Wyniki wyszukiwania - BazTech

1

Loading surface in the plastic and creep straining coupled with direct current

Rusinko Andrew, Varga Peter

Journal of Theoretical and Applied Mechanics

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2020

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Vol. 58 nr 1

195--207

EN

The paper is aimed to give a visual representation of the loading surface for different types of irrecoverable deformation in the electrical field. Three situations of deforming coupled with direct current (DC) are discussed: primary creep, secondary creep, and plastic deformation. Understanding the evolution of loading surface under the action of current is considered to be the necessary step pertaining to design forming processes. Therefore, the analysis of the evolution of loading surface in the electrical field and its comparison with the case of ordinary loading is the main subject of this paper.

2

Raman Spectroscopy Studies of Carbon-Based Cathode Materials during Aluminum Electrolysis

Wang Wei, Chen Weijie

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1257--1261

EN

The sodium expansion and creep strain of semi-graphitic cathodes are investigated using a modified Rapoport apparatus. To further understanding of the sodium and bath penetration damage processes, the impact of external stress fluence on the carbon cathode microstructure has been defined with XRD analysis, Raman spectroscopy and scanning electron microscope (SEM). Graphite atoms fracture into smaller fragments that are less directional than the pristine platelets, which allows for a possible filling of the cracks that thus develop by the sodium and bath during aluminum electrolysis. The average microcrystalline size (calculated by Raman spectroscopy) is reduced by the deformation. The decreased intensity and widened 'G' and 'D' peaks in the analysis indicate the poor order of the sheets along the stacking direction while the consistent layered graphite structure is sustained.

3

Analiza pełzania betonu na przykładzie wybranego modelu reologicznego dostępnego w programie SIMULIA Abaqus

Nowak K., Sidorov V.

Przegląd Mechaniczny

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2017

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nr 2

39--44

PL

W artykule przedstawiono wyniki uzyskane z analizy uwzględniającej własności materiału w warunkach pełzania. Rozważania przeprowadzono na przykładzie betonowego elementu ściskanego zaimplementowanego w środowisku programu SIMULIA Abaqus. Symulację komputerową wykonano, wykorzystując wybrany model reologiczny o optymalnie dobranych parametrach. Podstawę porównawczą stanowiły doświadczalne pomiary odkształceń pełzania uzyskane dla elementu betonowego poddanego działaniu stałego naprężenia. Dodatkowo, w pracy przedstawiono zarys badań teoretycznych dotyczących zachowania się wybranego komputerowego modelu reologicznego przy obciążeniu skokowo zmiennym. Porównanie otrzymanych rezultatów pozwoliło na sformułowanie wniosków, które mogą stanowić wskazówki dla projektantów przeprowadzających numeryczne analizy uwzględniające pełzanie betonu w konstrukcjach betonowych i żelbetowych.

EN

The paper presents the results obtained from the analysis which takes in-to account the properties of the material in the creep conditions. The analysis was performed for the concrete sample under compression. The computer simulation of creep in the concrete in program SIMULIA Abaqus was carried out using the selected rheological models with the choice of optimal parameters. The results obtained were compared with experimental measurement of the creep deformation. Conclusions can provide decisions for designers carrying out numerical analysis taking into account creep in concrete structures.

4

New 9-12% chromium steels for advanced power generation: microstructure, properties and application limits.

Ennis P.J., Czyrska-Filemonowicz A.

Inżynieria Materiałowa

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2001

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R. XXII, nr 4

311-318

EN

The thermal efficiency of steam power plant can be significantly increased by raising the temperature and the pressure of the steam entering the turbine. The development of the modified 9% chromium steels P91, P92 and E911 has provided the constructional materials for components capable of operation at temperatures up to and perhaps beyond 600 degrees centigrade. The emphasis in the development has been placed on improving the long-term creep rupture strength; this has been achieved by alloying the basic 9% Cr 1% Mo steel with V, Nb, and N to provide fine, stable precipitates. The strengthening mechanisms are transformation hardening which provides a high initial dislocation density; precipitation hardening by carbides at the martensite lath boundaries which eventually form the sub-grains; fine carbide, nitride and carbonitride precipitates within the sub-grains. Solid solution strengthening has also been enhanced by additions of W. Steam oxidation tests have shown that Cr contents above 11% are neccessary for the formation of protective oxide scales in steam-containing environments at 600-650 degrees centigrade; in air 9% Cr is sufficient. The temperature limits imposed by steam oxidation of the steels depend on the component wall thickness and on the maximum acceptable oxidation rate in terms of spalled oxide and reduction of load-bearing cross-section. The potential for further development of the high Cr martensitic steels towards a steel which combines in a single composition the strength of the 9% Cr steels with the steam oxidation resistance of the 12% Cr steels is discussed.