Stress-strain state of a pipeline subject to the influence of a combined load

2020 ◽  
Vol 10 (1) ◽  
pp. 22-31
Author(s):  
Anatoly A. Ignatik ◽  
Keyword(s):  
Strain State ◽  
Vertical Plane ◽  
Von Mises Stress ◽  
Shear Stresses ◽  
Principle Of Superposition ◽  
Stress Strain ◽  
Bending Force ◽  
Stress Strain State ◽  
Von Mises ◽  
Longitudinal Strains

Theoretical and experimental study of the stress-strain state of a pipeline under the influence of two types of loads was carried out: 1) bending force in vertical plane; 2) combined action of bending force in vertical plane and internal pressure. The experiments were performed on a pipe sample: steel grade Ст3, outside diameter 114 mm, wall thickness 4.5 mm, length 0.94 m. Hoop and longitudinal strains were measured in different areas of the pipe sample wall under the bending force in the vertical plane. To determine other parameters of the pipe stress-strain state the theories of thick-walled and thin-walled cylindrical shell, the Hooke’s law, the Zhuravsky–Vlasov formula for calculating the greatest shear stress in a circular tube, the principle of superposition were used. The distributions of the stress-strain state parameters (hoop, longitudinal, radial strains; hoop, longitudinal, shear stresses; von Mises stress) of the pipe sample wall around the perimeter of different pipe cross sections are found. It is revealed that hoop and shear stresses have a significant effect in the considered cases of loading. The values of hoop and shear stresses should be taken into account when calculating von Mises stress and assessing strength of the main pipeline according to the maximum-distortion-energy theory.

MODELING OF THE STRESS-STRAIN STATE OF A TRANSPORT TUNNEL UNDER LOAD AS A MEASURE TO REDUCE OPERATIONAL RISKS TO TRANSPORTATION FACILITIES

2020 ◽  
Vol 3 (8) ◽  
pp. 28-34
Author(s):  
N. V. IVANITSKAYA ◽  
◽  
A. K. BAYBULOV ◽  
M. V. SAFRONCHUK ◽  
◽  
...  
Keyword(s):  
Strain State ◽  
Moving Load ◽  
Element Model ◽  
Transport Infrastructure ◽  
Design Stage ◽  
Surface Load ◽  
Stress Strain ◽  
Stress Strain State ◽  
Operational Risks ◽  
Von Mises

In many countries economic policy has been paying increasing attention to the modernization and development of transport infrastructure as a measure of macroeconomic stimulation. Tunnels as an important component of transport infrastructure save a lot of logistical costs. It stimulates increasing freight and passenger traffic as well as the risks of the consequences of unforeseen overloads. The objective of the paper is to suggest the way to reduce operational risks of unforeseen moving load by modeling of the stress-strain state of a transport tunnel under growing load for different conditions and geophysical parameters. The article presents the results of a study of the stress-strain state (SSS) of a transport tunnel exposed to a mobile surface load. Numerical experiments carried out in the ANSYS software package made it possible to obtain diagrams showing the distribution of equivalent stresses (von Mises – stresses) according to the finite element model of the tunnel. The research results give grounds to assert that from external factors the stress state of the tunnel is mainly influenced by the distance to the moving load. The results obtained make it possible to predict in advance the parameters of the stress-strain state in the near-contour area of the tunnel and use the results in the subsequent design of underground facilities, as well as to increase their reliability and operational safety. This investigation gives an opportunity not only to reduce operational risks at the design stage, but to choose an optimal balance between investigation costs and benefits of safety usage period prolongation.

scholarly journals Mathematical Models and Evaluation Software for Stress-Strain State of the Earth’s Lithosphere

2019 ◽  
pp. 51-66
Author(s):  
Alexander O. Faddeev ◽  
Svetlana A. Pavlova ◽  
Tatiana M. Nevdakh
Keyword(s):  
Mathematical Model ◽  
Strain State ◽  
Uniform Grid ◽  
Shear Stresses ◽  
Stress Strain ◽  
Gravitation Field ◽  
Vertical Movements ◽  
Stress Strain State ◽  
The Earth ◽  
Viscous Shear

Introduction. For the purposes of this article, geodeformation processes mean processes associated with deformations arising from the movement of species and blocks of the lithosphere at various depths, including surfaces. The objective is to reconstruct geodynamic stress fields, which cause modern shifts and deformations in the Lithosphere. A mathematical model and software for estimating the stress-strain state of the Earth Lithosphere are considered. Materials and Methods.For mathematical modeling of stresses, isostatically reduced data on abnormal gravitation field were used. The methods of continuum mechanics and methods of the theory of differential equations were used to design a model for estimating the stressstrain state of the Earth Lithosphere. For processing input, intermediate and outcoming data, the Fourier transform method of spectral analysis for constructing grid functions and spectral-temporal method were used. To model for the stress-strain state of the Lithosphere globally, stress calculation was corrected on the basis of sputnik-derived velocity data at the surface of the earth crust. The data on the rates of horizontal and vertical movements at the surface of the Earth crust were processed to obtain a distribution of velocities in the uniform grid embracing longitudes and latitudes. The processing procedure was carried out on the basis of the Kraiging method. The software was developed in Borland Delphi 7.0 programming environment. Results. Based on the data on the abnormal gravitation field in isostatic reduction and information on the distribution of velocities of horizontal motions on the surface of the Earth crust, a mathematical model of the stress-strain state of the Lithosphere was constructed. With the help of the obtained mathematical model and software complex, the stress-strain state of the Lithosphere was calculated at various depth using elastic and elastic-viscous models, and maps of equipotential distribution of shear elastic-viscous deformations in the lithosphere at the depth of 10 km were constructed. Discussion and Conclusion. The presented mathematical model and software allow restoring fields of both elastic and elastic-viscous deformations that is fundamental for quantification of elastic-viscous shear stresses deep in the Earth Lithosphere.

scholarly journals Ultimate state criteria and strength characteristics of the rock massifs being undermined repeatedly

2021 ◽  
Vol 66 (4) ◽  
pp. 420-429
Author(s):  
S. A. Chizhik ◽  
M. A. Zhuravkov ◽  
A. B. Petrovskiy ◽  
V. Ya. Prushak ◽  
D. A. Puzanov
Keyword(s):  
Attenuation Coefficient ◽  
Failure Criterion ◽  
Strain State ◽  
Strength Characteristics ◽  
Shear Stresses ◽  
Ultimate State ◽  
Stress Strain ◽  
Stress Strain State ◽  
Failure State ◽  
Complex Criterion

Methodological approaches to the selection of ultimate state criteria and strength characteristics of the repeatedly undermined rock massifs were developed. These approaches were designed to provide parametric support to the geomechanical modelling of the massif stress-strain state and the mining systems of the Starobin potash deposit mine fields planned for the additional mining of the mineral reserves left. It was established that a complex criterion must be used to study the massif ultimate state. Determination of such criterion can be carried out using the developed approaches. The first approach is to select several criteria that evaluate the massif ultimate state by certain types of the massif stress-strain state. These criteria are the following: the criterion of the maximum normal stresses, criterion of the maximum linear strains, the criterion of the maximum shear stresses and the Coulomb–Mohr failure criterion. The second approach is to construct an integrated failure state criterion for materials whose ultimate tensile and compressive stresses differ significantly. In this case, parameters characterizing the type of stress state and properties of the material are introduced. These parameters together determine the destruction character – tear or shear. To describe the rocks behavior in the extreme strength stage of deformation, it is proposed to apply deformation theory of strength using the developed strain failure criterion. When calculating the strength characteristics of the repeatedly undermined rock massif, it is recommended to use a structural attenuation coefficient as the product of several factors, taking into account various types of disturbances in the primary undermined massif and the time factor. The Coulomb–Mohr strength condition is recommended to be used taking into account the composite structural attenuation coefficient. Dependencies have been developed to describe the change in the strength characteristics of rocks in the undermined massif, considering the attenuation coefficient.

scholarly journals STRESS-STRAIN STATE OF CURVED LAMINATED WOODEN ELEMENTS DURING PRODUCTION

2020 ◽  
Vol 5 (4) ◽  
pp. 51-59
Author(s):  
Alexander Schmidt ◽  
Keyword(s):  
Strain State ◽  
Initial Stresses ◽  
Internal Stresses ◽  
Shear Stresses ◽  
Stress Strain ◽  
Stress Strain State ◽  
Operational Load ◽  
Study Results ◽  
The Impact ◽  
Wooden Structures

Introduction: The stress-strain state (SSS) of curved laminated wooden elements may differ significantly from the SSS of straight laminated wooden elements, not only in terms of the curvature but also in terms of production specifics and operational load. A curved element is produced by bending wooden planks (lamellae) and gluing them together. In the process, the structure is subjected to initial internal stresses, as the lamellae tend to straighten out again. After production is complete, the element experiences unequal initial internal stresses, which alters its strength properties in different directions in relation to the timber fibers. At a later point, this is going to contribute to the stresses that the structure experiences under external pressure. The Russian and foreign regulations (SP, EuroCode 5, DIN) do not pay sufficient attention to this fact, which has merited this study. Methods: For the aforementioned purpose, we review a mathematical model of the SSS emergence in curved laminated wooden elements. We roughly divide the process into two stages: stage 1 involves bending separate lamellae, gluing them together, and pressing them down; stage 2 involves pressing out the laminated package. This results in prestress, which is a combination of tangential, radial, and shear stresses. Results: Our study results in a visual representation of the total prestress during stages 1 and 2. Such a representation allows for predicting stresses in curved laminated wooden structures under alternating operational loads. Discussion: We highlight the impact of the relaxation of initial stresses, which requires further study. Depending on the direction and amount of operational load, the curved laminated section of a structure may “attempt” to straighten out (i.e. with a decrease in curvature), or may curve even further. This is not properly reflected in the guidelines for wooden structures’ design and needs to be examined further.

scholarly journals Stress state in contact between wheel and rail in the presence of slip and adhesion

2021 ◽  
Vol 2021 (2) ◽  
pp. 177-187
Author(s):  
S. V. Krotov ◽  
◽  
D. P. Kononov ◽  
E. V. Pakulina ◽  
◽  
...  
Keyword(s):  
Stress State ◽  
Contact Zone ◽  
Traffic Safety ◽  
Strain State ◽  
Practical Importance ◽  
Normal Pressure ◽  
Shear Stresses ◽  
Stress Strain ◽  
Stress Strain State ◽  
Theoretical Approaches

Objective: Predicting the stress-strain state of a wheel or rail during their interaction depending on the normal pressure. Methods: The study of the stress-strain state in the car wheel and in its contact with the rail using the finite element method with all possible combinations of loading factors and taking into account the influence of temperature, dynamic influences, contact parameters, fatigue phenomena and the forces of interaction between the wheel and the rail are calculated, determining the stress state of the wheel, wear and deterioration of the contact surfaces and, as a consequence, the reliability of the carriage and traffic safety. Results: The effect of tangential loads on the stress-strain state when there is sliding in the wheel-rail contact zone was evaluated. The parameters of dangerous stresses are given depending on the axial load. Experimental and theoretical approaches to determining the stress-strain state of contacting elements in the presence of both slip and adhesion in the wheel-rail contact are shown. The components of the stress tensor are obtained depending on the contact pressure according to the calculation formulas. Diagrams of the distribution of shear stresses in the contact of the wheel with the rail in the presence of a zone of adhesion and sliding are made. The intensity of the stress state change in the wheel-rail contact is calculated. Practical importance: The results obtained show how the slip and adhesion zones affect the stress state in the contact zone in comparison with full slip. They are useful from the point of view of predicting the stress-strain state of a wheel or rail during their interaction depending on the normal pressure.

scholarly journals Influence of breakages of cable groups on strength ofrubber-cable tractive-transporting element

2021 ◽  
Vol 64 ◽  
pp. 166-174
Author(s):  
I Belmas ◽  
D Kolosov ◽  
O Dolgov ◽  
H Tantsura ◽  
S Onyshchenko
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Strain State ◽  
Elastic Shell ◽  
Practical Significance ◽  
Analytical Determination ◽  
Shear Stresses ◽  
Stress Strain ◽  
Stress Strain State

Purpose. Development and justification of a method of analytical determination of a stress-strain state of a flat rubber-cable tractive-transporting element with breakages of continuity of cable groups in different cross-sections. Methodology of research is in development of a mathematical model of interaction of tractive-transporting element parts considering breakages of groups of random cables, construction of analytical solutions for determining dependencies of force distribution between cables and shear stresses in an elastic shell of a tractive-transporting element with random locations of breakages of cable groups in different cross-sections. Findings. A model of a flat rubber-cable tractive-transporting element with random locations of breakages of cable groups in different cross-sections is developed. Expressions that allow determining a stress-strain state of a flat rubber-cable tractive-transporting element of a hoisting and transporting machine with random locations of breakages of cable groups in different cross-sections are obtained analytically in a closed form. Strength conditions are formulated. Scientific novelty is in establishment of dependencies of interaction of disturbance fields of a stress-strain state of a rubber-cable tractive-transporting element with breakages of continuity of random cable groups in different cross-sections. It is established that disturbance fields caused by breakages of adjacent cables overlap when the breakages are located in one cross-section and there are less than three whole cables located between the broken cables. Disturbance fields also overlap when the same cable or the adjacent cable is broken in both cross-sections and the distance between cross-sections of breakage does not exceed the value, which depends on the design of a flat rubber-cable tractive-transporting element and mechanical properties of its components. Practical significance. The obtained algorithms and strength conditions allow determining a stress-strain state and preventing the breakage of the entire flat rubber-cable tractive-transporting element with breakages of cable groups in different cross-sections. These cross-sections can be: cross-section of the edge of a butt joint, where cables have breakages of continuity; cross-section, which includes the edge of an area of partial restoration of a tractive ability of the element, lost due to breakage of a cable; cross-section of cable or cable group breakage during operation. A possibility of establishing a stress-strain state and the strength conditions of a tractive-transporting element under such conditions allows reasonable determination of a possibility of its further operation in a hoisting and transporting machine.

scholarly journals The investigation of the stress-strain state of beam crossings with a truss-form supporting element of the operating pipeline

2020 ◽  
pp. 71-84
Author(s):  
Т. Yu. Pyrih ◽  
Ya. V. Doroshenko ◽  
Ya. І. Matviichuk
Keyword(s):  
Strain State ◽  
Bending Moment ◽  
Isosceles Triangle ◽  
Internal Force ◽  
Gas Pipeline ◽  
Stress Strain ◽  
Scientific Publications ◽  
Stress Strain State ◽  
Supporting Element ◽  
Longitudinal Strains

The areas of application and advantages of the over-ground piping or pipe section layout are given. The classification according to the design features of the most common systems of overhead pipeline crossings on the basis of generalization of scientific publications and experience of pipeline construction are considered. The authors indicate the ranges of the effective spans for rectilinear single-span and multi-span crossings without compensators of longitudinal strains (with the fixed ends) and also in multi-span systems with compensators depending on the diameter of pipes, nominal pipe wall thickness and brand of pipe steel for gas, oil and oil-products pipelines respectively. The description of the design of beam systems of overhead pipeline crossings with a truss-form supporting element of the operating pipeline is given and the procedure for estimating their stress-strain state is suggested. According to the constructed cargo and unit calculation schemes of the truss with a cross-section in the form of an isosceles triangle (height – 3 m, width – 2.02 m) the stiffness coefficients of elastic-malleable supports is determined. The selection of cross-sections of truss members is carried out, the required deflections of the pipeline and the emerging internal force factors (bending moments and reactions of elastic-malleable supports) at the points where the pipeline rests on the truss are found. The strength of the pipeline to the action of the maximum bending moment is checked and the possibility of the cross-water layout of the beam crossing of the gas pipeline is shown. This is the  gas pipeline with the length of . It has compensators with a truss-form supporting element which eliminates the use of intermediate supports. Thus, it was shown that the truss makes it possible to double or triple the length of the span using no intermediate supports and preserving sufficient horizontal rigidity.

Comparison of Stress-Strain States of Rail-Wheel Pair Made of Steel and MoNiCa

2021 ◽  
Vol 320 ◽  
pp. 14-19
Author(s):  
Sergei Sherbakov ◽  
Aliaksandr Bahdanovich ◽  
Aleh Nasan ◽  
Daria Podgayskaya ◽  
Liudmila Shemet ◽  
...  
Keyword(s):  
Strain State ◽  
Rail Steel ◽  
Three Dimensional ◽  
High Strength ◽  
Bottom Surface ◽  
Stress Strain ◽  
Wheel Pair ◽  
Stress Strain State ◽  
Freight Car ◽  
Von Mises

Contact interaction in a wheel-rail pair and its corresponding stress-strain state for various combinations of materials of this pair and the weights of passenger and freight cars were considered. The materials under study were steel and high-strength cast iron based structural material MoNiCa with strength and wear-fatigue characteristics close to steel ones.The load on each wheel was: 53.9 and 294.3 kN for an empty and loaded freight car, 146.8 kN and 230.5 kN for an empty and loaded passenger car. The bottom surface of the rail was rigidly fixed.Young's modules were adopted as follows: 200 GPa for steel and 165 for MoNiCa. The results of finite element calculations of the three-dimensional stress-strain state showed that the largest von Mises stresses of 613.08 MPa occur in the wheel (steel)-rail (steel) pair of the loaded freight car. For all types of loading, the lowest stresses (15.8 % – 16.7 % less than in the steel-steel pair) are observed in the wheel (MoNiCa)-rail (MoNiCa) pair. This indicates the appropriateness of using MoNiCa for the manufacturing elements of the wheel-rail system.

scholarly journals Development of a technique for computer simulation of the stress state of the drive drum shell of a belt conveyor to optimize its design parameters

2021 ◽  
Vol 2 (7 (110)) ◽  
pp. 31-39
Author(s):  
Olzhas Jassinbekov ◽  
Madina Isametova ◽  
Gabit Kaldan
Keyword(s):  
Computer Simulation ◽  
Strain State ◽  
Computer Calculation ◽  
Variable Pressure ◽  
Design Parameters ◽  
Shear Stresses ◽  
Stress Strain ◽  
Tangential Stresses ◽  
Stress Strain State ◽  
Angle Of Rotation

The paper considers the method of computer simulation of the stress-strain state of the drive drum shell in the NASTRAN integrated environment. Due to the complexity of determining stresses and deformations in the drum sections by the analytical method, it is proposed to solve this important problem using the numerical finite-element method. At the preliminary stage of computer modeling, a mechanical design scheme was developed, including a variable pressure that changes depending on the angle of rotation of the drum, the deterministic relations describing the variable force factors are based on the Euler ratio. It is also proposed to take into account the pressure from the variable friction force, which depends on the changing coefficient of adhesion of the belt to the drum. As a result of the computer calculation, the equivalent Mises stresses of 65 MPa were determined, the safety factor was 4.2 and the components of the tangential stresses were determined using the stress tensor marker, the shear stress reached the level τ=16 MPa for fabric tape and τ=3.14 MPa for rubber tape. According to the results of the calculation, the dependence of the tangential stresses on the angle of rotation of the drum was constructed. A diagram of the change in the component of tangential stresses along the forming shell of the drum was constructed. Analysis of stress-strain state allowed us to determine the factor of safety of the drum shell. Based on the analysis of equivalent stresses, it is proposed to further calculate the durability of the drum using the method of long-term fatigue. The computer calculation of shear stresses in the component allows choosing the rational parameters of the lining, based on such indicators as peel strength and break, as well as determining the angle 61° of the slab lining required to improve the reliability and traction ability of the pipeline

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