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Badanie właściwości mechanicznych i mikrostruktury zaczynu cementowego z kulkami szklanymi z wykorzystaniem modelu faza - pole i funkcji ścieżki liniowej do opisu pękania

Han T. S., Chung S. Y., Kim J. S.

Cement Wapno Beton

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2018

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R. 21/83, nr 3

239--250

PL

Zrozumienie właściwości mechanicznych i ich związku z mikrostrukturą zaczynu cementowego jest kluczowe dla oceny jakości istniejących materiałów cementowych i projektowania nowych materiałów cementowych. W pracy tej zastosowano model pola dyfuzyjnego fazy pękania do symulacji propagacji wielu mikrospękań w materiałach cementowych z losowymi sferycznymi pustkami poddanych naprężeniom bezpośrednim. Właściwości mechaniczne oceniane za pomocą tego modelu porównywano z charakterystyką funkcji ścieżki liniowej, jednej z funkcji prawdopodobieństwa małego rzędu. Stwierdzono, że funkcja ścieżki liniowej może być skuteczna do charakteryzowania ciągłości fazy stałej w odniesieniu do właściwości mechanicznych i anizotropii.

EN

Understanding the mechanical properties and their relation to the microstructure of cement paste is crucial for evaluating the performance of existing cementitious materials and for designing new cementitious materials. In this work, a diffusive crack phase field model is applied to multiple-microcrack propagation simulations of cementitious materials with random spherical voids experiencing direct tension. The mechanical properties evaluated using this model are further compared with the characteristics of the lineal-path function, one of the low-order probability functions. Through the analysis, it is found that the lineal-path function can be effective for characterizing the solid phase connectivity in relation to mechanical properties and anisotropy.

2

Numerical Simulation of Solidification Microstructure based on Adaptive Octree Grids

Yin Y., Li Y., Wu K., Zhou J.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 2

33--40

EN

The main work of this paper focuses on the simulation of binary alloy solidification using the phase field model and adaptive octree grids. Ni-Cu binary alloy is used as an example in this paper to do research on the numerical simulation of isothermal solidification of binary alloy. Firstly, the WBM model, numerical issues and adaptive octree grids have been explained. Secondary, the numerical simulation results of three dimensional morphology of the equiaxed grain and concentration variations are given, taking the efficiency advantage of the adaptive octree grids. The microsegregation of binary alloy has been analysed emphatically. Then, numerical simulation results of the influence of thermo-physical parameters on the growth of the equiaxed grain are also given. At last, a simulation experiment of large scale and long-time has been carried out. It is found that increases of initial temperature and initial concentration will make grain grow along certain directions and adaptive octree grids can effectively be used in simulations of microstructure.

3

Simulation of Xe Redistribution in UO2

Trujillo L.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2011

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Vol. 15, No 2

157-190

EN

The transport of fission gases in UO2 based nuclear fuels has a significant effect on the fuel performance. They can induce swelling of the fuel by the nucleation of gas bubbles within the fuel, and increase the mechanical interaction between the UO2 pellet and the cladding; also these bubbles can escape through the grain boundaries and contribute to the gaseous atmosphere in the fuel pin. We propose a model for the redistribution of xenon in the presence of different sinks, including nucleation and growth of gas bubbles. The finite element method has been implemented for the numerical solution of the model.

4

The simulation of dendritic growth in Ni-Cu alloy using the phase field model

Adrian H., Spiradek-Hahn K.

Archives of Materials Science and Engineering

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2009

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Vol. 40, nr 2

89-93

EN

Purpose: The aim of this work was to develop a computer program for simulation of dendritic growth in a selected alloy using the phase field model. This model becomes very popular for modelling a variety of technological processes at the mesoscale level. Design/methodology/approach: In the phase field model a new variable, the phase field variable is introduced, which defines the physical state of the system (liquid or solid) at each point and the governing differential equations system. The main advantage of this method is to avoid interphase tracking in contrast to the conventional method with sharp interface. Findings: In this work an algorithm for calculation of the microstructural evolution formed during dendritic solidification is presented by application of a numerical finite difference method for solving partial differential equations. Research limitations/implications: The presented model for dendritic solidification will be extended for modelling of phase transformations in the solid state during technological processes in metallurgy. The calculation still has to be verified using experimental methods of microstructure analysis. Practical implications: The phase field method becomes very popular for modelling of variety of technological processes at the mesoscale. In the actual work the methodology for simulation of microstructural development during solidification is presented.