Session Details
MS13-1: Multiscale Methods for Complex Materials (Ganzes Minisymposium anzeigen)
Wednesday, 11. October 2017; 10:30 - 12:30 Uhr in Raum 7.31
Sitzungsleitung: Stefan Löhnert
10:30
Mesoscale influence on the macroscopic material behavior of concrete
Volker Hirthammer (Federal Institute for Materials Research and Testing), Jörg F. Unger (Federal Institute for Materials Research and Testing), Josko Ozbolt (University of Stuttgart)
Kurzfassung:
The heterogeneous mesostructure of concreted causes local stress concentrations. Stress dependent phenomena like damage and creep as well as their interactions are effected by those stress concentrations. Therefore a material model's macroscopic behavior will differ whether the mesoscale structure is considered or not. The differences between the mesoscale approach and an homogeneous approach will be presented. The results are discussed with focus on the true materials behavior.
Mesoscale influence on the macroscopic material behavior of concrete
Volker Hirthammer (Federal Institute for Materials Research and Testing), Jörg F. Unger (Federal Institute for Materials Research and Testing), Josko Ozbolt (University of Stuttgart)
Kurzfassung:
The heterogeneous mesostructure of concreted causes local stress concentrations. Stress dependent phenomena like damage and creep as well as their interactions are effected by those stress concentrations. Therefore a material model's macroscopic behavior will differ whether the mesoscale structure is considered or not. The differences between the mesoscale approach and an homogeneous approach will be presented. The results are discussed with focus on the true materials behavior.
10:50
Obtaining macroscopic properties from a mesoscale thermomechanical model of concrete
Christoph Pohl (Federal Institute for Materials Research and Testing), Jörg F. Unger (Federal Institute for Materials Research and Testing)
Kurzfassung:
A coupled thermomechanical mesoscale model for concrete under heating is presented. When considering the heterogeneous structure under coupled loads, complex macroscopic material properties can be modelled using simple constitutive relations. For instance, damage evolution is directly driven by the incompatibility of thermal strains between matrix and aggregates. Without prescribing $f_c=f(T)$, a decline in compressive strength with rising temperatures will be shown.
Obtaining macroscopic properties from a mesoscale thermomechanical model of concrete
Christoph Pohl (Federal Institute for Materials Research and Testing), Jörg F. Unger (Federal Institute for Materials Research and Testing)
Kurzfassung:
A coupled thermomechanical mesoscale model for concrete under heating is presented. When considering the heterogeneous structure under coupled loads, complex macroscopic material properties can be modelled using simple constitutive relations. For instance, damage evolution is directly driven by the incompatibility of thermal strains between matrix and aggregates. Without prescribing $f_c=f(T)$, a decline in compressive strength with rising temperatures will be shown.
11:10
Validation of a synthetic model of hot mix asphalt
Johannes Neumann (RWTH Aachen University), Jaan-Willem Simon (RWTH Aachen University), Stefanie Reese (RWTH Aachen University)
Kurzfassung:
We have recently extended a method to obtain 3D synthetic models of hot mix asphalt by capturing the particle size distribution. The model is applied in the context of first-order strain driven homogenisation. The morphological accuracy of the model is compared to XRCT data by means of several common shape measures. Furthermore, the usefulness of the homogenised mechanical properties is assessed by comparing to master-curve data of the mixture scale.
Validation of a synthetic model of hot mix asphalt
Johannes Neumann (RWTH Aachen University), Jaan-Willem Simon (RWTH Aachen University), Stefanie Reese (RWTH Aachen University)
Kurzfassung:
We have recently extended a method to obtain 3D synthetic models of hot mix asphalt by capturing the particle size distribution. The model is applied in the context of first-order strain driven homogenisation. The morphological accuracy of the model is compared to XRCT data by means of several common shape measures. Furthermore, the usefulness of the homogenised mechanical properties is assessed by comparing to master-curve data of the mixture scale.
11:30
The Heterogeneous Multiscale Finite Element Method (FE-HMM) for nonlinear problems in solid mechanics
Andreas Fischer (University of Siegen), Ajinkya Gote (University of Siegen), Bernhard Eidel (University of Siegen)
Kurzfassung:
The present work proposes a nonlinear extension of the FE-HMM for the homogenization of microheterogeneous solids. The advantage of FE-HMM compared with FE$^2$ is the existence of a priori convergence estimates, which allow for optimal strategies in mesh refinements. While these estimates were proved for linear problems so far, we assess their validity for geometrical nonlinearity and hyperelastic constitutive laws. Applications to complex microstructures showcase the performance of the method.
The Heterogeneous Multiscale Finite Element Method (FE-HMM) for nonlinear problems in solid mechanics
Andreas Fischer (University of Siegen), Ajinkya Gote (University of Siegen), Bernhard Eidel (University of Siegen)
Kurzfassung:
The present work proposes a nonlinear extension of the FE-HMM for the homogenization of microheterogeneous solids. The advantage of FE-HMM compared with FE$^2$ is the existence of a priori convergence estimates, which allow for optimal strategies in mesh refinements. While these estimates were proved for linear problems so far, we assess their validity for geometrical nonlinearity and hyperelastic constitutive laws. Applications to complex microstructures showcase the performance of the method.
11:50
A two-scale homogenization scheme for the simulation of micro-heterogeneous magneto-electric composites
Matthias Labusch (University of Duisburg-Essen), Jörg Schröder (University of Duisburg-Essen)
Kurzfassung:
We present the simulation of two-phase composites, consisting of a ferroelectric and a magnetostrictive phase, which generate a magneto-electric coupling. A two-scale finite element homogenization approach is performed. The typical hysteresis loops of the phases are approximated by considering the switching behavior of the spontaneous polarizations and the implementation of a Preisach operator.
A two-scale homogenization scheme for the simulation of micro-heterogeneous magneto-electric composites
Matthias Labusch (University of Duisburg-Essen), Jörg Schröder (University of Duisburg-Essen)
Kurzfassung:
We present the simulation of two-phase composites, consisting of a ferroelectric and a magnetostrictive phase, which generate a magneto-electric coupling. A two-scale finite element homogenization approach is performed. The typical hysteresis loops of the phases are approximated by considering the switching behavior of the spontaneous polarizations and the implementation of a Preisach operator.