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The new method of the formation of nanocomposite materials based on carbon nanotubes for the regeneration of connective tissues has been developed.Aim. Study of the structure, mechanical characteristics and biocompatibility of the obtained materials.Materials and methods. The experimental samples of nanocomposite materials were based on multi-walled and singlewalled carbon nanotubes, the matrix was bovine serum albumin. A layer of liquid dispersion of the components on a silicon substrate or in a container was irradiated with laser radiation to form the solid nanocomposite material. The microstructure of the obtained samples was analyzed with X-ray microtomography, the tensile strength was investigated using a testing machine. Fibroblast cells were incubated with experimental samples for 3, 24, 48, and 72 h and then fixed with glutaraldehyde. Cell growth during incubation with samples was studied using optical and atomic force microscopy.Results. It was found that a slight decrease in tensile strength and increase in the degree of deformation were observed with an increase in the concentration of carbon nanotubes. At the same time, the mechanical parameters of the samples corresponded to the requirements for materials for the restoration of connective tissue defects. Microscopic studies indicate good adhesion of cells to the nanocomposite material, no toxic effect of the samples on the cells was found. After 3 hours of incubation, the cells had their original rounded shape, after 24 hours of incubation cells began to proliferate on the sample's surface and were spindle-shaped. After 48 and 72 hours, the cells practically formed a monolayer on the surface of the samples.Conclusion. The results of the study show that the structural and mechanical parameters of the developed nanocomposite materials meet the requirements of biomedicine. It was also shown that nanocomposite materials do not suppress cell growth and can serve as a scaffold for the regeneration of damaged tissues.

The paper describes a technique for assessing the thermally stressed state of a concrete massif of a foundation slab made of a self-compacting concrete mixture. The proposed method consists in a preliminary calculation of temperature fields in hardening concrete. The objects of research have been self-compacting concrete mix and structural concrete in the structure mass. The choice of materials for the preparation of a concrete mixture is given and substantiated. The composition of self-compacting concrete has been used to assess the thermally stressed state. A binder with a reduced exotherm has been used in order to reduce the self-heating of concrete. Studies have been carried out to assess the specific heat release of the recommended cement depending on the initial water-cement ratio. The effect of a chemical additive on the rate and magnitude of the specific heat release of cement has been studied. The paper presents the main theoretical provisions and an algorithm for calculating the thermal stress state of a concrete massif. The finite difference method has been used to calculate the expected temperatures and their distribution in the structure mass, and the temperature stresses in the sections of the concrete mass have been calculated to assess the thermally stressed state. The performed calculations of the temperature fields have made it possible to estimate the maximum possible temperatures and temperature differences over the sections of the concrete massif depending on the initial temperature of the concrete mixture and the average daily temperature of the outside air. Analysis of the temperature distribution has revealed the most dangerous sections of the concrete mass. An assessment of the thermal stress state of the concrete mass has been made on the basis of the results pertaining to calculation of temperature fields. The calculation of temperature stresses in the most dangerous sections of the concrete massif has been performed. It is shown that the calculated value of the temperature stress can serve as a characteristic of the thermally stressed state of the concrete mass. The formation of temperature cracks in a concrete mass is possible when the calculated value of the temperature stress exceeds the actual tensile strength of concrete. Comparison of the calculated and actual values of temperatures in the sections of the foundation slab has made it possible to conclude that the calculations of the temperature fields and, as a consequence, possible temperature deformations are correct.

Objectives. Improvement of the technology for obtaining polymer-sprayed coatings based on polycarbodiimides (polyureas) with high chemical, hydrolytic, and abrasive resistance and improved physical and mechanical properties, as well as obtainment of polyurea compositions with a lifetime of at least 5 min without loss performance characteristics (i.e., “hand-applied” polyureas) suitable for repair of coatings already in use.Methods. The reaction rate between isocyanate and amino groups is almost a hundred times higher than that between isocyanate and hydroxyl groups, necessitating the use of special highperformance and high-pressure installations equipped with self-cleaning mixing chambers and heating of components. The following are determined from the obtained materials: strength, elongation at break according to the standard method, Taber abrasion, and Shore hardness.Results. Three methods of slowing down the reaction are investigated: 1) the synthesis of prepolymers with the content of NCO groups from 10.5% to 18%; 2) the addition of a plasticizer into the prepolymer in the amount of 1–10 mass parts; and 3) the introduction of polyesters into the composition and radiation of the so-called “hybrid” systems. When using 14% polyesters with a molecular weight of 2000 Da, only “hybrid” systems make it possible to obtain compositions with a lifetime of more than 5 min. At the same time, the tensile strength decreases by 20%, and the abrasion increases by 40%; however, such “hybrid” systems have a higher adhesion force and are cheaper than pure polyureas, allowing them to be used as “repair” systems.Conclusions. The developed composition and technology of applying “hybrid” systems allow for the repair of existing coatings without using specialized devices. “Manual” polyurea is easy to use and does not require special training.

Introduction. The ways of increasing the reliability of road construction machinery operation are considered. As a result, an option is proposed to replace the used 09Г2С steel with 30MnB5 boron steel. Using the example of a motor grader blade, the force effects on this working body of the road construction machinery are analyzed. In order to increase the level of physical and mechanical characteristics of 09Г2С and 30MnB5 steels, they are additionally exposed to thermo cyclic treatment. The experimental studies about the influence of this type thermal action on the structure and properties of steels are described. The comparative analysis of the obtained characteristics allows making a conclusion about the possibility of the considered replacement.Materials and methods. Through the metallographic analysis the influence of the number of thermal effects cycles on the grain size of steel is investigated. Alongside a set of physical and mechanical characteristics of these steels was determined at various stages of the thermo cyclic treatment.Results. It was determined that an increasing the level of physical and mechanical characteristics of the studied steels is possible through the use of thermo cyclic treatment. This is achieved by producing a fine-grained metal structure with a higher strength. The dependence of the tensile strength and yield strength of the steels under investigation on the number of cycles of thermal action is considered. Some correlation relationships were selected to describe these dependencies. The relationship between the yield stress and ultimate strength of 09Г2С and 30MnB5 steels and the grain size is considered. All investigated dependencies are presented in graphical form.Discussion and conclusion. Based on a comparative analysis of the complex of physical and mechanical characteristics, the conclusion about the possibility of replacing 09Г2С steel with 30MnB5 steel was made.

Currently, the need to create new multifunctional materials that meet the requirements of technology and the needs of society has sharply increased. In addition, with the increase in the number of various "gadgets", communication systems, sources of electromagnetic "pollution" of the environment caused by the functioning of cellular communications, personal computers and other sources, protection against radiation and electromagnetic waves of the radio frequency range from 30 Hz to 3000 GHz becomes relevant. For these purposes, you can use modified fibers and fabrics by metallization. As the objects of study, we chose a woven material based on a polyacrylonitrile flagellum for special purposes (START LLC) with factory properties: nominal linear density of elementary fiber, 0.12 tex, specific tensile load of the fiber 450 mN/tex, elongation of the elementary fiber at break 18 % In the work, chemical copper plating was carried out in two ways: the first was a classical metallization scheme for plastics; the second method was carried out according to a new low-stage and low-component technology, which included two main stages: surface activation and chemical copper plating. The analysis of the surface of a fibrous material metallized by a galvanic method with preliminary chemical copper plating, both by traditional technology and by low-stage, showed that in two cases the coatings are uniform over the entire surface of the fibrous material and have a characteristic copper color, and metallic copper has a granular structure with a dense Packed grains to each other. At the same time, the electrical resistivity of PAN-fibrous materials is reduced. Metallization of woven materials based on PAN-fibrous materials in a low-component electrolyte using a low-stage chemical copper plating technology is promising, since the resulting coatings are characterized by high electrical properties, while reducing environmental stress due to the absence of harmful electrolyte components (acids during etching) and washing water.

Objectives Reliability and durability of structures using materials with various properties (plaster coatings, cement glue, new concrete during repair and restoration of structures, etc.) largely depends on the adhesion of the layers and the deformation properties of the coatings. To obtain the required properties of materials used for coatings, modifiers based on polymers and low-modulus inclusions are introduced into the composition of new concretes, for example, entrained air. The aim of the work is to identify some patterns of change in the properties of concrete with the joint introduction of these modifiers.Method Experimental determination of the tensile strength in bending, compression, E-modulus, adhesion to the concrete base by standard methods.Result The influence of separate and joint introduction of dispersible polymer powders and various low-modulus inclusions into the composition of fine-grained concrete has been established.Conclusion The joint introduction to the composition of fine-grained concrete of various low-modulus inclusions and redispersible polymer powders provides a reduction in the stress level during forced deformations due to the different effects additives on the strength and deformation properties and contributes to increased adhesion to the concrete.

В настоящей работе проводится анализ работы анкерных болтов с отгибом, установленных в бетонном основании. Много­численными исследованиями и испытаниями выявлено три основных механизма разрушения указанных анкерных болтов при действии осевой растягивающей нагрузки: разрушение по металлу анкерного болта, разрушение, вызванное потерей сце­пления между телом анкерного болта и окружающим массивом бетона («проскальзывание» анкера в основании), и разрушение, вызванное откалыванием бетонного конуса, содержащего в себе анкер. При расчётах анкерных болтов следует определить предельные нагрузки для каждого из указанных видов раз­рушения с учётом диаметра и материала анкера, прочностных характеристик основания и глубины расположения анкерного болта. Актуальность рассматриваемой задачи связана с тем, что в действующем Приложении Г к СП 43.13330.2012 отсутствует методика расчёта несущей способности таких соединений по каждому из указанных механизмов разрушения, а глубина анке­ровки назначается в зависимости от диаметра анкерного болта, что в некоторых случаях приводит к существенным запасам (экономически нецелесообразно), либо попросту нереализуемо (например, при установки анкерных болтов в основание малой толщины). Кроме того, в отличие от, например, зарубежных рекомендаций для установки анкеров в готовое основание, в Приложении Г к СП 43.13330.2012 отсутствует методика учёта краевых и межосевых расстояний и её влияния на несущую способность анкерных болтов. В связи с вышеуказанным в статье предложены методики расчёта анкерных болтов, соответствующие основным меха­низмам их разрушения при действии осевых растягивающих и сдвигающих нагрузок, а также их комбинаций.

Introduction. Evaluation of the influence level of the pre-organized cracks in tensile zone of the reinforced concrete beams on their crack resistance, deformability under long-term loading is investigated in the article.Materials and methods. Concrete for specimen was produced in laboratory and factory on portland cement of the 500-grade at W/C=0,71; concrete composition 1:1,9:4 (by weight); strength of cube at 28th days – 13,85 MPa; strength of prism with dimensions 10/10*40 cm – 11,48 MPa; span calculation – 78 cm; steel rebar grade – A400 with diameter of 10 mm. Organized crack was formed by installing plate with thickness of 0,5 mm and height of 30 mm on the rebar in the zone of maximum moments.Results. The experiments confirmed the hypothesis about the beams rigidity with pre-organized cracks in comparison with stochastic cracks under the influence of long-term loading. As a result, the beams with pre-organized cracks provide the smaller deflection after long-term period than the beams without organized cracks. Thus, the proposed method of the deflections calculation of the reinforced concrete beams with pre-organized cracks under the long-term loading helps to reduce deflection to 33%.Discussion and conclusion. The findings of this study suggest that the presence of pre-organized cracks reduces the beams deflections in comparison with the specimens of section, and such method actually regulates the stress-strain state of reinforced concrete structures and leads to the smooth deformation at all stages under the influence of long-term loading.

The results of research on the problem of regeneration of rubbers based on butyl rubber are presented. The advantages of radiation destruction of butyl rubbers are substantiated. The diaphragms of the vulcanizer formers, which were exposed to ionizing radiation at the Co60 source, were chosen as the objects of the study. The effect of the irradiation dose on the technological properties of the recovered regenerates and the elasto-strength properties of the compositions based on them was studied. It is established that the treatment of diaphragm rubbers with a dose of 50, 70 kGy provides an optimal set of properties. An analysis of the structural changes that occur during irradiation of spent diaphragms showed that at high doses of 20-40 kGy a high level of high-elastic deformation remains, while a sufficient number of crosslinked structures remain. At an irradiation dose > 40 kGy, the destructant acquires the ability to roll. The effect of machining on diaphragm rubbers subjected to radiation exposure has been studied. It was found that processing on rotor-type equipment reduces the viscosity of the compositions. The procedure for optimizing the composition of roofing rubber compounds was performed depending on the irradiation dose of diaphragm rubbers and the dosage of the regenerate. Regression statistics and variance analysis confirmed the adequacy of the model and the significance of the coefficients of the equation. The error in the calculations for the tensile strength was 0.65%, for the MI viscosity, 1.23%. On the basis of the developed regenerants, roofing rubber compounds were made and their properties were investigated. It is shown that the use of butyl rubber regenerants in a recipe of roofing rubbers with a dose of 50, 70 kGy provides the required level of properties and reduces their cost price. It is recommended to use these materials in the composition of hydro-insulating materials to improve technological properties and reduce their cost.

The experimental and theoretical research of the single-span reinforced concrete beam with artificial flaw in tension area under the action of static short-term loads is performed. The stress-strain state of the structure, based on numerical simulation using finite element software system ANSYS, is investigated. The results of numerical simulation are compared with the experimental results. It is shown that under static short-term loads, the beams with pre-cracking have the crack formation of significantly different nature in comparison with the beams without pre-cracking. The comparative analysis of the experimental data of the reinforced concrete beam under short-term loading with the results of ANSYS Software program modeling is carried out in the article. The introduction of the artificial defects to the tension area of beams would lead to the significant change in the stress- strain state of the structure and to «mild» nature of its deformation. The result of such beams deflections under the load is less than deflections of beams without artificial flaws. The recommendations on the beams’ designing with artificial flaws are given in the article. The results of the modeling cracks’ feasibility in the manufacturing process are demonstrated in the research, because there are the possibilities to regulate the stress fields.

There are one of ways to save peoples heath is eating food, what rich in fiber. To the recovery of polyunsarurated fatty acids, protein, mineral substances, fibers it recommended to eat flax seeds and its products. One of these products are flaxes. The purpose of the work was a rational choice of the duration of soaking seeds, providing strong reception of finished products. Founds that when hydrated of 10 to 30 minutes of the study setting almost unchanged. After 30 minutes soaking the tensile strength increased, and then decreased. The maximum value observed in the samples in which lasted 40 minutes soaking. Probably, due to the fact that upon contact with water 30 minutes before the moisture is adsorbed on the surface of flax seed are thus formed in a small amount of mucus. From 30 to 40 minutes soaking carbohydrates undergo hydrolysis inner layers of the endosperm and seed shell. While the water absorption capacity of flax reaches limits. Also increases the amount of mucus, and after 40 minutes soaking becomes excessive, resulting in reduced tensile strength of the finished product. Therefore, rational while soaking flax 40 minutes, providing the maximum value of the parameter under study. Flux thus, thanks to the ability of flax seed soaking and store slime forming after drying alpha-linolenic acid is a source of polyunsaturated fatty acids, dietary fibers, vitamins, minerals.

Objectives The aim of the study is to clarify the dependence of the cement stone strength on additional porosity that is formed owing both to the cement stone’s development of free deformations and the expansion of the hardening concrete in the second stage as caused by the action of the expanding additive. Method The study is based on the introduction of a sulphoaluminate-type expanding additive in the composition of a binder based on alumina cement, natural gypsum stone and nitrilotrimethylphosphonic acid. Results It is shown that an important role is played in the technology of expanding concrete not only by the degree of expansion of the cement stone, but also by its strength, both during the development of deformations and following stabilisation. Among factors influencing the kinetics of hardening are not only recipe-related (composition and dosage of the additive, mineralogical composition of Portland cement clinker, composition of the concrete, presence of chemical additives), but also technological (fineness of cement grinding, hardening temperature, etc.) that makes the management of the processes of structure formation quite complex. The dependence of the strength of cement stone on the additional porosity formed due to the growth of the cement stone own free deformations and expansion of the hardening concrete in the second stage due to the action of the expanding additive is revealed; dependence of the influence of kinetics of the structure formation regulator - nitrilotrimethylphosphonic acid - on the consistency of the development of the intrinsic free expansion deformations and the formation of the strength of the cement stone in the second stage; the dependence of the strength of the cement stone on the additional porosity formed due to gas evolution and expansion of the mixture in the first stage due to the action of the gas-forming additive; the influence of the constraint of expansion on the formation of the structure of cement stone and its strength; the effect of hardening conditions on the strength characteristics of concrete with a two-stage expansion. Conclusion The process of expansion under the conditions of deformation free development is accompanied by an increase in the porosity of the cement stone of up to 9% and a regular decrease in the strength of the cement stone by compression up to 19.3%. The effect of hardening conditions on the compressive strength of concrete with a two-stage expansion is established: when exposed to air for 28 days at a temperature of 5 oC, the strength decreases to 50% relative to normal conditions, and at a temperature of 35 oС - to 14 %. With water aging the strength is reduced to 33% due to intensive expansion in the second stage. The dependence of the ratio of tensile strength to compressive strength for concretes with a two-stage expansion is specified, taking into account the hardening conditions.

The paper presents the results of experiments to improve the performance of insulating paper as a component of high-voltage paper-impregnated insulation by introducing the modifying additive into the paper mass. Environmentally safe and economically feasible method of obtaining modifying additives of the chitin-glucan complex of Aspergillus niger (A.n.) which is a large-tonnage waste production of citric acid is proposed. The modifying additive was introduced into the paper mass in an amount of 5–10% to the mass of absolutely dry fiber of sulfate insulating cellulose. The paper samples were subjected to accelerated thermal aging at 140°C for 250 hours. The values of the short – term electrical strength of the samples with the modifying additive, both in the initial and in the aged state, exceeded the similar characteristic of the paper sample without additives. for the paper made of 100% cellulose after 250 hours of accelerated thermal aging the maximal mechanical tensile strength decreased by 2.1 times; for paper containing 5% HGC A.n. – by 1.5 times and for the insulating paper, which was introduced into 10% of the modifying additive, the specified parameter during the test has not changed. Comparative evaluation of the sorption activity of the cellulose component was carried out by determining the light transmission coefficient of transformer oil relative to the standard at the process of thermal aging. It was found that the modification of insulating paper by biopolymer also increases its sorption activity in relation to the products of destruction of paper-impregnated insulation components under the catalytic effect of copper., В работе представлены результаты экспериментов по улучшению эксплуатационных характеристик электроизоляционной бумаги, как компонента высоковольтной бумажно-пропитанной изоляции, за счет введения в бумажную массу модифицирующей добавки. Предложен экологически безопасный и экономически целесообразный способ получения модифицирующей добавки из хитин-глюканового комплекса Aspergillus niger (ХГК A.n.) – многотоннажного отхода производства лимонной кислоты. Модифицирующую добавку вводили в бумажную массу в количестве 5–10% к массе абсолютно сухого волокна сульфатной электроизоляционной целлюлозы. Образцы бумаги подвергали ускоренному термическому старению при температуре 140°С в течение 250 ч. Значения кратковременной электрической прочности образцов бумаги с модифицирующей добавкой как в исходном, так и в состаренном состоянии превосходили аналогичную характеристику образца бумаги без добавок. Введение в состав целлюлозной основы модифицирующей добавки способствовало повышению нагревостойкости бумаги, сохраняя показатель механической прочности на высоком уровне в процессе длительного термического старения: у бумаги из 100% целлюлозы после 250 ч ускоренного термического старения предел механической прочности на разрыв снизился в 2.1 раза; у бумаги, содержащей 5% ХГК А.n. – в 1.5 раза, а у бумаги, в состав которой было введено 10% модифицирующей добавки, указанный показатель за время испытаний не изменился. Сравнительная оценка сорбционной активности целлюлозного компонента проводилась путем определения коэффициента светопропускания трансформаторного масла относительно эталона в процессе термического старения. Установлено, что модификация электроизоляционной бумаги биополимером также повышает ее сорбционную активность по отношению к продуктам деструкции компонентов бумажно-пропитанной изоляции в условиях каталитического влияния меди.

Актуальность. В настоящее время для сооружения скважин на нефть и газ наиболее эффективным инструментом являются долота, армированные пластинами PDC (polycrystalline diamond cutters). Такие долота работают по принципу резания–скалывания, так как из всех механизмов разрушения породы резание является наиболее эффективным по причине того, что прочность породы на растяжение и скол значительно меньше её прочности на сжатие. Анализ состояния отработанных буровых долот, армированных пластинами PDC, показывает, что они отрабатывают свой ресурс не полностью, так как часть режущих PDC элементов выходит из строя по причине скола. Многообразие форм сколов по форме и размерам требует провести классификацию, выявить причину появления и определить нагрузки, приводящие к их возникновению. Кроме того, слом пластин или их потеря в значительной степени сказываются на конечных технико-экономических показателях бурения разведочных и эксплуатационных скважин. Решение вопросов повышения качества долот путем уменьшения числа поломок будет способствовать повышению экономической эффективности работ при добыче и разведке полезных ископаемых. Целью исследования является определение размеров площадок скола пластин PDC для дальнейшей классификации в зависимости от толщины срезаемого слоя породы, причин возникновения крутильных и продольных колебаний в бурильной колонне, вызывающих поломки PDC, а также разработка конструкции бурового долота, армированного пластинами PDC, предупреждающего появление автоколебаний в бурильной колонне. Объекты: режущие элементы буровых долот, армированных пластинами PDC с плоской передней гранью и PDC с выпуклой передней гранью, сколы пластин PDC на буровых долотах, возникающие в процессе бурения скважин. Методы: экспериментально-аналитический метод исследования на лабораторных образцах и на отработанных буровых долотах, армированных пластинами PDC. Результаты. На основании анализа и обобщения результатов выполненных лабораторных исследований причин возникновения поломок пластин PDC и их характера разработан ряд технических и технологических решений, предупреждающих возникновение крутильных и продольных автоколебаний в бурильной колонне и повышающих эффективность породоразрушающего инструмента, армированного пластинами PDC. The relevance. Currently, for construction of oil and gas wells, the most effective tool are bits reinforced with PDC (polycrystalline diamond cutters). These bits work on cutting-chipping principle, as the cutting is the most effective among all the mechanisms of rock destruction, due to the fact that the tensile strength of the rock and chipping is much less than its compressive strength. The analysis of the state of spent drill bits reinforced with PDC plates shows that they work out their life not fully, as a part of the cutting PDC elements fails due to chipping. The variety of forms of chips in shape and size requires classification, identification of the reasons of occurrence and determination of loads that lead to their occurrence. In addition, the scrapping of plates or their loss significantly affects the final technical and economic performance of drilling exploration and production wells. Solving the issues of improving the quality of bits by reducing the number of breakdowns will help to improve the economic efficiency of work in extraction and exploration of minerals. The aim of the study is the sizing platform chips for possible classification depending on the thickness of the shear layer of rock cutting element, and determining the causes of torsional and longitudinal vibrations in the drill string, causing breakage of the PDC offered a constructive change of drill bits reinforced PDC plates, warning the appearance of self-oscillations in the drill string. Objects: cutting elements of drill bits reinforced with PDC plates with a flat front face and PDC with a convex front face, chips of PDC plates on drill bits arising during drilling. Methods: experimental and analytical method of research on laboratory samples and on spent drill bits reinforced with PDC plates. Result. Based on the analysis and generalization of the results of the laboratory studies of the PDC plate breakdown occurrence causes and their nature the authors have developed the number of technical and technological solutions that prevent the occurrence of torsional and longitudinal self-oscillations in the drill string, and increase the efficiency of rock-cutting tools reinforced with PDC plates.

Thermal processing zone status when threading in heatproof, high-strength and titanium alloys is a major problem in the general theory of metal cutting. Under other equal conditions temperature in the processing zone of these materials is higher than in cutting of carbon structural steels, as they have high strength and ductility, low thermal conductivity, that makes difficult the working conditions of the taps, increases the area of the tool contact with the workpiece, deteriorates lubrication and cooling of the cutting area because of the increased tendency of heatresistant materials for the curing. This causes an increase in the work and force of friction and as a consequence the rise of cutting temperature. Research of temperature state of the threaded coils formation zone with combined countersink tool-tap is one of the major challenges facing the authors of this work. When performing the work was used factorial experiment. The temperature in the cutting zone of the thread was determined by a built-in chromel-aluminum thermocouple with thermoelectrode cross-sectional area 0,23mm2 . Experiments were carried out using the apparatus of mathematical statistics. Studies have shown that the greatest impact on the temperature state of the cutting area has a tensile strength of the material. Effect of cutting speed in the studied variation range is relatively less noticeable. The explanation for this is a special scheme of cutting of combined countersink tap which allows significantly improve conditions in the cutting zone. The proposed design of the tap allows to reduce the temperature in the area of tapping for 20%.

The effect of new promoters on the adhesion of elastic and strength properties unfilled elastomeric compositions based on synthetic isoprene rubber SKI-3 and also on the structure of their vulcanizates are investigated. Synthesized adhesion promoters constitute silica fillers modified with cobalt, nickel, and a combination of cobalt and nickel. They contain on the surface a reduced number (compared with industrial stearate, cobalt) ions of metals of variable valence. Tests are carried out to determine the dependency of changes of the tensile strength, the elongation at break and the density of the crosslinking of rubbers on dosages of the investigated adhesion promoters and amounts of metal ions on their surface. The effect of type and dosage of the synthesized promoters of adhesion of rubber to steel brassedcord on heat aging resistance of elastomeric compositions are established. It is established that the vulcanizates containing synthesized adhesion promoters have greater high temperatures resistance as compared with the rubber materials containing industrial cobalt stearate. Increasing dosages of modified silica acid fillers in elastomeric compositions, quantity of metals on their surface leads to the decrease of the resistance of vulcanizates to heat ageing. While Nickel ions have less oxidation effect on rubber, compared to cobalt ions that may be due to their lesser activity It is determined that the introduction of adhesion promoters leads to the formation of additional cross-linking. It is revealed that use the mineral promoters in the elastomeric compositions affects less the density of cross-linkage of rubber after heat aging as compared with the cobalt stearate. When administered in an elastomeric composition the silica modified nickel, increasing the crosslinking density of rubber upon exposure to elevated temperatures was observed.

Model "structure-property", which takes into account the structural heterogeneity of polymer compositions has been developed. Experimental compositions based on styrene-butadiene rubber SCS 30ARK and crosslinked, high viscosity polymer (high-molecular filler - VMN) in different proportions, as well as softeners (industrial oil I-12A, oil PN-6, low-molecular polybutadiene PBN) were investigated. Samples that differ significantly in viscosity were obtained. The rubber blends and vulcanizates, based on the experimental of polymer compositions, were prepared. Physico-mechanical properties - tensile strength, elongation at break, Shore A. A hardness were determined. For describe the physical and mechanical properties of polymers logarithmic additivity rule was used. The properties of the polymer composition (PС) were determined by a single dominant component (resin composition consisting of a high rubber and a filler) and further components (softeners). Identification algorithm consists of four steps. The implementation of this algorithm is carried out using experimental design techniques. Estimation of the unknown parameters in the equation was carried out using the method of least squares. Quality evaluation of the model was conducted with the criteria Fisher, turning points, the Durbin-Watson, R / S-criterion. It is found that the model adequately describes the change of physicomechanical properties depending on the composition of polymer compositions. 3d graphics of the physical-mechanical properties of the polymer compositions were built. This allowed us to estimate the contribution of the dominant component and optional components (including combinations thereof) to change the parameters. It has been established that the introduction of rubber in total more than 50% of the components (BMH and softeners) reduced conventional tensile strength and dramatically increases the relative error of model calculations. (BMH and softeners) reduced conventional tensile strength and dramatically increases the relative error of model calculations.

Modern construction practice acquires such a tendency, at which it is required to use materials with increased physical, mechanical and operational characteristics, and at the same time, do not require significant material, labor and energy costs for their production. One of the most promising building materials that meet the requirements is fiber-reinforced concrete. However, the increase in the volume of its use is limited by the insufficient degree of study of its properties and characteristics. This problem is aggravated by the constantly expanding range of reinforcing fibers, which can give composites produced on their basis, completely different properties and characteristics. One of the most important characteristics of fiber-reinforced concrete is crack resistance. The most informative method of research of this characteristic is the construction and analysis of deformation and fracture diagrams of samples obtained during bending tensile strength tests. At the initial stage of the described study, several series of fiber-reinforced concrete samples were tested. During the tests, a standard method for assessing the fracture toughness of heavy and fine-grained concretes, governed by the requirements of GOST 29167, was used. A device specially designed for testing fiber-reinforced concrete was used. As a result of the tests, a general view of the deformation diagrams of fiber-reinforced concrete samples was established, strength and energy characteristics of crack resistance, as well as the modulus of elasticity were found, and the labor intensity of the tests was high. In this paper we describe a possible way of obtaining fracture patterns for fiber-reinforced concrete by calculation. The resulting diagrams of deformation of fiber-reinforced concrete samples are built on several key points, the determination of which coordinates is made by calculation. The paper compares the experimental and calculated fracture toughness characteristics of fiber-reinforced concrete manufactured using steel wire fiber. Comparison of the data presented indicates a satisfactory agreement between the calculated and experimental data, which proves the validity of the proposed method for obtaining fiber-reinforced concrete deformation diagrams.

The method for prediction of Paris’ curve shape through the results of tensiletest is suggested. For this purpose the author developed non-direct method for determinationof K th and K fc and corresponding to them da/dN values. The relationship between K th and b / y ratio was found. The correlation K fc (K Ic ) was also shown. It makes possible to estimatelifetime of different structures with cracks under cyclic loading.Key words: Paris’ curve, cyclic loading, lifetime, non-direct method, tensile test.IntroductionFor many years attempts have been made tounderstand the crack growth mechanism andpredict lifetime under conditions of cyclic loading.Cracks exist in many structural components. Thecrack growth resistance is an important propertyof the material which controls the lifetime of thecomponent. Studies on the growth of cracks haveled to the observation that fatigue life of manyengineering materials is primarily dependent onmicro-structural features, such as inclusion particles,voids, slip-bands or manufacturing defects. Thus,knowledge of the crack rate makes possible theprediction of residual lifetime of a component. Dueto that cracked component may be kept in servicefor an extended useful time. Applying the fracturemechanics principles makes possible to predict thenumber of cycles spent for crack growth to somespecified length or to final failure.Determining the critical cyclic loadingconditions is commonly performed by using aParis’ curve. The Paris’ curve is dependence ofcrack growth rate, da/dN on the stress intensityrange K = K