Partner: T. Wejrzanowski


Recent publications
1.Wejrzanowski T., Grybczuk M., Chmielewski M., Pietrzak K., Kurzydłowski K.J., Strojny-Nędza A., Thermal conductivity of metal-graphene composites, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2016.03.069, Vol.99, pp.163-173, 2016
Abstract:

In this paper the results of numerical simulations and experimental studies are presented which describe potential and limitation of applications of single-layer (SLG) and multi-layer (MLG) graphene for thermal conductivity enhancement (TCE) of copper. A series of composite structures were studied which are representative of most widely used systems. The influence of structural parameters on the macroscopic thermal conductivity was analyzed, both experimentally and by numerical simulations. Analytical and Finite Element Method modeling were carried out to investigate a wide range of phenomena, including the effect of copper-MLG interface, copper grain size, volume fraction, thickness and orientation of MLG platelets as well as spatial distribution of MLG defined by percolation factor. Both modeling and the experimental results show that the volume fraction of MLG regions, their size, orientation and spatial distribution may significantly affect the thermal conductivity of metal matrix composites. TCE can be obtained for the laminate-like structure or particulate composites with highly aligned MLG regions. The thermal conductivity of such composites is strongly anisotropic and enhanced in the direction perpendicular to the layers. The results obtained in this study predict that SLG will have a negative effect on the thermal conductivity of copper matrix composites.

Keywords:

Thermal conductivity, Composites, Graphene, Finite element method

Affiliations:
Wejrzanowski T.-other affiliation
Grybczuk M.-other affiliation
Chmielewski M.-Institute of Electronic Materials Technology (PL)
Pietrzak K.-other affiliation
Kurzydłowski K.J.-Warsaw University of Technology (PL)
Strojny-Nędza A.-Institute of Electronic Materials Technology (PL)
2.Regulski W., Szumbarski J., Łaniewski-Wołłk Ł., Gumowski K., Skibiński J., Wichrowski M., Wejrzanowski T., Pressure drop in flow across ceramic foams—A numerical and experimental study, CHEMICAL ENGINEERING SCIENCE, ISSN: 0009-2509, DOI: 10.1016/j.ces.2015.06.043, Vol.137, pp.320-337, 2015
Abstract:

The unique properties of ceramic foams make them well suited to a range of applications in science and engineering such as heat transfer, reaction catalysis, flow stabilization, and filtration. Consequently, a detailed understanding of the transport properties (i.e. permeability, pressure drop) of these foams is essential. This paper presents the results of both numerical and experimental investigations of the morphology and pressure drop in 10 ppi (pores per inch), 20 ppi and 30 ppi ceramic foam specimens with porosity in the range of 75–79%. The numerical simulations were carried out using a GPU implementation of the three-dimensional, multiple-relaxation-time lattice Boltzmann method (MRT-LBM) on geometries of up to 360 million nodes in size. The experiments were undertaken using a water channel. Foam morphology (porosity and specific surface area) was studied on post-processed, computed tomography (CT) images, and the sensitivity of these results to CT image thresholding was also investigated. Comparison of the numerical and experimental data for pressure drop exhibited very good agreement. Additionally, the results of this study were verified against other researchers׳ data and correlations, with varying outcomes.

Keywords:

Ceramic foam, Pressure drop, Lattice Boltzmann method, Darcy–Forchheimer equation, Specific surface area, Pore-scale simulation

Affiliations:
Regulski W.-other affiliation
Szumbarski J.-other affiliation
Łaniewski-Wołłk Ł.-other affiliation
Gumowski K.-other affiliation
Skibiński J.-other affiliation
Wichrowski M.-IPPT PAN
Wejrzanowski T.-other affiliation
3.Maździarz M., Young T.D., Dłużewski P., Wejrzanowski T., Kurzydłowski K.J., Computer modelling of nanoindentation in the limits of a coupled molecular-statics and elastic scheme, JOURNAL OF COMPUTATIONAL AND THEORETICAL NANOSCIENCE, ISSN: 1546-1955, DOI: 10.1166/jctn.2010.1469, Vol.7, pp.1-10, 2010
Abstract:

Our numerical approach to modeling elastic-plastic deformation comes back to the idea of the time-independent plasticity developed here at the molecular-statics level. We use a constitutive atomic model based on the second-moment approximation of the tight-binding potential coupled to a linear theory of elasticity solved simultaneously within the finite element method. Our model is applied to the nanoindentation problem for copper in which the indenter is represented by the equations of a sphere. For convenience the time-dependency of the nanoindentation problem is reduced to a quasi-static adiabatic scheme. A recurring theme in this paper is to determine the response of the proposed model for two differing systems: mono and polycrystalline copper. This paper discusses the force-depth response in terms of atomic bond-lengths, elastic-plastic deformations, and the instantaneous stiffness of the material. We report on an increased instantaneous stiffness of polycrystalline copper compared to that of its monocrystalline counterpart. From both a distinct and a comparative analysis of both systems, based on the relaxed positions of the atoms in the structure during the simulation, we deduce that plastic deformations at grain-boundaries are responsible for this change in the overall instantaneous stiffness of the material.

Keywords:

linear elasticity, material science, molecular statics, nanoindentation, quasicontinuum methods

Affiliations:
Maździarz M.-IPPT PAN
Young T.D.-IPPT PAN
Dłużewski P.-IPPT PAN
Wejrzanowski T.-other affiliation
Kurzydłowski K.J.-Warsaw University of Technology (PL)