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 Stress-strain state of a three-layer cylindrical shell under internal axisymmetric pulse load

2020 ◽  
pp. 145-151
Author(s):  
Viktor Gaidaichuk ◽  
Kostiantyn Kotenko
Keyword(s):  
Finite Element ◽  
Cylindrical Shell ◽  
Strain State ◽  
Layer Structure ◽  
Three Dimensional ◽  
Pulse Load ◽  
Geometrical Parameters ◽  
Time Interval ◽  
Stress Strain ◽  
Stress Strain State

The problem of dynamic deformation of a three-layer cylindrical shell under non-stationary loads in the case of rigid clamping of the shell ends is considered. The article presents the results of assessing the stress-strain state of a three-layer cylindrical shell, taking into account its structural feature, the ratio of the sheathing thickness and the physical and mechanical characteristics of a one-piece polymer filler. Calculations were performed by software complex Nastran. The values of displacements and stresses were calculated by the algorithm of direct transient dynamic process. The step duration of the time interval was 0.0000025 s, and the total number of steps was 200. The choice of the type of three-dimensional finite element was due to obtaining more detailed and accurate calculation results. The finite element model included 19000 three-dimensional finite elements and numbered 20800 nodes. The influence of geometrical parameters of shell layers with different physical and mechanical properties of one-piece filler on the stress-strain state under axisymmetric internal impulse load is investigated. Numerical results on the dynamics of the three-layer structure, obtained by the finite element method, allow to characterize the stress-strain state of the three-layer elastic structure of the cylindrical type at any time in the studied time interval. Optimization of the shell design is recommended. Changing the ratio of the thickness of the internal and external shells of the shell significantly affects the stress-strain state of the shell and its performance. Increasing the thickness of the internal layer of the shell significantly contributes to the increase of the latter. Comparison of the given results with materials of other similar researches and positions, testify to objectivity of the made approach.

Research the process of cold punching of hex nut blanks of increased height

2019 ◽  
Vol 75 (8) ◽  
pp. 979-984
Author(s):  
I. G. Shubin ◽  
A. A. Kurkin ◽  
A. R. Bazykov ◽  
F. A. Stolyarov
Keyword(s):  
Strain State ◽  
Metal Flow ◽  
Geometrical Parameters ◽  
Stress Strain ◽  
Industrial Testing ◽  
Stress Strain State ◽  
Metal Deformation ◽  
3D Software ◽  
Through Hole ◽  
Power Costs

The high nuts withstand increased load for expansion, facilitating its even distribution along the bolt length. The process of increased height nut blanks plastic deformation characterized by uneven metal flow and changing of stressed state by the blank section. In the process of closed-die stamping of such nuts a risk of their geometry distortion arises. Results of study of the process of production a hex nut of increased height presented. The object of the research was to study the process of the metal deformation when broach a hole for thread in a hexagonal nut blank of increased height. To simulate the stress-strain state, the QForm-3D software package was chosen, which made it possible to predict with sufficient accuracy the metal flow in the blank, calculate the deformation forces and determine the stresses that occur in the tool. The models of the blank and the tool were created in the Compass 3D program without internal and external defects. When performing the work, the parameters of the stress-strain state of a hexagonal nut blank of increased height were calculated. The simulation results showed the need to change the geometry of the end part of the punch to a conical one with an angle of 150 degrees and a reduction in the size of the baffle height from 10.4 mm to 5.4 mm. The adopted changes allowed to reduce the energy and power costs of forming a through hole for the threads. Industrial testing confirmed the correctness of the calculations. Nuts with edges perpendicular to its base and the required geometrical parameters were obtained.

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.

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 Influence of the choice of the base model on the stress-strain state of the vertical load-bearing elements of a monolithic-frame house

2020 ◽  
pp. 45-54
Author(s):  
Viktor Nosenko ◽  
Ostap Kashoida
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Strain State ◽  
Mutual Influence ◽  
Vertical Load ◽  
Soil Environment ◽  
Stress Strain ◽  
Single Node ◽  
Load Bearing ◽  
Stress Strain State

Comparison of the stress-strain state of vertical elements of the frame of a monolithic house (basement, first and fourth floors), depending on the method of modeling the soil environment and piles, is carried out. The use of pile foundations is due to the fact that they provide the transfer of loads to deeper soil layers and, as a rule, a greater bearing capacity compared to shallow foundations. In the design of foundations, engineers face the question of how to model the soil environment and piles? This paper presents the influence of the decision taken (the selected soil model and the method of modeling piles) on the stress-strain state of the vertical load-bearing elements of the house frame. Comparison of the stress-strain state of vertical elements of the frame (basement, first and fourth floors), which were obtained using the following models of the system «base - pile foundation - overhead supporting structures»: 1) the piles are modeled by single-node finite elements, have only vertical stiffness according to the results of testing the piles for vertical static pressing loads, the mutual influence of piles and soil characteristics are not taken into account (FE-56 hereinafter, this is the number of the finite element in the library of elements of the PС «Lira -SAPR») 2) the piles are modeled by single-node finite elements, are located with a given step along the length of the pile and have rigidity in different directions and approximately take into account the surrounding soil around the pile and under its tip (FE-57); 3) the soil environment is modeled by volumetric elastic finite elements; piles - rod finite elements. It is shown that the choice of the foundation model carries stress-strain state not only for the foundation structures, but also for the vertical bearing elements of the house. When using various options for modeling the base: using a single-node finite element that simulates a smoke like elastic ligature (FE-56), using a chain of single-node skinned elements (FE-57), or a volumetric soil massif, it is possible to obtain quantitative differences in stresses from 2 to 20%, and a qualitative change, which is observed in a change in the sign of bending moments.  

scholarly journals STUDY OF STRESS-STRAIN STATE OF MATHEMATICAL MODEL OF JAWS USING THE FINITE-ELEMENTS METHOD

2019 ◽  
Vol 19 (1-2) ◽  
pp. 131-139
Author(s):  
D. A Trunin ◽  
A. V Revyakin ◽  
M. A Postnikov ◽  
I. N Kolganov ◽  
I. A Zakharova ◽  
...  
Keyword(s):  
Finite Elements ◽  
Strain State ◽  
Soft Tissues ◽  
Finite Elements Method ◽  
Stress Strain ◽  
Jaw Bones ◽  
Stress Strain State ◽  
Lower Jaw ◽  
Characteristic Features ◽  
Bone Structures

This work is devoted to the study of the stress-strain state (SSS) model by using the finite-elements method (FEM) of jaw-bones (the system of lower jaw (LJ) - upper jaw (UJ)) and is the next step in understanding the mechanism of mastication as one of the main functions of the maxillofacial system (MFS). At the same time, reliable information about SSS of the LJ and UJ bones with account of the peculiarities of their anatomical and topographical structure will, firstly, reveal the main regularities of the jaw bone deformations. It will make possible to choose prosthetic appliances that will provide the minimum level of intensity of atrophic processes in supporting tissues and the most favorable biomechanical interaction of bone structures, soft tissues and elements of the prosthetic appliance. The results of mathematical calculations allowed to identify the characteristic features of the deformation and interaction of the LJ and UJ bones, which will ensure a scientifically based choice of those prosthetic appliances contributing to the most prolonged and normal functioning of the maxillofacial system in general.

scholarly journals Study of the stress-strain state of ribbed cylindrical shells by the finite elements method

1985 ◽  
Vol 17 (8) ◽  
pp. 1166-1169
Author(s):  
P. Z. Menabdishvili ◽  
M. Ya. Kodner ◽  
V. B. Babaev
Keyword(s):  
Finite Elements ◽  
Strain State ◽  
Cylindrical Shells ◽  
Finite Elements Method ◽  
Stress Strain ◽  
Stress Strain State ◽  
Ribbed Cylindrical Shells
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