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1
Content available Approach to Impact Assessment of the Rated Power Uprate of NPP Unit on the Service Life of the Turbine Critical Elements
Chernousenko Olga, Nikulenkova Tetyana, Peshko Vitaliy, Nikulenkov Anatolii
Rocznik Ochrona Środowiska
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2020
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Tom 22, cz. 1
105--116
EN
Nuclear power plants play an important role in power systems of many countries. Ability to reasonable increase installed capacity of nuclear power units allow to reduce the cost for building of new power plants. When increasing NPP capacity to 104% there is a need to estimate the residual life of plant’s typical elements and continue their operation. The mathematical model of estimation of service life indicators of steam turbine K-1000-60/3000 is developed. The effect of increasing the capacity of a nuclear reactor on the heat transfer coefficients of a steam in the nozzle segments of high-pressure cylinder was established by using CFD modeling. The thermal and stress-strain state of the high-pressure rotor for the most typical operating modes are calculated. Using the correlation dependences of low-cycle fatigue, the rate of accumulation of cyclic damage of the base metal is established. The resistance of the metal to the exhaustion of long-term strength is also determined. On the example of the high pressure rotor of the 3rd power unit of Rivne NPP the service life indicators are calculated. The validity of increasing the installed capacity of the power unit was also confirmed.
2
Content available remote Research on the durability of adhesive composites
Rośkowicz M., Smal T.
Engineering Transactions
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2013
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Vol. 61, iss. 1
47--64
EN
The paper presents research on the durability of adhesive composites, which may be used for the repair of technical objects. Durability of adhesive composites is understood in this paper as a material ability to transfer long lasting loads. Since that kind of information is not provided by manufacturers, the long-term strength and fatigue-life of selected adhesive composites are determined; especially with regard to their use in expedient (temporary) repairs of weapon systems. The results obtained show that safe values of the maximum long-term and fatigue loads of the adhesive composites investigated should be a half of the short-term strength obtained in a static tests.
3
Content available remote Linear and Non-linear Creep models for a multi-layered concrete composite
Balevicius R., Marciukaitis G.
Archives of Civil and Mechanical Engineering
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2013
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Vol. 13, no. 4
472--490
EN
One- and two-dimensional linear and nonlinear creep models for predicting the time-dependent behavior of a concrete composite under compression are proposed. These models use the analytical and iterative solutions of the Volterra integral equation. The analytical approach is based on the age-adjusted effective modulus method, and the nonlinear technique applies an iterative approach to the system of non-linear equations, implying a generalization of the principle of superposition. Both models are validated in this study. It has been recently found that negative values of the aging coefficient can emerge in early age multi-layered composites when the stress redistribution between the layers is governed by the combination of considerably different creep strains and aging of the layers. In the plane-strain state, the two-dimensional creep analysis of multi-layered composites yields the same vertical stress-time history as that in a one-dimensional case if the Poisson ratios of the layers are equal. This is valid even though the average value of the vertical stress used to calculate the Volterra integral term is dependent on the Poisson ratio of the layers. In particular, the evolution of vertical stress with time is dependent only on the vertical strain and compatibility conditions in a direction parallel to the lamination. A fracture mechanics approach is also introduced to predict the gradual degradation of long-term strength for a multi-layered composite under a sustained compressive load. The results show that the stress redistribution near the crack-tip under the final period of a high level of sustained loading may lead to an additional required compressive stress for complete failure of the composite. Long-term failure primarily begins with the less deformable (stiffer) layers because the more-deformable layers can relieve the initial stresses. Thus, the long-term strength of the composite can exceed its instantaneous strength for early age composites or for composites composed of layers that possess considerably different creep and aging properties.
4
Content available remote Problemy klejenia konstrukcyjnego
Godzimirski J.
Technologia i Automatyzacja Montażu
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2009
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nr 1
25-31
EN
The paper presents the problems of structural gluing using in machine building. The problems are connected with: constructional limitations of adhesive joints, them calculating strength, limited static long-lasting life and limited fatigue life.
5
Content available remote Wytrzymałość statyczna i długotrwała połączeń klejowych blach ocynkowanych
Rudawska A., Łukasz D.
Technologia i Automatyzacja Montażu
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2008
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nr 3
31-34
EN
This paper presents the results of zinc coated sheets bonding joints static and long-lasting strength. Long-lasting strength of bonding joints is a particularly interesting problem because knowledge of long-lasting strength will allow more detailed evaluation of bonding sheets behavior during their maintenance.
6
Content available remote Numerical analysis of long-lasting strength of adhesive bonds.
Godzimirski J., Rośkowicz M.
Advances in Manufacturing Science and Technology
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2004
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Vol. 28, nr 1
67-83
EN
In the paper some results of numerical analysis of durability glue joints under long-lasting loading are presented. In the numerical investigation software environment Nastran for Windows was made use of. In the numerical investigation viscosity-elastic properties were modelled by Burgers' body. The properties of component elements of Burgers' body were determined on the basis of glue creep curves. The coefficients of creep were presented in the table form. Some results of investgations were verified experimentally. It has been found, that the possibility of investigating the strength of long-lasting glue joints exists. It has been proved by experimental and numerical investigation, that the reinforcement of adhesive layer by means of glass fabric has insignificant effect on immediate strength of adhesive bond but simultaneously can essentially increase the long-lasting strength. Numerical analysis should limit time-consuming experimental investigations.
PL
W pracy przedstawiono wybrane wyniki analizy numerycznej trwałości spoin klejowych obciążonych długotrwale. W analizie stosowano środowisko programu Nastran for Windows. Lepkosprężyste właściwości spoiny klejowej modelowano ciałem Burgersa. Właściwości elementów składowych ciała Burgersa wyznaczono na podstawie krzywych pełzania kleju. Współczynniki pełzania kleju przedstawiono w postaci tabelarycznej. Niektóre rezultaty badań zweryfikowano eksperymentalnie. Stwierdzono, że istnieje możliwość analizy wytrzymałości długotrwałej połączeń klejowych metodami numerycznymi. Analiza numeryczna i badania ekperymentalne potwierdziły, że wzmocnienie spoiny klejowej warstwą tkaniny szklanej nieznacznie wpływa na wytrzymałość na rozciąganie połączenia klejowego, ale może jednocześnie istotnie zwiększyć jego wytrzymałość długotrwałą. Analiza numeryczna znacznie ogranicza czasochłonne badania eksperymentalne.
7
Content available remote Starzenie tworzyw wielkocząsteczkowych : zagadnienia podstawowe
Jachowicz T.
Przetwórstwo Tworzyw
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1998
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nr 4
93-99
PL
Przedstawiono podstawowe informacje dotyczące procesu starzenia tworzyw wielkocząsteczkowych, podano kryteria klasyfikacyjne podziału i odpowiadające im rodzaje starzenia, omówiono kryteria starzenia tworzyw. Scharakteryzowano metodę badawczą wykorzystującą model matematyczny oparty na prawie Arrheniusa pozwalającą na określanie wybranych właściwości mechanicznych tworzyw wielkocząsteczkowych, m. in. wytrzymałości długotrwałej. Przedstawiono podstawowe informacje o metodzie SEAM, umożliwiającej określanie wytrzymałości długoterminowej rur z tworzyw sztucznych do transportu cieczy. Omówiono stosowane w tej metodzie modele regresji liniowej.
EN
General information about polymer ageing process has been showed. Classification's criterion of ageing division has been presented. Kinds of ageing have been showed. Criterion of ageing has been discussed. Method of examination based on Arrhenius law, allowed to determine a selected mechanical properties of polymer has been characterised. Basic information about standard extrapolation method, which is enabled to determine long-term strength of polymer's pipe to liquid transport has been showed. Models of linear regression, used in this methods have been discussed.
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