Stochastic microstructure modeling of hierarchically structured particle systems – A tool for virtual materials testing -
Prof. Volker Schmidt
Institut für Stochastik - Universität Ulm
17:15 - 18:15 Tuesday 16 October 2018 TUG P2 Stochastic modeling of geometrically complex 3D microstructures is a powerful tool for virtual materials testing. By means of stochastic models, one can generate a large variety of virtual, but realistic 3D microstructures in short time. Furthermore, in combination with numerical modeling and simulation of transport in porous media, virtual microstructures can help to analyze the relationship between descriptors of microstructure and macroscopic physical properties of the considered materials. In this way, it is possible to express, e.g., the effective permeability or conductivity by microstructural characteristics of the considered material phase.
As an example, we consider a stochastic microstructure model for hierarchically structured electrodes consisting of nanoporous aggregate particles. The functional properties of such electrodes strongly depend on the spatial arrangement of aggregate particles in the electrode as well as on the 3D morphology of their nanopores. The model is fitted to 3D data obtained by imaging techniques on two different length scales: synchrotron X-ray tomography and FIB-SEM, see Fig. 1. The modeling idea consists of two steps. First, the system of aggregate particles (ignoring the nanopores) is modeled by random spherical harmonic functions. Then, the nanoporous inner structure of aggregate particles is modeled, using excursion sets of random fields. Model validation is performed by comparing structural characteristics on both length scales of simulated and tomographic image data. Moreover, the effective electric conductivity of individual aggregate particles is computed, which can be used for a numerical up-scaling to compute the electric conductivity of the entire electrode.
The image shows a combination of different imaging techniques aiming at studying of battery cathodes. Left: 3D synchrotron dataset of aggregate particle system; Center: Planar section of synchrotron data; Right: 3D FIB-SEM dataset of an individual aggregate particle.
The talk is based on joint work with M. Neumann (Ulm), S. Wetterauer and T. Carraro (Heidelberg), M. Osenberg, A. Hilger and I. Manke (Berlin), A. Wagner, N. Bohn and J. Binder (Karlsruhe)
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