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Institute: search.filters.UBSInstitut.Institut für Mechanik (Bauwesen)Start date: 2010End date: 2013Author: search.filters.author.Markert, Bernd

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    Weak or strong : on coupled problems in continuum mechanics
    (2010) Markert, Bernd; Ehlers, Wolfgang (Prof. Dr.-Ing.)
    The present work aims at giving a concise introduction to the vast field of coupled problems, particularly to those of importance in engineering and physics. Therefore, the common terminology and an appropriate classification of coupled equation systems is presented accompanied by some mathematical and computational issues. Attention is focused on volumetrically coupled multi-field formulations arising from the continuum mechanical treatment of multi-physics problems, but also geometrically coupled problems are addressed. Based on actual problems in the areas of poroelastodynamics, continuum biomechanics, and fluid-saturated porous media in general both the theoretical modeling by means of coupled continuum equations as well as the efficient numerical solution in the context of the finite element method (FEM) are presented and discussed in a problem-oriented fashion.
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    ItemOpen Access
    Porous media viscoelasticity with application to polymeric foams. Second revised edition
    (2010) Markert, Bernd
    The goal of this contribution is to merge the advances in porous media theories and the state of the art in single-phase finite viscoelasticity within a well-founded thermodynamical framework. In particular, a thermodynamically consistent constitutive setting is presented where, based on the internal variable concept, an extended Ogden-type viscoelasticity formulation is embedded into the macroscopic Theory of Porous Media (TPM). By focusing on immiscible binary solid-fluid aggregates, essential nonlinearities of the strongly coupled problem are included in the formulation. Thus, the developed biphasic continuum mechanical model accounts for the relevant physical properties stemming from the porous microstructure, the moving and interacting viscous pore fluid (compressible or incompressible), and the directly coupled intrinsic viscoelasticity of the skeleton material itself. In order to demonstrate its suitability, the presented model is especially adapted to the behavior of open-celled polymer foams, as these materials combine all nonlinearities under absolute finite viscoelastic deformations. Finally, after the numerical treatment of the governing model equations through the mixed finite element method (FEM), large strain 3-d simulations reveal the capabilities of the proposed macroscopic formulation and the efficiency of its numerical implementation.