A novel micro-mechanical model for prediction of multiaxial high cycle fatigue at small scales
A novel micro-mechanical model for prediction of multiaxial high cycle fatigue at small scales

Author: Eslami, Reza

Publisher: KIT Scientific Publishing

Published: 2017-05-03

Total Pages: 142

ISBN-13: 3731505835

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The grain microstructure and damage mechanisms at the grain level are the key factors that influence fatigue of metals at small scales. This is addressed in this work by establishing a new micro-mechanical model for prediction of multiaxial high cycle fatigue (HCF) at a length scale of 5-100?m. The HCF model considers elasto-plastic behavior of metals at the grain level and microstructural parameters, specifically the grain size and the grain orientation.

A Novel Micro-mechanical Model for Prediction of Multiaxial High Cycle Fatigue at Small Scales
A Novel Micro-mechanical Model for Prediction of Multiaxial High Cycle Fatigue at Small Scales

Author: Reza Eslami

Publisher:

Published: 2020-10-09

Total Pages: 130

ISBN-13: 9781013282836

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The grain microstructure and damage mechanisms at the grain level are the key factors that influence fatigue of metals at small scales. This is addressed in this work by establishing a new micro-mechanical model for prediction of multiaxial high cycle fatigue (HCF) at a length scale of 5-100?m. The HCF model considers elasto-plastic behavior of metals at the grain level and microstructural parameters, specifically the grain size and the grain orientation. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.

Phase-field Modeling of Phase Changes and Mechanical Stresses in Electrode Particles of Secondary Batteries
Phase-field Modeling of Phase Changes and Mechanical Stresses in Electrode Particles of Secondary Batteries

Author: Zhang, Tao

Publisher: KIT Scientific Publishing

Published: 2021-09-27

Total Pages: 224

ISBN-13: 3731510022

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Most storage materials exhibit phase changes, which cause stresses and, thus, lead to damage of the electrode particles. In this work, a phase-field model for the cathode material NaxFePO4 of Na-ion batteries is studied to understand phase changes and stress evolution. Furthermore, we study the particle size and SOC dependent miscibility gap of the nanoscale insertion materials. Finally, we introduce the nonlocal species concentration theory, and show how the nonlocality influences the results.

On the Electro-Chemo-Mechanical Coupling in Solid State Batteries and its Impact on Morphological Interface Stability
On the Electro-Chemo-Mechanical Coupling in Solid State Batteries and its Impact on Morphological Interface Stability

Author: Ganser, Markus

Publisher: KIT Scientific Publishing

Published: 2021-03-09

Total Pages: 272

ISBN-13: 3731510472

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Solid state batteries with a lithium metal electrode are considered the next generation of high energy battery technology. Unfortunately, lithium metal is prone to harmful protrusion or dendrite growth which causes dangerous cell failure. Within this work the problem of protrusion growth is tackled by deriving a novel electro-chemo-mechanical theory tailored for binary solid state batteries which is then used to discuss the impact of mechanics on interface stability by numerical studies.

Phase-field simulations of multi-component solidification and coarsening based on thermodynamic datasets
Phase-field simulations of multi-component solidification and coarsening based on thermodynamic datasets

Author: Schulz, Sebastian

Publisher: KIT Scientific Publishing

Published: 2017-02-22

Total Pages: 246

ISBN-13: 3731506181

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The utilization of thermodynamic and mobility data plays a major role in phase-field modeling. This work discusses different formulations for the thermodynamic quantities of a grand potential model along with practices to determine parameters from datasets. The framework is used to study solidification of Al-Si-Mg for a variation of composition, diffusivities and surface energy anisotropies. To verify the simulations, they are compared with solidification theories.

Structure evolution in tribological interfaces studied by multilayer model alloys
Structure evolution in tribological interfaces studied by multilayer model alloys

Author: Cihan, Ebru

Publisher: KIT Scientific Publishing

Published: 2020-10-21

Total Pages: 194

ISBN-13: 3731509997

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Recent studies of deformation mechanisms of metals and alloys pioneer the better investigation of the friction and wear behavior of materials with well-defined initial microstructures. Within this scope, in this work, the effect of sub-surface deformations on the resulting friction and wear behavior has been searched by means of a systematic experimental study on Au-Ni metallic multilayer model alloy system.

Dynamic Model-based Analysis of Oxygen Reduction Reaction in Gas Diffusion Electrodes
Dynamic Model-based Analysis of Oxygen Reduction Reaction in Gas Diffusion Electrodes

Author: Röhe, Maximilian

Publisher: KIT Scientific Publishing

Published: 2024-01-09

Total Pages: 178

ISBN-13: 3731512343

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In this work, the first simulation model of oxygen depolarized cathodes (ODC), which are silver catalyst-based gas diffusion electrodes, is presented that considers the phase equilibrium of the gas-liquid interface and structure-related inhomogeneities in electrolyte distribution. By means of the model it has been identified that mass transport of water and ions in the liquid phase is a crucial factor for electrode performance and how it is influenced by the electrode structure.

Modeling transport properties and electrochemical performance of hierarchically structured lithium-ion battery cathodes using resistor networks and mathematical half-cell models
Modeling transport properties and electrochemical performance of hierarchically structured lithium-ion battery cathodes using resistor networks and mathematical half-cell models

Author: Birkholz, Oleg

Publisher: KIT Scientific Publishing

Published: 2022-10-05

Total Pages: 246

ISBN-13: 373151172X

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Hierarchically structured active materials in electrodes of lithium-ion cells are promising candidates for increasing gravimetric energy density and improving rate capability of the system. To investigate the influence of cathode structures on the performance of the whole cell, efficient tools for calculating effective transport properties of granular systems are developed and their influence on the electrochemical performance is investigated in specially adapted cell models.

Microplasticity of idealized single crystalline Ag cantilevers characterized with methods of high resolution
Microplasticity of idealized single crystalline Ag cantilevers characterized with methods of high resolution

Author: Wobrock, Mark

Publisher: KIT Scientific Publishing

Published: 2017-11-22

Total Pages: 252

ISBN-13: 3731506823

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Single crystalline, μm-sized cantilevers are fabricated out of epitaxially grown Ag thin films by a lithography-based procedure and are deflected by a nanoindenter system. The microstructure of the plastically deformed cantile-vers is investigated using transmission Kikuchi diffraction (TKD) on the cantilever cross section. 3D discrete dislocation dynamics simulations (DDD) are performed for further analysis. A mechanism to explain the formation of dislocation networks upon loading is suggested.