Mechanics and Advanced Technologies

Dependence of the parts dimensions’ accuracy on the internal structure of the layers when 3D printing using Fused Filament Fabrication technology

Pavlo Mishchenko — 2025-03-18

This paper presents the results of the study of the obtained dimensions’ accuracy depending on the internal structure of the layers when manufacturing samples from the composite material ABS pro CCF using the Fused Filament Fabrication technology. The accuracy was estimated as the deviation of the actual obtained dimension from the nominal dimension of the sample in percent depending on the following factors: infill pattern, infill density and nominal dimension value. The experiments were conducted using the full factorial experiment method. Regression models were built using the PRIAM software. Analysis of the obtained model, in particular, the graphs of marginal regression equations and marginal response surfaces, showed that the structure of the infill can differently affect the accuracy of the obtained dimensions: for example, for larger dimension, the best result was obtained when using the “Grid” infill pattern. For a smaller dimension (10 mm), for different infill density options, different patterns showed different results: for a density of 80 %, the “Cubic Subdivision” infill pattern turned out to be the best; for a density of 60 %, the “Grid” infill pattern was the best. When using the “Grid” infill pattern, as the infill density increases from 60 % to 100 %, the response function behaves in the opposite way for small and medium dimensions: for a dimension of 10 mm, the response function moves away from the optimal value, and for a dimension of 150 mm, the response function, on the contrary, approaches the optimal value. The explanation of this phenomenon requires additional research, in particular with a larger number of levels of variation of the measured dimension, as well as taking into account the location of the measured dimension relative to the printer coordinate system during the build.

Formation of a microprofile of product surfaces during magneto-abrasive finishing of planes with heads based on high-energy permanent magnets

Dmytro Dzhulii — 2025-03-18

Experimental studies have been carried out on the possibility of using powder mixtures consisting of large and small particles of various shapes and diamond pastes for magneto-abrasive finishing of flat surfaces of ferromagnetic parts with end heads based on permanent neodymium magnets. It was shown that when using mixtures of powders of shattered shape, the decrease in surface roughness had been obtained from the initial roughness Ra = 0.8 μm to 0.125 μm with a polished microprofile, and the best results occur when the amount of fine fraction in the mixtures does not exceed 40%. The use of mixtures of rounded powders with a particle size of 1700/1200 μm and shattered shape particles of 640/400 μm at their equal amount in the magneto–abrasive tool made it possible to form a surface with a roughness value of Ra=0.1 μm after magneto–abrasive finishing. It has been determined that rounded coarse powders act as a moving lapping tool, transferring the force load to small particles. At the same time, in the process of direct contact with the finished surface, large rounded particles provide both plastic deformation of the surface micro-irregularities and directly of the surface layer of the samples, providing an increase in surface hardness by 1.4 times, which creates favorable conditions for the micro-cutting process with shattered small particles. When forming the magneto-abrasive tool from large rounded particles and diamond paste of different grain sizes, it was found that the best polishing ability is provided by the mixture formed from rounded powder with a particle size of 1500/1300 μm with the addition of diamond paste with a grain size of 5/3 μm. The roughness parameter Ra of the surfaces being finished using such mixtures is 0.03–0.04 μm.

Increasing the sensitivity of the tactile sensor to detect shredders in the patient’s body

Olexandr Salenko — 2025-03-18

Means of increasing the sensitivity of a tactile sensor for detecting foreign bodies in the wound of patients, the wound channel, which is advisable to use in field conditions in emergency situations, have been analyzed. Such a sensor is a device consisting of a probe and a block of mechanical and electronic means held by the paramedic's hand. To detect a foreign body, a probe containing an elastic thin flexible probe with an external quasi-elastic shell is inserted through the wound channel until contact with the foreign body. The signal from the dynamic contact is visualized and displayed on a display device, which allows the paramedic to make a decision on further medical care for the affected person.
Since the probe receives additional mechanical excitation, the signal has a long-lasting form, which increases the efficiency of primary diagnostics. However, at the same time, using the probe as a waveguide for both mechanical excitation and for transmitting vibrations to the means of amplification and spectral analysis significantly distorts the informativeness of the signal, impairs the accuracy of the studies.
It is proposed to use the probe shell as a waveguide for transmitting vibrations, while the probe acts directly as a waveguide for the contact signal.
It has been established that in this case it is possible to increase the signal-to-noise ratio in the range of 0.92…2.5 kHz to 2 dBA, which is extremely important for analyzing the spectral density patterns of vibrations from contact conditions in a viscous medium.

Methods for Enhancing the Energy Efficiency of Pneumatic Drives

Oleksandr Haletskii — 2025-03-18

This paper investigates various methods of increasing energy efficiency and energy recovery in pneumatic systems, namely reducing the amount of compressed air used by a pneumatic drive.
The low energy efficiency of pneumatic systems is a significant challenge for their development, as pneumatic systems are widely used in industry for various tasks, including equipment control, automation of manufacturing processes, and material transportation. The low energy efficiency of these systems leads to significant energy losses, which increases operating costs and reduces overall productivity.
As a result of the analysis of existing methods, tables of investment and operating costs, and schedules of the payback period for each of the methods were developed. The main researched methods include parameter optimization, exhaust air storage in the receiver, combination of parameter optimization and exhaust air storage in the receiver, quantitative air intake method, and air intake and exhaust optimization.
The obtained results showed that the greatest savings and efficiency are achieved when using methods that use compressed gas expansion. This is due to the possibility of reducing air costs and increasing the payback period of investments due to the reduction of energy losses, due to the use of a small amount of gas to move the pneumatic cylinder piston.
The field of practical application of the results covers industrial enterprises that use pneumatic systems. Implementation conditions include the need for initial investments and analysis of current system parameters to select the optimal energy efficiency improvement strategy. According to the results of the work, the possibility of reducing energy consumption by 43 to 76 percent was found.

Modeling of the precursor configuration influence on the thermoelectric parameters of the high-pressure apparatus during GaN recrystallization from the Fe–Ga–N system

Oleksiy Liudvichenko — 2025-03-18

To solve the actual problem of obtaining the gallium nitride polycrystals it is proposed to use a toroidal-type high-pressure apparatus for which a growth cell has been designed for the recrystallization of GaN from the Fe–Ga–N solution-melt by the temperature gradient method.
The purpose of the work is to study the thermal state of the cell and define the optimal conditions for resistive heating of the high-pressure apparatus, which provide the necessary temperature distributions for GaN crystallization.
Computer modeling of the thermal state of the high-pressure apparatus was carried out. The quasi-steady coupled problem of electrical and thermal conductivity was solved using the finite element method. The influence of the configuration of the GaN precursor on the nature of the change in the thermoelectric parameters of the high-pressure apparatus during GaN recrystallization was determined.
As a result of the calculations, the temperature and temperature gradient fields of the investigated system GaN precursor–Fe–Ga–N solution-melt–GaN polycrystal in successive stages of the crystallization process were obtained. It was defined that the GaN recrystallization process under high pressure and temperature conditions leads to a decrease in the temperature gradient in the growing system and an increase in the heating power of the high-pressure apparatus. This happens as a result of a change in the conductive properties of the growth medium as a result of the formation of a recrystallized GaN phase.
The proposed computer modeling technique allows designing cells and improving GaN crystal growth regimes using the temperature gradient method.

Research of double-layer polymer pipes coextrusion process

Roman Hurin — 2025-03-18

The extrusion of two-layer polymer pipes is widely used to combine the advantages of different materials in one product. However, controlling the thickness of each layer is a challenging task. In this work, a numerical study of the extrusion process of two-layer polymer pipes made of polypropylene (PP) and polyvinyl chloride (PVC) was carried out using the ANSYS Polyflow software package. The aim of the study was to develop a methodology for determining the required volumetric flow rates of PP and PVC melts to obtain a given inner layer thickness. For this purpose, a two-dimensional finite element model of the extrusion head was developed, taking into account the non-Newtonian behavior of the melts described by the Carreau-Yasuda model. Stationary and non-stationary modeling of the melt flow was performed. In contrast to traditional methods based on simplified analytical solutions, this work uses the method of constructing a response surface, which allows taking into account the complex interaction between process parameters and rheological properties of materials, as well as the influence of mutual diffusion. The simulation results showed that the thickness of the inner layer of PP can be accurately adjusted by varying the volume flow rates of PP and PVC. When the volume flow rates of PP and PVC were changed from 2.484 × 10^–6 to 3.036 × 10^–6 m³/s, the thickness of the inner layer varied in the range from 2.24 × 10^–3 to 2.54 × 10^–3 m. In addition, at a volume flow rate of the outer PVC layer equal to 3.036 × 10^–6 m³/s, a straightforward dependence of the thickness of the inner PP layer on the volume flow rate of PP with a linear approximation coefficient of 0.9992 was observed. The obtained response surface allows us to effectively determine the required volume flow rate to achieve the required thickness of the inner layer of PP and can be used to setting appropriate parameters the extrusion process of two-layer polymer pipes.

Hydrodynamic and Cavitation Characteristics of Static Models of Apparat-uses with Variable Inlet Channel Configurations

Dmytro Vitenko — 2025-03-18

Numerical calculation methods are an effective tool for developing new designs and analyzing and comparing existing designs of cavitation devices. The advantage of these methods is the ability to determine rational hydrodynamic parameters for different models without consuming materials and energy. The issue of improving the designs of cavitation devices to ensure a stable cavitation process and optimize their operation in various technological environments remains relevant today. One of the key aspects is the influence of the geometric characteristics of the device’s internal channel on the formation and distribution of the vapor-gas fraction, which directly affects the efficiency of the cavitation process.
To analyze the conditions of cavitation occurrence and compare the hydrodynamic parameters and volumes of the vapor-gas fraction in models of cavitation devices with different geometries of the internal channel of the confuser.
Numerical modeling was performed using the Flow Simulation module with the Navier-Stokes equations, equations of state that determine the physical properties of the fluid, as well as empirical dependences of density, viscosity, and thermal conductivity on temperature.
In all the studied structures with obstacles, a vapor-gas fraction is formed at Q = 0.002 m³/s. Stable cavitation occurs at
Q = 0.003 m³/s, with the volume of the formed vapor-gas phase for the model with a cone-shaped obstacle being V_v.f. = 5.39×10⁻⁶ m³ for the structure with a screw V_v.f. = 4.91×10⁻⁶ m³, and for the apparatus with a double cone V_v.f. = 3.77×10⁻⁶ m³. For comparison, the volume of the vapor-gas fraction for the model without obstacles is V_v.f. = 2.93×10⁻⁶ m³. The analysis of the histograms of the distribution of the vapor-gas fraction along the diffuser shows that installing a cone obstacle increases the volume of the vapor-gas fraction along the diffuser, ensuring a stable cavitation process. The screw obstacle creates localized areas characteristic of pulsations and disruptions. The double cone demonstrates smaller volumes of the vapor-gas fraction and a uniform increase and decrease in concentrations along the diffuser.
The obtained results can be used to improve and implement the design of static devices that ensure a stable cavitation process and optimize their operation under the conditions of certain technological environments.

Analysis of the results of experimental tests of hydraulic machines of various designs

Grigory Avrunin — 2025-03-18

Identification of the influence of the design features of axial and radial piston hydraulic machines on volumetric, hydrodynamic and mechanical power consumption based on the analysis of the results of tests of pumps and hydraulic motors published by the Innas company.
The object of the research is the characteristics and designs of volumetric pumps and hydraulic motors of the same working volume, which were obtained by the Innas company during comparative tests according to the ISO 4409 method.
The problem of providing design engineers and master's students with knowledge about the impact of design features of piston hydraulic machines on power loss and efficiency has been solved.
Based on the results of the analysis, an explanation of the obtained test results is given in relation to their connection with the design features of hydraulic machines. This is an attempt to assess the influence of temperature and force deformations of piston groups on leaks of the working fluid in Innas designs, known axial-piston hydraulic machines and hydraulic machines with ball-pistons.
It is shown that the types of piston groups and distribution nodes significantly affect the power loss and efficiency of hydraulic machines.
Due to the constructive and technological achievements of the Innas company, when creating new piston groups, it is possible to obtain small radial clearances between spherical pistons and thin-walled cylinders due to their deformation properties.
The obtained results are useful for developers of hydraulic machines, specialists in the creation of hydraulic drives and master's students.

Damage models of composite materials

Yaroslav Demeshko — 2025-03-21

An analysis of modern damage models and failure criteria for composite materials (CM) at the stage of macrocrack initiation is performed and the limits of their application are determined. The classification of CMs, as well as the main hypotheses and assumptions used to construct equations of state are considered. Particular attention is paid to the stage of initiation and accumulation of scattered damage at the micro- and meso-levels as a key phase of the life cycle of a CM product. The concepts of continuum damage mechanics, thermodynamics of irreversible processes, and mechanics of a solid deformable body are applied.
The relevance of the work is due to the growing requirements for the reliability and durability of CM structures, especially in the aviation, automotive, and construction industries. Despite significant progress in research, there is a need to improve damage models that take into account complex micro- and mesoscale fracture processes.
The methods of continuum damage mechanics, thermodynamics of irreversible processes, and deformable body mechanics are applied. Phenomenological and micromechanical models of damage are considered, which describe the accumulation of damage in the matrix, reinforcing fibers, and interfaces.
The main mechanisms of microfracture in reinforced CMs are described, including damage to the matrix, reinforcing fibers, and the interface between them. The necessity of taking into account a set of phenomenological parameters to describe the kinetics of damage accumulation is demonstrated. It is noted that complex processes in reinforced CMs require phenomenological modeling of damage with the use of tensor quantities and certain assumptions, particularly the “mixture” hypothesis. The expediency of using the hypothesis of equivalence of specific energies to determine the components of the damage parameter is confirmed

Surface Modification Technologies for Space and Planetary Applications

Jacob Kleiman — 2025-03-18

This paper presents an overview of processes developed in our company for applications in various space and planetary environments. A number of materials including polymers, paints and other organic-based materials undergo dramatic changes and irreversible degradation of physical and functional characteristics when exposed to space or planetary environments, like in LEO, GEO or on Moon, or Mars. Protective schemes including protective coatings, mechanical metal foil wrapping or cladding, specially synthesized bulk materials, etc. are used to reduce the effects of space environment on materials and their properties. However, the protection of polymers, paints and other organic-based materials in space still remains a major challenge, especially for future long duration exploration missions to other planets or permanent space stations or for an ever-growing array of nano-, micro- and macro-satellites in VLEO, LEO and GEO orbits. Surface modification processes and advanced coatings are used increasingly to protect existing or provide new properties to polymers, paints and other organic-based materials.
A number of surface modification solutions that include treatment of the surfaces by chemical or physical processes and that differ from the traditional protective coating approaches were developed by ITL in the last 30 years that change the surface properties of treated materials, protecting them from the hazards of low Earth orbit (LEO) and Geostationary orbit (GEO) environments or providing dust mitigation properties when used in Lunar environment. Examples of their testing, characterization and applications are provided. In addition, a surface treatment process for mitigation of lunar dust effects in lunar environment was developed and will be discussed.

Modelling of the process of interaction of multi-impulse local loading at electrohydraulic forming of large-dimensional bottoms

Mykhaylo Taranenko — 2025-03-18

Forming of large-dimensional thin-sheet bottoms usually leads to great complexity of technological processes. When forming is conducted on mechanical presses using male- and female dies one can observe phenomenon of loosing stability of bottom shape with uniform through perimeter movement of the workpiece flange during drawing and large areas of thin workpiece that do not support by rigid surfaces of the die and are prone to be loaded with compressive stresses. This leads to the formation of folds and corrugations on the flange and dome part. Application of presses for stamping with elastic media and high pressure is irrational from energy considerations, because different parts of the workpiece require different pressures for their shaping. Electro-hydraulic (EG) forming is more effective when stamping such parts occurs consequently by zones of the workpiece and require different loading at each zone. It is possible to implement sequence control and load locations on multi-electrode EG-presses.
Objective of the presented research was, on the one hand, to study the possibility of the formation of pulsed submerged flows of liquid medium, that transmits the load, their interaction with each other and the deforming workpiece in the technological zones of EG presses, and on the other hand, the possibility of using the LS Dyna software in combination with ALE method.
To achieve the specified goal, methods of mathematical modeling of forming processes and interaction of deformed environments having different mechanical parameters were used, as well as experimental methods to confirm the processes being studied.
The results obtained consider the possibility of creation of high energy-containing immersed jets of liquid, their interaction between themself and the deformable workpiece depending on the technological parameters. The parameters of the workpiece deformation process were studied. It is shown that blank shape change has a wave-like character and, by changing the temporal and spatial parameters of the load, it is possible to control the parameters of the blank stress-strain state.
Comparison of simulation results with experimental data substantiated the possibility of using the proposed modelling method in the study of pulsed flows in heterogeneous media.
The conclusions state the achievement of the mentioned goal, describe the mechanism of interaction of liquid jets in the case of energy concentration necessity in the given zones of the workpiece and the possibility of changing the direction of energy flows when the moment of the of EG discharges beginning in adjacent discharge cavities is changed. The accuracy of the simulation results was assessed when compared with experimental data.

Designing complex technical systems considering uncertainty factors

Svitlana Kryvova — 2025-03-18

A characteristic feature of projects aimed at creating complex technical systems (CTS) is a high level of uncertainty. Failure to account for uncertainty, especially in the early stages of project development, when uncertainty is at its peak, increases risks and raises costs for resolving unforeseen issues in later project phases. This can significantly impact the achievement of the project's final goals. Therefore, the problem of comprehensively addressing uncertainty in project management and systems engineering processes during CTS development is highly relevant and requires thorough investigation.
The primary objective of this research is to analyze the most significant approaches and assess the state of the issue regarding the consideration of uncertainty factors inherent in key activities aimed at creating CTS – namely, project management and systems engineering. This will enable the development of more effective strategies for managing uncertainty in CTS creation.
The research methodology included organizing and implementing expert evaluation procedures to identify the most significant uncertainty factors in CTS development. Additionally, a qualitative and quantitative analysis of the composition of uncertainty factors was conducted for various types of activities – project management and systems engineering – and the dynamics of uncertainty growth were evaluated depending on the degree of CTS uniqueness for different types of projects.
The research identified the most significant uncertainty factors characteristic of project management and systems engineering activities in CTS creation. The nature of the dynamics of uncertainty growth in relation to the uniqueness of various project types was also determined.
The conducted research has provided new insights and identified certain trends aimed at improving the processes of project management and systems engineering in the development of CTS.