scholarly journals RHEOLOGICAL MODELING OF THE STRESS-STRAIN STATE IN FLAT COMPACTION OF COMPOSITE MATERIALS

2021 ◽  
pp. 21-30
Author(s):  
B. M. Kumitsky ◽  
N. A. Savrasova ◽  
A. V. Nikolaichik ◽  
E. S. Aralov
Keyword(s):  
Strain State ◽  
Uniaxial Stress ◽  
Two Dimensions ◽  
Stress Strain ◽  
Stress Strain State ◽  
Pressing Process ◽  
Relaxation Of Stresses ◽  
Deformed State ◽  
Rheological Modeling ◽  
Coefficient Of Viscosity

Statement of the problem. The article investigates the deformation behavior of a composite material in the process of its flat pressing. To solve this problem, a rheological model is proposed, which is based on the phenomena occurring in a viscous (Newtonian) incompressible fluid, which occupies the volume between two absolutely rigid parallel planes of finite dimensions of rectangular shape approaching at a low speed. Within the framework of mechanics of a continuous medium under conditions of a plane deformed state, the problem is solved in two dimensions about a slow flow in the absence of volume forces and inertial effects. In this case, the solution of the equation of motion with continuity conditions is reduced to the well-known Laplace equation. In addition, on the basis of the model of linear viscoelasticity and uniaxial stress state, an attempt has been made to describe the relaxation phenomena occurring in the solidifying composite at the end of the active pressing process. Results and Conclusions. Analytical dependences of the power parameters of the stress-strain state of the compressed composite are obtained; relations for the kinematic characteristics of the pressing process are obtained; an expression is obtained for the relaxation of stresses during the technological holding of the material under pressure after the end of active pressing. The results of the study make it possible to experimentally determine the numerical values of the dynamic coefficient of viscosity and stress relaxation time, which are important characteristics in controlling the pressing processes.

RHEOLOGICAL MODELING OF THE STRESS-STRAIN IN FLAT COMPACTION OF COMPOSITE MATERIALS

2020 ◽  
pp. 78-86
Author(s):  
Б. М. Кумицкий ◽  
Н. А. Саврасова ◽  
А. В. Николайчик ◽  
Е. С. Аралов
Keyword(s):  
Continuous Medium ◽  
Uniaxial Stress ◽  
Two Dimensions ◽  
Inertial Effects ◽  
Stress Strain ◽  
Pressing Process ◽  
Relaxation Of Stresses ◽  
Deformed State ◽  
Rheological Modeling ◽  
Coefficient Of Viscosity

Постановка задачи. В статье исследуется деформационное поведение композиционного материала в процессе его плоского прессования. Для решения этой проблемы предложена реологическая модель, в основе которой лежат явления, протекающие в вязкой (ньютоновской) несжимаемой жидкости, занимающей объем между двумя сближающимися с малой скоростью абсолютно жесткими параллельными плоскостями конечных размеров прямоугольной формы. В рамках механики сплошной среды в условиях плоского деформированного состояния решается задача в двух измерениях о медленном течении в отсутствии объемных сил и инерционных эффектов. При этом решение уравнения движения с условиями неразрывности сводится к известному уравнению Лапласа. Кроме того, на основе модели линейной вязкоупругости и одноосного напряженного состояния предпринята попытка описания релаксационных явлений, протекающих в затвердевающем композите по окончании процесса активного прессования. Результаты и выводы. Получены аналитические зависимости силовых параметров напряженно-деформированного состояния прессуемого композита; получены соотношения для кинематических характеристик процесса прессования; получено выражение для релаксации напряжений в процессе технологической выдержки материала под давлением после окончания активного прессования. Результаты исследования позволяют экспериментально определять численные значения динамического коэффициента вязкости и времени релаксации напряжения, которые являются важными характеристиками при управлении процессами прессования. Statement of the problem. The article investigates the deformation behavior of a composite material in the process of its flat pressing. To solve this problem, a rheological model is proposed which is based on the phenomena occurring in a viscous (Newtonian) incompressible fluid that occupies the volume between two absolutely rigid parallel planes of finite dimensions of rectangular shape approaching at a low speed. Within the framework of mechanics of a continuous medium under conditions of a plane deformed state, the problem is addressed in two dimensions about a slow flow in the absence of volume forces and inertial effects. In this case, the solution of the equation of motion with continuity conditions is reduced to the well-known Laplace equation. In addition, based on the model of linear viscoelasticity and uniaxial stress, an attempt has been made to describe the relaxation phenomena occurring in the solidifying composite at the end of the active pressing process. Results and conclusions. Analytical dependences of the power parameters of the stress-strain of the compressed composite are obtained; relations for the kinematic characteristics of the pressing process are identified; an expression is designed for the relaxation of stresses during the technological holding of the material under pressure following the end of active pressing. The results of the study make it possible to experimentally determine the numerical values of the dynamic coefficient of viscosity and stress relaxation time which are important characteristics in controlling the pressing processes.

scholarly journals Mathematical modeling of stress-strain state of elements of joints of wooden structures on glued fiberglass washers

2021 ◽  
Vol 2131 (3) ◽  
pp. 032095
Author(s):  
M V Ariskin ◽  
D O Martyshkin ◽  
I V Vanin
Keyword(s):  
Mathematical Modeling ◽  
Bearing Capacity ◽  
Strain State ◽  
Single Component ◽  
Stress Strain ◽  
Design Models ◽  
Stress Strain State ◽  
Deformed State ◽  
Wooden Structures

Abstract Design models of single-component and three-component samples were developed on glued fiberglass washers in order to investigate the stress-strain state (SF) of the elements of joints of wooden structures. The picture and the nature of the actual stressed-deformed state of the wooden element with glued washers are obtained. Quite high bearing capacity of wooden structures connection is shown.

scholarly journals STUDY OF STRESSED-DEFORMED STATE OF THE POLYGONAL ARCH COVERINGS OF WOOD

World Science ◽  
2019 ◽  
Vol 1 (1(41)) ◽  
pp. 11-14
Author(s):  
O. V. Boіko ◽  
A. O. Boiadzhi ◽  
O. M. Korshak
Keyword(s):  
Strain State ◽  
Stress Strain ◽  
Load Bearing ◽  
Special Steel ◽  
Stress Strain State ◽  
Deformed State

In this work the use of wooden I-beams with OSB wall as the load bearing elements for polygonal arch coverings of buildings of various spans are considered. Special steel connecting pieces can shape the polygonal arch coverings. Calculations of the constructions with a span of 12 and 18 meters and an analysis of their stress-strain state are given.

scholarly journals DYNAMIC COMPRESSIBILITY OF BIRCH AT DIFFERENT TYPES OF STRESS-STRAINED STATE

2020 ◽  
Vol 82 (3) ◽  
pp. 269-282
Author(s):  
A.M. Bragov ◽  
A.K. Lomunov ◽  
T.N. Yuzhina
Keyword(s):  
Stress State ◽  
Strain State ◽  
Uniaxial Stress ◽  
Deformation Condition ◽  
Dynamic Tests ◽  
Stress Strain ◽  
Free Expansion ◽  
Noticeable Increase ◽  
Stress Strain State ◽  
Deformation Diagrams

The results of dynamic tests for compression across the fibers at room temperature of birch samples with air humidity are presented. Dynamic tests were carried out on a setup with a split Hopkinson bar according to the Kolsky method at a strain rate of ~2000 s–1. To assess the effect of the type of stress-strain state on the behavior of the material, in addition to specimens in the form of cylinders with its free expansion during loading (uniaxial stress state condition), specimens were tested in a rigid casing that prevents the radial expansion of the specimen (uniaxial deformation condition), as well as local compressive tests of rectangular board fragments. In the latter case, the material surrounding the loading zone plays the role of a compliant confining casing. In this case, a certain intermediate stress-strain state is realized in the sample. For these three types of stress-strain state, dynamic deformation diagrams were obtained with registration of additional loading cycles. Comparison of obtained deformation diagrams shows a significant effect of the type of stress-strain state on the behavior of the material under study. In the case of free expansion of the specimen in the radial direction, the absence of strain hardening is observed in the first loading cycle. In subsequent cycles, hardening is negligible. The deformation diagrams of specimens in the casing as well as board fragments are characterized by a noticeable increase in the modulus of the hardening branch with increasing deformation. In this case, it can be noted that the behavior of the material in the case of testing a piece of board is intermediate between the cases of uniaxial stress state and uniaxial strain state. Some mechanical characteristics of the material are determined using the diagrams obtained. The obtained experimental results can serve as the basis for the subsequent identification of the model of deformation and destruction of wood.

The Density of Deformations Distribution on the Side Edges during Strip Rolling

2021 ◽  
Vol 316 ◽  
pp. 340-345
Author(s):  
A.M. Rekov
Keyword(s):  
Cross Section ◽  
Joint Distribution ◽  
Strain State ◽  
Extrusion Ratio ◽  
Strip Rolling ◽  
Stress Strain ◽  
Stress Strain State ◽  
Deformation Intensity ◽  
Flat Rolling ◽  
Deformed State

Experimental densities of intensity distribution for main deformations, as well as the stress strain state of a metal on the side edges of an aluminum strip during its flat rolling, have been determined. Strain, spread and extrusion ratio have been evaluated. The dimensions of the strip cross-section have been chosen in a way that minimizes spreading. Therefore, the deformed state under rolling is close to a flat one. The correlation between the deformation intensity and the stress-strain state of macro-volumes occurred on strip edges has been estimated. The parameters of two-dimensional probability-density function for the joint distribution of deformation intensity and the Nadai-Lode stress-strain parameter have been determined. Distribution densities for longitudinal, transverse deformations and the intensity of main deformations in the zone of strip rolling are bimodal, which corresponds to both forward and backward slip zones under rolling. The results of the work can be used to predict the depletion of plasticity resources during strip rolling.

The Boundary Condition Influence on a Stress-Strain State of a Corrugated Plate on an Elastic Foundation

2018 ◽  
Vol 931 ◽  
pp. 60-65 ◽  
Author(s):  
Aleksey N. Beskopylny ◽  
Elena E. Kadomtseva ◽  
Grigory P. Strelnikov
Keyword(s):  
Boundary Condition ◽  
Elastic Foundation ◽  
Strain State ◽  
Polymer Coatings ◽  
Stress Strain ◽  
Stress Strain State ◽  
Different Types ◽  
Deformed State ◽  
Decorative Material ◽  
Construction Practice

In this paper, we consider the influence of the conditions for fixing a wavy plate lying on an elastic foundation on its stressed-deformed state. The profiled plates are widely used in construction practice as fencing structures, for siding works, for roofing and others. The stress-strain state of the wavy plates varies depending on geometry, materials mechanical properties, foundation characteristics and boundary condition. Steel with polymer coatings, which make the sheets a decorative material, is increasingly used in individual and low-rise buildings. The elastic foundation is considered as Winkler base, so we suppose that the reaction of the base is directly proportional to the deflection of the plate at each point. The Bubnov-Galerkin method is used to determine the stress-strain state of the plate. To solve the problem, we use special orthogonal Legendre polynomials satisfying the boundary conditions: simply supported and clamped edges. The results of the calculations were compared for different types of fixation.

scholarly journals STRESS-DEFORMED STATE OF STEEL-REINFORCED CONCRETE STRUCTURES OF FLOORS AT THE STAGE OF ESTABLISHMENT OF STRUCTURES

2021 ◽  
pp. 101-106
Author(s):  
M. V. Savytskyi ◽  
T.D. NIKIFOROVA ◽  
M. O. FROLOV
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Complex Stress ◽  
Time Interval ◽  
Stress Strain ◽  
Advantages And Disadvantages ◽  
Stress Strain State ◽  
Composite Section ◽  
History Of ◽  
Deformed State

Formulation of the problem. Many structures today require floor structures to meet increased requirements for strength, span coverage and surface quality. Steelcrete structures often fit the bill. However, despite a long history of success, the industry is still not fully understood, in particular, the behavior of this structure in the early stages of construction is not unambiguous. Due to the impossibility of creating a composite section, various effects and a complex stress-strain state immediately arise in the time interval between the combination of different materials in space and the combination of different materials in the work. Thus, the stage of erection of a structure before it became reinforced concrete is of interest for a complete understanding of the mechanics of the work of composite sections. The purpose of the study is to investigate the features of the operation of the steelcrete sections at the stage of installation and operation, as a composite structure that combines the advantages and disadvantages of steel and concrete. As a result of the research, it was found that the study of the stress-strain state, which affects the circumstances, both at the operation stage and at the construction stage, is an important task for further understanding the work of reinforced concrete. , and increasing its durability. In particular, at the time of erection, a complex stress-strain state occurs, which can lead to unpredictable changes in shape. This state is unstable up to the inclusion of the concrete shelf of the reinforced concrete section in the work due to the hardening of concrete in the area of the anchors and its subsequent inclusion in work. These issues require further study in order to better understand the work of concrete and steel as a single composite material at various stages of the life cycle of structures.

Method for determining process parameters in the repairing of pipelines with out-of-spec curvature

2020 ◽  
Vol 10 (1) ◽  
pp. 17-21
Author(s):  
Victor M. Varshitsky ◽  
◽  
Igor B. Lebedenko ◽  
Eldar N. Figarov ◽  
◽  
...  
Keyword(s):  
Process Parameters ◽  
Strain State ◽  
Repair Process ◽  
Operating Conditions ◽  
Stress Strain ◽  
Pipeline Section ◽  
Stress Strain State ◽  
Actual Operating ◽  
Deformed State ◽  
Inspection Data

Pipe sections with curvatures exceeding the required specified values are often found during the pigging of major pipelines. Process parameters for repairs have to be defined in order to develop a maintenance project that also includes works to restore the specified status of the section found. A corresponding method is known for cases of relocation of an initially straight pipeline. The authors developed a method for determining process parameters for repairing pipelines with out-of-project axis curvature. The method is based on modeling the deformation of a pipeline with initial axis curvature; it takes into account the actual operating conditions of the pipeline and in-line inspection data. Examples of calculating process parameters for repairs and stress-deformed state of pipeline sections with out-of-specs curvature have been presented. The modeling results confirm the possibility of using the method for evaluating the repair process parameters, the length of the required trench exposure, and the magnitude and boundaries of additional digging-in or the need to lift the pipeline in order to determine the stress–strain state of the pipeline section to be repaired during execution and after the completion of repairs.

scholarly journals COMPREHENSIVE ANALYSIS OF THE SHAFT STRUCTURE OF THE DNIPRO METRO

2021 ◽  
pp. 91-98
Author(s):  
O. L. TIUTKIN ◽  
V. А. MIROSHNYK ◽  
I. V. HELETIUK
Keyword(s):  
Numerical Analysis ◽  
Strain State ◽  
Complex Analysis ◽  
Comprehensive Analysis ◽  
Design Solution ◽  
Mine Shaft ◽  
Stress Strain ◽  
Stress Strain State ◽  
Deformed State ◽  
Shaft Lining

Purpose. The construction of the Dnipro Metro, which today is characterized by high efficiency and widespread introduction of new technologies, has proved the need for predesign, design and construction work. The purpose of the scientific article is to identify during the complex analysis of the structure of the mine shaft its stress-strain state, which was obtained during the numerical analysis and geodetic monitoring. Methodology. During the complex analysis of the shaft № 16-bis of the Dnipro Metro, prognostic calculations of the stress-strain state were performed. To do this, a finite-element model is built, in which fully reflects the geometric features of the shaft, the load on it and boundary conditions. Part of the comprehensive analysis is geodetic monitoring, which is carried out during the construction of the shaft and during its operation. The works included the measurement of deformations both in the lining of the shafts and in the sections of the mine workings, as well as on the surface near the houses along the route in the area of influence of the working workings. Findings. During the numerical analysis of the structure of the shaft № 16-bis of the Dnipro Metro, displacement and force factors (normal forces and bending moments) were determined. Based on these results, the reinforcement of the elements of the shaft lining (bored pile, cap beam, reinforced concrete ring beam) was selected. The value of the deformed state obtained from the prognostic analysis indicates on the insignificant displacements of the designed structure. During the geodetic monitoring, horizontal and vertical deformations of the № 16-bis shaft lining were recorded, which were caused by the influence of public transport and heavy vehicles. But the values of these deformations reached 1 … 2 mm, which for their effect on buildings and structures is within normal limits. Originality. A comparison of the deformed state obtained during numerical analysis and geodetic monitoring, which proved the high accuracy of the prognostic calculation. Practical value. The results of a comprehensive analysis of the mine shaft of the Dnipro Metro made it possible to carry out a test the design solution and ensure high strength and stability of the lining made of bored piles.

scholarly journals Systematic monitoring of the deformed state of long-length reinforced concrete structures with an assessment of their reliability

2021 ◽  
Vol 263 ◽  
pp. 02003
Author(s):  
Aleksandr Perunov ◽  
Aleksey Baulin
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Stress Strain ◽  
Systematic Monitoring ◽  
Stress Strain State ◽  
Deformed State ◽  
Time Of Year ◽  
Building Coating

The article shows the method of systematic monitoring of the stress-strain state of reinforced concrete structures covering one of the operated public railway stations. The description of large-span structures of the building, their defects and damages acquired during the operation of the building is given. The article describes the methodology and methods used for long-term, more than 2 years, continuous monitoring of the deformed state of coating structures in operation. The most damaged structures are examined in detail with the help of installed devices to obtain accurate data. The features of measurements in different periods of time and time of year are described. Based on the results of the obtained measurements of the stress-strain state of the building coating structures, the possibility of their further operation is predicted, taking into account the defects and damages found during the survey.

Sign in / Sign up

Export Citation Format

Share Document