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Для надежности транспортировки жидких сред требуются коррозионно-стойкие и прочные трубы. Эффективное использование их при подземной укладке необходимо определение НДС трубы с учетом воздействия температуры, грунта, жидких сред, а также на основе компонентов материала. Композиционный материал из которого изготовляются трубы относится к сложной механической системе. Основная проблема при решении задач моделирования механических свойств гетерогенной среды состоит в определении условий процедуры осреднения корректной с точки зрения прогнозирования эффективных свойств идеализированной среды на основании данных о механических свойствах и геометрических характеристиках компонентов реальной среды. В связи с этим задача оценки влияния упругих свойств материала на НДС подземного нефтепровода имеет важное прикладное значение и является актуальной., For reliable transportation of liquid media, corrosion-resistant and strong pipes are required. Effective use of them in underground laying it is necessary to determine the VAT of the pipe taking into account the effects of temperature, soil, liquid media, as well as on the basis of the material components. The composite material from which the pipes are made belongs to a complex mechanical system. The main problem in solving the problems of modeling the mechanical properties of a heterogeneous medium is to determine the conditions of the averaging procedure that is correct from the point of view of predicting the effective properties of an idealized medium based on data on the mechanical properties and geometric characteristics of the components of the real medium. In this regard, the task of assessing the influence of elastic properties of the material on the VAT of an underground oil pipeline is of great practical importance and is relevant.

Existing experimental researches show that in order to prevent the destruction of optical elements of modern opto-electronic devices (discs as the light filter linings for IR devices, the input protective windows of laser sighting systems for observation in IR areas of the spectrum, semispherical fairings of IR devices for homing and observation of objects, lightguides for laser medical devices, etc.), electron beam method becomes promising, as it provides cleaning of surfaces, increases their microhardness, makes them more resistant to external influences. The results of experimental studies to improve the properties of the surface layers of elements from optical ceramics after their processing with a moving electron beam with a heat density Fn = 106...1.6∙107 W/m2 and moving speed V = 10-3...10-1 m/s (increase in the surface microhardness from 1.2 ... 2.9 GPa (raw elements) to 5.7 ... 6.4 GPa (processed elements), the occurrence of hardened layers with a thickness of 210... 230 microns). It has been established that the improvement of these properties leads to an increase in the resistance of elements to external thermal effects: an increase of 1.3...1.7 times the critical values of external heat flows and their exposure times, exceeding which leads to the destruction of elements and the failure of devices for the studied range of change of external pressure is 105...107 Pa; increasing the maximum allowable values of thermoelastic stresses in elements from 50...140 MPa to 160...370 MPa at heating temperatures of 300...1200 K.

Till present, the heating processes of fairings from the optical ceramics haven't been sufficiently investigated in the form of semi-spherical shells with the oncoming supersonic airflow, as well as the complex influence of the heat-physical characteristics of ceramics material haven't been studied (volume heat -capacity and thermal conductivity coefficient) under the conditions of supersonic airflow on temperature distribution and thermoelastic stresses in the zones of maximum external thermal actions. This paper contains developed mathematical heating models of fairings in IR-devices by supersonic airflow, that encounter temperature dependencies of thermophysical properties of optical materials. Calculations of temperature distribution and thermoelastic stresses in the fairing are carried out. Critical values of airflow velocities of the fairing and the time of its thermal influence are determined, exceeding of which leads to destruction of the fairing and the failure of IR -devices. It is determined that the distribution of temperature along the surface of the fairing most essentially depends on the flow mode: temperature maximum is near its front point for laminar mode, and for turbulent mode temperature maximum is shifted along the surface of the fairing at a distance corresponding 18…22 deg. It is shown that the thermoelastic stress in the zones of maximum external thermal action in the thickness of the fairing is distributed as follows: squeezing stresses occur on the fairing surface and in its surface layers, while in the lower part of the fairing and in its adjacent layers these are stretching stresses; thus for turbulent flow mode exceeds its value for laminar mode by 5…6 times. The interdependence of critical velocity values of the fairing airflow and the times of its thermal influence, exceeding of which leads to the destruction of the fairing; thus, for the turbulent flow mode destruction of the fairing occurs near its surface, and for laminar mode destruction of the fairing is no longer observed.

Досліджується термопружний стан монокристалічної лопатки з вихровою і частково плівковою системами охолодження. Задача вирішується в тривимірній постановці з використанням методу скінченних елементів. Відомо, що орієнтація кристалографічних осей істотно впливає на розподіл полів напружень. Коли змінюється орієнтація кристалографічних осей, відбувається перерозподіл всіх напружень і зміна всієї картини напружено-деформованого стану лопатки. Дана робота є продовженням серії робіт авторів, в яких розглядається вплив відхилення азимутальної орієнтації кристалографічних осей на термопружний стан монокристалічної охолоджуваної лопатки. Тому в даній роботі проведено дослідження вплив аксіальної орієнтації кристалографічних осей на розподіл термопружних напружень в об’ємі лопатки. Чисельні дослідження дозволили показати зміну максимальних температурних напружень при повороті кристалографічних осей в площині yz навколо осі х і в площині хz навколо осі у. З міркувань забезпечення міцності лопатки доцільно обмежити просторовий поворот кристалографічної осі [001] в межах 12 - 15. Ці обмеження аналогічні необхідності забезпечення розкиду власних частот лопатки в межах 8 - 10%. Дослідження дозволило виявити вплив зміни аксіальної орієнтації кристалографічних осей на напружено-деформований стан лопатки. Виконано узагальнення результатів попередніх досліджень на обмеження відхилень кристалографічних осей. Загальна картина напружено деформованого стану циклічно повторюється при повороті кристалографічних осей на 90. Місця локалізації термопружних напружень часто збігаються з місцями локалізації вібраційних напружень, що створює додаткову небезпеку., Исследуется термонапряженное состояние монокристаллической лопатки с вихревой и частично пленочной системами охлаждения. Задача решается в трехмерной постановке с использованием метода конечных элементов. Известно, что ориентация кристаллографических осей оказывает существенное влияние на распределение полей напряжений. Когда меняется ориентация кристаллографических осей, происходит перераспределение всех напряжений и изменение всей картины напряженно-деформированного состояния лопатки. Данная работа является продолжением серии работ авторов, в которых рассматривается влияние отклонение азимутальной ориентации кристаллографических осей на термонапряженное состояние монокристаллической охлаждаемой лопатки. Поэтому в данной работе проведено исследование влияния аксиальной ориентации кристаллографических осей, на распределение термоупругих напряжений по объему лопатки. Численные исследования позволили показать изменение максимальных температурных напряжений при повороте кристаллографических осей в плоскости yz вокруг оси х и в плоскости хz вокруг оси у. Из соображений обеспечения прочности лопатки целесообразно ограничить пространственный поворот кристаллографической оси [001] в пределах 12 - 15. Эти ограничения аналогичны необходимости обеспечения разброса собственных частот лопатки в пределах 8 – 10 %. Исследование позволило выявить влияние изменения аксиальной ориентации кристаллографических осей на напряженно-деформированное состояние лопатки. Выполнено обобщение результатов предыдущих исследований на ограничения отклонений кристаллографических осей. Общая картина напряженно-деформированного состояния циклически повторяется при повороте кристаллографических осей на 90. Места локализации термоупругих напряжений часто совпадают с местами локализации вибрационных напряжений, что создает дополнительную опасность., The thermo-stressed state of a single-crystal blade with vortex and partially film cooling systems is studied. The problem is solved in a three-dimensional formulation using the finite element method. It is known that the orientation of the crystallographic axes exerts a significant influence on the distribution of the stress fields. When the orientation of crystallographic axes changes, the redistribution all of stress is occur and changing the whole picture of stress-strain state of the blade. This work is a continuation of a series of papers by the authors in which the effect of the deviation of the azimuth orientation of the crystallographic axes on the thermo-stressed state of a single-crystal cooled blade is considered. Therefore, in this paper the influence of the axial orientation of the crystallographic axes on the distribution of thermoelastic stresses in the volume of the blade is investigated. Numerical studies have made it possible to show the change in the maximum temperature stresses during the rotation of the crystallographic axes in the yz plane around the x axis and in the xz plane around the y axis. For reasons of ensuring the strength of the blade, it is advisable to limit the spatial rotation of the crystallographic axis [001] within 12 - 15. These limitations are similar to the need to ensure the spread of the natural frequencies of the blade in the range of 8 to 10%. The study made it possible to reveal the effect of a change in the axial orientation of the crystallographic axes on the stress-strain state of the blade. A generalization of the results of previous studies to the limitations of the deviations of the crystallographic axes is performed. The general picture of a stress-strain state is cyclically repeated when the crystallographic axes are rotated by 90. Places of localization of thermoelastic stresses often coincide with places of localization of vibration stresses, which creates an additional danger.

Исследуется термонапряженное состояние монокристаллической лопатки с вихревой и частично пленочной системами охлаждения. Задача решается в трехмерной постановке с использованием метода конечных элементов. Известно, что ориентация кристаллографических осей оказывает существенное влияние на распределение полей напряжений. Когда меняется ориентация кристаллографических осей, происходит перераспределение всех напряжений и изменение всей картины напряженно-деформированного состояния лопатки. Данная работа является продолжением серии работ авторов, в которых рассматривается влияние отклонение азимутальной ориентации кристаллографических осей на термонапряженное состояние монокристаллической охлаждаемой лопатки. Поэтому в данной работе проведено исследование влияния аксиальной ориентации кристаллографических осей, на распределение термоупругих напряжений по объему лопатки. Численные исследования позволили показать изменение максимальных температурных напряжений при повороте кристаллографических осей в плоскости yz вокруг оси х и в плоскости хz вокруг оси у. Из соображений обеспечения прочности лопатки целесообразно ограничить пространственный поворот кристаллографической оси [001] в пределах 12° - 15°. Эти ограничения аналогичны необходимости обеспечения разброса собственных частот лопатки в пределах 8 – 10 %. Исследование позволило выявить влияние изменения аксиальной ориентации кристаллографических осей на напряженно-деформированное состояние лопатки. Выполнено обобщение результатов предыдущих исследований на ограничения отклонений кристаллографических осей. Общая картина напряженно-деформированного состояния циклически повторяется при повороте кристаллографических осей на 90°. Места локализации термоупругих напряжений часто совпадают с местами локализации вибрационных напряжений, что создает дополнительную опасность. The thermo-stressed state of a single-crystal blade with vortex and partially film cooling systems is studied. The problem is solved in a three-dimensional formulation using the finite element method. It is known that the orientation of the crystallographic axes exerts a significant influence on the distribution of the stress fields. When the orientation of crystallographic axes changes, the redistribution all of stress is occur and changing the whole picture of stress-strain state of the blade. This work is a continuation of a series of papers by the authors in which the effect of the deviation of the azimuth orientation of the crystallographic axes on the thermo-stressed state of a single-crystal cooled blade is considered. Therefore, in this paper the influence of the axial orientation of the crystallographic axes on the distribution of thermoelastic stresses in the volume of the blade is investigated. Numerical studies have made it possible to show the change in the maximum temperature stresses during the rotation of the crystallographic axes in the yz plane around the x axis and in the xz plane around the y axis. For reasons of ensuring the strength of the blade, it is advisable to limit the spatial rotation of the crystallographic axis [001] within 12° - 15°. These limitations are similar to the need to ensure the spread of the natural frequencies of the blade in the range of 8 to 10%. The study made it possible to reveal the effect of a change in the axial orientation of the crystallographic axes on the stress-strain state of the blade. A generalization of the results of previous studies to the limitations of the deviations of the crystallographic axes is performed. The general picture of a stress-strain state is cyclically repeated when the crystallographic axes are rotated by 90°. Places of localization of thermoelastic stresses often coincide with places of localization of vibration stresses, which creates an additional danger.

We present the results of experimental studies of the plasma-chemical deposition method from the gas phase application to produce polycrystalline silicon films on sapphire substrate, which are the basis for the production of radiation-resistant integrated circuits. The obtained samples were examined by stylus profilometry and atomic force microscopy. We have found the set of parameters that influence the phase, crystal size values and root-mean-square roughness of the obtained films. We define the plasma-chemical deposition modes that ensure the homogeneous polycrystalline silicon films production with crystallite sizes up to 250 nm. The average surface roughness is 16.2 ± 2.1 nm. The effect of differences in the coefficients of silicon and sapphire thermal expansion is minimized at deposition temperatures of about 700 °C, and the density of defects in the resulting films is reduced. Plasma-chemical deposition of polycrystalline silicon film on sapphire substrate is accompanied by the emergence of thermoelastic stresses, which can cause destruction of the film coating and the substrate surface layer. The level of thermoelastic stresses in polycrystalline silicon films on sapphire substrate is estimated from the parameters of plasma-chemical deposition, film thickness, film and substrate properties in the ANSYS program using the control element method. We have found out that the value of thermoelastic stresses in the polycrys-talline silicon film – sapphire structure is proportional to the deposition temperature. The thermoelastic stresses growth with deposition temperature increment is associated with an increase in the influence of the difference in the temperature coefficients of the film and substrate linear expansion. The results of the research can be used to develop devices for micro- and nanoelectronics, in particular, specialized integrated circuits and solar energy.

The results of finite-element modeling of controlled laser thermosplitting of crystalline silicon are presented. The case of treatment by two laser beam with wavelengths, namely 0.808 μm and 1.06 μm is studied. Calculations of the thermoelastic fields formed in a single-crystalline silicon wafer as a result of consecutive two-beam laser heating and action of coolant were performed for silicon crystalline orientations: (100), (110), (111). Modeling was performed for circular and U-shaped laser beams. The results received in the presented work, can be used for the process optimization concerning the precise separation of silicon wafers by laser cutting.

Побудовано двовимірну термопружну модель Карпатського регіону на основі числового методу скінченних елементів. Фізико-математична модель максимально наближена дореального середовища. Отримано високоточний детальний розподіл термопружних напружень і переміщень Нерівномірне нагрівання гірських порід і структурні неоднорідності приводять до значних змін полів напружень і переміщень у Карпатському регіоні.

Thin coatings on metallic substrates are extensively used in mechanical, aerospace, microelectronic, optical, and medical applications. Coatings affect the surface properties of the system, while bulk properties and strength primarily depend on the substrate. In coated components subjected to thermal cycling, differences in physical properties and chemical nature between constituent parts of coating and substrate can cause thermal stresses, atomic diffusion, and chemical interactions, which decrease high-temperature stability and actual strength of the system. In this article, the microstructure of a thermal barrier coating is briefly described; then, the temperature field inside the coating is calculated from a transient or a steady periodic state analysis; hence, thermomechanical stresses are analytically determined for a double-layer system with planar or axisymmetric geometry. The present analysis leads to new formulas with which temperature and stress fields can be calculated.

Рассматривается температурное и термоупругое состояния охлаждаемой монокристаллической лопатки со сложной вихревой системой охлаждения и каналами для выхода охлаждающего воздуха. Задача определения напряженно деформируемого состояния лопатки под действием температурных полей и центробежных сил решается методом конечных элементов. Рассмотрено влияние ориентации кристаллографических осей, на распределение и величину термоупругих напряжений по объему лопатки. The thermal and thermo-elastic states of the single crystal cooled blade with the complex vortex cooling system and channels for output of the cooling air are considered. Temperature fields of cooled blades are determined by the temperature of gas and cooling air. They cause thermal expansion of the blade, which should be considered in case of definition of the clearances in the labyrinth sealings. Due to the large temperature gradients in such blades large thermoelastic stresses are arises. All this leads to the need to solve the thermal and thermoelastic problem for determining the stress strain state of the blade under the influence of temperature fields and centrifugal forces. Static stress strain state of the blade is determined by taking into account the temperature fields and centrifugal forces. The problem is solved by finite element method. The value of maximum stress depends mostly from the temperature condition of the blade, but the maximum stresses arising in the joint action of the centrifugal forces and temperature fields, but do not achieve the tensile strength. The influence of the orientation of the crystallographic axes on the distribution and value of thermoelastic stresses by volume of blade are considered. The stress distribution by volume the blades have rather complex character. When the vortex system of cooling, the channels for cooling air are arranged at an angle to the longitudinal axis of the blade. If change the orientation of the crystallographic axes occurs redistribution of the stress and changes the whole picture of the stress-strain state of the blades. Since the largest stress intensity can be in a new area of the blade, they will also depend on the geometrical features of this area and its temperature. If change the axial orientation of the crystallographic axes, the greatest stress intensity repeating periodically through the 900. The results of research allow estimating the stress-strain state of the cooled single crystal blades in the inhomogeneous temperature field with the taking into account of the influence of the crystallographic axes, which is of practical interest.

It is shown that using gyrotron irradiation it is possible to control the p-n junction in an already fabricated light-emitting structure. Shift of the compensated region of emitting structure based on GaAs:Si is conditioned by the motion of impurities in the field of thermoelastic stresses appearing during cooling of the samples after gyrotron irradiation. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/36013

Thermal stresses concern not renewed type of stresses, that is once having liberated, they cannot accumulate more. The estimation of purely thermoelastic contribution to a lithosphere stress state gives the additional information, allowing to predict the danger connected with such natural factors, as seismic and volcanic activity. Some theoretical thermoelastic problems for the geological environment of a difficult outline with non-uniform thermophysical characteristics are considered. The decision is received on the basis of a numerical finite elements method. Influence of the model fixation, the geometrical factor and boundary conditions on distribution of thermal stresses and dislocation is investigated. Computing experiments have shown, that the size of the maximum thermal stresses reaches 500 bar. The maximum values of vertical dislocation are reached by 90 m, and horizontal — 50 m. Neutral plane position are precisely defined.

This paper deals with thermoelastic effects in deformation of plates with arbitrarily changing elastic parameters and temperature through thickness. Using the semi-inverse method, a simple analytical solution is obtained for the thermoelastic problem of a nonhomogeneous plate with an arbitrary contour. Plates with free, sliding and fixed edges are considered. The results are applied to the layered plate. As an example of application, thermoelastic stresses and deformations are determined for a copper plate with a steel coating. The edge effects for this plate are examined by the finite element method.

International audience; This article aims at assessing the internal stresses in thick laminated pipes, composed of orthotropic plies, subjected to transient thermal fields. The original contribution of the work is to provide novel analytical solutions, based on well-founded assumptions, to compute the internal stresses due to transient thermal fields throughout the pipe thickness, within the framework of thermoelasticity. The structures considered here are thick, laminated and anisotropic pipes of infinite length. They are subjected to beat flux conditions on their inner and outer surfaces due to the environmental conditions. The transient thermal field is determined and the thermoelastic stresses are derived by using the classical equations of solid mechanics and assuming a themioelastic orthotropic ply behavior. Finally, particular attention is paid to wall thickness effect.

The objective of this investigation was to conduct a parametric study of the effect of a nonuniform temperature field on the system behavior of a trilayered medium. In particular, the resulting shear and normal stresses along the media interfaces are analyzed. A finite element model utilizing a recently developed element which provides for both axial and lateral displacement continuity is employed. First, the effect of the material properties, that is, Young's Modulus and coefficient of thermal expansion, is examined. Then, the effect of the geometric properties, that is, length and thickness dimensions of the midlayer, is analyzed. Finally, a study of the effect of a nonuniform temperature field on the trimaterial medium is conducted http://archive.org/details/thermalstresseso1094527308 Lieutenant, United States Navy Approved for public release; distribution is unlimited.