Olena Harashchenko

This study addresses the critical challenge of predicting residual deformations in industrial products manufactured using selective laser sintering (SLS) technology. Residual deformations represent one of the primary factors leading to geometric inaccuracies in SLS-produced parts, directly affecting their functional performance and dimensional precision. The research proposes and validates a novel hypothesis that existing prediction models developed for plastic injection molding can be effectively adapted for SLS applications through appropriate conversion factors. Given the absence of specialized tools for SLS deformation prediction in the current market, this approach leverages the mature capabilities of the SOLIDWORKS Plastics software as an alternative solution. The methodology involves creating finite element models of test components, specifying material properties similar to SLS powders, and simulating thermal conditions that mimic the SLS process. Through a comparative analysis of twelve distinct geometries, a significant correlation between predicted deformations and actual measured deformations was established. This coefficient enables reliable translation between simulation results and actual SLS outcomes. The findings demonstrate that technological compensating deformations can be effectively calculated and applied to original triangulation models, substantially reducing geometric deviations in final products. The research bridges the gap between established injection molding simulation techniques and the rapidly evolving field of additive manufacturing, providing a practical approach to enhance dimensional accuracy without requiring specialized SLS deformation prediction software. This research was developed at the Department of "Integrated Technologies of Mechanical Engineering" named after M. Semko of NTU "KhPI".

The presented results were obtained during a theoretical and experimental study of the geometric accuracy and surface quality parameters of concrete walls manufactured using additive technologies. Theoretical aspects of the classification of defects and deviations of surfaces obtained by layered concrete construction have been developed. The study examines the influence of layer thickness on printing precision and defect formation in 3D concrete printing (3DCP) processes. Two experimental samples were fabricated with different layer thicknesses: 20 mm and 15 mm. Systematic measurements were conducted to evaluate crack depth on vertical surfaces, pore depth on horizontal surfaces, track width variations, and deviations from straight-line geometry. The experimental methodology involved comprehensive measurement protocols using precision instruments to assess geometrical parameters and surface quality characteristics. Statistical analysis was performed to quantify the relationships between layer thickness and printing accuracy, including calculations of mean values, standard deviations, and coefficients of variation for all measured parameters. Results demonstrate significant improvements in geometrical accuracy when reducing layer thickness from 20 mm to 15 mm. Crack depth on vertical surfaces decreased by 56%, while deviations from straight-line geometry improved by 32%. Most notably, track width stability showed a remarkable enhancement, with the coefficient of variation improving by 91%, indicating substantially improved process repeatability. The 15 mm layer thickness configuration exhibited superior performance across all measured parameters, demonstrating enhanced layer adhesion, reduced surface defects, and improved dimensional consistency. The coefficient of variation for crack depth decreased from 43% to 24%, while deviation variability reduced from 32% to 12%, confirming improved process control and predictability. These findings provide valuable insights for optimizing 3D concrete printing parameters and establishing quality control protocols for additive construction applications. The research contributes to the development of standardized practices for concrete 3D printing technology and demonstrates the critical importance of layer thickness optimization for achieving high-quality printed concrete structures. The results confirm the effectiveness of implementing thinner layers, given the increased requirements for geometric accuracy and surface quality in automated concrete construction processes. This research was conducted at "Geopolimer" LTD to implement innovative technologies in the construction industry.

The study is devoted to a comprehensive analysis of the introduction of additive technologies into modern construction production, revealing the technical, economic, and managerial aspects of concrete 3D-printing of architectural structures. The work systematically analyzes the evolution of additive manufacturing technologies and identifies the main structural types of 3D-printers (an additive machine for layer-by-layer construction of objects), including portal, robotic, mobile, and hybrid systems. A detailed study of the technological parameters of concrete 3D-printing with concrete mixtures is presented, in particular, optimal printing speed modes, layer parameters, criteria for shaping and quality of building structures. A comparative analysis of the technological capabilities of leading world equipment manufacturers, such as ICON, COBOD International, Apis Cor, and WinSun, is conducted. The economic analysis demonstrates significant advantages of additive technologies: reduction of construction time by 2-6 times, reduction of construction cost by 20-35%, and increase in the load-bearing capacity of structures. The study comprehensively explores the structure of capital and operational expenses associated with technology implementation. Special emphasis is placed on the management aspects of introducing additive technologies, highlighting the critical need for an interdisciplinary approach and knowledge integration across architecture, engineering, management, and computer modeling. The study determines the prospects for the development of concrete 3D-printing technology in the construction industry and outlines the main directions of further scientific research and practical implementation of innovative solutions. This study was developed between the Department of "Integrated Technologies of Mechanical Engineering" named after M. Semko of NTU "KhPI" and "Geopolimer" LTD to implement innovative technologies in the construction industry.

The main aspects of color visualization of triangulated models of industrial products are presented. The implementation of visualization capabilities is based on RGB and HSV color models. The structure and key features of the software implementation of color visualization and the export of the displayed image in PLY, and AMF formats are discussed. Methods for transformations between RGB and HSV color models are described, as well as an algorithm for coloring the triangular faces of the model based on specified color ranges. The developed algorithms allow for a sufficiently informative representation of the desired areas of the product's surfaces by significantly altering one color component while minimally changing the other two. This is achieved by directing the assignment of functional dependencies and value ranges for each component of the color model. Examples of various methods for color shading of vertices and/or edges and/or faces of the model are provided. The visualization subsystem enables the analysis of the geometric characteristics of the polygonal model during the preparation phase of additive manufacturing processes. Significant advantages of these approaches to color visualization are evident when adapting the product design to technological requirements (design preparation) and when solving optimization tasks in technological preparation. The developed software is integrated into the technological preparation system for manufacturing enterprises in the machine engineering sector. This research was developed at the Department of "Integrated Technologies of Mechanical Engineering" named after M. Semko of NTU "KhPI".

Research results on improving the efficiency of the developed algorithm for adaptive layer-by-layer dissection are presented on the example of 3D models group placed in the workspace of an additive setup. This algorithm for 3D model adaptive cutting allows you to increase the productivity of the process and adjust the accuracy of manufacturing products, taking into account their geometry, by setting a rational value of the variable building step for each individual lowering of the work platform. Building step is calculated taking into account the distribution of the direction of surfaces normal of products group (relative to the construction direction) that fall into the current layer. The developed algorithm provides for some truncation of this distribution, which makes it possible to further increase the building step and, accordingly, reduce the number of layers. Thus, conditions can be created for rational support and given reduction in building time. This achieves a reduction in building time compared to existing strategies for variable dissection. Estimate of efficiency of adaptive layer-by-layer dissection was carried out taking into account the accuracy of determining (setting) building step in relation to 5 options for placing 3D models of industrial products in workspace. Comparative analysis of dissection options was performed by the number of layers and assessment of deviations from of surfaces correct shape. Increase in the efficiency of layer-by-layer shaping process with increased accuracy in determining variable step of building a group of complex products placed in workspace of installation has been revealed. This research was developed at the Department of "Integrated Technologies of Mechanical Engineering" named after M. Semko of NTU "KhPI".

Розглянуто питання досліджень структурних змін стосовно до зварних з'єднань паропроводів. Представлені результати металографічного аналізу структурних змін в металі паропроводів. Аналіз виконувався для ряду зразків, вирізаних з різних ділянок паропроводу при різному напрацюванні в умовах повзучості і малоциклової втоми. У процесі аналізу зображень отриманих мікрошліфів виявлені відносний вміст структурно-фазових складових і їх розподіл в металі. Виконано порівняльний аналіз статистичних характеристик розподілу і відносного змісту структурних складових для різних ділянок металу зварних з'єднань з різним напрацюванням. Дано науково обґрунтований опис структурних змін в металі різних ділянок зразків зварних з'єднань, а також можливість продовження ресурсу експлуатації елементів паропроводів з деградованою структурою і наявністю пошкоджуваності. Сформульовано та обґрунтовано найбільш перспективні, на думку авторів, напрямки подальшого дослідження зразків для забезпечення умов, що дозволять продовжити ресурс експлуатації паропроводів.