scholarly journals Stress-Strain State of Steam Turbine Lock Joint Under Plastic Deformation

2020 ◽  
Vol 23 (4) ◽  
pp. 28-37
Author(s):  
Ihor A. Palkov ◽  
◽  
Mykola H. Shulzhenko ◽  
Keyword(s):  
Plastic Deformation ◽  
Strain State ◽  
Contact Stresses ◽  
Rotor Blades ◽  
Bilinear Approximation ◽  
Stress Strain ◽  
Deformation Curves ◽  
Stress Strain State ◽  
Pressure Cylinder ◽  
Lock Joint

The stress-strain state problem for the lock joint of the rotor blades of the first stage of the medium-pressure cylinder under plastic deformation is solved. When solving the problem, the theory of elastic-plastic deformations is used. The problem is solved using two different approaches to specifying plastic deformation curves. The applicability of using a simpler bilinear approximation instead of the classical multilinear one is estimated. Based on the example of solving this problem, the time required to perform the calculation with the use of the bilinear and multilinear approximations is shown. Comparison of the results obtained in the form of the distribution of plastic deformations, equivalent stresses, and contact stresses over support pads made it possible to assess the difference when the two types of approximation are used. The obtained result error value when using the bilinear approximation made it possible to draw conclusions about the applicability of this approach to the processing of plastic deformation curves for solving problems of this kind. The problem is solved using the finite element method. To objectively assess the effect of plastic deformation on the redistribution of loads in the lock joint, a finite element model is used, obtained when solving the problem of the thermally stressed state of the rotor blade lock joint. The distribution of contact stresses in the lock joint is shown. The results are compared with those obtained earlier when solving the problem of thermoelasticity. Significant differences in the level of contact stresses are noted. Results of the computational assessment of the stress-strain state of the lock joint of the rotor blades of the first stage of the medium-pressure cylinder of a steam turbine are presented, which allow characterizing the degree of relaxation and redistribution of stresses in the structure in comparison with the results obtained earlier when solving the problem of thermoelasticity. Conclusions are made about the economic viability of using the calculation methods presented.

scholarly journals Stress Strain State of Steam Turbine Components under Plastic Deformation

2020 ◽  
pp. 14-17
Author(s):  
I. Palkov ◽  
S. Palkov
Keyword(s):  
Plastic Deformation ◽  
Steam Turbine ◽  
Calculation Method ◽  
Power Plants ◽  
Turbine Unit ◽  
Strain State ◽  
Operational Reliability ◽  
Stress Strain ◽  
Stress Strain State ◽  
Pressure Cylinder

Reliable operation of secondary equipment of PWR nuclear power plants is an integral part of nuclear and radiation safety of the entire NPP unit. The problem of stress strain state of steam turbine structural components under plastic deformation is considered. The theory of elastic-plastic deformations is used to solve the problem along with the finite element method. The paper presents the results of computer assessment of stress strain state of locking joint of working blades of the first stage of a intermediate-pressure cylinder (IPC) and high-pressure cylinder (HPC) body of a steam turbine, which makes it possible to characterize the degree of relaxation and stress redistribution in the structure in comparison with obtained earlier results. It is provided that the use of the presented calculation method in designing new structures of steam turbine components operating in the area of high thermal and power loads, taking into account the contact interaction of components, as well as different mechanical and physical properties of materials, and their changes depending on operating temperature, at this stage of software development allows one to identify problem areas in the design and prevent further breakdowns in the turbine. Based on the comparison of operational data of the developed design solutions and calculation assessment, it is proved that the chosen calculation method can significantly increase the operational reliability not only of the turbine unit but also the nuclear unit as a whole, as well as reduce economic costs caused by turbine unit downtime during maintenance.

scholarly journals Stress strain state of elastic plate with elliptical cut-out

2020 ◽  
pp. 3-8
Author(s):  
E.E. Deryugin ◽  
Keyword(s):  
Plastic Deformation ◽  
Stress Concentration ◽  
Driving Force ◽  
Strain State ◽  
Mechanical State ◽  
Concentration Coefficient ◽  
Stress Strain ◽  
Crack Driving Force ◽  
Stress Strain State ◽  
Stress Concentration Coefficient

The article considers a crack in the form of a narrow cut with a certain cfn at the cut out in an unbounded plate. The characteristics of the mechanical state of this system under uniaxial loading are determined: the stress concentration coefficient, the crack-driving force, and the energy of a solid with a crack. The elastic energy expenditure during crack propagation is determined. The general regularities of the mechanical state of a solid with a crack, not necessary having the form of an ellipse, are revealed. An important parameter of a crack is the curvature at the tip. It is shown that the Griffiths crack does not actually have a singularity at the tip. The stress strain state of the plate with an elliptical crack is identical to the same of the plate with a focus of homogeneous plastic deformation.

Effect of Stress-Strain State during Combined Deformation on Microstructure Evolution of High Carbon Steel Wire

2016 ◽  
Vol 870 ◽  
pp. 460-465 ◽  
Author(s):  
Alexandr Gulin ◽  
Marina Polyakova ◽  
Eduard Golubchik
Keyword(s):  
Plastic Deformation ◽  
Carbon Steel ◽  
Cross Section ◽  
Strain State ◽  
Steel Wire ◽  
High Carbon Steel ◽  
Grain Structure ◽  
Basic Operation ◽  
Stress Strain ◽  
Stress Strain State

It is shown that new methods of severe plastic deformation design require combining different methods of plastic deformation. As for carbon steel wire, using drawing as a basic operation is obvious. The combination of drawing with bending and twisting was estimated by the stress-strain uniformity complex. It allows choosing the deformation processing conditions which ensure the uniform stress-strain state in each point of the carbon steel wire cross section. Based on such combination, a new method for manufacturing of semi-products with ultra fine grain structure by drawing with torsion was developed. The combination of wire drawing in two consecutively arranged dies with simultaneous bending and torsion allows achieving complex stress-strain state of the processed metal and ensure the share stresses. Metallographic investigation shows that such scheme of combined plastic deformation provides the uniformity of metal microstructure in its cross section.

scholarly journals Assessment of stress-strain state in cylindrical parts after transverse running with flat plates

2017 ◽  
Vol 2 (5) ◽  
pp. 38-43 ◽  
Author(s):  
Семен Зайдес ◽  
Semen Zaides ◽  
Дак Фам ◽  
Dac Pham
Keyword(s):  
Plastic Deformation ◽  
Strain State ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Flat Plates ◽  
Stress Strain ◽  
Program Complex ◽  
Vertical Loading ◽  
Stress Strain State ◽  
Cylindrical Parts

For the deformation strengthening of parts like axles, pins, and bushes there is offered a method of surface plastic deformation based on blank rolling with flat plates. The method allows machining parts which do not have center holes. At transverse running a blank bending affected by transverse loading forces is excluded. With the aid of ANSYS program complex there is considered a change of a stress-strain state in cylindrical parts at transverse running. There are defined plastic and elastic cylinder deformations after loading. The distribution of residual stresses along cylinder section in the plane of vertical loading is obtained. The stress state of samples run with flat plates on equivalent stress is assessed. An efficient value of running at transverse running used as a basic parameter of surface plastic deformation is defined.

scholarly journals Investigation of the Tubular and Cylindrical Billets Stamping by Rolling Process with the Use of Computer Simulation

2021 ◽  
Author(s):  
Viktor Matvijchuk ◽  
Andrii Shtuts ◽  
Mykola Kolisnyk ◽  
Ihor Kupchuk ◽  
Iryna Derevenko
Keyword(s):  
Computer Simulation ◽  
Computer Modeling ◽  
Strain State ◽  
Cold Deformation ◽  
Rolling Process ◽  
Stress Strain ◽  
Workpiece Material ◽  
Deformation Curves ◽  
Stress Strain State ◽  
Sound Management

Forming of blanks during stamping by rolling (RS) is possible according to technological schemes of deposition, landing, direct and reverse extrusion, distribution and compression, etc. Controlling the relative position and shape of the deformed tool allows you to control the direction of flow of the workpiece material and the nature of its formation, as well as the stress-strain state of the material. The complexity and versatility of RS processes necessitate computer modeling for sound management of basic technological parameters.Physical experimental as well as computer modeling of the RS process in the DEFORM-3D software package was performed in the work.According to the results of computer simulation, the distribution of deformation components, stresses and temperatures in the deformed workpiece area was obtained, and using the Cockroft-Latham criterion, the destruction of metals during cold deformation was also predicted.Physical modeling of the SR process on lead blanks confirmed the nature of their deformation, obtained by computer simulation. And the analysis of the stress-strain state of the material based on the results of measurements of the deformed grid confirmed the validity of the appointment of boundary conditions in computer simulation.This approach is suitable for modeling by the method of SR of any metal models, for which it is necessary to know their mechanical characteristics, including boundary deformation curves.

scholarly journals Numerical Study of Stress-Strain State of Workpiece in Contact Problem of Surface Mandrel Drilling

2021 ◽  
Vol 20 (3) ◽  
pp. 259-267
Author(s):  
N. S. Sivtsev ◽  
V. V. Tarasov
Keyword(s):  
Plastic Deformation ◽  
Friction Coefficient ◽  
Contact Interaction ◽  
Computational Experiment ◽  
Strain State ◽  
Numerical Study ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Stress Strain ◽  
Stress Strain State

In recent years, the economic factor has played an increasingly important role in the selection of technologies for manufacturing machine parts with specified values of normalized parameters of geometric accuracy and quality of working surfaces. As applied to surface plastic deformation processes, this is noticeably manifested in the search for effective friction control methods in the “tool – workpiece” pair, which ultimately determines the distribution pattern and the magnitude of stresses and strains in the workpiece and the tool. It is not possible to obtain a rigorous analytical solution to the problem of establishing a connection between surface conditions, friction, and the stress-strain state of the contacted bodies. In this regard, the construction of mathematical models comes to the fore, the solution of which is possible by numerical methods. The paper presents the results of a numerical study (computational experiment) of a finite-element model of workpiece deformation under various conditions of contact interaction and friction by one of the methods of surface plastic deformation – surface mandrel drilling. The friction coefficient has been chosen as the criterion for assessing the conditions of contact interaction and friction. It is shown that a change in the friction coefficient in the process of surface mandrel has no noticeable effect on the formation of a stress field in the deformable workpiece both in the axial, and in the radial and circumferential directions. At the same time, with an increase in the value of the friction coefficient in the “tool – workpiece” pair and with the associated increase in the force of mechanical resistance to deformation of the workpiece, their growth is observed. A computational experiment has confirmed the presence of non-contact deformations of the workpiece and tool during surface mandrel drilling, as well as  as a decrease in the value of residual deformations in the workpiece with a decrease in the coefficient of friction. Balance assessment of contact surface displacements in the workpiece (the inner surface of the hole to be machined) and the tool (mandrel) has shown that the deformations of the tool in the elastic region can lead to a significant decrease in the real tightness of surface mandrel drilling.

Dressing of shafts by surface plastic deformation with elastic bending of a billet at machining process

2020 ◽  
pp. 62-66
Author(s):  
G.V. Muratkin ◽  
V.A. Sarafanova
Keyword(s):  
Plastic Deformation ◽  
Strain State ◽  
Residual Deformation ◽  
Surface Plastic Deformation ◽  
Machining Process ◽  
Surface Plastic ◽  
Stress Strain ◽  
Elastic Bending ◽  
Stress Strain State ◽  
Accuracy Stress

A method for dressing of non-rigid parts by surface plastic deformation is proposed, which is based on a change in the stress-strain state of the billet during finishing and hardening processing. Keywords non-rigid shaft, dressing, surface plastic deformation, technological residual deformation, accuracy, stress. [email protected]

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