which included four projects (project 5 - creation of a nature reserve and restoration of the local ecosystem, project 3 - installation of video surveillance in public places, project 6 - development of an organic waste recycling system, and project 4 - expansion of the volunteer patrol program formations). The total budget for these projects was $1,700,000, with a total value for stakeholders of 1.96. Further research is needed to develop a decision-making support system for project managers based on the proposed adaptive value approach to the management of community and regional development projects.

Elastic bending of a strip under the action of applied forces

S. Pylypaka — 2024-01-19

Elastic bending of a rod involves restoring its elastic axis to its initial rectilinear state after the deformation forces have stopped. Rectilinear structures are widely used in construction for various types of bridges and overlaps. These structures must not deflect significantly, as it can lead to their destruction. Therefore, finding the permissible limits of deflection of these building elements is an urgent task. The permissible deflection of such rectilinear elements is extremely small, i.e. disproportionate to the length of the element, therefore simplified theoretical formulas, which satisfy the practice, are used to calculate its value. The simplification means that the second-order differential equations of the elastic axis are replaced by the first-order differential equations, which gives sufficiently acceptable results of the deflection of the rectilinear element with minor deformations. In the engineering practice, there are rectilinear rods that undergo significant deformations. The simplified formulas cannot be used to calculate their deflections. In addition, curvilinear elastic elements, which already have the initial curvilinear shape of the elastic axis, have become widespread. These are risers of cultivator paws that smooth out pulsating dynamic loads, springs, piston rings, etc. It is the calculation of the shape of the elastic axis of the piston ring that is most considered in the article.

Finding the shape of the elastic axis of a cantilever clamped rod is based on the position of the theory of resistance of materials, according to which the curvature of the elastic axis is directly proportional to the applied moment and inversely proportional to its stiffness. At the same time, two types of load are considered, namely a concentrated force at the free end or a uniformly distributed force along the rod. The effect of these forces on both a rectilinear rod and a rod with a given constant curvature, that is, a rod outlined along the arc of a circle, is considered. Examples are given for all cases and their elastic axes after deformation.

Investigation of the influence of the mechanism of changing the compression ratio on the rate of reduction of the compression ratio depending on the engine operating mode

T. Kolesnikova — 2024-01-19

Studies have demonstrated that popular engines are limited to a maximum compression ratio between 12 to 14 at low loads due to significant friction losses that reduce efficiency. This puts a cap on improving fuel economy by increasing the compression ratio beyond 14. However, researchers have identified a potential solution to this limitation in the form of a pistonless internal combustion engine with a crank-slider mechanism, which allows for a variable compression ratio above 14. This engine design boasts low friction losses across all loads and speeds, complete dynamic balance, a uniform stroke, as well as a compact and lightweight structure. These benefits are made possible by the straight-line motion of pistons in a pistonless engine, which eliminates lateral loads on them.

Theoretical and computational studies have been conducted on the pistonless internal combustion engine with a crank-slider mechanism, which suggest the feasibility of utilizing a variable compression ratio in such engine.

A methodology for calculating the mechanism of variable compression ratio (VCR) has been developed, taking into account the interrelation of parameters of the mechanism and the engine's operating cycle.

It has been determined that based on the pistonless engine with a crank-slider mechanism, it is possible to create an engine with variable compression ratio (VCR) ε = var with a sufficiently fast VCR mechanism to prevent detonation.

The research proves that reducing the crankshaft rotation frequency significantly increases the speed of the mechanism, with the average rate of compression ratio change ranging from 0.29 to 0.5 cycles per second at the maximum torque mode and potentially increasing up to seven times according to the engine's external speed characteristic.

On tension in composites under heating

T. Bubniak — 2024-01-19

Spatial problems of the theory of elasticity often arise when solving various technical and technological problems of modern production, in particular when building composite materials and structural elements.

The behavior of structural materials can be studied at three structural levels: macro-, micro-, and atomic level. In construction mechanics, the concept of continuous medium is essential only at the micro level. Consideration of the effect of material heterogeneity at this level in the analysis of macrostresses significantly depends on the size of the structure itself.

Development and introduction of new structural materials require evaluating their strength properties under various types of load.

When creating composite materials, the inclusions that appear in the matrix significantly affect the stress-strain state of the composite as a whole under various mechanical or thermal loads.

The achievement of extreme values by stress components at the interface of phases is due to the production technology in some cases, and, heterogeneity in others. It is introduced to improve the strength of the material.

The study of spatial problems of the static theory of elasticity and thermoelasticity for homogeneous isotropic and anisotropic bodies in the general formulation is associated with great mathematical difficulties caused by the complexity of constructing a solution of a system of partial differential equations that satisfies the boundary conditions.

One of the effective methods of solving problems of elasticity theory is the Fourier method, which is based on the representation of general solutions of equilibrium equations through potential functions. A feature of the Fourier method is the use of different representations of the solution of the Lamé equations through harmonic functions, which allows searching for a solution in the form of a series.

In this direction, important results were presented in the works of Yu. M. Koliano, Ya. S. Pidstryhach, Yu. M. Podilchuk and many others, in which exact solutions of spatial problems of the theory of elasticity and static thermoelasticity in spherical, cylindrical, spheroidal, parabolic and other coordinate systems are constructed.

The paper considers the problem of distribution of thermal stresses in an unbounded transversely isotropic medium, which contains anisotropic inclusions in the form of a compressed spheroid with uniform heating, relative to mechanical and thermal properties.

When solving spatial problems of the theory of elasticity with spheroidal inclusions, it is convenient to use coordinate systems for a compressed spheroid.

The conducted studies show that with uniform heating of the medium, the stresses on the inclusion surface are local both along the X axis and along the Z axis.

Methodological approach to choosing military vehicles

V. Kokhan — 2024-01-19

It is important to understand that it may take a while before the required number of military vehicles of different classes and tonnage can be produced. As a result, there could be a problem in quickly and completely solving this issue. The best way to address this problem is to choose wheeled vehicles that are most suitable for domestic conditions based on their technical characteristics and indicators to adequately complete the wheeled vehicle fleet of the Armed Forces of Ukraine and the units of the National Guard of Ukraine.

After analyzing the wheeled vehicle fleet of the main countries that manufacture military vehicles and reviewing normative and technical documents on mobility issues, the author has proposed approaches to define mobility in complicated Ukrainian conditions. Specifically, mobility is a complex indicator that encompasses speed, maneuverability, controllability, cross-country ability, stability, and autonomy of military vehicles (MV).

The research proposes a methodological approach to quickly assess the situation using the method of analytic hierarchy, which takes into account the technical criteria used to select wheeled vehicle equipment.

The method of analytic hierarchy involves constructing a hierarchical model, determining the eigenvectors and eigennumbers of square inverse symmetric matrices, and verifying the consistency of the results.

This approach enables ranking the basic properties of MV mobility and identifying those that are currently the most important for selecting military equipment. The selection criteria are based on the current legislative and regulatory framework concerning defense procurement at public expense.

The performed calculations help determine the weight share of each of the seven main technical indicators that significantly affect the mobility performance of military motor vehicles on the modern battlefield, as well as in assessments of other military equipment.

Evaluation of the off-road suspension efficiency for all-wheel-drive vehicles

M. Manziak — 2024-01-19

Armed conflicts, especially the Russian-Ukrainian war, have emphasized the importance of high mobility for military vehicles. This requirement increases the need for off-road vehicle designs, especially regarding suspension systems. The maximum speed limitations are determined based on the vibration loads experienced by the driver and crew, caused by irregularities, micro-profile of the terrain, and the respective transmission functions of the suspension and tires.

This article focuses on determining the influence of suspension travel on the speed of movement for a highly mobile multi-purpose wheeled transport vehicle, using the American HMMWV vehicles as an example, which are currently used by the Ukrainian Armed Forces. The study took into account the suspension characteristics, tire properties, and oscillation system of the vehicle. Results show that a larger suspension travel avoids suspension failure within the speed range of 10-60 km/h and provides the necessary mobility and operational lifespan of the suspension system in off-road conditions. The study also obtained recommendations concerning the required values of suspension travel to ensure the necessary mobility of wheeled vehicles, which is crucial during the design phase and the establishment of corresponding legislative regulations, particularly for heavy automotive vehicles. The methodology presented for evaluating suspension efficiency during obstacle traversal allows for quantitatively assessing the maximum speed with consideration of the kinematics of specific vehicle designs.