scholarly journals Peculiarities of the stress-strain state of the “excavation – geo-environment” and “embankment – geo-environment” systems in the process of erecting them (part II)

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Mikhail Krasnov ◽  
Nikolay Gorshkov ◽  
Yuan Jingwen ◽  
Svetlana Jdanova
Keyword(s):  
Finite Elements ◽  
Strain State ◽  
Common Ground ◽  
Displacement Vector ◽  
Limit State ◽  
The Body ◽  
Volume Deformation ◽  
Stress Strain ◽  
Stress Strain State ◽  
The Stability

Excavations and embankments are the most common ground transport structures, operational reliability and durability of which is determined by the stability of their sides and slopes. The first article deals with the features of stress-strain state and changes in stability of ground transport structures (excavations) based on modeling according to the certified program of finite element method GenIDE32. At modeling the layer-by-layer excavation of homogeneous soil from excavations with finite geometrical sizes was carried out. In the excavation edge array, in the field of displacement vector ui, appeared are poorly studied phenomena in the form of «rotation circles» or short vortices. These phenomena, discovered in model experiments (Yu.I. Soloviev, 1956), require detailed research in the future. Graphic results of the calculations performed allow one to see the appearance and development of zones of «plasticity» or limit state in the form of zones of «shift-compression», «compression-shift» and «stretching». Shift-compression zones and vice versa are shown as shaded finite elements at an angle crosswise, while stretch zones are shown as shaded vertically, horizontally and vertically, and horizontally finite elements. These zones, in the process of modeling, are drawn in the edges of the projections of a slide with vertical and horizontal cracks. The contours of the landslide prisms show themselves well when the average relative volume deformation values of ε are displayed on the screen. The display of this value in two colors defines the landslide contours in this figure. Sliding lines with the minimum value of the stability coefficient kst min pass near the borders, where values of this parameter are equal to zero. In this figure, in the upper part of the array, you can see the places where vertical cracks are formed. The analysis also uses graphs of stress-strain state trajectories in the space of stress tensor invariants σij and relative deformations εij in significant nodes and finite elements, located, including, in places of sliding lines with kst min. They make it possible to see from the volume and shape deformation graphs where the system with the calculated condition is located, for example, from the condition at which the body of the landslide was formed.

scholarly journals Peculiarities of the stress-strain state of the “excavation – geo-environment” and “embankment – geo-environment” systems in the process of erecting them (part I)

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Nikolay Gorshkov ◽  
Mikhail Krasnov ◽  
Yuan Jingwen ◽  
Svetlana Jdanova
Keyword(s):  
Finite Elements ◽  
Strain State ◽  
Common Ground ◽  
Displacement Vector ◽  
Limit State ◽  
The Body ◽  
Volume Deformation ◽  
Stress Strain ◽  
Stress Strain State ◽  
The Stability

Excavations and embankments are the most common ground transport structures, operational reliability and durability of which is determined by the stability of their sides and slopes. The first article deals with the features of stress-strain state and changes in stability of ground transport structures (excavations) based on modeling according to the certified program of finite element method GenIDE32. At modeling the layer-by-layer excavation of homogeneous soil from excavations with finite geometrical sizes was carried out. In the excavation edge array, in the field of displacement vector ui, appeared are poorly studied phenomena in the form of «rotation circles» or short vortices. These phenomena, discovered in model experiments (Yu.I. Soloviev, 1956), require detailed research in the future. Graphic results of the calculations performed allow one to see the appearance and development of zones of «plasticity» or limit state in the form of zones of «shift-compression», «compression-shift» and «stretching». Shift-compression zones and vice versa are shown as shaded finite elements at an angle crosswise, while stretch zones are shown as shaded vertically, horizontally and vertically, and horizontally finite elements. These zones, in the process of modeling, are drawn in the edges of the projections of a slide with vertical and horizontal cracks. The contours of the landslide prisms show themselves well when the average relative volume deformation values of ε are displayed on the screen. The display of this value in two colors defines the landslide contours in this figure. Sliding lines with the minimum value of the stability coefficient kst min pass near the borders, where values of this parameter are equal to zero. In this figure, in the upper part of the array, you can see the places where vertical cracks are formed. The analysis also uses graphs of stress-strain state trajectories in the space of stress tensor invariants σij and relative deformations εij in significant nodes and finite elements, located, including, in places of sliding lines with kst min. They make it possible to see from the volume and shape deformation graphs where the system with the calculated condition is located, for example, from the condition at which the body of the landslide was formed.

Research of opening reliability of blast easily disposable systems with honeycomb polycarbonate sheets by finite elements method

2020 ◽  
pp. 107-115
Author(s):  
Yu.Yu. Pidhoretskyi ◽  
Keyword(s):  
Finite Elements ◽  
Strain State ◽  
Numerical Algorithms ◽  
Honeycomb Structure ◽  
Geometrical Parameters ◽  
Stress Strain ◽  
Stress Strain State ◽  
Relief Elements ◽  
Explosion Overpressure ◽  
Applied Approach

In the article, the author presents results of mathematical modeling of operation of the venting relief structures made of honeycomb polycarbonate sheets and fixed in the standard window profiles, under the effect of explosion. In order to reproduce the explosion effect on venting relief structures, an approach to modeling dynamic systems was applied, which used a finite element method to approximate the basic general equations of dynamics added by the equations of the stress-strain state of a solid body. The applied approach differs by reproduction of the explosion process impact on the venting relief structures of this type by using equations which describe the motion of the dynamic system with accounting a contact interaction with the friction of honeycomb polycarbonate sheets and corresponding surfaces of the standard window profile locks. The honeycomb structure of the polycarbonate sheet was modeled by appropriate finite elements with considering the polycarbonate elastic properties. In order to implement numerical algorithms of this approach, a program code of the LS-DYNA computer system was used. The conducted numerical experiment on reproducing the explosion effect on the relief elements of this type of the venting relief structures made it possible to trace all stages of the honeycomb polycarbonate sheets deforming and moving under the action of explosion up to the exit of their edges from the window profile locks with the study of the corresponding stress-strain state parameters. By using this approach, reliably disclosure of the venting relief structures based on honeycomb polycarbonate sheets was investigated, and conditions for their reliable disclosure were identified with considering geometrical parameters of such type of venting relief structures opening and thickness of the honeycomb polycarbonate sheets. Results of the research have shown that reliable disclosure of the honeycomb polycarbonate sheets occurs within the range of the explosion overpressure, hence, confirming the effectiveness of such type of the venting relief structures used for protecting buildings against the explosion action.

scholarly journals REGULARITIES OF THE LINING STRESS-STRAIN STATE DURING OF THE PYLON METRO STATION CONSTRUCTION

2021 ◽  
pp. 19-27
Author(s):  
D. O. BANNIKOV ◽  
V. P. KUPRII ◽  
D. YU. VOTCHENKO
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Finite Elements ◽  
Strain State ◽  
Finite Element Models ◽  
Bending Moments ◽  
Stress Strain ◽  
Normal Forces ◽  
Stress Strain State ◽  
Station Structure

Purpose. Perform numerical analysis of the station structure. Take into account in the process of mathematical modeling the process of construction of station tunnels of a three-vaulted station. Obtain the regularities of the stress-strain state of the linings, which is influenced by the processes of soil excavation and lining construction. Methodology. To achieve this goal, a series of numerical calculations of models of the deep contour interval metro pylon station was performed. Three finite-element models have been developed, which reflect the stages of construction of a three-vaulted pylon station. Numerical analysis was performed on the basis of the finite element method, implemented in the calculation complex Lira for Windows. Modeling of the stress-strain state of the station tunnel linings and the soil massif was performed using rectangular, universal quadrangular and triangular finite elements, which take into account the special properties of the soil massif. Station tunnel linings are modeled by means of rod finite elements. Findings. Isofields of the stress-strain state in finite-element models reflecting the stages of construction are obtained. The vertical displacements and horizontal stresses that are characteristic of a three-vaulted pylon station are analyzed. The analysis of horizontal stresses proved that at the stage of opening of the middle tunnel the scheme of pylon operation is rather disadvantageous. The analysis of bending moments and normal forces was also carried out and the asymmetry of their distribution was noted. Originality. Based on the obtained patterns of distribution of stress-strain state and force factors, it is proved that numerical analysis of the station structure during construction is necessary to take measures to prevent or reduce deformation of frames that are in unfavorable conditions. Practical value. In the course of research, the regularities of changes in stresses, displacements, bending moments and normal forces in the models of the pylon station, which reflect the sequence of its construction, were obtained.

scholarly journals INVESTIGATION OF LOCAL UNLOADING OF AN ELEMENT IN A FINITE ELEMENT CONTINUUM

2021 ◽  
pp. 86-96
Author(s):  
A.Yu. Burtsev ◽  
◽  
V.V. Glagolev ◽  
A.A. Markin ◽  
◽  
...  
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
Strain State ◽  
Plastic Region ◽  
Elastoplastic Problem ◽  
The Body ◽  
Stress Strain ◽  
Adjacent Element ◽  
Stress Strain State ◽  
Ansys Workbench

The subcritical elastoplastic deformation and the fracturing of an element of a finite element continuum in the Ansys Workbench complex are considered. When solving the elastoplastic problem of the subcritical deformation, a finite element with the failure criterion reached is selected. In a pre-fracture state of the element, the nodal forces provided by the interaction with an adjacent element are determined using the Ansys Workbench internal procedure. The following step is the consideration of the varying stress-strain state of the body during the element destruction. The elastoplastic problem is solved in the conditions of simple unloading of the body surface adjacent to the destructible element while maintaining the external load corresponding to the destruction initiation. When implementing the local unloading, a possibility of the new plastic region formation and the partial unloading are studied. As a result, the stress-strain state of the body at the beginning of local unloading is not the same as that at the end of the process. The proposed approach differs from the “element killing” procedure when the element stiffness after the failure criterion reached is assumed to be close to zero. The paper provides solutions to the problems of deformation of elastic and elastoplastic plates with a side cut taking into account their element destruction.

scholarly journals COMPUTATIONAL-EXPERIMENTAL STUDY OF CONTACT INTERACTION OF BODIES WITH NEARLY FORM SURFACES

2021 ◽  
pp. 23-32
Author(s):  
Andrey Grabovskiy ◽  
Mykola А. Tkachuk ◽  
Natalia Domina ◽  
Ganna Tkachuk ◽  
Olha Ishchenko ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Contact Interaction ◽  
Strain State ◽  
The Body ◽  
Contact Pressure Distribution ◽  
Interaction Method ◽  
Stress Strain ◽  
Stress Strain State ◽  
Flat Shape ◽  
Keywords Stress

  In many constructions, their elements are in contact with nominally matching (congruent) surfaces. In reality, this contact is disturbed due to deviations in the shape of these surfaces from the nominal. To study the effect of this perturbation on the distribution of contact pressure, the analysis of the stress-strain state of the body system of punched sheet-die is carried out. The middle element of this system deviates from the nominally flat shape. This causes a change in the contact pressure distribution. The proportionality between the clamping force and the level of contact pressure is also lost. The reliability and accuracy of the results obtained by numerical calculation have been experimentally confirmed. Keywords: stress-strain state; contact pressure; contact interaction; method of variational inequalities; Kalker variational principle; finite element method

scholarly journals Stress-strain state of a combined toroidal baromembrane apparatus

2021 ◽  
Vol 21 (2) ◽  
pp. 123-132
Author(s):  
S. I. Lazarev ◽  
О. V. Lomakina ◽  
V. Е. Bulanov ◽  
I. V. Khorokhorina
Keyword(s):  
Strain State ◽  
Liquid Waste ◽  
The Body ◽  
Transmembrane Pressure ◽  
Toroidal Shell ◽  
Outer Diameter ◽  
Stress Strain ◽  
Load Bearing ◽  
Stress Strain State ◽  
Membrane Apparatus

Introduction. Currently, the purification of wastewater and technological solutions by membrane methods is considered a promising way to neutralize liquid waste. Therefore, the task of developing an engineering method for calculating baromembrane devices is a challenge. Studies on methods involving calculation of design and process variables, membrane equipment design, research of technological features of membrane devices, selection of design schemes, as well as methods of strength and rigidity analysis, are investigated.Materials and Methods. Basic elements of the body of the combined membrane apparatus are considered, a design scheme is proposed, and a method for calculating the strength and rigidity of the main load-bearing element, the cover, is described.  Results. The methods determine the required dimensions of shells and plates for the development of a combined membrane apparatus, and evaluate the strength properties of the devices of this class. The construction elements of the apparatus (primarily, the load-bearing covers) must meet not only the requirements of efficiency and quality of separation and cleaning of solutions, but also the conditions for safe operation. Therefore, the design of the device covers should be based on the optimal design dimensions (thicknesses of round plates, toroidal shells, and support rings). To test the method, the stress-strain state of the membrane apparatus structure was calculated for strength and rigidity. As an example, we consider one cover presented in the form of an open toroidal shell. The evaluation of the application of this technique, taking into account the fact that the shell is mated with a round plate in the inner diameter, and with a ring in the outer diameter, has provided the determination of the required parameters.Discussion and Conclusions. The obtained method of analytical description of the mechanical impact on the elements of the combined apparatus and the example of calculating the toroidal shell and plate, enables to evaluate the stressstrain state of the structure for strength and rigidity. The results of the calculation of covers made of various materials at different pressures are presented. Loading the combined apparatus with transmembrane pressure made it possible to determine the required dimensions of the shells and plates for its design and development. 

Stress-Strain State Of The Structure When Lifting And Leveling As A Result Of Uneven Settlement

2019 ◽  
pp. 60-64
Keyword(s):  
Finite Elements ◽  
Strain State ◽  
Spatial Problem ◽  
Reinforced Concrete Structure ◽  
Stress Strain ◽  
Entire Area ◽  
Stress Strain State ◽  
Foundation Base ◽  
Filtration Regime ◽  
Base Soil

This article is devoted to the calculated substantiation of lifting (leveling) of a massive reinforced concrete structure which changed its position after uneven settlement. To determine the stress-strain state of the structure, a spatial problem is solved by the method of local variations using 32 node finite elements, based on the energy model of the soil (L.N. Rasskazov) with the use of the Saint-Venant’s principle. The problem is solved without taking into account the effect of the base soil and the filtration regime in it. To evaluate of the sequence of loading of the foundation base of the structure the so-called “sectional lift” is modeled. In this case the load is applied not to the entire area of the basement footing, but only to certain zones (load sections). By calculation, the required value of the applied lift load, the number of application sections of this load, the required and the most adequate boundary conditions of the problem are selected. The stress-strain state of the structure is analyzed during its successive lifting. Information on the order of changing the vertical coordinates of the foundation bottom is given.

The stress-strain state at the junction of a jacket shell to the body of a vessel

1971 ◽  
Vol 7 (3) ◽  
pp. 205-207
Author(s):  
V. D. Babanskii ◽  
V. F. Kurylev ◽  
S. M. Kutepov
Keyword(s):  
Strain State ◽  
The Body ◽  
Stress Strain ◽  
Stress Strain State

scholarly journals Research of stress-strain state and stability of a rokfill dam under seismic actions

Vestnik MGSU ◽  
2015 ◽  
pp. 157-166
Author(s):  
Vyacheslav Valentinovich Orekhov
Keyword(s):  
Strain State ◽  
Initial Conditions ◽  
The Body ◽  
Cohesionless Soil ◽  
Soil Base ◽  
Stress Strain ◽  
Stress Strain State ◽  
Soil Skeleton ◽  
Water Saturated ◽  
Seismic Impacts

One of the main factors determining the safety of earth sea and river hydraulic structures erected on water-saturated grounds is the process of consolidation, manifested under the action of static and seismic loads. A feature of cohesionless soils located in the structure itself or in its base, is their potential ability to liquefaction under seismic impacts. This paper describes the method of calculating the saturated soil’s environments under seismic actions based on the numerical solution of differential equations of the theory of consolidation by finite element method. The results of the static problem solving for the phased construction of the installation are used as the initial conditions. In order to describe the deformability of soil materials mathematical model formed by the theory of plastic flow with hardening is used. The parameters of this model are determined by the results of triaxial testing of soils. As an example, we study the interaction of a sea rockfill dam with a sandy base under seismic impacts, determined by the synthetic accelerograms. The results of calculations of the stress-strain state of the two sections of the dam (shallow and deep) are presented, and assessment is made of the possibility of liquefaction of sandy soil base. It is shown that the pore pressure that occurs in water-saturated cohesionless soil base and the body of the dam under seismic impacts, unloads the soil skeleton, which leads to a decrease in local shear safety factors. And, in the less dense soil base of the shallow section of the dam, the soil skeleton is unloaded to a greater extent, which negatively affects its overall safety factor.

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