scholarly journals Vibrational Stresses of Damaged Steam Turbine Blades After Renovation Repair

2021 ◽  
Vol 24 (1) ◽  
pp. 42-52
Author(s):  
Mykola H. Shulzhenko ◽  
◽  
Anton S. Olkhovskyi ◽  
Keyword(s):  
Mechanical Properties ◽  
Strain State ◽  
Turbine Blades ◽  
Excitation Frequency ◽  
Physical And Mechanical Properties ◽  
Erosion Damage ◽  
Trailing Edges ◽  
Blade System ◽  
Last Stage ◽  
Maximum Stresses

The last-stage blades of K-1000-60/3000 steam turbines operate in a humid steam environment, which causes erosion damage in the blades and reduction in their residual life. The relevance of this work is related to the need to continue the safe operation of such turbine blades. A number of variants of the finite-element models of individual blades and last-stage blades in the disk-blade systems of the above turbines are considered. Results of the numerical study of the influence of blade part removals in erosion damage zones after renovation repair on the vibration characteristics of individual blades and blades in the disk-blade system are presented. An analysis of the stress-strain state under the conditional load from the steam flow during the forced oscillations of individual blades and blades in the disk-blade system is carried out. The loads are given as evenly distributed and linearly variable on blade surfaces. The dependence of the maximum equivalent vibration stresses on excitation frequency is determined. It is assumed that the physical and mechanical properties of the blade material are preserved (as for the original version) after the renovation repair of blades and processing of their surfaces. There is a significantly greater reduction in the vibration stresses of blades in the disk-blade system than in the stresses of individual blades. Graphs of the dependence of the maximum stresses on excitation frequency both for undamaged individual blades and blades in the disk-blade system after their renovation repair are given. Various variants of blade part removals in areas of blade leading and trailing edges are considered. It is shown that with decreasing chords of blades after renovation repair, frequency regions of increased vibration may appear in lower blade parts. In the lower parts of individual blades and blades in the disk-blade system, the maximum stresses increase in comparison with their values in undamaged blades. With the change in the stress-strain state of rotor blades in comparison with the original version of undamaged blades, the possibility of extending their safe lifetime in case of multi-cycle fatigue is assessed. The safe lifetime of the considered blades with a chord of at least 150 mm after their renovation repair can be extended according to their stresses, if the cyclic symmetry of the disk-blade system is not violated, and the physical and mechanical properties of the material are preserved after the processing of damage removal zones on blade trailing edges.

scholarly journals Specific solution of problem of water filtering in the rocks by the finite element method

2019 ◽  
Vol 109 ◽  
pp. 00093 ◽  
Author(s):  
Olena Slashchova ◽  
Ihor Slashchov ◽  
Iryna Sapunova
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Strain State ◽  
Water Saturation ◽  
Physical And Mechanical Properties ◽  
Critical Parameters ◽  
The Finite Element Method ◽  
Water Saturated ◽  
Element Method

The article is devoted to development of methods for geofiltration calculations with taking into account peculiarities of changes of the rock physical and mechanical properties at water saturation. Methods: mathematical modeling of geomechanical and filtration processes with the help of finite element method and laboratory and underground studies. A mathematical model was formulated for solving a problem of elasticity theory by the finite element method, which took into account peculiarities of water-saturated rocks. Pattern of stress-strain state changing in the fractured water-saturated rocks under the action of critical loads, which occurred around the preparatory roadways during their operation, were established. In order to solve the filtration problems, a bank of collected initial data on physical and mechanical properties of water-saturated rocks was processed with the help of variation coefficients, which were taken into account by the method, which assumed calculation of the model loading with critical parameters.

scholarly journals Compressed Flexible Steel Reinforced Concrete Elements Investigation

2018 ◽  
Vol 7 (3.2) ◽  
pp. 436
Author(s):  
Leonid Storozhenko ◽  
Pavlo Semko ◽  
Olena Yefimenko
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Strain State ◽  
Raw Materials ◽  
Physical And Mechanical Properties ◽  
Experimental Sample ◽  
Sample Design ◽  
Stress Strain ◽  
Steel Reinforced Concrete ◽  
Concrete Elements

Stress-strain state and compressed flexible steel-reinforced concrete elements resistance capacity are investigated in the work. The experiment program is complied and steel reinforced concrete elements calculations methods are analyzed. Experimental sample design drawings are shown. Raw materials physical and mechanical properties are determined. Steel reinforced-concrete elements experimental and research studies have been carried out. Coboundary dependences N-M for steel reinforced concrete elements construction method is proposed. Resistance capacity diagrams for steel reinforced concrete elements are constructed depending on the element height and the applied eccentricity.  

scholarly journals About One of the Approaches for the Research of the Stress-Strain State of a Flange Connection with a Seal Made of an Alloy with Shape Memory

2022 ◽  
Author(s):  
A. Boikov
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Contact Zone ◽  
Axial Compression ◽  
Strain State ◽  
Physical And Mechanical Properties ◽  
Stress Strain ◽  
Flange Connection ◽  
Stress Strain State ◽  
Alternative Approach

Abstract. Design features of a flange connection with a seal made of an alloy with shape memory and the most commonly used methods of researching of the stress-strain state of such connections are estimated. Alternative approach for stress-strain state analysis is proposed, it is based on modeling of the contact zone of the sealing surfaces by means of an equivalent gap between the layers, the value of which changes during axial compression of the multilayer ring and goes into tension. Formulas for determining of contact stresses at the border of layers, which take into consideration the variable physical and mechanical properties of the materials of each layer are presented.

scholarly journals Experimental Investigations of the Stress and Strain State of Continuous Reinforced Concrete Beams Under the Action of Low-Cyclic Repetitive and Alternating Loads

2018 ◽  
Vol 7 (3.2) ◽  
pp. 236
Author(s):  
Grigoriy Masiuk ◽  
Oleksandr Yushchuk ◽  
Andrii Paschenko
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Strain State ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Reinforced Concrete Beams ◽  
Experimental Investigations ◽  
Stress And Strain ◽  
Static Loads

The article is devoted to the experimental studies of the stress and strain state of the two-pass reinforced concrete beams under the influence of low-cyclic repeated and alternating loads. Based on the results of experimental studies, the effect of low-cyclic repeated and alternating loads on the change of the stress and strain state of continuous reinforced concrete beams has been established. In the course of testing the sample, it was found that the stress and strain state of the beams under the action of the above mentioned loads is significantly different from the stress and strain state of the beams under the action of nonalternating static loads, namely, the decrease of the bearing capacity, the increase of the deflections and the width of the cracking. All this is due to the change in the physical and mechanical properties of concrete in response to the above-mentioned loads on experimental.  

Study of Stress-Corrosion Cracks, Physical and Mechanical Properties of Steel After Hydrostatic Re-Testing

1996 ◽  
Author(s):  
S. Karpov ◽  
M. Korolyov ◽  
T. Sergeyeva
Keyword(s):  
Mechanical Properties ◽  
High Risk ◽  
Stress Corrosion ◽  
Strain State ◽  
Harmful Effect ◽  
Physical And Mechanical Properties ◽  
Service Reliability ◽  
Stress Strain ◽  
Corrosion Defects

The hydrostatic re-testing of pipelines is one of the general methods of determination of service reliability of pipes in the zones characterized by high risk of stress corrosion. The detailed complex metal-physics studies of structural and stress-strain state of steel, as well as topography of stress-corrosion cracks, hydrogenation in fragments of pipes damaged at various stages of loading during re-testing were carried out due to the idea of “damage” of steel caused by harmful effect of increased pipes deformation. Templates of pipes having fractures and zones with or without stress-corrosion defects were cut out for studies. It has been shown that no deterioration of mechanical and ductility properties occurs in the parts of pipes without stress-corrosion defects. No considerable changes of character and degree of cracking as well as cracks topography have been detected during various stages of re-testing.

Reinforcement of Structures with Composite Materials

2019 ◽  
Vol 974 ◽  
pp. 535-541
Author(s):  
Galina M. Kravchenko ◽  
Elena V. Trufanova ◽  
Artem S. Osadchiy ◽  
Alina Sazonova
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Composite Materials ◽  
Dynamic Characteristics ◽  
Strain State ◽  
Physical And Mechanical Properties ◽  
The Finite Element Method ◽  
New Materials

The aim of the work is to study the ways to strengthen the elements of the parametric architecture object framework based on the use of the new materials. The problem of strengthening the elements of the building frame is particularly relevant in connection with the development of the parametric architecture. Unlike the traditional methods of regulation and amplification, composite materials allow to change the stress-strain state and improve the dynamic characteristics of the parametric architecture object without increasing its own structures weight. The studies were performed using numerical simulation by the finite element method. Recommendations are given on the use of the physical and mechanical properties of the composite materials when strengthening the building framework.

scholarly journals Microplasma surfacing on turbine blades

2020 ◽  
Vol 329 ◽  
pp. 03059
Author(s):  
Rashit Latypov ◽  
Mikhail Silensky ◽  
Gulnara Latypova
Keyword(s):  
Mechanical Properties ◽  
Turbine Blades ◽  
Base Material ◽  
Physical And Mechanical Properties ◽  
Combustion Products ◽  
Term Strength ◽  
Levels Of Automation ◽  
Plasma Surfacing ◽  
Modern Technologies

In modern technologies for the production of turbine blades, plasma surfacing processes of various levels of automation are increasingly used. Plasma surfacing is applied to the working surfaces of critical parts in order to obtain zones with special physical and mechanical properties or restore the specified geometric dimensions, correct defects in the base material, etc. The design of the turbine blades must meet all the requirements of the product’s service life, including long-term strength and creep, anti-friction characteristics under shock and alternating loads, corrosion resistance in fuel combustion products, etc. Plasma surfacing can help meet these requirements.

Sign in / Sign up

Export Citation Format

Share Document