Numerical Evaluation Of Effective Thermal Properties For Materials With Variable Porosity

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Abstract

In this paper a computational homogenization technique is applied to thermal analyses in porous materials. A volume fraction of pores on the microstructural level is the key factor that changes the macroscopic thermal properties. Thus, the distribution of thermal fields at the macroscopic level is analysed through the incorporation of the microstructural response on the representative volume element (RVE) assuming a uniform distribution of pores. For the numerical analysis the scaled boundary finite element method (SBFEM) is introduced to compute the thermal response of RVE. The SBFEM combines the main advantages of the finite element method (FEM) and the boundary element method (BEM). In this method, only the boundary is discretized with elements leading to the reduction of spatial dimension by one, similarly as in the BEM. It reduces computational efforts in the mesh generation and CPU time. The proposed method is used to study square RVE with a circular and elliptic pore under the thermal load. Dimensions of the pore are varied to obtain different volume fractions of matrix material. Numerical results for effective thermal conductivities obtained via SBFEM modelling show an excellent agreement with the finite element analysis using commercial software COMSOL Multiphysics.

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