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Multiobjective optimiaztion of microstructure parameters in a thermoelastic porous material by means of differential evolution and elements of game theory

Długosz Adam, Schlieter Tomasz

Computer Methods in Materials Science

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2022

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Vol. 22, No. 3

117--124

EN

The paper is devoted to the optimization of the microstructure parameters of a porous medium under thermo-mechanical loading. Four different criteria related to the properties of the porous material have been proposed and numerically implemented. To solve a multiobjective problem, a novel method based on the coupling of differential evolution and elements of game theory is used. The proposed algorithm features an appropriate balance between exploration and exploitation of objective space, which is necessary for the successful optimization of these types of tasks with the use of numerical simulations. The model of the thermo-elastic porous material is composed of two-scale direct analysis based on a numerical homogenization. Direct thermoelastic analysis with representative volume element (RVE) and finite element method (FEM) is performed. Numerical example of the optimization illustrating the usefulness of the proposed method is included.

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Evolutionary identification of microstructure parameters in the thermoelastic porous material

Długosz Adam, Schlieter Tomasz

Journal of Theoretical and Applied Mechanics

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2020

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Vol. 58 nr 2

373--384

EN

The work is devoted to the identification of microstructure parameters of a porous body under thermal and mechanical loads. The goal of the identification is to determine the parameters of the microstructure on the basis of measurements of displacements and temperatures at the macro level. A two-scale 3D coupled thermomechanical model of porous aluminum is considered. The representative volume element (RVE) concept modeled with periodical boundary conditions is assumed. Boundary-value problems for RVEs (micro-scale) are solved by means of the finite element method (FEM). An evolutionary algorithm (EA) is used for the identification as the optimization technique.

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The unipore and bidisperse diffusion models for methane in hard coal solid structures related to the conditions in the Upper Silesian Coal Basin

Karbownik Marcin, Krawczyk Jerzy, Schlieter Tomasz

Archives of Mining Sciences

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2020

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Vol. 65, no. 3

591--603

EN

The safety of mining operations in hard coal mines must be constantly developed and improved. There is ongoing multi-directional research focused at best recognition of the phenomenon associated with the properties of the coal-gas system and its connections with mining and geological conditions. This article presents the results of sorption experiments on coals from the Upper Silesian Coal Basin, which are characterized by varying degrees of coalification. One of the parameters that describes the kinetics of methane sorption, determining and providing valuable information about gas hazard and in particular the risk of gas and rock outbursts, is the effective diffusion coefficient De. It is derived from the solution of Fick’s second law using many simplifying assumptions. Among them is the assumption that the carbon matrix consists of only one type of pore-micropores. In fact, there are quite often at least two different mechanisms, which are connected to each other, related to the diffusion of methane from the microporous matrix and flows occurring in voids and macropores. This article presents both the unipore and bidisperse models and a set of comparisons which fit them to experimental curves for selected coals. For some samples the more complex bidisperse model gave much better results than the classic unipore one. The supremacy of the bidisperse model could be associated with the differences in the coal structure related to the coalification degree. Initial results justify further analyses on a wider set of coals using the methodology developed in this paper.