scholarly journals Determination of Stiffness Characteristics for WWER-1000 Support Components

2019 ◽  
pp. 12-17
Author(s):  
V. Vasylchenko ◽  
А. Koliadiuk ◽  
V. Posokh ◽  
V. Dubkovsky
Keyword(s):  
Strain State ◽  
Torsional Stiffness ◽  
Geometric Features ◽  
Stress Strain ◽  
Support Ring ◽  
Strength Assessment ◽  
Stress Strain State ◽  
Stiffness Characteristics ◽  
Remote Points ◽  
Lifetime Extension

Available approaches to computer justification of safe operation of reactor support components (RSC) are generally presented in the reports justifying RSC lifetime extension at Ukrainian NPPs. The experience of performing such calculations and analyzing the results indicates that there are issues to be improved. Thus, in particular, RSC stress-strain state is not analyzed for all force factors in the available calculations. It is typical for the reports on RSC lifetime extension justification that the strength assessment of the RSC is performed in an axisymmetric formulation (1/30). Meanwhile, a complex asymmetrical load from the main circulation pipelines is not considered, which affects RSC stress-strain state calculations as some stiffness characteristics (horizontal and torsional stiffness) cannot be determined correctly in a 1/30 axisymmetric formulation. The paper proposes a methodology for determining RSC stiffness in a complete formulation (without applying symmetry conditions), taking into account all geometric features and the interaction between individual structures and nodes of RSC. Thus, for each RSC (support ring, thrust ring, separating bellows), based on geometric features and types of connection to other components, stiffness to be determined to calculate the forces is defined (six for support ring and separating bellows and three for thrust ring respectively). Single loads in the form of forces and moments were imposed on the remote points connected to corresponding RSC surfaces to determine stiffness. This load made it possible to obtain the displacements and rotation angles of the corresponding remote points, which were used to calculate the stiffness characteristics. The described approach was first used in the calculations performed within justification of KhNPP Unit 1.

Optimization Problems Arising from the Design of Pipes Made of Composite Materials

2020 ◽  
Vol 992 ◽  
pp. 1024-1029
Author(s):  
T. Bobyleva ◽  
A. Shamaev
Keyword(s):  
Strain State ◽  
Optimization Problems ◽  
Analytical Form ◽  
Radial Symmetry ◽  
Elastic Rod ◽  
Stress Strain ◽  
Stress Strain State ◽  
Fixed Weight ◽  
Applied Forces ◽  
Stiffness Characteristics

The work is devoted to the construction of analytical solutions for the stress-strain state of a cylindrical hollow elastic rod with a layered structure along the radius. Earlier, the problem of finding the stress-strain state of a rod of composite material fixed at one end with the applied forces and moments of forces at the other end was considered. An approximate representation of the solutions was given, which included auxiliary problems on one fragment of the cylinder, consisting of periodically repeating similar fragments. Such auxiliary problems in the general case do not have an analytical solution. In this paper it is shown that in the presence of radial symmetry of the rod section, it is possible to construct a stress-strain state in an analytical form. In addition, tensile and bending stiffness can be presented in an analytical form. The latter circumstance allows us to set a problem of optimizing the stiffness characteristics of a rod with its fixed weight. Optimization is carried out by varying the thickness of the layers of the same materials.

scholarly journals Strength assessment of earth dams

2019 ◽  
Vol 265 ◽  
pp. 04015 ◽  
Author(s):  
Tokhirjon Sultanov ◽  
Bakhtiyor Yuldoshev ◽  
Elyor Toshmatov ◽  
Javlonbek Yarashov ◽  
Rustam Ergashev ◽  
...  
Keyword(s):  
Spatial Model ◽  
Strain State ◽  
Static Load ◽  
Comparative Method ◽  
Calculation Model ◽  
Earth Dams ◽  
Stress Strain ◽  
Strength Assessment ◽  
Stress Strain State ◽  
Assessment Of Stress

A comparative method for estimating the stress-strain state of earth dams under the effect of static load is given in the paper using spatial and plane-strain models. The results of assessment of stress-strain state of several earth dams using these methods are given. Analysis of the results obtained allows us to conclude that a plane calculation model gives results almost identical to the ones obtained with spatial model; in future that can be the basis for developing recommendations on the use of certain calculation models. Some features of stress state in a spatial case are revealed, indicating the occurrence of dangerous areas with the greatest stresses.

MATHEMATICAL MODELING OF THE PROCESS OF POSSIBLE DAMAGE TO NPP PIPELINES DUE TO THEIER LOCAL EROSION AND CORROSION SINKING

2021 ◽  
pp. 18-24
Author(s):  
A. E. Gusarov ◽  
L. V. Sergeeva
Keyword(s):  
Computer Modeling ◽  
Crack Growth ◽  
Nuclear Power ◽  
Power Plants ◽  
Strain State ◽  
Complex Shape ◽  
Operating Conditions ◽  
Stress Strain ◽  
Strength Assessment ◽  
Stress Strain State

The article is devoted to computer modeling of the process of possible damage to the pipelines of nuclear power plants that received local thinning of the walls.The geometric features of pipelines are essential not only for assessing the intensity of erosion and corrosion of a metal, but also for the final strength assessment, in particular, when calculating local thinning of the walls of pipelines. The accuracy of forecasts of the life of pipeline structures directly depends on the ability to evaluate the strength of pipeline elements that have received local thinning, especially if these elements themselves have a complex shape. Such elements include elbows, nozzles, adapters (transitions), shells. All of these elements are thin-walled structures of complex shape. Computer modeling of the process of crack formation and growth requires solving several problems. A review and critical analysis of the available experimental information on the growth rates of cracks in specific structural materials and in the environment that is characteristic of given operating conditions is required. An assessment of the crack growth rate is impossible without determining the stresses and strains in the shell structure of complex spatial geometry. The development of routine criteria for crack growth and their attachment to a stress-strain state calculation program is the next task. To solve these problems, a complex of three-dimensional finite element methodologies and programs based on the theory of thick shells has been created. The article presents some results of calculating the stress-strain state of adapters and the growth of cracks in them.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

Sign in / Sign up

Export Citation Format

Share Document