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Logo: Institute of Continuum Mechanics/Leibniz Universität Hannover
Logo Leibniz Universität Hannover
Logo: Institute of Continuum Mechanics/Leibniz Universität Hannover
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Multiscalemodelling/ Multiphysics

Micro-Mechanically Based Modeling of Degradation of Composite Materials with Random Microstructure

Bild zum Projekt Micro-Mechanically Based Modeling of Degradation of Composite Materials with Random Microstructure

Supervisor:

Prof. P. Wriggers

Researcher:

Dipl.-Ing. V. Krupennikova

Funded by:

DFG (Graduiertenkolleg 1627)

Brief description:

Materials undergo degradation in different situations that are characterized by the environmental conditions. Here a thermo-chemo-mechanical investigation using knowledge of the microstructure will be performed. However usually the microstructures have a random distribution of the phases. For such microstructures a continuum damage mechanics framework has to be developed at micro-level that depends on thermal but also chemical reactions. The associated coupled problem includes partial differential equations of different type and thus robust numerical schemes have to be designed for the solution of the problem. Validation at micro level will be needed to calibrate the continuum modeling. This will be achieved in collaboration with the Institute for Material Science.

 

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Entropic approach to modeling Mullins effect in non-crystallizing filled elastomers

Bild zum Projekt Entropic approach to modeling Mullins effect in non-crystallizing filled elastomers

Supervisor:

P. Wriggers, J. J. Rimoli

Researcher:

A. B. Harish, A. B. Shah

Brief description:

The work was done in collaboration with Mrs. Aarohi B. Shah and Dr. Julian J Rimoli of School of Aerospace Engineering, Georgia Tech, USA. In this work, we investigate non-crystallizing nanoparticle-reinforced polymers. The effects of the interface rubber between elastomeric matrix and filler particles and its alteration are investigated as a primary cause of Mullins and Payne effect.

 

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Towards multiscale modeling of Abrasive wear

Bild zum Projekt Towards multiscale modeling of Abrasive wear

Supervisor:

P. Wriggers

Researcher:

A. B. Harish

Brief description:

The work is motivated towards understanding wear as a multiscale-multiphysics approach. A 3D framework is developed to simulate cracks propagation in a microstructure due to contact loading to eventually predict wear trends in filled elastomeric compounds.

 

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Multi-Fluid Simulations for High Density Ratios

Bild zum Projekt Multi-Fluid Simulations for High Density Ratios

Supervisor:

P. Wriggers, B. Avci

Researcher:

J.-P. Fürstenau

Brief description:

Although the contact between fluids or gases of different densities is a common event in nature, like the interaction of water and air, the simulation of multiple fluids often comes along with numerous problems. With the Lagrangian description of continuous fluids in terms of the Smoothed Particle Hydrodynamics (SPH) method multi-fluid interactions within the particle scale can simulated. Nevertheless with the standard SPH algorithms multi-fluid problems can not be solved because of the density jumps at the interfaces. Within the project the state of the art of current multi-fluid approaches are compared and evaluated to develop appropriate methods for the simulation of multi-fluid systems with high density ratios.

 

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Homogenization procedures for coupled thermo-chemo-mechanical problems

Bild zum Projekt Homogenization procedures for coupled thermo-chemo-mechanical problems

Supervisor:

P. Wriggers, E. Baranger

Researcher:

Jin Man Mok

Brief description:

In order to understand processes of continuum damage mechanics it is necessary to investigate thermo-chemo-mechanical coupled processes at micro scale. However for engineering purposes it is still necessary to be able to model these processes at macro scale, especially when large structures have to be designed. Thus a homogenization procedure or a FE^2 framework is necessary to transform the relation, describing the coupled thermo-chemo-mechanical response at micro scale to the macro scale. The related equations and procedures have to be developed and implemented in a finite element software system.

 

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Direct Numerical Simulation of Multiphase Flows

Bild zum Projekt Direct Numerical Simulation of Multiphase Flows

Supervisor:

P. Wriggers

Researcher:

B. Avci

Brief description:

Multiphase flows consisting of a continuous fluid phase and a dispersed phase of macroscopic particles are present in many engineering applications. In general, a main task in the study of the particle-laden fluid flow of an application is to make predictions about the system's nature for various boundary conditions, since, depending on the volume fraction and mass concentration of the dispersed phase a fluid-particle system shows quite different flow properties. Unfortunately, often it is impossible to investigate such a system experimentally in detail or even at all. An option to capture and to predict its properties is performing a direct numerical simulation of the particulate fluid. For this purpose, an efficient approach is developed in this project by coupling the discrete element method and finite element method.

 

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Multiscale Method for Hydro-Chemo-Thermo-Mechanics Coupling due to Alkali Silica Reaction in Concrete

Bild zum Projekt Multiscale Method for Hydro-Chemo-Thermo-Mechanics Coupling due to Alkali Silica Reaction in Concrete

Supervisor:

P. Wriggers

Researcher:

T. Wu

Brief description:

Alkali Silica Reaction(ASR) is one of most determinant reasons leading to the deterioration of concrete structures, which can be ascribed to the expansion of gel produced by ASR in the microstructural level of concrete. The challenge in the modeling of ASR is due to the necessity to take into account the presence of heterogeneities and physical processes distributed over multiple length scales. With increasing computation power and the tomography scan technology, it can be implemented by numerical simulation . In this contribution, 3D multiscale hydro-chemo-thermal-mechanical coupling based on a staggered method is demonstrated, which explicitly describes the damage evolution originating from the chemical reaction in the microscale and the dependence on environmental factors.

 

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