Impact Estimation of a Transient Temperature Field on the Service Life of the High Pressure Rotor of K-1000-60/3000 Turbine

2021 ◽  
Vol 23 ◽  
pp. 408-419
Author(s):  
Olga Chernousenko ◽  
Tetyana Nikulenkova ◽  
Anatolii Nikulenkov
Keyword(s):  
High Pressure ◽  
Service Life ◽  
Steam Turbine ◽  
Strain State ◽  
Life Assessment ◽  
Single Type ◽  
Stress Strain ◽  
Stress Strain State ◽  
Operation Modes ◽  
Numerical Examination

The one of purposes of this paper is to estimation some impact on the service life of the high-pressure cylinder rotor of a typical high-speed turbine K-1000-60/3000. The residual life assessment of power equipment would require determining viability and damage of its base metal. Typical degradation mechanisms of steam turbine equipment include long-term strength reduction and low cycle fatigue accumulation. Intensity of their impact is determined by a numerical examination of equipment thermal (TS) and stress strain states (SSS) for standard operation modes. To perform a numerical examination of the stress strain state would require solving a thermal conductivity boundary problem in quasi-stationary (for nomal operation modes) and nonstationary models (for transients). It is convenient to solve such problems of mathematical physics through discretization of the calculation object using the finite element method (Chernousenko et al. 2018). The service life of steam turbine is determined as an individual one and is assigned based on the results of individual an inspection of a separate element or the largest group of single-type equipment elements of the considered plant. The fleet service life being reached is followed by diagnostics of specific units of power installations and analysis of their operation, measurement of actual dimensions of components, examination of structure, properties and damage accumulation in the metal, non-destructive testing and estimate of stress strain state and residual service life of the component. The results of performed studies are used to determine an individual service life of each element of energy equipment (Nikulenkov et al. 2018).

Experimental study of the strength and durability of metal-composite high-pressure tanks

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 49-56 ◽  
Author(s):  
A. M. Lepikhin ◽  
V. V. Moskvichev ◽  
A. E. Burov ◽  
E. V. Aniskovich ◽  
A. P. Cherniaev ◽  
...  
Keyword(s):  
High Pressure ◽  
Strain State ◽  
Full Scale ◽  
Fracture Mechanisms ◽  
Metal Composite ◽  
Test Results ◽  
Stress Strain ◽  
Pneumatic Pressure ◽  
Stress Strain State ◽  
Composite Tank

The results of unique experimental studies of the strength and service life of a metal-composite high-pressure tank are presented. The goal of the study is to analyze the fracture mechanisms and evaluate the strength characteristics of the structure. The methodology included tests of full-scale samples of the tank for durability under short-term static, long-term static and cyclic loading with internal pneumatic pressure. Generalized test results and data of visual measurements, instrumental and acoustic-emission control of deformation processes, accumulation of damages and destruction of full-scale tank samples are presented. Analysis of the strength and stiffness of the structure exposed to internal pneumatic pressure is presented. The types of limiting states of the tanks have been established experimentally. Change in the stress-strain state of the tank under cyclic and prolonged static loading is considered. Specific features of the mechanisms of destruction of a metal-composite tank are determined taking into account the role of strain of the metal liner. The calculated and experimental estimates of the energy potential of destruction and the size of the area affected upon destruction of the tank are presented. Analysis of test results showed that the tank has high strength and resource characteristics that meet the requirements of the design documentation. The results of the experiments are in good agreement with the results of numerical calculations and analysis of the stress-strain state and mechanisms of destruction of the metal-composite tank.

scholarly journals Assessment of the mutual influence of deformation-strength characteristics of the fastening system elements

2019 ◽  
Vol 123 ◽  
pp. 01006 ◽  
Author(s):  
Iryna Kovalevska ◽  
Zenon Pilecki ◽  
Oleksandr Husiev ◽  
Vasyl Snihur
Keyword(s):  
Mine Working ◽  
Strain State ◽  
Mutual Influence ◽  
Strength Characteristics ◽  
Stress Strain ◽  
Load Bearing ◽  
Stress Strain State ◽  
Operation Modes ◽  
Mine Workings ◽  
Rigid Element

The degree of influence has been determined of diversified deformation-strength characteristics of load-bearing elements in the fastening system of the preparatory mine workings, while maintaining them in a laminal massif of soft rocks. The analysis has been performed of multivariate computational experiments of the stress-strain state of the load-bearing elements of the fastening system in the preparatory mine workings from the position of the mutual influence of their deformation-strength characteristics and the support loading as a whole. An analysis is represented of the mutual influence of the operation modes of the mine working support elements between themselves and the fastening system as a whole; it has been studied the stress-strain state of the mine working fastening system with a central hydraulic prop stay, as well as a significant increase in reliability of the support performance has been analysed and determined. The tendency has been substantiated of minimizing the load on the mine working fastening system – increasing the coherence of the diversified operation modes of fastening elements by enhancing preferentially the yielding property of the rigid element. The application has been substantiated of the central yielding prop stays of the strengthening support of a frame in case of intensive rock pressure manifestation in the zone of the stope works active influence.

scholarly journals On extending the life of nuclear reactors

2021 ◽  
Vol 2131 (2) ◽  
pp. 022030
Author(s):  
A V Kramskoi ◽  
Y G Lyudmirsky ◽  
M E Zhidkov ◽  
M I Kramskaia
Keyword(s):  
Service Life ◽  
Base Metal ◽  
Strain State ◽  
Mutual Influence ◽  
Nuclear Reactors ◽  
Test Procedure ◽  
Reactor Vessel ◽  
Stress Strain ◽  
Stress Strain State ◽  
Additional Service

Abstract To extend the service life of nuclear reactors, witness samples from the shells of the core of the reactor vessel are placed in their core. According to the requirements in force in the industry, the reference samples are loaded into the reactor plant unloaded up to the design stresses. This can lead to a biased assessment of the possible extension of the reactor’s life. In connection with the above, in order to assess the mutual influence of operating factors and the stress-strain state of the base metal and welded joints on embrittlement, the reference specimens must be loaded with a force that causes the maximum possible stresses in the specimens during the operation of the reactor. On the basis of domestic and international experience, a test procedure, design and loading scheme for compact witness samples are proposed for modeling and assessing the mutual influence of operating factors and stress-strain state on the object under study (VVER power reactor vessel). For VVER RPVs, the duration of the additional service life should be confirmed by the justification that by the end of the additional service life, the fracture toughness values of the base metal and metal of the welded seams located in the irradiation zone will allow without destruction to withstand all operational and emergency loads, as well as loads at hydraulic tests.

Prediction of contact-fatigue damage to rails using computational-experimental methods

2020 ◽  
Vol 86 (4) ◽  
pp. 46-55
Author(s):  
N. A. Makhutov ◽  
V. S. Kossov ◽  
E. S. Oganyan ◽  
G. M. Volokhov ◽  
M. N. Ovechnikov ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Software Package ◽  
Strain State ◽  
Contact Fatigue ◽  
Cumulative Distribution ◽  
Stress Strain ◽  
Stress Strain State ◽  
Contact Fatigue Life ◽  
The Impact

Analysis of the operational data related to rails failure showed that contact-fatigue defects consistently hold a prominent place. The goal of the study is to show the possibilities of using modern numerical methods in calculation assessment of the service life of rails before the onset of contact fatigue crack formation on a running surface depending on the values of axial load. To calculate a stress-strain state in the area of contact interaction between the wheel and rail a detailed finite-element model implemented in the MSC. Marc software package is used. The analysis revealed complex multiaxial and non-proportional nature of the stress-strain state. The Brown – Miller multiaxial fatigue model implemented in the MSC. Fatigue software package was taken to determine accumulation of the contact fatigue damages on a rail running surface. The model is based on the assumption that maximum fatigue damages in the metal occur in the area with the maximum shear stress. The impact of normal stresses in this area is also taken into account. The results of a comparative computational analysis of the rail life time confirm that the service life decreases with increasing axial loads, all other conditions being the same. With a share of 20% of freight trains with axle loads of 25 tonf in a daily pattern one should expect a decrease in the contact fatigue life of rails by 3 – 4 %. It is possible to improve the method for prediction of the contact fatigue life of rails in terms of experimental definition of the fatigue and strength characteristics of the rail steel depending on the degree of hardening of the running surface, their probabilistic properties and the use of a cumulative distribution of vertical forces taking into account the structure of the freight traffic passing through the section.

Critical Zone Approach for Structural Integrity of Power Engineering Components

2015 ◽  
Vol 750 ◽  
pp. 89-95
Author(s):  
V.N. Shlyannikov
Keyword(s):  
Steam Turbine ◽  
Strain State ◽  
Turbine Disk ◽  
Loading Conditions ◽  
Loading History ◽  
Test Cycle ◽  
Stress Strain ◽  
Stress Strain State ◽  
Turbine Disks ◽  
Critical Zones

This study is concerned with assessing the integrity of cracked steam turbine rotors components which operate under cyclic loading conditions. Damage accumulation and growth have occurred on the inner surface of slot fillet of key and in a disk and blade rivet attachment. Full-size stress-strain state analysis of turbine disk was performed for different stage of lifetime under considering loading conditions. As a result accumulated damage in critical zones of turbine disks depending on time of loading is defined. The tensile tests were performed for determination the main mechanical properties of disk’s material after loading history. The smooth and notched specimens were cut out from critical zones of turbine disk with given operating time. The low-cycle fatigue tests were performed with the harmonic test-cycle. Additional tests were performed on special designed program test-cycle, which equivalent to start-stop cycle of turbine disk. An engineering approach to the prediction of residual lifetime of turbine disks which is sensitive to the loading history at maintenance is proposed. Approximate estimations of carrying capacity are presented for the different stress-strain state of steam turbine disks at the operation.

scholarly journals IMPACT ASSESSMENT OF MODERNIZATION OF STEAM TURBINE END SEALS ON THE RESIDUAL RESOURCE

2020 ◽  
pp. 56-62
Author(s):  
O.Yu. Chernousenko ◽  
V.A. Peshko ◽  
D.V. Ryndiuk
Keyword(s):  
High Pressure ◽  
Strain State ◽  
Thermal State ◽  
Honeycomb Structure ◽  
Temperature Fields ◽  
Steam Turbines ◽  
Stress Strain ◽  
Direct Flow ◽  
Main Metal ◽  
Stress Strain State

Modernization of sealing units with a change of design is carried out in order to improve the technical and economic parameters of steam turbines. It is known from experience of operation of the turbine equipment that, ring cracks in rotors arise in sealing areas. This is due to both seals design features and the accumulation of thermocyclic fatigue. The research is devoted to the study of resource parameters of the high-pressure rotor of the T-250/300-240 turbine equipped with seals of labyrinth, honeycomb and direct-flow type. Numerical experiments were performed on the basis of three-dimensional geometric models of interflow end seals of the high pressure rotor. The finite element method is used to discretize the computational area. The thermal state of the turbine is calculated for the starting mode from the cold state of the metal by solving the boundary value problem of thermal conductivity in a non-stationary setting. The calculation of the stress-strain state of the turbine takes into account the obtained data on temperature stresses and forces from the non-uniformity of temperature fields, as well as centrifugal forces and steam pressure. Differences in the stress-strain state of the rotor for different seal designs are established. It is indicated that after grooving of labyrinth interflow seals to the honeycomb structure, the stress level in the rotor decreased by 8 %, and when grooving to the direct-flow structure — by 21 %. The accumulated damage in the main metal of the turbine was determined using experimental curves of long-term strength of steel 25Cr1Mo1V. The calculation of resource indicators showed that in the transition from the labyrinth to the honeycomb design of the seals, the individual resource of the high-pressure rotor increases by 6.1 %, and in the transition to direct-flow — by 14.4 %. Ref. 10, Fig. 5, Tab. 1.

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