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Aluminosilicate (Al-Si-O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 degrees C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al-O-Al vibrational band (at 1050 cm-1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hard-ness. The same Al-O-Al vibrational band (at 1050 cm-1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.

Aluminosilicate (Al-Si-O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 degrees C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al-O-Al vibrational band (at 1050 cm-1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hard-ness. The same Al-O-Al vibrational band (at 1050 cm-1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.

Aluminosilicate (Al–Si–O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 °C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al–O–Al vibrational band (at 1050 cm−1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hardness. The same Al–O–Al vibrational band (at 1050 cm−1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al., SK and PE acknowledge financial support by the Swedish Energy Agency (grant no. 52740-1). SK acknowledge financial support by FORMAS, the Swedish Research Council for Sustainable Development (grant no. 2018-00707). SA acknowledge the financial support from the KKL Advanced Materials, LNU (grant no. 87202002) and Crafoord Foundation (grant no. 2022-0692)., Energi- och resurseffektiva produktionsprocesser för hållbara ytbeläggningsmaterial, Tunnare och starkare glas för hållbar produktion och konsumtion

Aluminosilicate (Al-Si-O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 degrees C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al-O-Al vibrational band (at 1050 cm-1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hard-ness. The same Al-O-Al vibrational band (at 1050 cm-1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.

Aluminosilicate (Al-Si-O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 degrees C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al-O-Al vibrational band (at 1050 cm-1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hard-ness. The same Al-O-Al vibrational band (at 1050 cm-1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.

Aluminosilicate (Al–Si–O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 °C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al–O–Al vibrational band (at 1050 cm−1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hardness. The same Al–O–Al vibrational band (at 1050 cm−1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al., SK and PE acknowledge financial support by the Swedish Energy Agency (grant no. 52740-1). SK acknowledge financial support by FORMAS, the Swedish Research Council for Sustainable Development (grant no. 2018-00707). SA acknowledge the financial support from the KKL Advanced Materials, LNU (grant no. 87202002) and Crafoord Foundation (grant no. 2022-0692)., Energi- och resurseffektiva produktionsprocesser för hållbara ytbeläggningsmaterial, Tunnare och starkare glas för hållbar produktion och konsumtion

Aluminosilicate (Al-Si-O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 degrees C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al-O-Al vibrational band (at 1050 cm-1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hard-ness. The same Al-O-Al vibrational band (at 1050 cm-1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.

The paper presents results of a research on fabrication of magneto-optical ceramics based on Ho2O3 and Dy2O3 sesquioxides. The ceramics were made by hot pressing of powders prepared by self-propagating high-temperature synthesis. The methods and modes of the powder treatment developed made it possible to significantly increase the thickness of the ceramics without deterioration in optical quality in comparison with the samples obtained by vacuum sintering. The characteristics of the ceramics, such as transmission spectrum, thermal conductivity, linear thermal expansion coefficient, microhardness, elastic modulus, and crack resistance have been investigated. © 2021 The Author(s).

Double network (DN) gels, consisting of two contrasting interpenetrated polymer networks, exhibit large resistances to crack initiation and propagation. For practical applications, crack resistances of materials in highly stretched states are important. In this study, we investigated the crack growth behaviors of DN gels in stretched states by inducing crack seeds into these gels under various degrees of tension. This examination enables the analysis of crack propagation for a wide range of bulk energy release rate G. The power-law elationship between G and crack growth velocity v was investigated for DN gels with different tensile behaviors. We found that for brittle and unnecking DN gels, the velocities changed from slow mode (quasi-stationary fracture) to fast mode (dynamic fracture) with an increase in G, similar to that of a single network gel; in contrast, for necking DN gels having higher crack resistances than those of the unnecking DN gels, only fast modes were observed once the G is above a threshold. Real-time birefringence observation reveals a large damage zone around the crack tip at G slightly lower than the threshold, while the damage zone is hardly observed at G higher than the threshold. The results indicate that, for the necking DN gels, crack initiation has a large energy barrier owing to the formation of the damage zone; once this barrier is overcome, the excess energy release accelerates the crack propagation and therefore the gels exhibit dynamic fracture.

Double network (DN) gels, consisting of two contrasting interpenetrated polymer networks, exhibit large resistances to crack initiation and propagation. For practical applications, crack resistances of materials in highly stretched states are important. In this study, we investigated the crack growth behaviors of DN gels in stretched states by inducing crack seeds into these gels under various degrees of tension. This examination enables the analysis of crack propagation for a wide range of bulk energy release rate G. The power-law elationship between G and crack growth velocity v was investigated for DN gels with different tensile behaviors. We found that for brittle and unnecking DN gels, the velocities changed from slow mode (quasi-stationary fracture) to fast mode (dynamic fracture) with an increase in G, similar to that of a single network gel; in contrast, for necking DN gels having higher crack resistances than those of the unnecking DN gels, only fast modes were observed once the G is above a threshold. Real-time birefringence observation reveals a large damage zone around the crack tip at G slightly lower than the threshold, while the damage zone is hardly observed at G higher than the threshold. The results indicate that, for the necking DN gels, crack initiation has a large energy barrier owing to the formation of the damage zone; once this barrier is overcome, the excess energy release accelerates the crack propagation and therefore the gels exhibit dynamic fracture.

Double network (DN) gels, consisting of two contrasting interpenetrated polymer networks, exhibit large resistances to crack initiation and propagation. For practical applications, crack resistances of materials in highly stretched states are important. In this study, we investigated the crack growth behaviors of DN gels in stretched states by inducing crack seeds into these gels under various degrees of tension. This examination enables the analysis of crack propagation for a wide range of bulk energy release rate G. The power-law elationship between G and crack growth velocity v was investigated for DN gels with different tensile behaviors. We found that for brittle and unnecking DN gels, the velocities changed from slow mode (quasi-stationary fracture) to fast mode (dynamic fracture) with an increase in G, similar to that of a single network gel; in contrast, for necking DN gels having higher crack resistances than those of the unnecking DN gels, only fast modes were observed once the G is above a threshold. Real-time birefringence observation reveals a large damage zone around the crack tip at G slightly lower than the threshold, while the damage zone is hardly observed at G higher than the threshold. The results indicate that, for the necking DN gels, crack initiation has a large energy barrier owing to the formation of the damage zone; once this barrier is overcome, the excess energy release accelerates the crack propagation and therefore the gels exhibit dynamic fracture.

На основе анализа экспериментальных исследований предложены критерии хрупкости для высокопрочного бетона при высоких температурах и рекомендованы их пороговые значения, которые определяются по разработанной методике для бетона при t = 20°C. Критерии хрупкости для высокопрочного бетона при высоких температурах для эксплуатируемых конструкций определяются на основе зависимости E и KIС от поверхностной твердости Н. На основании полученных экспериментальных данных предложено значение поверхностной твердости (при t = 20°C ) высокопрочного бетона H > 450 МПа, при нагреве которого будет происходить хрупкое разрушение.

Свойства усадки и ползучести бетона характеризуются способностью деформироваться с течением времени без приращения внешних нагрузок. Данные свойства бетона оказывают влияние на напряженно-деформированное состояние железобетонных элементов. В зависимости от вида железобетонной конструкции (балки, колонны) отличается и влияние усадки и ползучести на напряженно-деформированное состояние. В статье приводятся результаты анализа напряженно-деформированного состояния нормальных сечений железобетонных элементов с учетом деформаций усадки и ползучести бетона на основе деформационной расчетной модели, применимой для вычисления параметров трещинообразования и деформаций железобетонных элементов при произвольной форме и компоновке поперечного сечения, любом расположении арматуры в пределах сечения.

Робота виконана на кафедрі «Наноінженерія в галузевому машинобудуванні» ДВНЗ «Приазовський державний технічний університет» Міністерства освіти і науки України, Дисертація присвячена формуванню модифікованих шарів з субмікро- і нанокристалічною структурою і підвищеним рівнем експлуатаційних властивостей при поверхневій обробці різьбонарізного інструменту зі швидкорізальних сталей та твердих сплавів висококонцентрованим плазмовим струменем. У літературному огляді виконаний аналіз умов роботи різьбонарізного інструменту. Показан характер зносу різьбонарізного інструменту, механізми зносу, зони зносу. показана перспективність розвитку різних методів зміцнення для підвищення працездатності різьбонарізного інструменту. Особливість різьбонарізного інструмента це дуже велика номенклатура як по розмірах, від дуже дрібних мітчиків, до крупних фрез, різців, так і за різноманітністю видів. Нині існує 4 підходи до зміцнення. Найбільш розвиваються останнім часом це нанесення покриттів, і поверхневе модифікування. Ці два найбільш поширених метода якраз розвиваються у бік отримання дисперсних структур у тому числі і наноструктур. Дисертаційна робота виконана на плазмовому комплексі в умовах кафедри «Наноінженерія в галузевому машинобудуванні», основний елемент цього комплексу це плазматрон. Плазматрон використовується побічної дії: деталь і інструмент електрично нейтральні. Особлтвість його конструкції це сенкціонована міжелектродна вставка. Спеціально для того, щоб підвищити швидкість охолодження і отримати плазмове наноструктурування. Експериментами встановлено, що можна впливати на цей процес шляхом виконання каналу плазматрона не циліндричної форми, а конічної. Міра звуження каналу впливає на твердість при обробці. Розроблена методика математичного моделювання процесу плазмового модифікування різьбонарізного інструмента. У основі розрахунку теплової дії висококонцентрованих джерел нагріву на метал лежить закон теплопровідності Фур'є. Для вирішення цього завдання використано звичайно-елементне моделювання із застосуванням прикладного пакету МСS.Nastran. Розроблено математичну модель оптимального керування процесом плазмового поверхнево

Робота виконана на кафедрі «Наноінженерія в галузевому машинобудуванні» ДВНЗ «Приазовський державний технічний університет» Міністерства освіти і науки України, Дисертація присвячена формуванню модифікованих шарів з субмікро- і нанокристалічною структурою і підвищеним рівнем експлуатаційних властивостей при поверхневій обробці різьбонарізного інструменту зі швидкорізальних сталей та твердих сплавів висококонцентрованим плазмовим струменем. У літературному огляді виконаний аналіз умов роботи різьбонарізного інструменту. Показан характер зносу різьбонарізного інструменту, механізми зносу, зони зносу. показана перспективність розвитку різних методів зміцнення для підвищення працездатності різьбонарізного інструменту. Особливість різьбонарізного інструмента це дуже велика номенклатура як по розмірах, від дуже дрібних мітчиків, до крупних фрез, різців, так і за різноманітністю видів. Нині існує 4 підходи до зміцнення. Найбільш розвиваються останнім часом це нанесення покриттів, і поверхневе модифікування. Ці два найбільш поширених метода якраз розвиваються у бік отримання дисперсних структур у тому числі і наноструктур. Дисертаційна робота виконана на плазмовому комплексі в умовах кафедри «Наноінженерія в галузевому машинобудуванні», основний елемент цього комплексу це плазматрон. Плазматрон використовується побічної дії: деталь і інструмент електрично нейтральні. Особлтвість його конструкції це сенкціонована міжелектродна вставка. Спеціально для того, щоб підвищити швидкість охолодження і отримати плазмове наноструктурування. Експериментами встановлено, що можна впливати на цей процес шляхом виконання каналу плазматрона не циліндричної форми, а конічної. Міра звуження каналу впливає на твердість при обробці. Розроблена методика математичного моделювання процесу плазмового модифікування різьбонарізного інструмента. У основі розрахунку теплової дії висококонцентрованих джерел нагріву на метал лежить закон теплопровідності Фур'є. Для вирішення цього завдання використано звичайно-елементне моделювання із застосуванням прикладного пакету МСS.Nastran. Розроблено математичну модель оптимального керування процесом плазмового поверхнево, Dissertation is sanctified to forming of the modified layers from submicro- and by a nanocrystalline structure and increase level of operating properties at superficial treatment of thread instrument from high speed steel and carboloies by a plasma stream. In a literary review the executed analysis of terms of work of thread instrument. The character of wear of thread instrument, mechanisms of wear, zone of wear. the shown perspective of development of different methods of strengthening is for the increase of capacity of thread instrument. The feature of thread instrument it a very large nomenclature as on sizes, from ultrafine markers, to the large milling cutters, chisels, so on the variety of kinds. Presently there are 4 approaches to strengthening. Most develop lately this causing of coverages, and superficial retrofitting. These two most widespread метода just develop toward the receipt of dispersible structures including nanostructures. Dissertation work is executed on a plasma complex in the conditions of department "Nanoengineering in a branch engineer", the basic element of this complex it a plasmatron. A plasmatron is used indirect action: a detail and instrument are electric neutral. Feature of his construction this partitioned interelectrode insertion. Specially in an order to promote cooling speed and get plasma nanostructure. It is set experiments, that it is possible to influence on this process by implementation of channel of plasmatron not cylindrical form, but conical. Measure of narrowing of channel influences on hardness at treatment. Worked out methodology of mathematical design of process of the plasma retrofitting of thread instrument. In basis of calculation of thermal action of concentrate sources of heating the law of heat-conducting of Fourier lies on a metal. For the decision of this task an usually-element design is used with application of the applied package of МСS.Nastran. A mathematical optimal case of the plasma superficial retrofit, Диссертация посвящена формированию модифицированных слоев из субмикро- и нанокристаллической структурой и повышенным уровнем эксплуатационных свойств при поверхностной обработке резьбонарезного инструмента из быстрорежущих сталей и твердых сплавов высококонцентрированной плазменной струей. Разработана математическая модель оптимального управления процессом плазменного поверхностного модифицирования резьбонарезного инструмента и инженерная методика расчета оптимальных режимов обработки. Исследовано механизмы структурных превращений гребенки из быстрорежущей стали и резьбонарезного резца с напаяной твердосплавной пластиной при плазменном поверхностном модифицировании. Разработана методика испытаний и исследована трещиностойкость, механизмы разрушения и изнашивания резьбонарезного инструмента с поверхностным модифицированным слоем. Разработано технологическое оборудование для проведения плазменной обработки. Разработаны технологические процессы плазменного модифицирования резьбонарезного инструмента из твердых сплавов и быстрорежущих сталей. Разработана структурная схема управления наностуруктурированием после плазменного модифицирования. Разработаны рекомендации по выбору оптимального размещения модифицированной зоны на резьбонарезном резце с напаяными твердосплавными пластинами и резьбонарезной гребенки из быстрорежущей стали. Проведены стойкостные исследования резьбонарезного инструмента после плазменного модифицирования.

On the basis of the analysis of experimental studies, brittleness criteria for high-strength concrete at high temperatures are proposed and their threshold values are recommended, which are determined by the developed method for concrete at t=20°C. The brittleness criteria for high-strength concrete at high temperatures for operating structures are determined on the basis of the dependence of E and KIC on the surface hardness H. Based on the experimental data obtained, the value of the surface hardness (at) of high-strength concrete H>450 MPa is proposed, when heated, brittle fracture will occur.     &nbsp, На основе анализа экспериментальных исследований предложены критерии хрупкости для высокопрочного бетона при высоких температурах и рекомендованы их пороговые значения, которые определяются по разработанной методике для бетона при t=20 оС. Критерии хрупкости для высокопрочного бетона при высоких температурах для эксплуатируемых конструкций определяются на основе зависимости E и KIС от поверхностной твердости Н. На основании полученных экспериментальных данных предложено значение поверхностной твердости (при ) высокопрочного бетона H>450 МПа, при нагреве которого будет происходить хрупкое разрушение.     &nbsp

The shrinkage and creep properties of concrete are characterized by the ability to deform over time without changing of external loads. These concrete properties affect the stress-strain state of reinforced concrete elements. Depending on the type of reinforced concrete structure (beams, columns), the effect of shrinkage and creep on the stress-strain state is also different. The article presents the results of the analysis of the stress-strain state of normal sections of reinforced concrete elements, taking into account shrinkage and creep deformations of concrete, based on a deformation design model, applicable to analyze the parameters of deformations and cracking of reinforced concrete elements with an arbitrary shape of the cross section, any arrangement of reinforcement within the section.     &nbsp, Свойства усадки и ползучести бетона характеризуются способностью деформироваться с течением времени без приращения внешних нагрузок. Данные свойства бетона оказывают влияние на напряженно-деформированное состояние железобетонных элементов. В зависимости от вида железобетонной конструкции (балки, колонны), отличается и влияние усадки и ползучести на напряженно-деформированное состояние. В статье приводятся результаты анализа напряженно-деформированного состояния нормальных сечений железобетонных элементов с учетом деформаций усадки и ползучести бетона на основе деформационной расчетной модели, применимой для вычисления параметров трещинообразования и деформаций железобетонных элементов при произвольной форме и компоновке поперечного сечения, любом расположении арматуры в пределах сечения.     &nbsp

A novel approach to determine the translaminar crack resistance curve of composite laminates by means of a machine learning model is presented in this paper. The main objective of the proposed method is to extract hidden information of crack resistance from strength values of center-cracked laminates. Compared to traditional measurements, the notable advantage is that only tensile strength values are required which can be obtained by a rather simpler experimental procedure. This is achieved by the incorporation of the finite fracture mechanics, which links crack resistance with strength values. In order to get training dataset, a semi-analytical method using both finite element method and finite fracture mechanics is employed to generate strength values of center-cracked specimens with different random R-curves, which serve as inputs for our artificial neural network. Regarding the outputs, principal component analysis is performed to reduce dimensionality and find suitable descriptors for crack resistance curves. After successfully training machine learning model, experimental studies on basalt fiber reinforced laminates are conducted as validation. Results have proven the effectiveness of the proposed strategy for predicting crack resistance curves, as well as the feasibility of using machine learning-based framework to find out more information about composites from simple experimental data. © 2020 World Scientific Publishing Company.

Moisture transfer in concrete is a set of physical processes as a result of which, under certain conditions, prerequisites are created leading, in particular, to the emergence of destructive processes in the composite. Therefore, the study of such complex phenomena, the establishment of the laws of their course is of certain scientific interest

Moisture transfer in concrete is a set of physical processes as a result of which, under certain conditions, prerequisites are created leading, in particular, to the emergence of destructive processes in the composite. Therefore, the study of such complex phenomena, the establishment of the laws of their course is of certain scientific interest

Moisture transfer in concrete is a set of physical processes as a result of which, under certain conditions, prerequisites are created leading, in particular, to the emergence of destructive processes in the composite. Therefore, the study of such complex phenomena, the establishment of the laws of their course is of certain scientific interest

Moisture transfer in concrete is a set of physical processes as a result of which, under certain conditions, prerequisites are created leading, in particular, to the emergence of destructive processes in the composite. Therefore, the study of such complex phenomena, the establishment of the laws of their course is of certain scientific interest

Moisture transfer in concrete is a set of physical processes as a result of which, under certain conditions, prerequisites are created leading, in particular, to the emergence of destructive processes in the composite. Therefore, the study of such complex phenomena, the establishment of the laws of their course is of certain scientific interest

Moisture transfer in concrete is a set of physical processes as a result of which, under certain conditions, prerequisites are created leading, in particular, to the emergence of destructive processes in the composite. Therefore, the study of such complex phenomena, the establishment of the laws of their course is of certain scientific interest

A novel approach to determine the translaminar crack resistance curve of composite laminates by means of a machine learning model is presented in this paper. The main objective of the proposed method is to extract hidden information of crack resistance from strength values of center-cracked laminates. Compared to traditional measurements, the notable advantage is that only tensile strength values are required which can be obtained by a rather simpler experimental procedure. This is achieved by the incorporation of the finite fracture mechanics, which links crack resistance with strength values. In order to get training dataset, a semi-analytical method using both finite element method and finite fracture mechanics is employed to generate strength values of center-cracked specimens with different random R-curves, which serve as inputs for our artificial neural network. Regarding the outputs, principal component analysis is performed to reduce dimensionality and find suitable descriptors for crack resistance curves. After successfully training machine learning model, experimental studies on basalt fiber reinforced laminates are conducted as validation. Results have proven the effectiveness of the proposed strategy for predicting crack resistance curves, as well as the feasibility of using machine learning-based framework to find out more information about composites from simple experimental data. © 2020 World Scientific Publishing Company.

Moisture transfer in concrete is a set of physical processes as a result of which, under certain conditions, prerequisites are created leading, in particular, to the emergence of destructive processes in the composite. Therefore, the study of such complex phenomena, the establishment of the laws of their course is of certain scientific interest

A novel approach to determine the translaminar crack resistance curve of composite laminates by means of a machine learning model is presented in this paper. The main objective of the proposed method is to extract hidden information of crack resistance from strength values of center-cracked laminates. Compared to traditional measurements, the notable advantage is that only tensile strength values are required which can be obtained by a rather simpler experimental procedure. This is achieved by the incorporation of the finite fracture mechanics, which links crack resistance with strength values. In order to get training dataset, a semi-analytical method using both finite element method and finite fracture mechanics is employed to generate strength values of center-cracked specimens with different random R-curves, which serve as inputs for our artificial neural network. Regarding the outputs, principal component analysis is performed to reduce dimensionality and find suitable descriptors for crack resistance curves. After successfully training machine learning model, experimental studies on basalt fiber reinforced laminates are conducted as validation. Results have proven the effectiveness of the proposed strategy for predicting crack resistance curves, as well as the feasibility of using machine learning-based framework to find out more information about composites from simple experimental data. © 2020 World Scientific Publishing Company.

The paper presents studies of the structure and mechanical properties of alloys hardened with niobium carbides at temperatures of 20–1500 °C. It is shown that the mechanical properties of the studied alloys are superior to the properties of highalloyed alloys of the Nb–Si system. The alloys demonstrated higher short.term and 100.hour strengths than Nb–Si system alloys at a temperature of 1500 °C. However, it was found that the alloys have low crack resistance., В работе представлены исследования структуры и механических свойств сплавов, упрочненных карбидами ниобия, при температурах 20–1500 °C. Показано, что механические свойства исследуемых сплавов превосходят свойства высоколегированных сплавов системы Nb–Si. Сплавы продемонстрировали более высокие, чем сплавы системы Nb–Si, кратковременную и 100.часовую прочность при температуре 1500 °C. Вместе с тем установлено, что сплавы обладают низкой трещиностойкостью.

The results of tests for hardness and crack resistance of optical fiber samples doped with germanium during indentation by the Vickers pyramid are presented. Using the Niihara technique, the stress intensity factor K1c was experimentally determined and compared with published data., Приведены результаты испытаний на твердость и трещиностойкость образцов оптического волокна легированных германием при индентировании пирамидкой Виккерса. С помощью методики Ниихары экспериментально определен коэффициент интенсивности напряжений K1c кварца и сопоставлен с литературными данными.

The effect of aluminum-magnesium spinel on the physical and mechanical characteristics of aluminum oxide is considered in the work. The density of the material does not depend on the amount of additive. The crack resistance of the material increases by 1,5 times., В работе исследовано влияние добавки алюмомагниевой шпинели на физические и механические характеристики оксида алюминия. Использование добавки не оказывает влияния на плотность материала, но приводит к повышению трещиностойкости в 1,5 раза.

We studied heat-resistant composites from alloys (Ti-Al) and (Mo-Si-C) with intermetallic and carbide-silicide hardening. Composites were obtained by diffusion welding under pressure of packages of titanium and aluminum foils and packages of Mo-foils with (Si-C)-coating. Layered structures were formed due to the solid-phase interaction between: Ti- and Al-foils, Mo-foils and coatings., Исследовались жаропрочные композиты из сплавов (Ti-Al) и (Mo-Si-C) с интерметаллидным и карбидо-силицидным упрочнением. Композиты получали диффузионной сваркой под давлением пакетов из фольг титана и алюминия и пакетов из Mo-фольг с (Si-C)-покрытием. Слоистые структуры формировались вследствие твердофазного взаимодействия между Ti- и Al-фольгами, Mo-фольгами и покрытиями.

The article considers the effect of surface roughness on cyclic durability. The effect of electrolytic polishing on the cyclic durability of metal materials has been studied. Some parameters of surface roughness after electrolytic polishing and untreated surface are determined. Tests for cyclic durability of samples with surface treatment by electrolytic polishing and samples without surface treatment were carried out., В статье рассмотрено влияние шероховатости поверхности на циклическую долговечность. Исследовано, как влияет электролитическое полирование на циклическую долговечность металлических материалов. Определены некоторые параметры шероховатости поверхности после электролитического полирования и необработанной поверхности. Проведены испытания на циклическую долговечность образцов с поверхностной обработкой электролитическим полированием и образцов без поверхностной обработки.

Проект містить опис технологічного процесу, виготовлення автомобільних шин, опис, призначення та місце в технологічній схемі агрегатів які використовуються при виготовлені автомобільних шин. У проекті виконано літературний пошук на тему дослідження технічних та експлуатаційних характеристик шин, модифікованих вуглецевими наночастинками. В результати роботи: розроблено розрахункову модель типової автомобільної шини; розроблено скінчено-елементну модель композиту «нанортубка-гума»; досліджено вплив на межу міцності наномодифікованої гуми від коефіцієнту армування її нанотрубками; встановлено оптимальне значення коефіцієнту армування; результат аналізу даних розрахунків було виявлено слабкі місця у клейовому шарі, який з’єднує протектор і основу шини; розглянуто вимоги охорони праці на лінії по виробництву шин., The project contains a description of the technological process, the manufacture of automobile tires, a description, purpose and place in the technological diagram of the units that are used in the manufacture of automobile tires. The project conducted a literary search on the study of the technical and operational characteristics of tires modified with carbon nanoparticles. Results of work: design model of typical automobile tyre has been developed; A skincene-element model of the nanotube-rubber composite has been developed; Effect of nanomodified rubber strength on its nanotube reinforcement from coefficient has been investigated; the optimal value of the reinforcement factor is set; The result of these calculations revealed weaknesses in the adhesive layer that connects the tread and the tire base; labor protection requirements on the tyre production line were considered.

Al-Cr-Nb-Y-Zr-N films have been deposited with reactive dc magnetron sputtering at various N-2 flow ratios to achieve films with different nitrogen content, from purely metallic to fully nitrided films. The structure evolved from mainly amorphous with a minor crystalline intermetallic phase for the film without nitrogen, to nanocomposites with a cubic crystalline phase in an amorphous matrix for intermediate nitrogen content (15-41 at.% N), and at higher nitrogen content (46-51 at.% N) to crystalline solid solution nitrides with a NaCl-type structure. Partial elemental segregation on the nanoscale was found in all studied samples and the films exhibited different segregation behaviour depending on the nitrogen content, implying that the structural evolution on the nanoscale of films in this material system complex and highly composition-dependent. The hardness increased with increasing nitrogen content, reaching a maximum at about 30 GPa at for the nitride films with 50 at.% N. Deformation behaviour, studied by indentation measurements, of the nitride films was found to be ductile, where no sign of crack formation could be observed. This can be attributed to a metallic phase in the columnar boundaries caused by partial elemental segregation of mainly yttrium. Hence, films within in this material system, although the nanostructure is found to be relatively complex, show very promising mechanical properties and the structural complexity can be used as a guide for designing nitride materials that combine high hardness with ductility.

Магістерська дисертація: 92 с., 33 рис., 10 табл., 37 посилань. Об’єкт дослідження – технологічний процес отримання жаростійких чавунів. Предмет дослідження – експлуатаційна стійкість деталей склоформ: росто- та окалиностійкість. Мета роботи – встановити вплив хімічного складу чавунів на жаростійкість склоформ для підвищення експлуатаційних характеристик склоформ. Методи дослідження – окалиностійкість досліджуваних чавунів визначали ваговим методом за збільшенням маси зразків, ростостійкість – виявленням на зразках тріщин та їх розмірів під дією циклічних нагрівань та охолоджень. Результати дослідження – встановлено залежність експлуатаційних характеристик від хімічного складу чавунів, що працюють у термоціклічних режимах; запропановано чавун для виготовлення формокомплекту скляних виробів. Галузь застосування – склотарне виробництво. Пропозиції про можливі напрямки розвитку, продовження виконаних досліджень – виготовлення дослідного формокомплекту для випробувань в умовах промислового виробництва., Master's dissertation: 92 pp., 33 figs., 10 tables, 37 references. The object of research is the technological process of obtaining heat-resistant cast irons. The subject of research is the operational stability of glass mold parts: growth and scale resistance. The purpose of the work is to establish the influence of the chemical composition of cast irons on the heat resistance of glass molds to improve the performance of glass molds. Research methods - scale resistance of the studied cast irons was determined by the weight method by increasing the mass of the samples, growth resistance - detection of cracks on the samples and their size under the action of cyclic heating and cooling. The results of the study - the dependence of the performance characteristics on the chemical composition of cast irons operating in thermocyclic modes; cast iron for the manufacture of glass molds is proposed. Field of application - glass container production. Proposals on possible directions of development, continuation of the performed researches - production of an experimental form set for tests in the conditions of industrial production.

Об’єкт дослідження: сплави систем Nb-Si-(B, Cr, Mo, Ti) ат. %: Nb-25Si-13B, Nb-Si-25Cr, Nb-6Si-30Cr, Nb-6Si-35Cr, Nb-20Si-2Mo, Nb-20Si-4Mo, Nb-20Si-6Mo, Nb-20Si-22Ti, Nb-20Si-24Ti, одержані електронно-променевим спіканням. Метою роботи є вивчення структури та властивостей евтектичних сплавів систем Nb-Si-(B, Cr, Mo, Ti), одержаних електронно-променевим оплавленням. Методи дослідження та апаратура: отримання сплавів систем Nb-Si-(B, Cr, Mo, Ti) здійснювалось в установці ЭЛА-6. За допомогою комплексу високоінформативних методів фізичного матеріалознавства (електронної мікроскопії, мікрорентгеноспектрального аналізу) досліджено мікро- та макроструктуру, хімічний склад фазових складових сплавів систем Nb-Si-(B, Cr, Mo, Ti). Також виміряна мікротвердість та тріщиностійкість на мікротвердомірі ПМТ-3., The object of study: the alloys of the system Nb-Si-(B, Cr, Mo, Ti) at. %: Nb-25Si-13B, Nb-Si-25Cr, Nb-6Si-30Cr, Nb-6Si-35Cr, Nb-20Si-2Mo, Nb-20Si-4Mo, Nb-20Si-6Mo, Nb-20Si-22Ti, Nb-20Si-24Ti obtained by electron beam sintering. The purpose of the work is to study the structure and properties of alloys of the Nb-Si-(B, Cr, Mo, Ti) system obtained by electron beam sintering. Research methods and equipment: the alloys of system Nb-Si-(B, Cr, Mo, Ti) were obtained by ELA-6. The micro- and macrostructure, the chemical composition of the phase components of the resulting Nb-Si-(B, Cr, Mo, Ti) alloys, was studied using a set of highly informative methods of physical material science (electron microscopy, chemical analysis). It was measured is microhardness and crack resistance., Объект исследования: сплавы систем Nb-Si-(B, Cr, Mo, Ti) ат. %: Nb-25Si-13B, Nb-Si-25Cr, Nb-6Si-30Cr, Nb-6Si-35Cr, Nb-20Si-2Mo, Nb-20Si-4Mo, Nb-20Si-6Mo, Nb-20Si-22Ti, Nb- 20Si-24Ti, полученные электронно-лучевым оплавлением. Целью работы является изучение структуры и свойств эвтектических сплавов систем Nb-Si-(B, Cr, Mo, Ti), полученных электронно-лучевым оплавлением. Методы исследования и аппаратура: получение сплавов систем Nb-Si-(B, Cr, Mo, Ti) осуществлялось в установке Эла-6. С помощью комплекса высокоинформативных методов физического материаловедения (электронной микроскопии, микрорентгеноспектрального анализа) исследованы микро- и макроструктура, химический состав фазовых составляющих сплавов систем Nb-Si-(B, Cr, Mo, Ti). Также измерена микротвердость и трещиностойкость на Микротвердомере ПМТ-3.

In the current paper we present a concept combining metal organic chemical vapor deposition with thermal strengthening process of flat glass. As the flat glass is heated to be thermally strengthened, which takes up to 20 minutes, there is an opportunity for performing a surface modification. We describe the application of transparent and amorphous Al2O3 thin films during the thermal strengthening process. Al2O3 was chosen due to the following desirable properties: increased surface mechanical properties and increased chemical durability, the latter has not been investigated in the current paper. The residual surface compressive stresses after performed strengthening of the coated glasses were quantified to be in the range of 80–110 MPa. The Al2O3 content in the surface was measured using the Surface Ablation Cell employed with Inductively Coupled Plasma Atomic Emission Spectroscopy and found to be at least doubled at the surface and having an increased Al2O3 content at least 0.5 μm underneath the glass surface. During the surface reaction, sodium is migrating to the surface giving a hazy salt layer on the glass which can easily be washed off with water. The applied coatings are transparent and provide increased surface hardness and crack resistance at low indentation loads. At higher indentation loads the interaction volume is larger and displays the same effect on the surface mechanical properties as for thermally strengthened glass. The contact angle with water compared to annealed float glass is significantly increased from 5° to 45° due to the different surface chemistry and surface topography.

In the current paper we present a concept combining metal organic chemical vapor deposition with thermal strengthening process of flat glass. As the flat glass is heated to be thermally strengthened, which takes up to 20 minutes, there is an opportunity for performing a surface modification. We describe the application of transparent and amorphous Al2O3 thin films during the thermal strengthening process. Al2O3 was chosen due to the following desirable properties: increased surface mechanical properties and increased chemical durability, the latter has not been investigated in the current paper. The residual surface compressive stresses after performed strengthening of the coated glasses were quantified to be in the range of 80–110 MPa. The Al2O3 content in the surface was measured using the Surface Ablation Cell employed with Inductively Coupled Plasma Atomic Emission Spectroscopy and found to be at least doubled at the surface and having an increased Al2O3 content at least 0.5 μm underneath the glass surface. During the surface reaction, sodium is migrating to the surface giving a hazy salt layer on the glass which can easily be washed off with water. The applied coatings are transparent and provide increased surface hardness and crack resistance at low indentation loads. At higher indentation loads the interaction volume is larger and displays the same effect on the surface mechanical properties as for thermally strengthened glass. The contact angle with water compared to annealed float glass is significantly increased from 5° to 45° due to the different surface chemistry and surface topography.

Oxide glasses are one of the most important engineering and functional material families owing to their unique features, such as tailorable physical properties. However, at the same time intrinsic brittleness has been their main drawback, which severely restricts many applications. Despite much progress, a breakthrough in developing ultra-damage-resistant and ductile oxide glasses still needs to be made. Here, a critical advancement toward such oxide glasses is presented. In detail, a bulk oxide glass with a record-high crack resistance is obtained by subjecting a caesium aluminoborate glass to surface aging under humid conditions, enabling it to sustain sharp contact deformations under loads of ≈500 N without forming any strength-limiting cracks. This ultra-high crack resistance exceeds that of the annealed oxide glasses by more than one order of magnitude, making this glass micro-ductile. In addition, a remarkable indentation behavior, i.e., a time-dependent shrinkage of the indent cavity, is demonstrated. Based on structural analyses, a molecular-scale deformation model to account for both the ultra-high crack resistance and the time-dependent shrinkage in the studied glass is proposed.

The goal of the research is to establish the effect of stabilizing additives on a number of deformation and strength indicators responsible for ensuring the durability of stone matrix asphalt (SMA), which are the complex modulus of elasticity, shear stability and bending tension. The modulus of elasticity value measurement was made on KhNAHU’s vibration table using electrodynamic transducer in the temperature range from -20 °C to +50 °C. In the deformation frequency range from 0.01 Hz to 50 Hz, shear stability was estimated by the value of shear limit strength at the temperature of 50 °C on special cylinder samples in conditions of their torsion (simple shear). The bending tension value was estimated on beam sample at different load application rate at the design temperatures of 20 °C, 10 °C and 0 °C. According to temperature dependences of modulus of elasticity, the estimate of SMA physical parameters, such as conditional mechanical glass transition temperature, viscoplastic transition temperature, temperature sensitivity of material and plasticity coefficient, was obtained. The values of shear limit strength with different stabilizing additives (VIATOP, DOLONIT) were obtained. A correlation between shear stability and compressive strength at the temperature of 50 °C was established. Comparison of deformation properties of SMA with asphalt concrete and polymer asphalt concrete using the same consistency of binder was made. The effectiveness of SMA hardening by different stabilizing additives on the basis of temperature dependences of bending strength was determined. The plastic range and temperature sensitivity values of SMA are similar to those of asphalt concrete and polymer asphalt concrete. These parameters are mainly determined by the properties of binder, such as penetration, softening temperature, etc. Polymer asphalt concrete has the highest value of plastic range and the lowest one of temperature sensitivity. The similar patterns are obtained for shear s

Ferroconcrete pipes, used in drainage and water disposal systems of roads, works in conditions, in which the direction of the main tensile stresses is either unknown, or can change during exploitation. One of the ways of solving this problem is using of steel fibrous concrete, i.e. concrete on hydraulic tenacious substances with addition of reinforcing elements in the form of short lengths (fibers). Using of steel fibrous concrete allows to get the construction of low pressure centrifuged pipe for drainage and water disposal systems at places of automobile and railway transport heavy traffic with higher tensile and bending strength, crack resistance for the work under conditions when the direction of the main tensile stresses is unknown. © 2019 Published under licence by IOP Publishing Ltd.

Oxide glasses are one of the most important engineering and functional material families owing to their unique features, such as tailorable physical properties. However, at the same time intrinsic brittleness has been their main drawback, which severely restricts many applications. Despite much progress, a breakthrough in developing ultra-damage-resistant and ductile oxide glasses still needs to be made. Here, a critical advancement toward such oxide glasses is presented. In detail, a bulk oxide glass with a record-high crack resistance is obtained by subjecting a caesium aluminoborate glass to surface aging under humid conditions, enabling it to sustain sharp contact deformations under loads of ≈500 N without forming any strength-limiting cracks. This ultra-high crack resistance exceeds that of the annealed oxide glasses by more than one order of magnitude, making this glass micro-ductile. In addition, a remarkable indentation behavior, i.e., a time-dependent shrinkage of the indent cavity, is demonstrated. Based on structural analyses, a molecular-scale deformation model to account for both the ultra-high crack resistance and the time-dependent shrinkage in the studied glass is proposed.

Oxide glasses are one of the most important engineering and functional material families owing to their unique features, such as tailorable physical properties. However, at the same time intrinsic brittleness has been their main drawback, which severely restricts many applications. Despite much progress, a breakthrough in developing ultra‐damage‐resistant and ductile oxide glasses still needs to be made. Here, a critical advancement toward such oxide glasses is presented. In detail, a bulk oxide glass with a record‐high crack resistance is obtained by subjecting a caesium aluminoborate glass to surface aging under humid conditions, enabling it to sustain sharp contact deformations under loads of ≈500 N without forming any strength‐limiting cracks. This ultra‐high crack resistance exceeds that of the annealed oxide glasses by more than one order of magnitude, making this glass micro‐ductile. In addition, a remarkable indentation behavior, i.e., a time‐dependent shrinkage of the indent cavity, is demonstrated. Based on structural analyses, a molecular‐scale deformation model to account for both the ultra‐high crack resistance and the time‐dependent shrinkage in the studied glass is proposed.

Серйозною перешкодою у вивченні сучасних досягнень в області прикладних інженерних досліджень є недостатня математична підготовка випускників вищих навчальних закладів, і особливо – в розділах нелінійних диференційних рівнянь, статистичного моделювання, перетворення лінійних просторів, векторного і тензорного аналізу. З даних розділів у магістрантів, як правило – фрагментарні знання. В той же час аналіз напружено-деформованого стану, кінематики і динаміки руху твердого тіла в просторі, електротермічні, електромеханічні ефекти, п’єзо- та піроелектричний ефекти, кінематика сучасних роботів, так як і створення нових матеріалів (особливо - пористих) для забезпечення потреб машинобудування, будівельної індустрії, мікробіології, медицини тощо неможливе без елементарних знань тензорного аналізу та уявлень про фрактали. Дана робота присвячена вивченню інтегральних та локальних польових характеристик мікро неоднорідних середовищ з позиції фракталів та тензорного аналізу. Особливо актуальна ця задача, коли до традиційних вимог міцності, тріщиностійкості, довговічності, стійкості проти зношування, корозії добавляється низка нових вимог, і перш за все – це формування пористості заданої структури. Посібник розрахований на магістрантів інженерних спеціальностей ВНЗ та може бути корисним інженерам і науковцям, що вивчають суміжні проблеми., An inadequate mathematical training of graduates of higher education institutions, and especially in sections of nonlinear differential equations, statistical simulation, transformation of linear spaces, vector and tensor analysis, is a serious obstacle in the study of modern achievements in the field of applied engineering research. Of these sections, masters, as a rule, are fragmentary knowledge. At the same time, the analysis of the stress-strain state, kinematics and dynamics of the motion of a solid in space, electrothermal, electromechanical effects, piezoelectric and pyroelectric effects, kinematics of modern robots, as well as the creation of new materials (especially porous ones) to meet the needs mechanical engineering, construction industry, microbiology, medicine, etc., is impossible without elementary knowledge of tensor analysis and representations of fractals. This paper is devoted to the study of integral and local field characteristics of micro heterogeneous media from the standpoint of fractals and tensor analysis. This problem is especially important when a number of new requirements are added to traditional requirements of durability, fatigue resistance, durability, resistance to wear, corrosion, and above all – the formation of porosity of a given structure. The manual is intended for undergraduates of engineering specialties of higher educational institutions and can be useful for engineers and scientists who are studying related problems., Серьезным препятствием в изучении современных достижений в области прикладных инженерных исследований является недостаточная математическая подготовка выпускников высших учебных заведений, и особенно – в разделах нелинейных дифференциальных уравнений, статистического моделирования, преобразования линейных пространств, векторного и тензорного анализа. Из данных разделов у магистрантов, как правило – фрагментарные знания. В то же время анализ напряженно-деформированного состояния, кинематики и динамики движения твердого тела в пространстве, электротермические, электромеханические эффекты, пьезо- и пироэлектрический эффекты, кинематика современных роботов, как и создание новых материалов (особенно – пористых) для обеспечения потребностей машиностроения, строительной индустрии, микробиологии, медицины и т.д. не возможно без элементарных знаний тензорного анализа и представлений о фракталах. Данная работа посвящена изучению интегральных и локальных полевых характеристик микро неоднородных сред с позиции фракталов и тензорного анализа. Особенно актуальна эта задача, когда к традиционным требований прочности, трещиностойкости, долговечности, устойчивости к износу, коррозии добавляется ряд новых требований и прежде всего – это формирование пористости заданной структуры. Пособие рассчитано на магистрантов инженерных специальностей вузов и может быть полезным инженерам и ученым, изучающим смежные проблемы.

Серйозною перешкодою у вивченні сучасних досягнень в області прикладних інженерних досліджень є недостатня математична підготовка випускників вищих навчальних закладів, і особливо – в розділах нелінійних диференційних рівнянь, статистичного моделювання, перетворення лінійних просторів, векторного і тензорного аналізу. З даних розділів у магістрантів, як правило – фрагментарні знання. В той же час аналіз напружено-деформованого стану, кінематики і динаміки руху твердого тіла в просторі, електротермічні, електромеханічні ефекти, п’єзо- та піроелектричний ефекти, кінематика сучасних роботів, так як і створення нових матеріалів (особливо - пористих) для забезпечення потреб машинобудування, будівельної індустрії, мікробіології, медицини тощо неможливе без елементарних знань тензорного аналізу та уявлень про фрактали. Дана робота присвячена вивченню інтегральних та локальних польових характеристик мікро неоднорідних середовищ з позиції фракталів та тензорного аналізу. Особливо актуальна ця задача, коли до традиційних вимог міцності, тріщиностійкості, довговічності, стійкості проти зношування, корозії добавляється низка нових вимог, і перш за все – це формування пористості заданої структури. Посібник розрахований на магістрантів інженерних спеціальностей ВНЗ та може бути корисним інженерам і науковцям, що вивчають суміжні проблеми., An inadequate mathematical training of graduates of higher education institutions, and especially in sections of nonlinear differential equations, statistical simulation, transformation of linear spaces, vector and tensor analysis, is a serious obstacle in the study of modern achievements in the field of applied engineering research. Of these sections, masters, as a rule, are fragmentary knowledge. At the same time, the analysis of the stress-strain state, kinematics and dynamics of the motion of a solid in space, electrothermal, electromechanical effects, piezoelectric and pyroelectric effects, kinematics of modern robots, as well as the creation of new materials (especially porous ones) to meet the needs mechanical engineering, construction industry, microbiology, medicine, etc., is impossible without elementary knowledge of tensor analysis and representations of fractals. This paper is devoted to the study of integral and local field characteristics of micro heterogeneous media from the standpoint of fractals and tensor analysis. This problem is especially important when a number of new requirements are added to traditional requirements of durability, fatigue resistance, durability, resistance to wear, corrosion, and above all – the formation of porosity of a given structure. The manual is intended for undergraduates of engineering specialties of higher educational institutions and can be useful for engineers and scientists who are studying related problems., Серьезным препятствием в изучении современных достижений в области прикладных инженерных исследований является недостаточная математическая подготовка выпускников высших учебных заведений, и особенно – в разделах нелинейных дифференциальных уравнений, статистического моделирования, преобразования линейных пространств, векторного и тензорного анализа. Из данных разделов у магистрантов, как правило – фрагментарные знания. В то же время анализ напряженно-деформированного состояния, кинематики и динамики движения твердого тела в пространстве, электротермические, электромеханические эффекты, пьезо- и пироэлектрический эффекты, кинематика современных роботов, как и создание новых материалов (особенно – пористых) для обеспечения потребностей машиностроения, строительной индустрии, микробиологии, медицины и т.д. не возможно без элементарных знаний тензорного анализа и представлений о фракталах. Данная работа посвящена изучению интегральных и локальных полевых характеристик микро неоднородных сред с позиции фракталов и тензорного анализа. Особенно актуальна эта задача, когда к традиционным требований прочности, трещиностойкости, долговечности, устойчивости к износу, коррозии добавляется ряд новых требований и прежде всего – это формирование пористости заданной структуры. Пособие рассчитано на магистрантов инженерных специальностей вузов и может быть полезным инженерам и ученым, изучающим смежные проблемы.

Low heat Portland (LHP) cement is one type of low energy and emission cement. In this work, the abrasion resistance, heat releasing properties, shrinkage behavior and pore structures of LHP cement based materials are comprehensively investigated, and compared with those of moderate heat Portland (MHP) cement and PC ones. The utilization of LHP cement instead of Portland cement (PC) can effectively reduce the energy consumption (14.1%-15.3%) and CO2 emission (14.9%-15.7%) of concrete. LHP concrete shows the highest final compressive strength among three types of concrete mixtures in this study, which consequently leads to the strongest abrasion resistance. The slow developments of autogenous and drying shrinkage of LHP concrete are exhibited. LHP cement paste possesses better early crack resistance than MHP and PC ones due to its lower shrinkage strain at early age. Besides, the hydration heat of LHP cement paste and adiabatic temperature rise of LHP cement concrete are lower than those of MHP cement and PC ones in all hydration ages. In addition, LHP cement paste has a more refined porous structure than MHP cement and PC ones at late ages, which makes the microstructure of LHP concrete denser and improves the final mechanical properties and abrasion resistance to some degree. (C) 2018 Elsevier Ltd. All rights reserved.

The utilization of low heat Portland (LHP) cement is considered to be one of the most effective methods to decrease the thermal stresses and cracking risk in the dam concrete. The long-term hydration heat of LHP cement paste up to 360 days and adiabatic temperature rise of four-graded LHP cement dam concrete (LHP concrete for short) with the maximal aggregate size of 120 mm at all hydration age is low. Due to the relatively high C2S content and slow hydration rate of LHP cement, LHP concrete possesses smaller autogenous and drying shrinkage at late age and consequently leads to better crack resistance than that of ordinary Portland cement (OPC) four-graded concrete. In addition, LHP cement paste has a denser pore structure than the OPC one at late age, which improves the final mechanical properties of LHP concrete. The shrinkage behavior of LHP concrete is closely associated with the fraction of pores in the range of 2.5–50 nm. “LHP cement + fly ash” combination seems to be a good means to decrease the temperature rise and improve the crack resistance of dam concrete structures. © 2018 Elsevier Ltd

Дисертаційна робота присвячена встановленню впливу мікроструктури, напружено-деформованого стану фазових складових на механічні властивості армованих керамічних композиційних матеріалів та створенню на їх основі макрогетерогенних композитів з металевою матрицею поліфункціонального застосування. Досліджено вплив концентраційного та кінетичного переохолодження, температури відпалу на морфологію, кристалографічну орієнтацію, напруженодеформований стан, фазовий склад та механічні властивості керамічних композитів систем LaB6-TiB2, LaB6-ZrB2. Проведені дослідження дозволили отримати відцентровим плазмовим розпиленням ізотропно-армований порошковий композит з меншим в 3 рази роміром армуючої складової TiB2, в 2-3 рази залишковими макронапруженнями, з стехіометричним фазовим складом, більш досконалою субструкторою на макрорівні та вищою на порядок міцністю, ніж композити, отримані спрямованою кристалізацією. Застосування отриманого порошкового керамічного композиту LaB6-TiB2 в якості зміцнюючої фази дозволило підвищити міцність металевих матриць у 2-2,5 рази і зберегти пластичність на рівні металів. При використанні порошкового композиту з витравленою матричною фазою LaB6, за рахунок армування границь зерен на межі розділу композит-металева матриця, міцність зростає більш ніж у 2 рази. Електроопір металоматричних композитів Cu-LaB6-TiB2 знаходиться на рівні міді., The work is devoted to solving the actual scientific and technical problem - the creation of macroheterogenic composites of polyfunctional applications. In order to create new metal-ceramic composite materials for the manufacture of contact welding electrodes and maintaining high electrical conductivity, the possibility of creating copper and aluminum metal-ceramic composites with doping with their powder LaB6-TiB2 composite material is considered. Given that the strength of materials is primarily determined by defects in the microstructure, it is important to find out the effects of the defects of the crystalline structure of the matrix phase and the material of the fibers on the mechanical properties. Since the greatest defect is the grain boundaries, then the possibility of creating materials with reinforced grain boundaries is explored. It is important to find out the characteristics of these structural parameters and the possibility of strengthening the interphase boundaries, depending on the methods of obtaining composites of various bulk forms. Solving the problem of manufacturing reinforced ceramic materials can be realized by obtaining powders with an eutectic structure, which is a composite of ceramic matrix with regularly located monocrystalline fibers of another refractory compound. It was first established that under conditions of high-speed cooling from 102 to 105 °C /s during crystallization from the melt of the eutectic alloy of the LaB6-11wt.% TiB2 with an excess of 1 wt.% boron, the diameter of the fibers of the reinforcing phase TiB2 decreases in 4-5 times and their number increases by 2-2.5 times. The influence of concentration and kinetic supercooling, annealing temperature on morphology, crystallographic orientation, stress-deformed state, phase composition and mechanical properties of ceramic composites of LaB6-TiB2, LaB6-ZrB2 systems have been investigated. It was found that the overlay of mechanical vibrations on the crystal of the eutectic, Диссертация посвящена установлению влияния микроструктуры, напряженнодеформированного состояния фазовых составляющих на механические свойства армированных керамических композиционных материалов и созданию на их основе макрогетерогенних композитов с металлической матрицей полифункционального применения. Исследовано влияние концентрационного и кинетического переохлаждения, температуры отжига на морфологию, кристаллографическую ориентацию, напряженно-деформированное состояние, фазовый состав и механические свойства керамических композитов систем LaB6-TiB2, LaB6-ZrB2. Проведенные исследования позволили получить центробежным плазменным распылением изотропно-армированный порошковый композит с меньшим в 3 раза размером армирующей составляющей TiB2, в 2-3 раза остаточными микронапряжениями и стехиометрическим фазовым составом, более совершенной субструкторою на макроуровне и выше на порядок прочностью, чем композиты, полученные направленной кристаллизацией. Применение полученного порошкового керамического композита LaB6-TiB2 в качестве упрочняющей фазы позволило повысить прочность металлических матриц в 2-2,5 раза и сохранить пластичность на уровне металлов. При использовании порошкового композита с вытравлены матричной фазой LaB6, за счет армирования границ зерен на границе раздела композит-металлическая матрица, прочность возрастает более чем в 2 раза. Электросопротивление металоматричних композитов Cu-LaB6-TiB2 находится на уровне меди.

The utilization of low heat Portland (LHP) cement is considered to be one of the most effective methods to decrease the thermal stresses and cracking risk in the dam concrete. The long-term hydration heat of LHP cement paste up to 360 days and adiabatic temperature rise of four-graded LHP cement dam concrete (LHP concrete for short) with the maximal aggregate size of 120 mm at all hydration age is low. Due to the relatively high C2S content and slow hydration rate of LHP cement, LHP concrete possesses smaller autogenous and drying shrinkage at late age and consequently leads to better crack resistance than that of ordinary Portland cement (OPC) four-graded concrete. In addition, LHP cement paste has a denser pore structure than the OPC one at late age, which improves the final mechanical properties of LHP concrete. The shrinkage behavior of LHP concrete is closely associated with the fraction of pores in the range of 2.5–50 nm. “LHP cement + fly ash” combination seems to be a good means to decrease the temperature rise and improve the crack resistance of dam concrete structures. © 2018 Elsevier Ltd

Low heat Portland (LHP) cement is one type of low energy and emission cement. In this work, the abrasion resistance, heat releasing properties, shrinkage behavior and pore structures of LHP cement based materials are comprehensively investigated, and compared with those of moderate heat Portland (MHP) cement and PC ones. The utilization of LHP cement instead of Portland cement (PC) can effectively reduce the energy consumption (14.1%-15.3%) and CO2 emission (14.9%-15.7%) of concrete. LHP concrete shows the highest final compressive strength among three types of concrete mixtures in this study, which consequently leads to the strongest abrasion resistance. The slow developments of autogenous and drying shrinkage of LHP concrete are exhibited. LHP cement paste possesses better early crack resistance than MHP and PC ones due to its lower shrinkage strain at early age. Besides, the hydration heat of LHP cement paste and adiabatic temperature rise of LHP cement concrete are lower than those of MHP cement and PC ones in all hydration ages. In addition, LHP cement paste has a more refined porous structure than MHP cement and PC ones at late ages, which makes the microstructure of LHP concrete denser and improves the final mechanical properties and abrasion resistance to some degree. (C) 2018 Elsevier Ltd. All rights reserved.