Investigations on Joule heating applications by multiphysical continuum simulations in nanoscale systems
Investigations on Joule heating applications by multiphysical continuum simulations in nanoscale systems

Author: Feuchter, Manuel Klaus Ludwig

Publisher: KIT Scientific Publishing

Published: 2014-10-01

Total Pages: 258

ISBN-13: 3731502615

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This work furthers the overall understanding of a 3w-measurement, by considering previously unexamined macroscopic influence factors within measurement by Finite Element simulations (FES). Moreover, new measuring configurations are developed to determine (an)isotropic thermal conductivities of nanoscale samples. Since no analytic solutions are available for these configurations, a new evaluation methodology is presented to determine emergent thermal conductivities by FES and Neural Networks.

Investigations on Joule Heating Applications by Multiphysical Continuum Simulations in Nanoscale Systems
Investigations on Joule Heating Applications by Multiphysical Continuum Simulations in Nanoscale Systems

Author: Manuel Klaus Ludwig Feuchter

Publisher:

Published: 2020-10-09

Total Pages: 248

ISBN-13: 9781013280856

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This work furthers the overall understanding of a 3w-measurement, by considering previously unexamined macroscopic influence factors within measurement by Finite Element simulations (FES). Moreover, new measuring configurations are developed to determine (an)isotropic thermal conductivities of nanoscale samples. Since no analytic solutions are available for these configurations, a new evaluation methodology is presented to determine emergent thermal conductivities by FES and Neural Networks. 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.

Experimental Investigation of Crack Initiation in Face-Centered Cubic Materials in the High and Very High Cycle Fatigue Regime
Experimental Investigation of Crack Initiation in Face-Centered Cubic Materials in the High and Very High Cycle Fatigue Regime

Author: Straub, Thomas

Publisher: KIT Scientific Publishing

Published: 2016

Total Pages: 234

ISBN-13: 3731504715

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This book investigates the fatigue mechanisms and crack initiation of Ni, Al and Cu on a small-scale in the Very High Cycle Fatigue regime by means of innovative fatigue experimentation. A novel custom-built resonant fatigue setup showed that the sample resonant frequency changes with increasing cycle number due to fatigue damage. Mechanisms such as slip band formation have been observed. Cyclic hardening, vacancy and oxidation formation may be considered as early fatigue mechanisms.

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.

Characterisation and Modelling of Continuous-Discontinuous Sheet Moulding Compound Composites for Structural Applications
Characterisation and Modelling of Continuous-Discontinuous Sheet Moulding Compound Composites for Structural Applications

Author: Trauth, Anna

Publisher: KIT Scientific Publishing

Published: 2020-12-11

Total Pages: 468

ISBN-13: 3731509504

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The main objective of this work is to significantly deepen the understanding of the material and the structural behaviour of continuous-discontinuous SMC composites, following a holistic approach to investigate microscopic aspects, macroscopic mechanical behaviour as well as failure evolution at the coupon, structure and component level. In addition, criteria to evaluate the effect of hybridisation are introduced and modelling approaches are presented and discussed.

Grain growth behavior and efficient large scale simulations of recrystallization with the phase-field method
Grain growth behavior and efficient large scale simulations of recrystallization with the phase-field method

Author: Vondrous, Alexander

Publisher: KIT Scientific Publishing

Published: 2014-12-15

Total Pages: 162

ISBN-13: 3731502801

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This book summarizes the found insights of grain growth behavior, of multidimensional decomposition for regular grids to efficiently parallelize computing and how to simulate recrystallization by coupling the finite element method with the phase-field method for microstructure texture analysis. The frame of the book is created by the phase-field method, which is the tool used in this work, to investigate microstructure phenomena.

Phase-field modeling of microstructural pattern formation in alloys and geological veins
Phase-field modeling of microstructural pattern formation in alloys and geological veins

Author: Ankit, Kumar

Publisher: KIT Scientific Publishing

Published: 2016-05-31

Total Pages: 240

ISBN-13: 373150491X

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With the advent of high performance computing, the application areas of the phase-field method, traditionally used to numerically model the phase transformation in metals and alloys, have now spanned into geoscience. A systematic investigation of the two distinct scientific problems in consideration suggest a strong influence of interfacial energy on the natural and induced pattern formation in diffusion-controlled regime.

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.

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.

Characterization and Modeling of the Ratcheting Behavior of the Ferritic-Martensitic Steel P91
Characterization and Modeling of the Ratcheting Behavior of the Ferritic-Martensitic Steel P91

Author: Zhang, Kuo

Publisher: KIT Scientific Publishing

Published: 2017-07-12

Total Pages: 224

ISBN-13: 3731505037

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In this work, the ratcheting-behavior of 9%Cr-1%Mo ferritic-martensitic steel is studied with uniaxial cyclic loading. To describe the ratcheting-behavior of this steel, a visco-plastic constitutive model with consideration of cyclic softening of Reduced Activation Ferritic Martensitic steels is further modified, based on the analysis of back stress.